Mokhtar Ali - Academia.edu (original) (raw)
Papers by Mokhtar Ali
DESALINATION AND WATER TREATMENT, 2018
In the recent past, intensive studies have been directed towards the use of zinc oxide nanopartic... more In the recent past, intensive studies have been directed towards the use of zinc oxide nanoparticles (ZnO-NPs) for pollutant uptake and pathogens deactivation from water. However, the chemical behaviour of these suspended colloids in water and their solubility measurements is still not fully understood. Herein, a green synthesis approach was used to fabricate surface-modified ZnO-NPs using Dracaena cinnabari (Dragon's blood) extract. A ZnO control sample for comparison was synthesized at similar conditions but without the extract. The obtained powder samples were characterized for structural, morphological and surface properties using various multidisciplinary tools. The environmental stability and adsorption behaviour of surface-modified ZnO-NPs (S1) and pristine ZnO (S2) were studied in aqueous solution at various conditions. S1 sample showed high adsorption capacity for Arsenite (As (III)) and least leaching of Zn ions into water as compared with S2. The results of Zn ions leaching into water (in case of S2) inferred that pristine ZnO sample (S2) was unstable in alkaline and acidic conditions, suggesting its unviability as an adsorbent in most conditions. However, the green synthesis approach for the synthesis of ZnO-NPs has proved a potential step forward towards the safe use of ZnO-NPs for water purification systems.
Case Studies in Construction Materials, Dec 1, 2022
Journal of Quality in Maintenance Engineering, Oct 13, 2020
Purpose-This study provides a unique integrated diagnosis system to investigate the causes of low... more Purpose-This study provides a unique integrated diagnosis system to investigate the causes of low productivity, profitability, machinery health conditions and wear severity of medium-size biscuit industry assets in Taiz, Yemen. Design/methodology/approach-The evaluation is based on an integrating of the overall equipment effectiveness (OEE) and oil-based maintenance (OBM) approaches. The data are collected using the company's operational records, interviews and observations, while the used lubricating oil samples are also collected from production lines' machineries. Scanning electron microscope (SEM) is used to study the wear debris particle features and wear mechanism. Different other analysis tools such as fishbone, 5 whys and Pareto charts are also used to investigate the root causes and plausible recovery solutions of machinery failures. Findings-This study demonstrated that a large proportion of machinery failures and production loss are of management concerns. Also, this study inferred that the analysis of wear debris is unique and informative for determining machinery wear severity and useful life. Finally, the current conditions of production lines are clarified and suggestions to use a mixed preventive/predictive maintenance management approach are also elucidated. Originality/value-This work implemented an integrated OEE/OBM diagnostic maintenance system to investigate the root causes of low productivity and machine failures in real production lines and suggested robust decisions on the maintenance duties.
Machines, Mar 29, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
International Journal of Energy Research, May 23, 2022
2022 13th International Renewable Energy Congress (IREC)
Journal of Energy and Environmental Sustainability, 2018
Increased carbon dioxide (CO 2) emissions from combustion of fossil fuels are the major contribut... more Increased carbon dioxide (CO 2) emissions from combustion of fossil fuels are the major contributor towards overall greenhouse gas emissions. Considering the significant reserves of fossil fuels in India and elsewhere, producing cleaner energy using fossil fuels with CO 2 capture and sequestration is one of the practical options to meet future energy demand and greenhouse gas commitments. Chemical Looping Combustion (CLC) is one of the efficient techniques with inherent potential for Carbon Capture. CLC is a greener way for combustion of fuel, using a metal oxide as oxygen carrier for providing the necessary oxygen for the fuel combustion. The reduced metal or metal oxide can again be oxygenated through air oxidation to form its original chemical state. This review sheds light on current energy scenario in India as one of the major energy users in future, the relevance and technical advancements in chemical looping combustion, with special reference to oxygen carriers
Applied Sciences, 2020
Arsenite (As(III)) and Selenate (Se(VI)) are universally touted as extremely toxic oxyanions in n... more Arsenite (As(III)) and Selenate (Se(VI)) are universally touted as extremely toxic oxyanions in natural and industrial water systems. Thus, the production of low-cost adsorbents that are scalable and toxic-free is of great importance today. In this work, a large-scale goethite nanorods (α-FeOOH NRs) is synthesized using a modified rapid hydrolysis method. The obtained powder is characterized using different multidisciplinary techniques. Accordingly, the results showed uniform and straight nanorods (length ~400 nm and diameter ~40 nm) resembling cigar-like morphology while the structure is confirmed to be of orthorhombic α-FeOOH phase. The potential application of this material to adsorb As (III) and Se (VI) ions in water is explored. In particular, for initial adsorbate concentrations (~500 µg/L), the removal efficiencies are found exceptional with α-FeOOH doses of 0.33 g/L and ~0.5 g/L for As (III) and Se (VI), respectively. Attractively, the adsorption capacities were estimated us...
Journal of Water Process Engineering, 2020
Abstract The development of robust, cost-effective remediation technologies of selenium uptake fr... more Abstract The development of robust, cost-effective remediation technologies of selenium uptake from ground and surface water is challenging and at the same time urgently needed. The present study provides a new, facile synthesis protocol for lepidocrocite (γ-FeOOH) nanoflakes and lepidocrocite decorated on multi-layered graphene (γ-FeOOH-MLG) and their possible application for Selenate [Se(VI)] ions removal from drinking water. The morphological and structural properties of γ-FeOOH were studied by using different techniques. There is a limited data on the adsorption of Se(VI) ions onto the 2D γ-FeOOH nanosheets. This work delineates adsorption mechanism and merits of incorporating graphene for enhancing adsorbent’s potential for selenium removal from contaminated water. The extraordinary electronic and textural properties of graphene sheets make it a physical support to stabilize γ-FeOOH nanoflakes, substantially improving adsorption capacities and kinetics besides strengthening particle stability. Maximum adsorption capacity of γ-FeOOH and γ-FeOOH-MLG samples estimated by Langmuir adsorption isotherms observed to be ∼40.09 and ∼83.44 mg/g, respectively. The adsorption mechanism of Se(VI) to the surfaces of adsorbents was found to be monolayer and of chemisorption in nature. The pH dependence experiments showed that γ-FeOOH exhibited maximum adsorption capacity at a pH close to the PZC 5.97 (±1), which are in suitable for real ground water conditions.
Albaydha University Journal
Metal oxide powders at the macro-scale level exhibit low properties as compared to nanoscale powd... more Metal oxide powders at the macro-scale level exhibit low properties as compared to nanoscale powder despite their wide-availability, low-cost processing, and bulk quantities production. The present study introduced a two-step synthesis method for the continuous and high yield production of copper oxide nanoparticles. The first step comprises a chemical reduction process to synthesis copper tartrate micro-flakes of larger than 1µm. In the subsequent step, these micro flakes are physically fragmented to nanoparticles in water medium using picosecond laser pulses (532 nm, 10Hz, 30 ps.). Besides, a time-based study showed that the particle size increases as the laser exposure time increases. The obtained copper tartrate nanoparticles from laser fragmentation are calcinated at 250 °C to remove tartrate, and then copper oxide nanoparticles are produced at the end of the experiments. The acquired particles at different stages are characterized by XRD, TEM, and FESEM to study their morpholo...
Optical Materials, May 1, 2022
Journal of water process engineering, Oct 1, 2021
The synthesis of nanoparticles using plant extracts has received great attentions during the last... more The synthesis of nanoparticles using plant extracts has received great attentions during the last two decades. That is plausibly due to its simple, rapid, toxic-free, and efficient reactions. In this study, a unique green method for preparing silver nanoparticles (Ag NPs) using the extract of Qat (or Khat) leaves is reported. The method is cheap, easy and has a potential for mass production of nanoparticles. Qat is a fast growing plant used mostly as stimulant in Yemen and South African countries and contains dozens of phytochemicals in its leaves. These chemicals are extracted from Qat leaves in an aqueous solution and used as a reducing agent and surfactant in the reaction. The structure and morphology of Ag nanoparticles are confirmed using multidisciplinary characterization tools. The results showed well dispersed spherical particles with an average size of 18.11 nm. The surfactant coated on the particles are confirmed using FTIR technique. Moreover, this green method is applicable for large scale production with an efficient cost due to rapid reaction and the wide availability of the plant leaves.
Science and Technology of Advanced Materials, 2016
In this study, an environmentally friendly, cost-effective, and single-step procedure is used for... more In this study, an environmentally friendly, cost-effective, and single-step procedure is used for the synthesis of polycrystalline Cu 2 O particles with controlled morphologies. Simple sugars are extracted from date fruit pulp (Phoenix dactylifera) and used as a reducing agent for the formation of Cu 2 O particles in aqueous medium. The feasibility of this solution is compared with the standard glucose solution. The Cu 2 O particles are characterized by electron microscopy, X-ray diffraction, optical absorption and Raman scattering techniques. It is concluded that the morphology of the particles is mainly influenced by the solvents. The obtained Cu 2 O particles are then used as an adsorbent to uptake As(III) ions from water. The maximum adsorption capacity (Q max) is estimated by Langmuir and Freundlich isotherms and it is found that Q max = 14.3 mg g-1. Adsorption kinetics study showed that the adsorption equilibrium could be achieved in 1 h and that the purified water meets the standards of World Health Organization (WHO) for acceptable amount of As(III) in drinking water. Adsorption kinetic models showed that the adsorption is chemisorption in nature.
Solid State Sciences, 2017
Applied Surface Science, 2015
Journal of Nanoscience and Nanotechnology, 2015
Rapid mixing chemical oxidative polymerization method is used to synthesize carbon nanofibers (CN... more Rapid mixing chemical oxidative polymerization method is used to synthesize carbon nanofibers (CNFs) and polyaniline nanofibers (PANI NF) containing composite. Morphological, structural and phase analyses reveal that the composite is constituted by PANI coated CNFs and PANI NF. The intrinsic defects on the CNFs' surfaces allowed the nucleation and growth of PANI on them. At the same time, the use of optimal aniline concentration facilitated the simultaneous nucleation and growth of PANI NF The composite exhibits an excellent electrochemical activity with a specific capacitance of -156.92 F/g. The synergic contribution of the constituents to the overall electrochemical activity of the composite are identified.
ABSTRACT Amongst various carbon nanomaterials, carbon nanofibers (CNFs) have lately attracted con... more ABSTRACT Amongst various carbon nanomaterials, carbon nanofibers (CNFs) have lately attracted considerable interest as a promising reinforcement in polymer matrix composites. CNFs are often synthesized using copper nanoparticles as catalysts and by using chemical vapor deposition (CVD). In this work iron (Fe) nanoparticles are used as catalysts to synthesize amorphous carbon nanofibers. This owes significance since Fe nanoparticles often lead to tubes rather than fibers. Fe nanoparticles (size ~30-60nm) are prepared by first mixing an appropriate quantity of potassium sodium tartrate tetrahydrate salt with iron (II) chloride dehydrate to obtain iron tartrate and then dried and heated in vacuum oven at about 250°C to remove tartrate. In a subsequent step, CNFs are obtained by using CVD. Acetylene was used as the carbon source in the CVD process. Scanning and transmission electron microscopy show the formation of nanofibers whose diameter is dependent on the size of Fe catalysts. Raman scattering from the fibers show that they are made up of carbon and are amorphous.
Materials Letters, 2014
ABSTRACT Cuprous oxide (Cu2O) particles are synthesized using an easy solution synthesis process ... more ABSTRACT Cuprous oxide (Cu2O) particles are synthesized using an easy solution synthesis process that involved the use of honey. Experimentally it was found that the glucose content in honey plays an important role in the formation of Cu2O particles. The size and morphology of Cu2O particles could be easily altered by changing the solvents in the synthesis procedure. Cu2O particles showed good anti-bacterial activity against Staphylococcus aureus and Escherichia coli. (C) 2014 Published by Elsevier B.V.
DESALINATION AND WATER TREATMENT, 2018
In the recent past, intensive studies have been directed towards the use of zinc oxide nanopartic... more In the recent past, intensive studies have been directed towards the use of zinc oxide nanoparticles (ZnO-NPs) for pollutant uptake and pathogens deactivation from water. However, the chemical behaviour of these suspended colloids in water and their solubility measurements is still not fully understood. Herein, a green synthesis approach was used to fabricate surface-modified ZnO-NPs using Dracaena cinnabari (Dragon's blood) extract. A ZnO control sample for comparison was synthesized at similar conditions but without the extract. The obtained powder samples were characterized for structural, morphological and surface properties using various multidisciplinary tools. The environmental stability and adsorption behaviour of surface-modified ZnO-NPs (S1) and pristine ZnO (S2) were studied in aqueous solution at various conditions. S1 sample showed high adsorption capacity for Arsenite (As (III)) and least leaching of Zn ions into water as compared with S2. The results of Zn ions leaching into water (in case of S2) inferred that pristine ZnO sample (S2) was unstable in alkaline and acidic conditions, suggesting its unviability as an adsorbent in most conditions. However, the green synthesis approach for the synthesis of ZnO-NPs has proved a potential step forward towards the safe use of ZnO-NPs for water purification systems.
Case Studies in Construction Materials, Dec 1, 2022
Journal of Quality in Maintenance Engineering, Oct 13, 2020
Purpose-This study provides a unique integrated diagnosis system to investigate the causes of low... more Purpose-This study provides a unique integrated diagnosis system to investigate the causes of low productivity, profitability, machinery health conditions and wear severity of medium-size biscuit industry assets in Taiz, Yemen. Design/methodology/approach-The evaluation is based on an integrating of the overall equipment effectiveness (OEE) and oil-based maintenance (OBM) approaches. The data are collected using the company's operational records, interviews and observations, while the used lubricating oil samples are also collected from production lines' machineries. Scanning electron microscope (SEM) is used to study the wear debris particle features and wear mechanism. Different other analysis tools such as fishbone, 5 whys and Pareto charts are also used to investigate the root causes and plausible recovery solutions of machinery failures. Findings-This study demonstrated that a large proportion of machinery failures and production loss are of management concerns. Also, this study inferred that the analysis of wear debris is unique and informative for determining machinery wear severity and useful life. Finally, the current conditions of production lines are clarified and suggestions to use a mixed preventive/predictive maintenance management approach are also elucidated. Originality/value-This work implemented an integrated OEE/OBM diagnostic maintenance system to investigate the root causes of low productivity and machine failures in real production lines and suggested robust decisions on the maintenance duties.
Machines, Mar 29, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
International Journal of Energy Research, May 23, 2022
2022 13th International Renewable Energy Congress (IREC)
Journal of Energy and Environmental Sustainability, 2018
Increased carbon dioxide (CO 2) emissions from combustion of fossil fuels are the major contribut... more Increased carbon dioxide (CO 2) emissions from combustion of fossil fuels are the major contributor towards overall greenhouse gas emissions. Considering the significant reserves of fossil fuels in India and elsewhere, producing cleaner energy using fossil fuels with CO 2 capture and sequestration is one of the practical options to meet future energy demand and greenhouse gas commitments. Chemical Looping Combustion (CLC) is one of the efficient techniques with inherent potential for Carbon Capture. CLC is a greener way for combustion of fuel, using a metal oxide as oxygen carrier for providing the necessary oxygen for the fuel combustion. The reduced metal or metal oxide can again be oxygenated through air oxidation to form its original chemical state. This review sheds light on current energy scenario in India as one of the major energy users in future, the relevance and technical advancements in chemical looping combustion, with special reference to oxygen carriers
Applied Sciences, 2020
Arsenite (As(III)) and Selenate (Se(VI)) are universally touted as extremely toxic oxyanions in n... more Arsenite (As(III)) and Selenate (Se(VI)) are universally touted as extremely toxic oxyanions in natural and industrial water systems. Thus, the production of low-cost adsorbents that are scalable and toxic-free is of great importance today. In this work, a large-scale goethite nanorods (α-FeOOH NRs) is synthesized using a modified rapid hydrolysis method. The obtained powder is characterized using different multidisciplinary techniques. Accordingly, the results showed uniform and straight nanorods (length ~400 nm and diameter ~40 nm) resembling cigar-like morphology while the structure is confirmed to be of orthorhombic α-FeOOH phase. The potential application of this material to adsorb As (III) and Se (VI) ions in water is explored. In particular, for initial adsorbate concentrations (~500 µg/L), the removal efficiencies are found exceptional with α-FeOOH doses of 0.33 g/L and ~0.5 g/L for As (III) and Se (VI), respectively. Attractively, the adsorption capacities were estimated us...
Journal of Water Process Engineering, 2020
Abstract The development of robust, cost-effective remediation technologies of selenium uptake fr... more Abstract The development of robust, cost-effective remediation technologies of selenium uptake from ground and surface water is challenging and at the same time urgently needed. The present study provides a new, facile synthesis protocol for lepidocrocite (γ-FeOOH) nanoflakes and lepidocrocite decorated on multi-layered graphene (γ-FeOOH-MLG) and their possible application for Selenate [Se(VI)] ions removal from drinking water. The morphological and structural properties of γ-FeOOH were studied by using different techniques. There is a limited data on the adsorption of Se(VI) ions onto the 2D γ-FeOOH nanosheets. This work delineates adsorption mechanism and merits of incorporating graphene for enhancing adsorbent’s potential for selenium removal from contaminated water. The extraordinary electronic and textural properties of graphene sheets make it a physical support to stabilize γ-FeOOH nanoflakes, substantially improving adsorption capacities and kinetics besides strengthening particle stability. Maximum adsorption capacity of γ-FeOOH and γ-FeOOH-MLG samples estimated by Langmuir adsorption isotherms observed to be ∼40.09 and ∼83.44 mg/g, respectively. The adsorption mechanism of Se(VI) to the surfaces of adsorbents was found to be monolayer and of chemisorption in nature. The pH dependence experiments showed that γ-FeOOH exhibited maximum adsorption capacity at a pH close to the PZC 5.97 (±1), which are in suitable for real ground water conditions.
Albaydha University Journal
Metal oxide powders at the macro-scale level exhibit low properties as compared to nanoscale powd... more Metal oxide powders at the macro-scale level exhibit low properties as compared to nanoscale powder despite their wide-availability, low-cost processing, and bulk quantities production. The present study introduced a two-step synthesis method for the continuous and high yield production of copper oxide nanoparticles. The first step comprises a chemical reduction process to synthesis copper tartrate micro-flakes of larger than 1µm. In the subsequent step, these micro flakes are physically fragmented to nanoparticles in water medium using picosecond laser pulses (532 nm, 10Hz, 30 ps.). Besides, a time-based study showed that the particle size increases as the laser exposure time increases. The obtained copper tartrate nanoparticles from laser fragmentation are calcinated at 250 °C to remove tartrate, and then copper oxide nanoparticles are produced at the end of the experiments. The acquired particles at different stages are characterized by XRD, TEM, and FESEM to study their morpholo...
Optical Materials, May 1, 2022
Journal of water process engineering, Oct 1, 2021
The synthesis of nanoparticles using plant extracts has received great attentions during the last... more The synthesis of nanoparticles using plant extracts has received great attentions during the last two decades. That is plausibly due to its simple, rapid, toxic-free, and efficient reactions. In this study, a unique green method for preparing silver nanoparticles (Ag NPs) using the extract of Qat (or Khat) leaves is reported. The method is cheap, easy and has a potential for mass production of nanoparticles. Qat is a fast growing plant used mostly as stimulant in Yemen and South African countries and contains dozens of phytochemicals in its leaves. These chemicals are extracted from Qat leaves in an aqueous solution and used as a reducing agent and surfactant in the reaction. The structure and morphology of Ag nanoparticles are confirmed using multidisciplinary characterization tools. The results showed well dispersed spherical particles with an average size of 18.11 nm. The surfactant coated on the particles are confirmed using FTIR technique. Moreover, this green method is applicable for large scale production with an efficient cost due to rapid reaction and the wide availability of the plant leaves.
Science and Technology of Advanced Materials, 2016
In this study, an environmentally friendly, cost-effective, and single-step procedure is used for... more In this study, an environmentally friendly, cost-effective, and single-step procedure is used for the synthesis of polycrystalline Cu 2 O particles with controlled morphologies. Simple sugars are extracted from date fruit pulp (Phoenix dactylifera) and used as a reducing agent for the formation of Cu 2 O particles in aqueous medium. The feasibility of this solution is compared with the standard glucose solution. The Cu 2 O particles are characterized by electron microscopy, X-ray diffraction, optical absorption and Raman scattering techniques. It is concluded that the morphology of the particles is mainly influenced by the solvents. The obtained Cu 2 O particles are then used as an adsorbent to uptake As(III) ions from water. The maximum adsorption capacity (Q max) is estimated by Langmuir and Freundlich isotherms and it is found that Q max = 14.3 mg g-1. Adsorption kinetics study showed that the adsorption equilibrium could be achieved in 1 h and that the purified water meets the standards of World Health Organization (WHO) for acceptable amount of As(III) in drinking water. Adsorption kinetic models showed that the adsorption is chemisorption in nature.
Solid State Sciences, 2017
Applied Surface Science, 2015
Journal of Nanoscience and Nanotechnology, 2015
Rapid mixing chemical oxidative polymerization method is used to synthesize carbon nanofibers (CN... more Rapid mixing chemical oxidative polymerization method is used to synthesize carbon nanofibers (CNFs) and polyaniline nanofibers (PANI NF) containing composite. Morphological, structural and phase analyses reveal that the composite is constituted by PANI coated CNFs and PANI NF. The intrinsic defects on the CNFs' surfaces allowed the nucleation and growth of PANI on them. At the same time, the use of optimal aniline concentration facilitated the simultaneous nucleation and growth of PANI NF The composite exhibits an excellent electrochemical activity with a specific capacitance of -156.92 F/g. The synergic contribution of the constituents to the overall electrochemical activity of the composite are identified.
ABSTRACT Amongst various carbon nanomaterials, carbon nanofibers (CNFs) have lately attracted con... more ABSTRACT Amongst various carbon nanomaterials, carbon nanofibers (CNFs) have lately attracted considerable interest as a promising reinforcement in polymer matrix composites. CNFs are often synthesized using copper nanoparticles as catalysts and by using chemical vapor deposition (CVD). In this work iron (Fe) nanoparticles are used as catalysts to synthesize amorphous carbon nanofibers. This owes significance since Fe nanoparticles often lead to tubes rather than fibers. Fe nanoparticles (size ~30-60nm) are prepared by first mixing an appropriate quantity of potassium sodium tartrate tetrahydrate salt with iron (II) chloride dehydrate to obtain iron tartrate and then dried and heated in vacuum oven at about 250°C to remove tartrate. In a subsequent step, CNFs are obtained by using CVD. Acetylene was used as the carbon source in the CVD process. Scanning and transmission electron microscopy show the formation of nanofibers whose diameter is dependent on the size of Fe catalysts. Raman scattering from the fibers show that they are made up of carbon and are amorphous.
Materials Letters, 2014
ABSTRACT Cuprous oxide (Cu2O) particles are synthesized using an easy solution synthesis process ... more ABSTRACT Cuprous oxide (Cu2O) particles are synthesized using an easy solution synthesis process that involved the use of honey. Experimentally it was found that the glucose content in honey plays an important role in the formation of Cu2O particles. The size and morphology of Cu2O particles could be easily altered by changing the solvents in the synthesis procedure. Cu2O particles showed good anti-bacterial activity against Staphylococcus aureus and Escherichia coli. (C) 2014 Published by Elsevier B.V.