Dhanapati Deka - Academia.edu (original) (raw)

Papers by Dhanapati Deka

Sustainable Environment, 2023

Journal of Fundamentals of Renewable Energy and Applications, Sep 4, 2015

Indian journal of forestry, 2001

The focus of this paper is to review the history of underwater robotics, advances in underwater r... more The focus of this paper is to review the history of underwater robotics, advances in underwater robot navigation and sensing techniques, and an emphasis towards its applications. Following an introduction, the paper reviews development of the underwater robots since the mid 19th century to recent times. Advancements in navigation and sensing techniques for underwater robotics, and their applications in seafloor mapping and seismic monitoring of underwater oil fields were reviewed. Recent navigation and sensing techniques in underwater robotics has enabled their applications in visual imaging of sea beds, detection of geological samples, seismic monitoring of underwater oil fields and the like. This paper provides a recent review of underwater robotics in terms of history, navigation and sensing techniques, and their applications in seafloor mapping and seismic monitoring of underwater oil fields.

Energy, Sep 1, 2018

Current research reports the synthesis of in-situ TiO 2 /RGO nanocomposite and used as a heteroge... more Current research reports the synthesis of in-situ TiO 2 /RGO nanocomposite and used as a heterogeneous catalyst for the transesterification of waste cooking oil into biodiesel. The prepared catalyst was characterized viz. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Transmission Electron Microscopy (TEM), Thermogravimetric analysis (TGA) techniques conforming the successful formation of nanocomposite. The effects of various reaction parameters used for transesterification were examined to optimize the reaction conditions. The best operational conditions were oil to methanol molar ratio of 1:12 at 65 0 C with 1.5 wt% catalyst loading and reaction time of 3 hours. The catalyst showed good catalytic activity in biodiesel production and biodiesel conversion of 98% was obtained under optimum reaction conditions. Biodiesel conversion was confirmed by Proton Nuclear Magnetic Resonance (1 H NMR), Carbon Nuclear Magnetic Resonance (13 C NMR) and Gas Chromatography-Mass Spectroscopy (GC-MS) techniques. The excellent catalytic activity of TiO 2 /RGO could be attributed to the enhanced surface area of the composite.

Fuel Processing Technology, Jun 1, 2014

A series of Li doped egg shell derived CaO is prepared for biodiesel production from nonedible oi... more A series of Li doped egg shell derived CaO is prepared for biodiesel production from nonedible oil feedstock. The catalyst is characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), Brunauer-Emmett-Teller (BET) surface area measurements and their basic strengths were measured by Hammett indicators. Maximum conversion of 94% is observed with 5% of catalyst amount and 2% of Li loading is observed to be optimum for better conversions. Though the catalyst is not reusable its catalytic activity can be improved by activating it at appropriate temperature and reloading it with Li. NMR studies showed that the final product separated after transesterification is biodiesel.

Industrial Crops and Products, Nov 1, 2018

Herein, the potato peels which are the huge household and agro-industrial disposable waste materi... more Herein, the potato peels which are the huge household and agro-industrial disposable waste material have been evaluated as a promising and sustainable natural antioxidant for enhancing the oxidation stability of the biodiesel produced from Nahar (Mesua ferrea L.) oil. A sample of biodiesel without PPE (Potato peel extract) denoted as BP 0 (0 ppm) and total of four treatments of biodiesel with PPE i.e., 100 ppm (BP 1), 150 ppm (BP 2), 200 ppm (BP 3), 250 ppm (BP 4) were prepared for evaluating the effectiveness of PPE in oxidation stability enhancement. The oxidation stability of all the samples was evaluated with the help of Rancimat instrument manufactured by metrohm. The results revealed that a minimum concentration of 150 ppm of PPE in Mesua ferrea L. biodiesel was capable of enhancing its IP (induction period) from 5.63 h to 6.21 h, which met the standard European (ENE14214) biodiesel specification for oxidation stability. Comparison of PPE with TBHQ (tert-butylhydroquinone) has also been accomplished to know the effectiveness of PPE against TBHQ. The results in this study have shown that PPE is equally capable of enhancing oxidation stability of Mesua ferrea L. biodiesel as compared to TBHQ. Hence, PPE can be used as natural antioxidant for biodiesel instead of using synthetic antioxidant TBHQ procured from non-renewable source.

Renewable & Sustainable Energy Reviews, 2014

Catalyst plays an important role in biodiesel production. Owing to the advantages of heterogeneou... more Catalyst plays an important role in biodiesel production. Owing to the advantages of heterogeneous catalysts in terms of separation and reusability over the traditionally used homogeneous catalyst, the research has now been focused on these heterogeneous catalysts in recent years. In order to make the process fully "green", researchers are trying to prepare catalysts from renewable sources such as biomass. Within this concept the carbon based catalysts have been introduced. Carbon based materials are considered as ideal catalysts due to desirable features such as low material cost, high surface area and thermal stability. They are easily prepared by functionalizing carbon surface with acids or bases; in other cases carbon material was reported to be used as a support. Additionally, the carbon could be produced from most of the waste generated in different industrial processes. Therefore, its utilization as catalyst makes the biodiesel production a "greener" one. Under optimal conditions biodiesel (FAME) yields up to 90-98.3% were reported over various carbon based catalysts.

Journal of Bioprocess Engineering and Biorefinery, Mar 1, 2013

ABSTRACT The aim of this work is to find a green catalyst prepared straight from biomass for biod... more ABSTRACT The aim of this work is to find a green catalyst prepared straight from biomass for biodiesel production. In this work ash obtained from Vigna radiata plant has been proposed as heterogeneous base catalyst in transesterification of waste cooking oil. EDX studies showed that the ash content of Vigna radiata (mung bean) mainly contains calcium and potassium in the form of carbonates, sulphates and hydroxides. The optimum reaction conditions such as catalyst amount, reaction time, reaction temperature for biodiesel production are investigated in order to obtain the maximum conversion. The catalyst is characterized with by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), Brunauer–Emmett–Teller(BET) surface area measurements and their basic strengths were measured by Hammett indicators.

Molecules

Catalytic conversion of ethanol to 1-butanol was studied over MgO–Al2O3 mixed oxide-based catalys... more Catalytic conversion of ethanol to 1-butanol was studied over MgO–Al2O3 mixed oxide-based catalysts. Relationships between acid-base and catalytic properties and the effect of active metal on the hydrogen transfer reaction steps were investigated. The acid-base properties were studied by temperature-programmed desorption of CO2 and NH3 and by the FT-IR spectroscopic examination of adsorbed pyridine. Dispersion of the metal promoter (Pd, Pt, Ru, Ni) was determined by CO pulse chemisorption. The ethanol coupling reaction was studied using a flow-through microreactor system, He or H2 carrier gas, WHSV = 1 gEtOH·gcat.−1·h−1, at 21 bar, and 200–350 °C. Formation and transformation of surface species under catalytic conditions were studied by DRIFT spectroscopy. The highest butanol selectivity and yield was observed when the MgO–Al2O3 catalyst contained a relatively high amount of strong-base and medium-strong Lewis acid sites. The presence of metal improved the activity both in He and H2...

Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2013

Domestic energy consumption along with the modern use of biomass fuel in the households were stud... more Domestic energy consumption along with the modern use of biomass fuel in the households were studied for Bijini (South Blocks), Betanapara, and Oxiguri villages of Chirang District in Assam, which are categorized as Urban, Peri-urban, and Rural villages, respectively, based on their locations from Bijni town. The annual per capita consumption of domestic energy in Urban, Peri-urban, and Rural areas is estimated to be 7.2, 7.99, and 8.44 GJ/yr, respectively, against the National average of 9.09 GJ/yr per capita. The majority of the households' responses was unknown or showed no interest for the modern biomass energy sources or devices.

Journal of Agricultural and Food Chemistry, Nov 1, 2013

Valorization of oilseed processing wastes is thwarted due to the presence of several antinutritio... more Valorization of oilseed processing wastes is thwarted due to the presence of several antinutritional factors such as phenolics, tannins, glucosinolates, allyl isothiocyanates, and phytates; moreover, literature reporting on their simultaneous extraction and subsequent practical application is scanty. Different solvent mixtures containing acetone or methanol pure or combined with water or an acid (hydrochloric, acetic, perchloric, trichloroacetic, phosphoric) were tested for their efficiency for extraction of these antinutritive compounds from rapeseed press-cake. Acidified extraction mixtures (nonaqueous) were found to be superior to the nonacidified ones. The characteristic differences in the efficacy of these wide varieties of solvents were studied by principal component analysis, on the basis of which the mixture 0.2% perchloric acid in methanol/acetone (1:1 v/v) was deemed as "the best" for detoxification of rapeseed meal. Despite its high reductive potential, hemolytic activity of the extract from this solvent mixture clearly indicated the toxicity of the above-mentioned compounds on mammalian erythrocytes. Because of the presence of a high amount of antinutritive antioxidants, the study was further extended to examine the influence of this solvent extract on the stability of waste cooking oil-derived biodiesel. Treatment with the extract harbored significant improvement (p < 0.05) in the induction periods and pronounced reduction in microbial load of stored biodiesel investigated herein. Thus, a suitable solvent system was devised for removing the major antinutrients from rapeseed press-cake, and the solvent extract can, thereafter, be used as an effective exogenous antioxidant for biodiesel. In other words, integrated valorization of two different industrial wastes was successfully achieved.

Industrial Crops and Products

Chemosphere

The green synthesis of nanoparticles (NPs) is the safest, ecofriendly, cost-effective, and non-ha... more The green synthesis of nanoparticles (NPs) is the safest, ecofriendly, cost-effective, and non-hazardous approach of nanotechnology. In the current study, we described the green synthesis of silver nanoparticles (AgNPs) using Cuphea carthagenensis aqueous leaf extract as a reducing, capping, and stabilizing agent. The study aims at the synthesis, characterization, optimization, and determination of the antibacterial activity of Cc-AgNPs against clinically important human pathogens. Coating of cotton fabrics with Cc-AgNPs and their efficacy against skin infection causing organisms was also evaluated. Furthermore, antioxidant activity, growth assay and time kill assay of Cc-AgNPs were also performed in the study. The biosynthesized Cc-AgNPs were characterized by UV-visible spectrometry, energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The spectroscopic and microscopic analysis demonstrated biosynthesis of face-centered cubic (fcc) crystalline spherical Cc-AgNPs with an average particle size of 10.65 ± 0.1 nm. Optimized peak synthesis of Cc-AgNPs was reported at pH7, 55 °C, 4 mM silver nitrate, and 5:45 (plant extract: silver nitrate). Cc-AgNPs exhibited potent antioxidant effect and antibacterial activity against both Gram-positive and Gram-negative bacteria. The lowest MIC (15 μg/ml) and MBC (25 μg/ml) values were reported against S. typhimurium. The Cc-AgNPs coated fabrics demonstrated potent antibacterial activity against tested strains. This application could be helpful in wound healing management. Furthermore, the hemolytic analysis demonstrated that Cc-AgNPs exhibit non-toxic nature against Red Blood Cells (RBCs) at the tested concentrations. In conclusion, the investigation demonstrated a fast, stable, and eco-friendly approach to the biosynthesis of Cc-AgNPs along with their antibacterial and antioxidant properties.