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Papers by Subba Ramaiah

ACS sustainable resource management, Apr 25, 2024

Due to the global depletion of natural resources, developing economically and environmentally sus... more Due to the global depletion of natural resources, developing economically and environmentally sustainable energy sources is critical. Biodiesel can substitute for diesel without significant modification of existing engines. Biodiesel production has accelerated in recent years, because of aggressive government policies and incentives to meet energy demand and environmental concerns. A surplus amount of glycerol (Gly) is generated during biodiesel production as a byproduct. Thus, developing viable routes for the valorization of Glyl is crucial for the sustainability of the biodiesel industry. Valorization of Gly-to-glycerol carbonate (Glc) is considered an attractive route due to its wide industrial applicability. This paper discusses the potential synthesis routes including glycerolysis of urea, direct carbonation of Gly with CO 2 , enzymatic transesterification of Gly, and catalytic transesterification of Gly with alkyl carbonate to produce Glc. This paper addresses the performance of various homogeneous and heterogeneous catalysts used in Glc synthesis. Among various synthesis routes, catalytic transesterification of Gly with dimethyl carbonate (DMC) is considered as green and environmentally friendly, operates under mild reaction conditions, and is an industrially feasible process with high selectivity and yield. In order to achieve high yield and selectivity of Glc, key influencing process parameters such as catalyst dose, molar ratio of DMC/Gly, reaction temperature, reaction time, and basic sites of the catalyst are discussed. Repurposing of surplus glycerol for Glc production enhances biodiesel economics. Finally, this paper suggests future prospects for various pathways for the sustainable production of Glc.

The Canadian Journal of Chemical Engineering, 2021

A rice husk-derived MCM-41 catalyst has been synthesized, and active metal Co 3 O 4 nanoparticles... more A rice husk-derived MCM-41 catalyst has been synthesized, and active metal Co 3 O 4 nanoparticles were incorporated. The synthesized MCM-41 derived from rice husk exhibited highly ordered p6mm hexagonal symmetry. The catalytic activity of the prepared catalyst was investigated for glycerol carbonate (GLc) synthesis through transesterification of glycerol (GLy) with dimethyl carbonate (DMC). Experimentally, it was found that 5 wt.% cobalt incorporated MCM-41 activated at 400 C showed a higher yield of GLc, 60.2%, due to its optimum basicity. Approximately, 98.7 ± 1.2% GLy conversion and 94.1 ± 0.7% GLc yield was achieved with the batch reactor at adjusted conditions: a molar ratio of DMC-to-glycerol = 3, catalyst dosage = 6 wt.% (based on glycerol mass), reaction temperature = 90 C, and reaction time = 2 h. The transesterification reaction kinetics were also studied using the ODE 15s tool in MATLAB. The catalyst's activation energy was calculated as 58.2 ± 2.4 kJ/mol.

Can J Chem Eng. 2021;1–16, 2021

A rice husk-derived MCM-41 catalyst has been synthesized, and active metal Co 3 O 4 nanoparticles... more A rice husk-derived MCM-41 catalyst has been synthesized, and active metal Co 3 O 4 nanoparticles were incorporated. The synthesized MCM-41 derived from rice husk exhibited highly ordered p6mm hexagonal symmetry. The catalytic activity of the prepared catalyst was investigated for glycerol carbonate (GLc) synthesis through transesterification of glycerol (GLy) with dimethyl carbonate (DMC). Experimentally, it was found that 5 wt.% cobalt incorporated MCM-41 activated at 400 C showed a higher yield of GLc, 60.2%, due to its optimum basicity. Approximately, 98.7 ± 1.2% GLy conversion and 94.1 ± 0.7% GLc yield was achieved with the batch reactor at adjusted conditions: a molar ratio of DMC-to-glycerol = 3, catalyst dosage = 6 wt.% (based on glycerol mass), reaction temperature = 90 C, and reaction time = 2 h. The transesterification reaction kinetics were also studied using the ODE 15s tool in MATLAB. The catalyst's activation energy was calculated as 58.2 ± 2.4 kJ/mol.

Chemical Engineering Journal 488 (2024) 150938, 2024

Glycerol monolaurate (GML) is a versatile green chemical with wide industrial applicability, incl... more Glycerol monolaurate (GML) is a versatile green chemical with wide industrial applicability, including in the food, pharmaceutical, and personal care product industries. This review provides a thorough analysis of the processes involved in GML production, along with the diverse applications of GML. And also, addresses various limitations and challenges associated with esterification of lauric acid with glycerol to produce GML through enzymatic, homogeneous, and heterogeneous catalytic pathways. Among these routes, heterogeneous catalytic routes exhibited superior catalytic activity, achieving over 90% selectivity with good stability. Furthermore, the review offers a constructive assessment of the process parameters associated with catalysts and reaction conditions that influence the GML yield and selectivity. Notably, wide pore and short pore length were found to be suitable for attaining higher selectivity in esterification of lauric acid. Techno-economic assessments suggest that the enzyme route is more environmentally sustainable. However, in practice, the heterogeneous catalytic route proves more suitable for industrial-scale production. Therefore, this review may provide crucial guidance for researchers and industries aiming to produce GML in an economic and eco-friendly manner.

ACS Sustainable Resource Management, 2024

Due to the global depletion of natural resources, developing economically and environmentally sus... more Due to the global depletion of natural resources, developing economically and environmentally sustainable energy sources is critical. Biodiesel can substitute for diesel without significant modification of existing engines. Biodiesel production has accelerated in recent years, because of aggressive government policies and incentives to meet energy demand and environmental concerns. A surplus amount of glycerol (Gly) is generated during biodiesel production as a byproduct. Thus, developing viable routes for the valorization of Glyl is crucial for the sustainability of the biodiesel industry. Valorization of Gly-to-glycerol carbonate (Glc) is considered an attractive route due to its wide industrial applicability. This paper discusses the potential synthesis routes including glycerolysis of urea, direct carbonation of Gly with CO 2 , enzymatic transesterification of Gly, and catalytic transesterification of Gly with alkyl carbonate to produce Glc. This paper addresses the performance of various homogeneous and heterogeneous catalysts used in Glc synthesis. Among various synthesis routes, catalytic transesterification of Gly with dimethyl carbonate (DMC) is considered as green and environmentally friendly, operates under mild reaction conditions, and is an industrially feasible process with high selectivity and yield. In order to achieve high yield and selectivity of Glc, key influencing process parameters such as catalyst dose, molar ratio of DMC/Gly, reaction temperature, reaction time, and basic sites of the catalyst are discussed. Repurposing of surplus glycerol for Glc production enhances biodiesel economics. Finally, this paper suggests future prospects for various pathways for the sustainable production of Glc.

Separation and Purification Technology, 2014

Abstract In the present study, catalytic wet peroxidation (CWPO) process has been applied for the... more Abstract In the present study, catalytic wet peroxidation (CWPO) process has been applied for the degradation of nitrobenzene bearing wastewater using copper impregnated granular activated carbon with hydrogen peroxide as oxidant. Various catalysts were prepared by varying the Cu loading on activated carbon and these were characterized by N2 adsorption–desorption, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FE-SEM), thermogravimetric analysis (TGA), temperature programmed reduction (TPR) and UV–visible diffuse reflectance spectra (UV-DRS). Effect of parameters such as copper loading, pH, catalyst dose, hydrogen peroxide dose and temperature were explored on nitrobenzene and total organic carbon (TOC) removal. TOC removal of 89% was achieved after 4 h treatment at optimum condition of Cu loading = 2.5 wt%, pH ≈ 3.0, catalyst dosage = 0.25 g/l, oxidant dosage = 4.5 (moles of oxidant/moles of NB) and temperature = 55 °C.

Environmental Quality Management

The primary objective of this work was to investigate the simultaneous removal of refractory sulf... more The primary objective of this work was to investigate the simultaneous removal of refractory sulfur (dibenzothiophene, DBT) and nitrogen compounds (indole, IND) from model gasoline. This research aimed to develop an efficient adsorption process to mitigate the emission of sulfur oxide and nitrogen oxides, which pose direct threats to human health and the environment. Additionally, the study focused on addressing technical challenges encountered in the refinery process, particularly the poisoning of catalysts due to the presence of these compounds. To achieve the study's goals, granular activated carbon (GAC) was subjected to acid treatment for modification. Molybdenum species were then incorporated into the acid‐treated GAC using the wet impregnation technique. The composition and distribution of elements on the surface of the modified GAC (Mo‐AAC) were analyzed via X‐ray photoelectron spectroscopy (XPS). Various characterization techniques were employed to confirm the uniform d...

Journal of Chemical & Engineering Data

The present study investigated the viability of deep eutectic solvents (DESs) to extract dibenzot... more The present study investigated the viability of deep eutectic solvents (DESs) to extract dibenzothiophene (DBT) from model gasoline (iso-octane). Tetrabutylammonium bromide (TBAB)-based DES showed significant DBT extraction capability from the model fuel oil. Furthermore, the sigma profile confirmed that all TBAB-based DES had a significant capacity for DBT extraction from the model oil. The affinity order for the TBABbased DES is as follows: TBAB/TEG (tri-ethylene glycol) > TBAB/PA (propionic acid) > TBAB/EG (ethylene glycol). To achieve maximum DBT extraction, the influencing parameters were adjusted, and 89% DBT extraction was achieved using the optimum conditions of oil to DES volume ratio of 1:1, with a DBT concentration of 500 ppm, residence time of 30 min, an extraction temperature of 303 K, and extraction stirring speed of 200 rpm.

Journal of Chemical & Engineering Data, 2018

The present study explores the usage of acetic-acid-treated cobalt-modified activated carbon as a... more The present study explores the usage of acetic-acid-treated cobalt-modified activated carbon as an adsorbent material for the adsorptive desulfurization of DBT-containing model oil. Modification of granular activated carbon (GAC) with acetic acid treatment and incorporation of cobalt species in GAC framework significantly improved its adsorption capacity by improving oxygen-containing functional groups and acidic sites. The surface area of GAC improved from 257 to 393.8 m 2 /g when it was treated with cobalt species and acid. The average size of the Co 3 O 4 crystallites in the Co-loaded activated carbon was found to be 13.8 nm. The effect of various operating parameters such as cobalt loading, adsorbent dose, temperature, and time was studied. Furthermore, the reusability of spent adsorbent and the effect of the presence of other aromatics compounds were also investigated. Under optimized operating conditions, ∼92% of DBT removal was achieved. The equilibrium data of DBT adsorption were analyzed by Langmuir, Freundlich, Temkin, and Redlich and Peterson (R−P) isotherm models by using nonlinear regression analysis. Among these, the Redlich−Peterson model is the best fit to represent the experimental data. The adsorption of DBT was found to be endothermic in nature. Values of changes in entropy and heat of adsorption were estimated to be 0.177 kJ/(mol K) and 35.67 kJ/mol, respectively. Moreover, a possible adsorption mechanism of DBT was also proposed. Finally, it can be concluded that cobalt-incorporated acetic-acid-activated GAC proves to be a potential adsorbent for the removal DBT from fuel oil in an economic and ecofriendly way.

Environmental Science and Pollution Research

In this study, copper-loaded activated alumina (Cu/AA) was synthesized and used for the CWPO of c... more In this study, copper-loaded activated alumina (Cu/AA) was synthesized and used for the CWPO of catechol (a representative refractory organic pollutant). Various characterization techniques were deployed to characterize the catalysts, e.g., activated alumina (AA), as well as pristine and spent 1% Cu/AA. The innovative 1% Cu/AA catalyst exhibited good thermal stability up to 1173 K with a marginal weight loss of 13%. The Cu species were well dispersed on the activated alumina framework with no significant cluster formation. Typically, the average copper particle size of 5 nm was dispersed on the AA framework. Catechol removal was observed to be 92% with 87% mineralization at optimized conditions (initial catechol concentration = 200 mg/L, catalyst dose of 1% Cu/AA = 2 g/L; temperature = 323 K; pH = 6; and H 2 O 2 /catechol stoichiometric ratio = 0.5). The mineralization of catechol was analyzed using mass spectroscopy, with the associated mechanism has been elucidated. Results of this study indicated that synthesized catalyst has phenomenal advantages in terms of simple separation and high removal efficiency of catechol, suggesting the feasibility of employing Cu/AA as the effective catalyst for the CWPO of catechol.

J. Chem. Eng. Data

The present study explores the usage of acetic-acid-treated cobalt-modified activated carbon as a... more The present study explores the usage of acetic-acid-treated cobalt-modified activated carbon as an adsorbent material for the adsorptive desulfurization of DBT-containing model oil. Modification of granular activated carbon (GAC) with acetic acid treatment and incorporation of cobalt species in GAC framework significantly improved its adsorption capacity by improving oxygen-containing functional groups and acidic sites. The surface area of GAC improved from 257 to 393.8 m 2 /g when it was treated with cobalt species and acid. The average size of the Co 3 O 4 crystallites in the Co-loaded activated carbon was found to be 13.8 nm. The effect of various operating parameters such as cobalt loading, adsorbent dose, temperature, and time was studied. Furthermore, the reusability of spent adsorbent and the effect of the presence of other aromatics compounds were also investigated. Under optimized operating conditions, ∼92% of DBT removal was achieved. The equilibrium data of DBT adsorption were analyzed by Langmuir, Freundlich, Temkin, and Redlich and Peterson (R−P) isotherm models by using nonlinear regression analysis. Among these, the Redlich−Peterson model is the best fit to represent the experimental data. The adsorption of DBT was found to be endothermic in nature. Values of changes in entropy and heat of adsorption were estimated to be 0.177 kJ/(mol K) and 35.67 kJ/mol, respectively. Moreover, a possible adsorption mechanism of DBT was also proposed. Finally, it can be concluded that cobalt-incorporated acetic-acid-activated GAC proves to be a potential adsorbent for the removal DBT from fuel oil in an economic and ecofriendly way.

Environmental Science and Pollution Research

In this study, copper-loaded activated alumina (Cu/AA) was synthesized and used for the CWPO of c... more In this study, copper-loaded activated alumina (Cu/AA) was synthesized and used for the CWPO of catechol (a representative refractory organic pollutant). Various characterization techniques were deployed to characterize the catalysts, e.g., activated alumina (AA), as well as pristine and spent 1% Cu/AA. The innovative 1% Cu/AA catalyst exhibited good thermal stability up to 1173 K with a marginal weight loss of 13%. The Cu species were well dispersed on the activated alumina framework with no significant cluster formation. Typically, the average copper particle size of 5 nm was dispersed on the AA framework. Catechol removal was observed to be 92% with 87% mineralization at optimized conditions (initial catechol concentration = 200 mg/L, catalyst dose of 1% Cu/AA = 2 g/L; temperature = 323 K; pH = 6; and H 2 O 2 /catechol stoichiometric ratio = 0.5). The mineralization of catechol was analyzed using mass spectroscopy, with the associated mechanism has been elucidated. Results of this study indicated that synthesized catalyst has phenomenal advantages in terms of simple separation and high removal efficiency of catechol, suggesting the feasibility of employing Cu/AA as the effective catalyst for the CWPO of catechol.

Reaction Kinetics, Mechanisms and Catalysis, 2021

The present manuscript investigated the facile route for the synthesis of heterogeneous catalyst ... more The present manuscript investigated the facile route for the synthesis of heterogeneous catalyst from marble waste (MW) for transesterification of glycerol to glycerol carbonate. The catalytic properties of MW derived catalyst were enhanced with active metal (Cerium) incorporation. The developed catalyst was characterized by different methods. The Brunauer-Emmet-Teller (BET) surface area was found to be 10.90 m 2 /g for CaO/MgO derived from MW and 5.80 m 2 /g for cerium loaded CaO/ MgO (Ce-CaO/MgO) catalyst. In X-ray photoelectron spectroscopy, the coexistence of Ce 3+ and Ce 4+ species was found, which creates more oxygen vacancies (active sites) and improves catalytic activity and stability of the catalyst. Results revealed that a dosage of 5 wt% of Ce-CaO/MgO catalyst, calcined at 850 °C imparted a maximum yield of glycerol carbonate (91.74 ± 2.37%). The reusability study of the catalyst was also examined, and the novel catalyst would maintain its activity up to four cycles. The activation energy was found to be 39.046 ± 3.18 kJ/mol, and the rate of glycerol depletion was estimated as 2.08 × 10-02 ± 0.006 min −1 at 85 °C. The novel Ce-CaO/MgO catalyst may have the potential for industry-scale transesterification of glycerol into glycerol carbonate.

J. Chem. Eng. Data

The present study investigated the viability of deep eutectic solvents (DESs) to extract dibenzot... more The present study investigated the viability of deep eutectic solvents (DESs) to extract dibenzothiophene (DBT) from model gasoline (iso-octane). Tetrabutylammonium bromide (TBAB)-based DES showed significant DBT extraction capability from the model fuel oil. Furthermore, the sigma profile confirmed that all TBAB-based DES had a significant capacity for DBT extraction from the model oil. The affinity order for the TBABbased DES is as follows: TBAB/TEG (tri-ethylene glycol) > TBAB/PA (propionic acid) > TBAB/EG (ethylene glycol). To achieve maximum DBT extraction, the influencing parameters were adjusted, and 89% DBT extraction was achieved using the optimum conditions of oil to DES volume ratio of 1:1, with a DBT concentration of 500 ppm, residence time of 30 min, an extraction temperature of 303 K, and extraction stirring speed of 200 rpm.

Can. J. Chem. Eng

A rice husk-derived MCM-41 catalyst has been synthesized, and active metal Co 3 O 4 nanoparticles... more A rice husk-derived MCM-41 catalyst has been synthesized, and active metal Co 3 O 4 nanoparticles were incorporated. The synthesized MCM-41 derived from rice husk exhibited highly ordered p6mm hexagonal symmetry. The catalytic activity of the prepared catalyst was investigated for glycerol carbonate (GLc) synthesis through transesterification of glycerol (GLy) with dimethyl carbonate (DMC). Experimentally, it was found that 5 wt.% cobalt incorporated MCM-41 activated at 400 C showed a higher yield of GLc, 60.2%, due to its optimum basicity. Approximately, 98.7 ± 1.2% GLy conversion and 94.1 ± 0.7% GLc yield was achieved with the batch reactor at adjusted conditions: a molar ratio of DMC-to-glycerol = 3, catalyst dosage = 6 wt.% (based on glycerol mass), reaction temperature = 90 C, and reaction time = 2 h. The transesterification reaction kinetics were also studied using the ODE 15s tool in MATLAB. The catalyst's activation energy was calculated as 58.2 ± 2.4 kJ/mol.

Rev Chem Eng

Environmental concerns have given a great deal of attention for the production of ultra-low-sulfu... more Environmental concerns have given a great deal of attention for the production of ultra-low-sulfur fuels. The conventional hydrodesulfurization (HDS) process has high operating cost and also encounters difficulty in removing sulfur compound with steric hindrance. Consequently, various research efforts have been made to overcome the limitation of conventional HDS process and exploring the alternative technologies for deep desulfurization. The alternative processes being explored for the production of ultra-low-sulfur content fuel are adsorptive desulfurization (ADS), biodesulfurization (BDS), oxidative desulfurization (ODS), and extractive desulfurization (EDS). The present article provided the comprehensive information on the basic principle, reaction mechanism, workability, advantages, and disadvantages of conventional and alternative technologies. This review article aims to provide valuable insight into the recent advances made in conventional HDS process and alternative techniques. For deep desulfurization of liquid fuels, integration of conventional HDS with an alternative technique is also proposed.

International Journal of Chemical Reactor Engineering

The profitability margin of biodiesel production hampering due to surplus amount of glycerol with... more The profitability margin of biodiesel production hampering due to surplus amount of glycerol with the low market price. Thus, developing an alternative route highly demanded for the conversion of glycerol into valueadded chemicals. In the present manuscript, green synthesis route was explored by utilizing rice husk derived catalyst. The catalytic properties of the prepared catalyst were investigated by using various characterization techniques. The basic strength of the catalyst was influenced by varying the calcination temperature (200 °C to 500 °C) as well as active metal (cerium) loading (5 wt. % to 20 wt. %). The present investigation revealed that 10 wt. % Ce on Na 2 SiO 3 catalyst calcined at 400 °C exhibited the moderate basic sites of 13.89 mmol/g, which showed potential catalytic activity for the transesterification of glycerol to glycerol carbonate under optimum condition: 92 % glycerol carbonate yield and 98 % glycerol conversion. The catalyst stability study revealed that the catalyst could be reused up to four consecutive cycles without an appreciable drop in catalytic activity. The kinetics of the reaction was also studied, and the activation energy was calculated as 23.80 kJ/mol.

Journal of Environmental Chemical Engineering

Coal fly ash (CFA) has been employed as a catalytic support for lithium ions by impregnation. The... more Coal fly ash (CFA) has been employed as a catalytic support for lithium ions by impregnation. The basicity, basic strength, and stability of the resultant catalyst were further tuned by varying active species concentration (1 wt %-7 wt%) and calcination temperature (300-600 • C). The relationship between the basic properties of catalyst and their catalytic activity towards the conversion of glycerol (GL) was determined experimentally. It was found that 2 wt% lithium loaded CFA, calcined at 500 • C exhibited a maximum yield of glycerol carbonate (GC). The maximum catalytic activity was achieved at 90 • C with a reaction time of 2 h, 96.33% GL conversion, and 91.74% GC yield. Furthermore, ODE 15 s solver was used to evaluate reaction kinetics of the transesterification reaction. The activation energy was calculated and as 26.50 kJ/mol. The proposed work has the potential to uplift the economy of biodiesel industry.

Journal of Environmental Chemical Engineering

Current study presents the synthesis of mesoporous silica material (MCM-41) derived from coal fly... more Current study presents the synthesis of mesoporous silica material (MCM-41) derived from coal fly ash as a catalyst support material for the catalytic oxidative desulfurization (ODS) of liquid fuels. In this work, molybdenum active species were incorporated into the mesoporous silica (Mo/MCM-41) by the incipient wetimpregnation process. The obtained Mo/MCM-41 was characterized by FESEM, HRTEM, XRD, and FT-IR to confirm its structure and functional groups present on the catalyst. Characterization study revealed that mesoporous silica was successfully synthesized from coal fly ash. Desulfurization of dibenzothiophene (DBT) containing model fuel was investigated by using synthesized catalyst, approximately 94% of DBT removal was achieved by optimizing the influencing parameters of ODS process. The ODS results proved that Mo/MCM-41 could be the potential catalyst for reduction of DBT from liquid fuels. Oxidative reaction of DBT follows the pseudo first order reaction kinetic. DBT oxidation mechanism was proposed.

Journal of Cleaner Production, 2022

The present study explored the catalytic activity of the heterogeneous catalyst for transesterifi... more The present study explored the catalytic activity of the heterogeneous catalyst for transesterification of glycerol into glycerol carbonate, a versatile compound. Transesterification of glycerol was investigated with different active metals (Li, La, Ce, Mg, K) impregnated on MCM-41 (Mobil Composition of Matter No. 41) framework. Among these, lithium incorporated MCM-41 proved the better catalytic activity towards the formation of glycerol carbonate. The shortening of a long-range hexagonal array was observed with active metal incorporation due to the accumulation of non-framework Li species in the MCM-41 structure. BET study revealed that Li/MCM-41 possess type IV hysteresis loop according to IUPAC standards. The average pore diameter was increased from 25.43 Å to 62.02 Å with active metal incorporation in the MCM-41 framework. The catalytic activity of Li/MCM-41 was observed by varying different weight ratios of active metal and the calcination temperature. The results demonstrated that 5 wt% Li impregnated on MCM-41, calcined at 450 C, appeared to have a maximum yield of glycerol carbonate. Additionally, the influence of reaction operating parameters was also investigated. The results showed that 99 ± 1.89% glycerol conversion and 93.14 ± 2.52% glycerol carbonate yield was achieved at dimethyl carbonate-to-glycerol molar ratio of 3, catalyst dosage of 4 wt% (relative to glycerol mass) and a reaction temperature of 90 C in 3 h. The recyclability and stability of the screened catalyst was also studied under optimized conditions. The activation energy of the catalyst was determined by solving the differential equation using MATLAB ODE15s tool, and the obtained value was 53.77 ± 3.26 kJ/mol. The E-factor and PMI (Process mass intensity) values of glycerol carbonate synthesis were determined as 1.16 and 2.16, respectively, which demonstrate the less waste generation during the process.

ACS sustainable resource management, Apr 25, 2024

Due to the global depletion of natural resources, developing economically and environmentally sus... more Due to the global depletion of natural resources, developing economically and environmentally sustainable energy sources is critical. Biodiesel can substitute for diesel without significant modification of existing engines. Biodiesel production has accelerated in recent years, because of aggressive government policies and incentives to meet energy demand and environmental concerns. A surplus amount of glycerol (Gly) is generated during biodiesel production as a byproduct. Thus, developing viable routes for the valorization of Glyl is crucial for the sustainability of the biodiesel industry. Valorization of Gly-to-glycerol carbonate (Glc) is considered an attractive route due to its wide industrial applicability. This paper discusses the potential synthesis routes including glycerolysis of urea, direct carbonation of Gly with CO 2 , enzymatic transesterification of Gly, and catalytic transesterification of Gly with alkyl carbonate to produce Glc. This paper addresses the performance of various homogeneous and heterogeneous catalysts used in Glc synthesis. Among various synthesis routes, catalytic transesterification of Gly with dimethyl carbonate (DMC) is considered as green and environmentally friendly, operates under mild reaction conditions, and is an industrially feasible process with high selectivity and yield. In order to achieve high yield and selectivity of Glc, key influencing process parameters such as catalyst dose, molar ratio of DMC/Gly, reaction temperature, reaction time, and basic sites of the catalyst are discussed. Repurposing of surplus glycerol for Glc production enhances biodiesel economics. Finally, this paper suggests future prospects for various pathways for the sustainable production of Glc.

The Canadian Journal of Chemical Engineering, 2021

A rice husk-derived MCM-41 catalyst has been synthesized, and active metal Co 3 O 4 nanoparticles... more A rice husk-derived MCM-41 catalyst has been synthesized, and active metal Co 3 O 4 nanoparticles were incorporated. The synthesized MCM-41 derived from rice husk exhibited highly ordered p6mm hexagonal symmetry. The catalytic activity of the prepared catalyst was investigated for glycerol carbonate (GLc) synthesis through transesterification of glycerol (GLy) with dimethyl carbonate (DMC). Experimentally, it was found that 5 wt.% cobalt incorporated MCM-41 activated at 400 C showed a higher yield of GLc, 60.2%, due to its optimum basicity. Approximately, 98.7 ± 1.2% GLy conversion and 94.1 ± 0.7% GLc yield was achieved with the batch reactor at adjusted conditions: a molar ratio of DMC-to-glycerol = 3, catalyst dosage = 6 wt.% (based on glycerol mass), reaction temperature = 90 C, and reaction time = 2 h. The transesterification reaction kinetics were also studied using the ODE 15s tool in MATLAB. The catalyst's activation energy was calculated as 58.2 ± 2.4 kJ/mol.

Can J Chem Eng. 2021;1–16, 2021

A rice husk-derived MCM-41 catalyst has been synthesized, and active metal Co 3 O 4 nanoparticles... more A rice husk-derived MCM-41 catalyst has been synthesized, and active metal Co 3 O 4 nanoparticles were incorporated. The synthesized MCM-41 derived from rice husk exhibited highly ordered p6mm hexagonal symmetry. The catalytic activity of the prepared catalyst was investigated for glycerol carbonate (GLc) synthesis through transesterification of glycerol (GLy) with dimethyl carbonate (DMC). Experimentally, it was found that 5 wt.% cobalt incorporated MCM-41 activated at 400 C showed a higher yield of GLc, 60.2%, due to its optimum basicity. Approximately, 98.7 ± 1.2% GLy conversion and 94.1 ± 0.7% GLc yield was achieved with the batch reactor at adjusted conditions: a molar ratio of DMC-to-glycerol = 3, catalyst dosage = 6 wt.% (based on glycerol mass), reaction temperature = 90 C, and reaction time = 2 h. The transesterification reaction kinetics were also studied using the ODE 15s tool in MATLAB. The catalyst's activation energy was calculated as 58.2 ± 2.4 kJ/mol.

Chemical Engineering Journal 488 (2024) 150938, 2024

Glycerol monolaurate (GML) is a versatile green chemical with wide industrial applicability, incl... more Glycerol monolaurate (GML) is a versatile green chemical with wide industrial applicability, including in the food, pharmaceutical, and personal care product industries. This review provides a thorough analysis of the processes involved in GML production, along with the diverse applications of GML. And also, addresses various limitations and challenges associated with esterification of lauric acid with glycerol to produce GML through enzymatic, homogeneous, and heterogeneous catalytic pathways. Among these routes, heterogeneous catalytic routes exhibited superior catalytic activity, achieving over 90% selectivity with good stability. Furthermore, the review offers a constructive assessment of the process parameters associated with catalysts and reaction conditions that influence the GML yield and selectivity. Notably, wide pore and short pore length were found to be suitable for attaining higher selectivity in esterification of lauric acid. Techno-economic assessments suggest that the enzyme route is more environmentally sustainable. However, in practice, the heterogeneous catalytic route proves more suitable for industrial-scale production. Therefore, this review may provide crucial guidance for researchers and industries aiming to produce GML in an economic and eco-friendly manner.

ACS Sustainable Resource Management, 2024

Due to the global depletion of natural resources, developing economically and environmentally sus... more Due to the global depletion of natural resources, developing economically and environmentally sustainable energy sources is critical. Biodiesel can substitute for diesel without significant modification of existing engines. Biodiesel production has accelerated in recent years, because of aggressive government policies and incentives to meet energy demand and environmental concerns. A surplus amount of glycerol (Gly) is generated during biodiesel production as a byproduct. Thus, developing viable routes for the valorization of Glyl is crucial for the sustainability of the biodiesel industry. Valorization of Gly-to-glycerol carbonate (Glc) is considered an attractive route due to its wide industrial applicability. This paper discusses the potential synthesis routes including glycerolysis of urea, direct carbonation of Gly with CO 2 , enzymatic transesterification of Gly, and catalytic transesterification of Gly with alkyl carbonate to produce Glc. This paper addresses the performance of various homogeneous and heterogeneous catalysts used in Glc synthesis. Among various synthesis routes, catalytic transesterification of Gly with dimethyl carbonate (DMC) is considered as green and environmentally friendly, operates under mild reaction conditions, and is an industrially feasible process with high selectivity and yield. In order to achieve high yield and selectivity of Glc, key influencing process parameters such as catalyst dose, molar ratio of DMC/Gly, reaction temperature, reaction time, and basic sites of the catalyst are discussed. Repurposing of surplus glycerol for Glc production enhances biodiesel economics. Finally, this paper suggests future prospects for various pathways for the sustainable production of Glc.

Separation and Purification Technology, 2014

Abstract In the present study, catalytic wet peroxidation (CWPO) process has been applied for the... more Abstract In the present study, catalytic wet peroxidation (CWPO) process has been applied for the degradation of nitrobenzene bearing wastewater using copper impregnated granular activated carbon with hydrogen peroxide as oxidant. Various catalysts were prepared by varying the Cu loading on activated carbon and these were characterized by N2 adsorption–desorption, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FE-SEM), thermogravimetric analysis (TGA), temperature programmed reduction (TPR) and UV–visible diffuse reflectance spectra (UV-DRS). Effect of parameters such as copper loading, pH, catalyst dose, hydrogen peroxide dose and temperature were explored on nitrobenzene and total organic carbon (TOC) removal. TOC removal of 89% was achieved after 4 h treatment at optimum condition of Cu loading = 2.5 wt%, pH ≈ 3.0, catalyst dosage = 0.25 g/l, oxidant dosage = 4.5 (moles of oxidant/moles of NB) and temperature = 55 °C.

Environmental Quality Management

The primary objective of this work was to investigate the simultaneous removal of refractory sulf... more The primary objective of this work was to investigate the simultaneous removal of refractory sulfur (dibenzothiophene, DBT) and nitrogen compounds (indole, IND) from model gasoline. This research aimed to develop an efficient adsorption process to mitigate the emission of sulfur oxide and nitrogen oxides, which pose direct threats to human health and the environment. Additionally, the study focused on addressing technical challenges encountered in the refinery process, particularly the poisoning of catalysts due to the presence of these compounds. To achieve the study's goals, granular activated carbon (GAC) was subjected to acid treatment for modification. Molybdenum species were then incorporated into the acid‐treated GAC using the wet impregnation technique. The composition and distribution of elements on the surface of the modified GAC (Mo‐AAC) were analyzed via X‐ray photoelectron spectroscopy (XPS). Various characterization techniques were employed to confirm the uniform d...

Journal of Chemical & Engineering Data

The present study investigated the viability of deep eutectic solvents (DESs) to extract dibenzot... more The present study investigated the viability of deep eutectic solvents (DESs) to extract dibenzothiophene (DBT) from model gasoline (iso-octane). Tetrabutylammonium bromide (TBAB)-based DES showed significant DBT extraction capability from the model fuel oil. Furthermore, the sigma profile confirmed that all TBAB-based DES had a significant capacity for DBT extraction from the model oil. The affinity order for the TBABbased DES is as follows: TBAB/TEG (tri-ethylene glycol) > TBAB/PA (propionic acid) > TBAB/EG (ethylene glycol). To achieve maximum DBT extraction, the influencing parameters were adjusted, and 89% DBT extraction was achieved using the optimum conditions of oil to DES volume ratio of 1:1, with a DBT concentration of 500 ppm, residence time of 30 min, an extraction temperature of 303 K, and extraction stirring speed of 200 rpm.

Journal of Chemical & Engineering Data, 2018

The present study explores the usage of acetic-acid-treated cobalt-modified activated carbon as a... more The present study explores the usage of acetic-acid-treated cobalt-modified activated carbon as an adsorbent material for the adsorptive desulfurization of DBT-containing model oil. Modification of granular activated carbon (GAC) with acetic acid treatment and incorporation of cobalt species in GAC framework significantly improved its adsorption capacity by improving oxygen-containing functional groups and acidic sites. The surface area of GAC improved from 257 to 393.8 m 2 /g when it was treated with cobalt species and acid. The average size of the Co 3 O 4 crystallites in the Co-loaded activated carbon was found to be 13.8 nm. The effect of various operating parameters such as cobalt loading, adsorbent dose, temperature, and time was studied. Furthermore, the reusability of spent adsorbent and the effect of the presence of other aromatics compounds were also investigated. Under optimized operating conditions, ∼92% of DBT removal was achieved. The equilibrium data of DBT adsorption were analyzed by Langmuir, Freundlich, Temkin, and Redlich and Peterson (R−P) isotherm models by using nonlinear regression analysis. Among these, the Redlich−Peterson model is the best fit to represent the experimental data. The adsorption of DBT was found to be endothermic in nature. Values of changes in entropy and heat of adsorption were estimated to be 0.177 kJ/(mol K) and 35.67 kJ/mol, respectively. Moreover, a possible adsorption mechanism of DBT was also proposed. Finally, it can be concluded that cobalt-incorporated acetic-acid-activated GAC proves to be a potential adsorbent for the removal DBT from fuel oil in an economic and ecofriendly way.

Environmental Science and Pollution Research

In this study, copper-loaded activated alumina (Cu/AA) was synthesized and used for the CWPO of c... more In this study, copper-loaded activated alumina (Cu/AA) was synthesized and used for the CWPO of catechol (a representative refractory organic pollutant). Various characterization techniques were deployed to characterize the catalysts, e.g., activated alumina (AA), as well as pristine and spent 1% Cu/AA. The innovative 1% Cu/AA catalyst exhibited good thermal stability up to 1173 K with a marginal weight loss of 13%. The Cu species were well dispersed on the activated alumina framework with no significant cluster formation. Typically, the average copper particle size of 5 nm was dispersed on the AA framework. Catechol removal was observed to be 92% with 87% mineralization at optimized conditions (initial catechol concentration = 200 mg/L, catalyst dose of 1% Cu/AA = 2 g/L; temperature = 323 K; pH = 6; and H 2 O 2 /catechol stoichiometric ratio = 0.5). The mineralization of catechol was analyzed using mass spectroscopy, with the associated mechanism has been elucidated. Results of this study indicated that synthesized catalyst has phenomenal advantages in terms of simple separation and high removal efficiency of catechol, suggesting the feasibility of employing Cu/AA as the effective catalyst for the CWPO of catechol.

J. Chem. Eng. Data

The present study explores the usage of acetic-acid-treated cobalt-modified activated carbon as a... more The present study explores the usage of acetic-acid-treated cobalt-modified activated carbon as an adsorbent material for the adsorptive desulfurization of DBT-containing model oil. Modification of granular activated carbon (GAC) with acetic acid treatment and incorporation of cobalt species in GAC framework significantly improved its adsorption capacity by improving oxygen-containing functional groups and acidic sites. The surface area of GAC improved from 257 to 393.8 m 2 /g when it was treated with cobalt species and acid. The average size of the Co 3 O 4 crystallites in the Co-loaded activated carbon was found to be 13.8 nm. The effect of various operating parameters such as cobalt loading, adsorbent dose, temperature, and time was studied. Furthermore, the reusability of spent adsorbent and the effect of the presence of other aromatics compounds were also investigated. Under optimized operating conditions, ∼92% of DBT removal was achieved. The equilibrium data of DBT adsorption were analyzed by Langmuir, Freundlich, Temkin, and Redlich and Peterson (R−P) isotherm models by using nonlinear regression analysis. Among these, the Redlich−Peterson model is the best fit to represent the experimental data. The adsorption of DBT was found to be endothermic in nature. Values of changes in entropy and heat of adsorption were estimated to be 0.177 kJ/(mol K) and 35.67 kJ/mol, respectively. Moreover, a possible adsorption mechanism of DBT was also proposed. Finally, it can be concluded that cobalt-incorporated acetic-acid-activated GAC proves to be a potential adsorbent for the removal DBT from fuel oil in an economic and ecofriendly way.

Environmental Science and Pollution Research

In this study, copper-loaded activated alumina (Cu/AA) was synthesized and used for the CWPO of c... more In this study, copper-loaded activated alumina (Cu/AA) was synthesized and used for the CWPO of catechol (a representative refractory organic pollutant). Various characterization techniques were deployed to characterize the catalysts, e.g., activated alumina (AA), as well as pristine and spent 1% Cu/AA. The innovative 1% Cu/AA catalyst exhibited good thermal stability up to 1173 K with a marginal weight loss of 13%. The Cu species were well dispersed on the activated alumina framework with no significant cluster formation. Typically, the average copper particle size of 5 nm was dispersed on the AA framework. Catechol removal was observed to be 92% with 87% mineralization at optimized conditions (initial catechol concentration = 200 mg/L, catalyst dose of 1% Cu/AA = 2 g/L; temperature = 323 K; pH = 6; and H 2 O 2 /catechol stoichiometric ratio = 0.5). The mineralization of catechol was analyzed using mass spectroscopy, with the associated mechanism has been elucidated. Results of this study indicated that synthesized catalyst has phenomenal advantages in terms of simple separation and high removal efficiency of catechol, suggesting the feasibility of employing Cu/AA as the effective catalyst for the CWPO of catechol.

Reaction Kinetics, Mechanisms and Catalysis, 2021

The present manuscript investigated the facile route for the synthesis of heterogeneous catalyst ... more The present manuscript investigated the facile route for the synthesis of heterogeneous catalyst from marble waste (MW) for transesterification of glycerol to glycerol carbonate. The catalytic properties of MW derived catalyst were enhanced with active metal (Cerium) incorporation. The developed catalyst was characterized by different methods. The Brunauer-Emmet-Teller (BET) surface area was found to be 10.90 m 2 /g for CaO/MgO derived from MW and 5.80 m 2 /g for cerium loaded CaO/ MgO (Ce-CaO/MgO) catalyst. In X-ray photoelectron spectroscopy, the coexistence of Ce 3+ and Ce 4+ species was found, which creates more oxygen vacancies (active sites) and improves catalytic activity and stability of the catalyst. Results revealed that a dosage of 5 wt% of Ce-CaO/MgO catalyst, calcined at 850 °C imparted a maximum yield of glycerol carbonate (91.74 ± 2.37%). The reusability study of the catalyst was also examined, and the novel catalyst would maintain its activity up to four cycles. The activation energy was found to be 39.046 ± 3.18 kJ/mol, and the rate of glycerol depletion was estimated as 2.08 × 10-02 ± 0.006 min −1 at 85 °C. The novel Ce-CaO/MgO catalyst may have the potential for industry-scale transesterification of glycerol into glycerol carbonate.

J. Chem. Eng. Data

The present study investigated the viability of deep eutectic solvents (DESs) to extract dibenzot... more The present study investigated the viability of deep eutectic solvents (DESs) to extract dibenzothiophene (DBT) from model gasoline (iso-octane). Tetrabutylammonium bromide (TBAB)-based DES showed significant DBT extraction capability from the model fuel oil. Furthermore, the sigma profile confirmed that all TBAB-based DES had a significant capacity for DBT extraction from the model oil. The affinity order for the TBABbased DES is as follows: TBAB/TEG (tri-ethylene glycol) > TBAB/PA (propionic acid) > TBAB/EG (ethylene glycol). To achieve maximum DBT extraction, the influencing parameters were adjusted, and 89% DBT extraction was achieved using the optimum conditions of oil to DES volume ratio of 1:1, with a DBT concentration of 500 ppm, residence time of 30 min, an extraction temperature of 303 K, and extraction stirring speed of 200 rpm.

Can. J. Chem. Eng

A rice husk-derived MCM-41 catalyst has been synthesized, and active metal Co 3 O 4 nanoparticles... more A rice husk-derived MCM-41 catalyst has been synthesized, and active metal Co 3 O 4 nanoparticles were incorporated. The synthesized MCM-41 derived from rice husk exhibited highly ordered p6mm hexagonal symmetry. The catalytic activity of the prepared catalyst was investigated for glycerol carbonate (GLc) synthesis through transesterification of glycerol (GLy) with dimethyl carbonate (DMC). Experimentally, it was found that 5 wt.% cobalt incorporated MCM-41 activated at 400 C showed a higher yield of GLc, 60.2%, due to its optimum basicity. Approximately, 98.7 ± 1.2% GLy conversion and 94.1 ± 0.7% GLc yield was achieved with the batch reactor at adjusted conditions: a molar ratio of DMC-to-glycerol = 3, catalyst dosage = 6 wt.% (based on glycerol mass), reaction temperature = 90 C, and reaction time = 2 h. The transesterification reaction kinetics were also studied using the ODE 15s tool in MATLAB. The catalyst's activation energy was calculated as 58.2 ± 2.4 kJ/mol.

Rev Chem Eng

Environmental concerns have given a great deal of attention for the production of ultra-low-sulfu... more Environmental concerns have given a great deal of attention for the production of ultra-low-sulfur fuels. The conventional hydrodesulfurization (HDS) process has high operating cost and also encounters difficulty in removing sulfur compound with steric hindrance. Consequently, various research efforts have been made to overcome the limitation of conventional HDS process and exploring the alternative technologies for deep desulfurization. The alternative processes being explored for the production of ultra-low-sulfur content fuel are adsorptive desulfurization (ADS), biodesulfurization (BDS), oxidative desulfurization (ODS), and extractive desulfurization (EDS). The present article provided the comprehensive information on the basic principle, reaction mechanism, workability, advantages, and disadvantages of conventional and alternative technologies. This review article aims to provide valuable insight into the recent advances made in conventional HDS process and alternative techniques. For deep desulfurization of liquid fuels, integration of conventional HDS with an alternative technique is also proposed.

International Journal of Chemical Reactor Engineering

The profitability margin of biodiesel production hampering due to surplus amount of glycerol with... more The profitability margin of biodiesel production hampering due to surplus amount of glycerol with the low market price. Thus, developing an alternative route highly demanded for the conversion of glycerol into valueadded chemicals. In the present manuscript, green synthesis route was explored by utilizing rice husk derived catalyst. The catalytic properties of the prepared catalyst were investigated by using various characterization techniques. The basic strength of the catalyst was influenced by varying the calcination temperature (200 °C to 500 °C) as well as active metal (cerium) loading (5 wt. % to 20 wt. %). The present investigation revealed that 10 wt. % Ce on Na 2 SiO 3 catalyst calcined at 400 °C exhibited the moderate basic sites of 13.89 mmol/g, which showed potential catalytic activity for the transesterification of glycerol to glycerol carbonate under optimum condition: 92 % glycerol carbonate yield and 98 % glycerol conversion. The catalyst stability study revealed that the catalyst could be reused up to four consecutive cycles without an appreciable drop in catalytic activity. The kinetics of the reaction was also studied, and the activation energy was calculated as 23.80 kJ/mol.

Journal of Environmental Chemical Engineering

Coal fly ash (CFA) has been employed as a catalytic support for lithium ions by impregnation. The... more Coal fly ash (CFA) has been employed as a catalytic support for lithium ions by impregnation. The basicity, basic strength, and stability of the resultant catalyst were further tuned by varying active species concentration (1 wt %-7 wt%) and calcination temperature (300-600 • C). The relationship between the basic properties of catalyst and their catalytic activity towards the conversion of glycerol (GL) was determined experimentally. It was found that 2 wt% lithium loaded CFA, calcined at 500 • C exhibited a maximum yield of glycerol carbonate (GC). The maximum catalytic activity was achieved at 90 • C with a reaction time of 2 h, 96.33% GL conversion, and 91.74% GC yield. Furthermore, ODE 15 s solver was used to evaluate reaction kinetics of the transesterification reaction. The activation energy was calculated and as 26.50 kJ/mol. The proposed work has the potential to uplift the economy of biodiesel industry.

Journal of Environmental Chemical Engineering

Current study presents the synthesis of mesoporous silica material (MCM-41) derived from coal fly... more Current study presents the synthesis of mesoporous silica material (MCM-41) derived from coal fly ash as a catalyst support material for the catalytic oxidative desulfurization (ODS) of liquid fuels. In this work, molybdenum active species were incorporated into the mesoporous silica (Mo/MCM-41) by the incipient wetimpregnation process. The obtained Mo/MCM-41 was characterized by FESEM, HRTEM, XRD, and FT-IR to confirm its structure and functional groups present on the catalyst. Characterization study revealed that mesoporous silica was successfully synthesized from coal fly ash. Desulfurization of dibenzothiophene (DBT) containing model fuel was investigated by using synthesized catalyst, approximately 94% of DBT removal was achieved by optimizing the influencing parameters of ODS process. The ODS results proved that Mo/MCM-41 could be the potential catalyst for reduction of DBT from liquid fuels. Oxidative reaction of DBT follows the pseudo first order reaction kinetic. DBT oxidation mechanism was proposed.

Journal of Cleaner Production, 2022

The present study explored the catalytic activity of the heterogeneous catalyst for transesterifi... more The present study explored the catalytic activity of the heterogeneous catalyst for transesterification of glycerol into glycerol carbonate, a versatile compound. Transesterification of glycerol was investigated with different active metals (Li, La, Ce, Mg, K) impregnated on MCM-41 (Mobil Composition of Matter No. 41) framework. Among these, lithium incorporated MCM-41 proved the better catalytic activity towards the formation of glycerol carbonate. The shortening of a long-range hexagonal array was observed with active metal incorporation due to the accumulation of non-framework Li species in the MCM-41 structure. BET study revealed that Li/MCM-41 possess type IV hysteresis loop according to IUPAC standards. The average pore diameter was increased from 25.43 Å to 62.02 Å with active metal incorporation in the MCM-41 framework. The catalytic activity of Li/MCM-41 was observed by varying different weight ratios of active metal and the calcination temperature. The results demonstrated that 5 wt% Li impregnated on MCM-41, calcined at 450 C, appeared to have a maximum yield of glycerol carbonate. Additionally, the influence of reaction operating parameters was also investigated. The results showed that 99 ± 1.89% glycerol conversion and 93.14 ± 2.52% glycerol carbonate yield was achieved at dimethyl carbonate-to-glycerol molar ratio of 3, catalyst dosage of 4 wt% (relative to glycerol mass) and a reaction temperature of 90 C in 3 h. The recyclability and stability of the screened catalyst was also studied under optimized conditions. The activation energy of the catalyst was determined by solving the differential equation using MATLAB ODE15s tool, and the obtained value was 53.77 ± 3.26 kJ/mol. The E-factor and PMI (Process mass intensity) values of glycerol carbonate synthesis were determined as 1.16 and 2.16, respectively, which demonstrate the less waste generation during the process.