Multiwall carbon nanotubes（MWCNTs） were synthesized using a tubular microwave chemical vapor deposition technique, using acetylene and hydrogen as the precursor gases and ferrocene as catalyst. The novel MWCNT sampl...Multiwall carbon nanotubes（MWCNTs） were synthesized using a tubular microwave chemical vapor deposition technique, using acetylene and hydrogen as the precursor gases and ferrocene as catalyst. The novel MWCNT samples were tested for their performance in terms of Pb（Ⅱ）binding. The synthesized MWCNT samples were characterized using Fourier Transform Infrared（FT-IR）, Brunauer, Emmett and Teller（BET）, Field Emission Scanning Electron Microscopy（FESEM） analysis, and the adsorption of Pb（Ⅱ） was studied as a function of p H,initial Pb（Ⅱ） concentration, MWCNT dosage, agitation speed, and adsorption time, and process parameters were optimized. The adsorption data followed both Freundlich and Langmuir isotherms. On the basis of the Langmuir model, Qmaxwas calculated to be 104.2 mg/g for the microwave-synthesized MWCNTs. In order to investigate the dynamic behavior of MWCNTs as an adsorbent, the kinetic data were modeled using pseudo first-order and pseudo second-order equations. Different thermodynamic parameters, viz., ΔH0, ΔS0and ΔG0were evaluated and it was found that the adsorption was feasible, spontaneous and endothermic in nature. The statistical analysis revealed that the optimum conditions for the highest removal（99.9%） of Pb（Ⅱ） are at p H 5, MWCNT dosage 0.1 g, agitation speed 160 r/min and time of 22.5 min with the initial concentration of 10 mg/L. Our results proved that microwave-synthesized MWCNTs can be used as an effective Pb（Ⅱ） adsorbent due to their high adsorption capacity as well as the short adsorption time needed to achieve equilibrium.展开更多
The increasing focus on electrocatalysis for sustainable hydrogen(H_(2))production has prompted significant interest in MXenes,a class of two-dimensional(2D)materials comprising metal carbides,carbonitrides,and nitrid...The increasing focus on electrocatalysis for sustainable hydrogen(H_(2))production has prompted significant interest in MXenes,a class of two-dimensional(2D)materials comprising metal carbides,carbonitrides,and nitrides.These materials exhibit intriguing chemical and physical properties,including excellent electrical conductivity and a large surface area,making them attractive candidates for the hydrogen evolution reaction(HER).This scientific review explores recent advancements in MXene-based electrocatalysts for HER kinetics.It discusses various compositions,functionalities,and explicit design principles while providing a comprehensive overview of synthesis methods,exceptional properties,and electro-catalytic approaches for H_(2) production via electrochemical reactions.Furthermore,challenges and future prospects in designing MXenes-based electrocatalysts with enhanced kinetics are highlighted,emphasizing the potential of incorporating different metals to expand the scope of electrochemical reactions.This review suggests possible efforts for developing advanced MXenes-based electrocatalysts,particularly for efficient H_(2) generation through electrochemical water-splitting reactions..展开更多
Microalgae cultivation has gained tremendous attention in recent years due to its great potential in green biofuel production and wastewater treatment application. Membrane technology is a great solution in separating...Microalgae cultivation has gained tremendous attention in recent years due to its great potential in green biofuel production and wastewater treatment application. Membrane technology is a great solution in separating the microalgae biomass while producing high quality of permeate for recycling. The main objective of this study was to investigate the filtration performance of Ag/GO-PVDF(silver/graphene oxide-polyvinylidene fluoride) membrane in an algalmembrane photoreactor(A-MPR) by benchmarking with a commercial PVDF(com-PVDF) membrane. In this study, Chlorella vulgaris microalgae was cultivated in synthetic wastewater in an A-MPR for ammoniacal-nitrogen and phosphorus recovery and the wastewater was further filtered using Ag/GO-PVDF and com-PVDF membranes to obtain high quality water. Spectrophotometer was used to analyze the chemical oxidation demand(COD), ammoniacal nitrogen(NH3-N) and phosphate(PO43-). The concentration of proteins and carbohydrates was measured using Bradford method and phenol-sulfuric acid method, respectively. The COD of the synthetic wastewater was reduced from(180.5 ± 5.6) ppm to(82 ± 2.6) ppm due to nutrient uptake by microalgae. Then, the Ag/GO-PVDF membrane was used to further purify the microalgae cultivated wastewater, resulting in a low COD permeate of(31 ± 4.6) ppm. The high removal rate of proteins(100%) and carbohydrates(86.6%) as the major foulant in microalgae filtration, with low membrane fouling propensity of Ag/GO-PVDF membrane is advantageous for the sustainable development of the microalgae production. Hence, the integrated A-MPR system is highly recommended as a promising approach for microalgae cultivation and wastewater polishing treatment.展开更多
The present paper describes the statistical modeling and optimization of a multistage gas-solid fluidized bed reactor for the control of hazardous pollutants in flue gas. In this work, we study the hydrodynamics of th...The present paper describes the statistical modeling and optimization of a multistage gas-solid fluidized bed reactor for the control of hazardous pollutants in flue gas. In this work, we study the hydrodynamics of the pressure drop and minimum fluidization velocity. The hydrodynamics of a three-stage fluidized bed are then compared with those for a single-stage unit. It is observed that the total pressure drop over all stages of the three-stage fluidized bed is less than that of an identical single-stage system. However, the minimum fluidization velocity is higher in the single-stage unit. Under identical conditions, the minimum fluidization velocity is highest in the top bed, and lowest in the bottom bed. This signifies that the behavior of solids changes from a well-mixed flow to a plug-flow, with intermediate behavior in the middle bed.展开更多
Conventional plastics exacerbate climate change by generating substantial amounts of greenhouse gases and solid wastes throughout their lifecycle.To address the environmental and economic challenges associated with pe...Conventional plastics exacerbate climate change by generating substantial amounts of greenhouse gases and solid wastes throughout their lifecycle.To address the environmental and economic challenges associated with petroleum-based plastics,bioplastics have emerged as a viable alternative.Bioplastics are a type of plastic that are either biobased,biodegradable,or both.Due to their biodegradability and renewability,bioplastics are established as earth-friendly materials that can replace nonrenewable plastics.However,early bioplastic development has been hindered by higher production costs and inferior mechanical and barrier properties compared to conventional plastics.Nevertheless,studies have shown that the addition of additives and fillers can enhance bioplastic properties.Recent advancements in bioplastics have incorporated special additives like antibacterial,antifungal,and antioxidant agents,offering added values and unique properties for specific applications in various sectors.For instance,integrating antibacterial additives into bioplastics enables the creation of active food packaging,extending the shelf-life of food by inhibiting spoilage-causing bacteria and microorganisms.Moreover,bioplastics with antioxidant additives can be applied in wound dressings,accelerating wound healing by preventing oxidative damage to cells and tissues.These innovative bioplastic developments offer promising opportunities for developing sustainable and practical solutions in various fields.Within this review are two main focuses:an outline of the bioplastic classifications to understand how they fit in as the coveted conventional plastics substitute and an overview of the recent bioplastic innovations in the antibacterial,antifungal,and antioxidant applications.We cover the use of different polymers and additives,presenting the findings and potential applications within the last decade.Although current research primarily focuses on food packaging and biomedicine,the exploration of bioplastics with specialized properties is still in its early stages,offering a wide range of undiscovered opportunities.展开更多
Lignocellulosic biomass especially,sugarcane bagasse Saccharum barberi sp.,appears to be a more suitable material for partial substi-tution of transport fuel(diesel)than Saccharum officinarum sp.,due to its structural...Lignocellulosic biomass especially,sugarcane bagasse Saccharum barberi sp.,appears to be a more suitable material for partial substi-tution of transport fuel(diesel)than Saccharum officinarum sp.,due to its structural similarity to transport fuel(diesel).Besides that,less research has been implemented on this type of species.Bio-oil can be implemented as biodiesel by processing it further using chemical reactions such as hydrodeoxygenation and cracking with zeolite catalyst.Hence,the purpose of this study is to determine the compatibility of pyrolytic bio-oil produced from Saccharum barberi sp.in comparison with S.officinarum sp.for use as transport fuel(diesel)in automotive applications.This purpose can be accomplished by comparing the oil’s bio-physiochemical properties for both species.The experiment is conducted on a bench-scale on which bio-oil of Saccharum barberi sp.is secured from the catalytic pyrolysis process at a temperature of 500°C and heating rate of 50°C/min with the addition of ZSM-Zeolite catalyst.Thermogravimetric analysis of Saccharum barberi sp.reveals that cellulose is more reactive than lignin,evidenced by the high percentage of weight loss at tem-peratures ranging from 251°C to 390°C.The high contents of carbon(40.7%)and hydrogen(6.50%),as well as slight traces of sulphur(0.08%)and nitrogen(0.85%),in bio-oil(Saccharum barberi sp.)indicate that it is conceivable to be partially used for replacement in biofuel production.Overall physiochemical properties reveal that Saccharum barberi sp.shows more potential than S.officinarum sp.Gas chromatography-mass spectrometry analysis reveals that bio-oil consists of high amounts of aromatic hydrocarbon(26.2%),phenol(14.8%)and furfural(13.0%)in comparison to S.officinarum sp.展开更多
基金financially supported by the University of Malaya, Ministry of Higher Education High Impact Research (UM.C/HIR/MOHE/ENG/20)
文摘Multiwall carbon nanotubes（MWCNTs） were synthesized using a tubular microwave chemical vapor deposition technique, using acetylene and hydrogen as the precursor gases and ferrocene as catalyst. The novel MWCNT samples were tested for their performance in terms of Pb（Ⅱ）binding. The synthesized MWCNT samples were characterized using Fourier Transform Infrared（FT-IR）, Brunauer, Emmett and Teller（BET）, Field Emission Scanning Electron Microscopy（FESEM） analysis, and the adsorption of Pb（Ⅱ） was studied as a function of p H,initial Pb（Ⅱ） concentration, MWCNT dosage, agitation speed, and adsorption time, and process parameters were optimized. The adsorption data followed both Freundlich and Langmuir isotherms. On the basis of the Langmuir model, Qmaxwas calculated to be 104.2 mg/g for the microwave-synthesized MWCNTs. In order to investigate the dynamic behavior of MWCNTs as an adsorbent, the kinetic data were modeled using pseudo first-order and pseudo second-order equations. Different thermodynamic parameters, viz., ΔH0, ΔS0and ΔG0were evaluated and it was found that the adsorption was feasible, spontaneous and endothermic in nature. The statistical analysis revealed that the optimum conditions for the highest removal（99.9%） of Pb（Ⅱ） are at p H 5, MWCNT dosage 0.1 g, agitation speed 160 r/min and time of 22.5 min with the initial concentration of 10 mg/L. Our results proved that microwave-synthesized MWCNTs can be used as an effective Pb（Ⅱ） adsorbent due to their high adsorption capacity as well as the short adsorption time needed to achieve equilibrium.
基金the financial support from the Sunway University International Research Network Grant Scheme(STR-IRNGSSET-GAMRG-01-2022)the Universiti Kebangsaan Malaysia Grant(GUP-2022-080)。
文摘The increasing focus on electrocatalysis for sustainable hydrogen(H_(2))production has prompted significant interest in MXenes,a class of two-dimensional(2D)materials comprising metal carbides,carbonitrides,and nitrides.These materials exhibit intriguing chemical and physical properties,including excellent electrical conductivity and a large surface area,making them attractive candidates for the hydrogen evolution reaction(HER).This scientific review explores recent advancements in MXene-based electrocatalysts for HER kinetics.It discusses various compositions,functionalities,and explicit design principles while providing a comprehensive overview of synthesis methods,exceptional properties,and electro-catalytic approaches for H_(2) production via electrochemical reactions.Furthermore,challenges and future prospects in designing MXenes-based electrocatalysts with enhanced kinetics are highlighted,emphasizing the potential of incorporating different metals to expand the scope of electrochemical reactions.This review suggests possible efforts for developing advanced MXenes-based electrocatalysts,particularly for efficient H_(2) generation through electrochemical water-splitting reactions..
基金supported by Universiti Kebangsaan Malaysia [Grant No.DIP-2016-031]CRIM(Center for Research and Instrumentation Management,UKM)for sponsoring the postgraduate study of W.C.Chong via Research University Zamalah Scheme and the technical supports in this work.
文摘Microalgae cultivation has gained tremendous attention in recent years due to its great potential in green biofuel production and wastewater treatment application. Membrane technology is a great solution in separating the microalgae biomass while producing high quality of permeate for recycling. The main objective of this study was to investigate the filtration performance of Ag/GO-PVDF(silver/graphene oxide-polyvinylidene fluoride) membrane in an algalmembrane photoreactor(A-MPR) by benchmarking with a commercial PVDF(com-PVDF) membrane. In this study, Chlorella vulgaris microalgae was cultivated in synthetic wastewater in an A-MPR for ammoniacal-nitrogen and phosphorus recovery and the wastewater was further filtered using Ag/GO-PVDF and com-PVDF membranes to obtain high quality water. Spectrophotometer was used to analyze the chemical oxidation demand(COD), ammoniacal nitrogen(NH3-N) and phosphate(PO43-). The concentration of proteins and carbohydrates was measured using Bradford method and phenol-sulfuric acid method, respectively. The COD of the synthetic wastewater was reduced from(180.5 ± 5.6) ppm to(82 ± 2.6) ppm due to nutrient uptake by microalgae. Then, the Ag/GO-PVDF membrane was used to further purify the microalgae cultivated wastewater, resulting in a low COD permeate of(31 ± 4.6) ppm. The high removal rate of proteins(100%) and carbohydrates(86.6%) as the major foulant in microalgae filtration, with low membrane fouling propensity of Ag/GO-PVDF membrane is advantageous for the sustainable development of the microalgae production. Hence, the integrated A-MPR system is highly recommended as a promising approach for microalgae cultivation and wastewater polishing treatment.
基金the AICTE,New Delhi,for providing the financial support necessary to carry out this workthe partial support of the University of Malaya,Ministry of Higher Education High Impact Research(UM.C/HIR/MOHE/ENG/20)
文摘The present paper describes the statistical modeling and optimization of a multistage gas-solid fluidized bed reactor for the control of hazardous pollutants in flue gas. In this work, we study the hydrodynamics of the pressure drop and minimum fluidization velocity. The hydrodynamics of a three-stage fluidized bed are then compared with those for a single-stage unit. It is observed that the total pressure drop over all stages of the three-stage fluidized bed is less than that of an identical single-stage system. However, the minimum fluidization velocity is higher in the single-stage unit. Under identical conditions, the minimum fluidization velocity is highest in the top bed, and lowest in the bottom bed. This signifies that the behavior of solids changes from a well-mixed flow to a plug-flow, with intermediate behavior in the middle bed.
基金the Ministry of Higher Education Malaysia through the Fundamental Research Grant Scheme(No.FRGS/1/2019/TK10/UMS/02/3)the Universiti Malaysia Sabah through the Niche Fund Scheme(No.SDN0071-2019).
文摘Conventional plastics exacerbate climate change by generating substantial amounts of greenhouse gases and solid wastes throughout their lifecycle.To address the environmental and economic challenges associated with petroleum-based plastics,bioplastics have emerged as a viable alternative.Bioplastics are a type of plastic that are either biobased,biodegradable,or both.Due to their biodegradability and renewability,bioplastics are established as earth-friendly materials that can replace nonrenewable plastics.However,early bioplastic development has been hindered by higher production costs and inferior mechanical and barrier properties compared to conventional plastics.Nevertheless,studies have shown that the addition of additives and fillers can enhance bioplastic properties.Recent advancements in bioplastics have incorporated special additives like antibacterial,antifungal,and antioxidant agents,offering added values and unique properties for specific applications in various sectors.For instance,integrating antibacterial additives into bioplastics enables the creation of active food packaging,extending the shelf-life of food by inhibiting spoilage-causing bacteria and microorganisms.Moreover,bioplastics with antioxidant additives can be applied in wound dressings,accelerating wound healing by preventing oxidative damage to cells and tissues.These innovative bioplastic developments offer promising opportunities for developing sustainable and practical solutions in various fields.Within this review are two main focuses:an outline of the bioplastic classifications to understand how they fit in as the coveted conventional plastics substitute and an overview of the recent bioplastic innovations in the antibacterial,antifungal,and antioxidant applications.We cover the use of different polymers and additives,presenting the findings and potential applications within the last decade.Although current research primarily focuses on food packaging and biomedicine,the exploration of bioplastics with specialized properties is still in its early stages,offering a wide range of undiscovered opportunities.
基金This study received no specific funding from public,commercial or not-for-profit funding agencies.
文摘Lignocellulosic biomass especially,sugarcane bagasse Saccharum barberi sp.,appears to be a more suitable material for partial substi-tution of transport fuel(diesel)than Saccharum officinarum sp.,due to its structural similarity to transport fuel(diesel).Besides that,less research has been implemented on this type of species.Bio-oil can be implemented as biodiesel by processing it further using chemical reactions such as hydrodeoxygenation and cracking with zeolite catalyst.Hence,the purpose of this study is to determine the compatibility of pyrolytic bio-oil produced from Saccharum barberi sp.in comparison with S.officinarum sp.for use as transport fuel(diesel)in automotive applications.This purpose can be accomplished by comparing the oil’s bio-physiochemical properties for both species.The experiment is conducted on a bench-scale on which bio-oil of Saccharum barberi sp.is secured from the catalytic pyrolysis process at a temperature of 500°C and heating rate of 50°C/min with the addition of ZSM-Zeolite catalyst.Thermogravimetric analysis of Saccharum barberi sp.reveals that cellulose is more reactive than lignin,evidenced by the high percentage of weight loss at tem-peratures ranging from 251°C to 390°C.The high contents of carbon(40.7%)and hydrogen(6.50%),as well as slight traces of sulphur(0.08%)and nitrogen(0.85%),in bio-oil(Saccharum barberi sp.)indicate that it is conceivable to be partially used for replacement in biofuel production.Overall physiochemical properties reveal that Saccharum barberi sp.shows more potential than S.officinarum sp.Gas chromatography-mass spectrometry analysis reveals that bio-oil consists of high amounts of aromatic hydrocarbon(26.2%),phenol(14.8%)and furfural(13.0%)in comparison to S.officinarum sp.
