The adsorption characteristics and mechanisms of the biosorbent from waste activated sludge were investigated by adsorbing Pb2＋and Zn2＋in aqueous single-metal solutions. A p H value of the metal solutions at 6.0 was...The adsorption characteristics and mechanisms of the biosorbent from waste activated sludge were investigated by adsorbing Pb2＋and Zn2＋in aqueous single-metal solutions. A p H value of the metal solutions at 6.0 was beneficial to the high adsorption quantity of the biosorbent. The optimal mass ratio of the biosorbent to metal ions was found to be 2. A higher adsorption quantity of the biosorbent was achieved by keeping the reaction temperature below 55°C. Response surface methodology was applied to optimize the biosorption processes, and the developed mathematical equations showed high determination coefficients（above 0.99 for both metal ions） and insignificant lack of fit（p = 0.0838 and 0.0782 for Pb2＋and Zn2＋, respectively）. Atomic force microscopy analyses suggested that the metal elements were adsorbed onto the biosorbent surface via electrostatic interaction. X-ray photoelectron spectroscopy analyses indicated the presence of complexation（between –NH2,-CN and metal ions） and ion-exchange（between –COOH and metal ions）. The adsorption mechanisms could be the combined action of electrostatic interaction, complexation and ion-exchange between functional groups and metal ions.展开更多
Adsorption is an important process in wastewater treatment,and conversion of waste materials to adsorbent offers a solution to high material cost related to the use of commercial activated carbon.This study investigat...Adsorption is an important process in wastewater treatment,and conversion of waste materials to adsorbent offers a solution to high material cost related to the use of commercial activated carbon.This study investigated the adsorption behaviour of Reactive Black 5（RB5）and methylene blue（MB）onto activated carbon produced from textile sludge（TSAC）.The activated carbon was synthesized through chemical activation of precursor followed with carbonization at 650℃ under nitrogen flow.Effects of time（0–200 min）,pH（2–10）,temperature（25–60℃）,initial dye concentration（0–200 mg·L^-1）,and adsorbent dosage（0.01–0.15 g）on dye removal efficiency were investigated.Preliminary screening revealed that TSAC synthesized via H2SO4activation showed higher adsorption behaviour than TSAC activated by KCl and ZnCl2.The adsorption capacity of TSAC was found to be 11.98 mg·g^-1（RB5）and 13.27 mg·g^-1（MB）,and is dependent on adsorption time and initial dye concentration.The adsorption data for both dyes were well fitted to Freundlich isotherm model which explains the heterogeneous nature of TSAC surface.The dye adsorption obeyed pseudo-second order kinetic model,thus chemisorption was the controlling step.This study reveals potential of textile sludge in removal of dyes from aqueous solution,and further studies are required to establish the applicability of the synthesized adsorbent for the treatment of waste water containing toxic dyes from textile industry.展开更多
Sewage sludge with the additive corn cob was used as prescusor to prepare sludge-based carbon adsorbents by pyrolysis method. And then, the carbonizated products were activated with potassium hydroxide. The mixing rat...Sewage sludge with the additive corn cob was used as prescusor to prepare sludge-based carbon adsorbents by pyrolysis method. And then, the carbonizated products were activated with potassium hydroxide. The mixing ratio of the corn cob to sewage sludge was investigated. The surface area and pore size distribution, elemental composition, surface chemistry structure and the surface physical morphology were determined and compared. The results demonstrated that the addition of corn cob into the sewage sludge sample could effectively improve the surface area （from 287 to 591 m 2 /g） and the microporosity （from 5% to 48%） of the carbon based adsorbent, thus enhancing the adsorption behavior. The sulfur dioxide adsorption capacity was measured according to breakthrough test. It was found that the sulfur dioxide adsorption capacity of the adsorbents was obviously enhanced after the addition of the corn cob. It is presumed that not only highly porous adsorbents, but also a high metallic content of these materials are required to achieve good performances.展开更多
Drinking water treatment sludge,characterized as accumulated suspended solids and organic and inorganic matter,is produced in large quantities during the coagulation process.The proper disposal,regeneration or reuse o...Drinking water treatment sludge,characterized as accumulated suspended solids and organic and inorganic matter,is produced in large quantities during the coagulation process.The proper disposal,regeneration or reuse of sludge is,therefore,a significant environmental issue.Reused sludge at low temperatures is an alternative method to enhance traditional coagulation efficiency.In the present study,the recycling mass of mixed sludge and properties of raw water （such as pH and turbidity） were systematically investigated to optimize coagulation efficiency.We determined that the appropriate dosage of mixed sludge was 60 mL/L,effective initial turbidity ranges were below 45.0 NTU,and optimal pH for DOMs and turbidity removal was 6.5-7.0 and 8.0,respectively.Furthermore,by comparing the flocs characteristics with and without recycling sludge,we found that floc structures with sludge were more irregular with average size growth to 64.7 μm from 48.1 μm.Recycling sludge was a feasible and successful method for enhancing pollutants removal,and the more irregular flocs structure after recycling might be caused by breakage of reused flocs and incorporation of powdered activated carbon into larger flocs structure.Applied during the coagulation process,recycling sludge could be significant for the treatment of low temperature and micro-polluted source water.展开更多
Solid–liquid separation is a vital step in drilling sludge disposal, and the filterability and settleability of drilling sludge are the main evaluating indicators for the separation process. The influence of Na^+,K^+...Solid–liquid separation is a vital step in drilling sludge disposal, and the filterability and settleability of drilling sludge are the main evaluating indicators for the separation process. The influence of Na^+,K^+,Mg^(2+),Ca^(2+),and Fe^(3+) on drilling sludge filterability and settleability was investigated in our research. The water content,filtration rate, supernatant volume and supernatant turbidity were measured to evaluate the filterability and settleability of drilling sludge. Meanwhile, the zeta potential, specific surface area of sludge flocs, particle size distribution and Fourier-transformed infrared spectra were employed to clarify the influencing mechanism.The experimental results showed that the filterability and settleability of drilling sludge were related to concentration and types of cations. Mg^(2+),Ca^(2+),and Fe^(3+) performed better than Na^+, K^+, and the cations with smaller hydrated radius got superior solid–liquid separation behavior at same valence. Finally, the spectra indicated that no chemical adsorption occurred between inorganic cations and drilling sludge flocs. The variation of surface charge and flocs growth after adding different inorganic cations were the reasons for the changes of the filterability and settleability.展开更多
Low-cost but high-efficiency composites of iron-containing porous carbons were prepared using sewage sludge and ferric salts as raw materials. Unlike previous time- and energy-consuming manufacturing procedures, this ...Low-cost but high-efficiency composites of iron-containing porous carbons were prepared using sewage sludge and ferric salts as raw materials. Unlike previous time- and energy-consuming manufacturing procedures, this study shows that pyrolyzing a mixture of sludge and ferric salt can produce suitable composites for lead adsorption. The specific surface area, the total pore volume and the average pore width of the optimal composite were 321 m^2/g, 0.25 cm^3/g, and 3.17 nm, respectively. X-ray diffraction analysis indicated that ferric salt favored the formation of metallic iron, while Fourier transform infrared spectroscopy revealed the formation of hydroxyl and carboxylic groups. The result of batch tests indicated that the adsorption capacity of carbons activated with ferric salt could be as high as 128.9 mg/g, while that of carbons without activation was 79.1 mg/g. The new manufacturing procedure used in this study could save at least 19.5 k J of energy per gram of activated carbon.展开更多
Excess phosphorus(P)in water can lead to eutrophication and upset ecological balance.In this study,biochar with ultrathin two-dimensional nanosheets from the natural mesocarp of shaddock was chosen as the carrier.The ...Excess phosphorus(P)in water can lead to eutrophication and upset ecological balance.In this study,biochar with ultrathin two-dimensional nanosheets from the natural mesocarp of shaddock was chosen as the carrier.The highly dispersed and small particle size of La(OH)_(3) on the surface of the nanosheets(MSBL3)was successfully achieved using chemical impregnation for the adsorption of P in aqueous solution,and the maximum adsorption capacity was 260.0 mg P g^(−1)[La].The differences in surface crystallization of La(OH)_(3) on biochar at different La loadings were analyzed using the high-precision characterization methods.After six adsorption-desorption cycles,MSBL3 retained 76.7%of its initial performance in terms of the P adsorption capacity.The preparation of 1 g of MSBL3 costs about RMB 1,and it could reduce the P concentration in 2.6 ton of Laoyu River water to below the eutrophication threshold;and the inhibitory effect of MSBL3 on the eutrophication of water bodies was confirmed by the growth state of water hyacinth.Furthermore,0.1 M MSBL3 could inhibit Escherichia coli and Staphylococcus aureus up to 98.7%and 85.0%,respectively,which indicates that MSBL3 can be used to recover P from water and also to improve water quality.In addition,the growth of the maize seedlings verified that the P-absorbed MSBL3 waste is a good soil fertilizer and can solve the problem of post-treatment of the adsorbent.In conclusion,MSBL3 prepared in this study is a promising P sorbent for application.展开更多
基金the support provided by China Scholarship Council, Sheng Yun-Fei College Students Scientific and Technological Innovation Fundthe National Science & Technology Pillar Program (No. 2013BAD21B03)
文摘The adsorption characteristics and mechanisms of the biosorbent from waste activated sludge were investigated by adsorbing Pb2＋and Zn2＋in aqueous single-metal solutions. A p H value of the metal solutions at 6.0 was beneficial to the high adsorption quantity of the biosorbent. The optimal mass ratio of the biosorbent to metal ions was found to be 2. A higher adsorption quantity of the biosorbent was achieved by keeping the reaction temperature below 55°C. Response surface methodology was applied to optimize the biosorption processes, and the developed mathematical equations showed high determination coefficients（above 0.99 for both metal ions） and insignificant lack of fit（p = 0.0838 and 0.0782 for Pb2＋and Zn2＋, respectively）. Atomic force microscopy analyses suggested that the metal elements were adsorbed onto the biosorbent surface via electrostatic interaction. X-ray photoelectron spectroscopy analyses indicated the presence of complexation（between –NH2,-CN and metal ions） and ion-exchange（between –COOH and metal ions）. The adsorption mechanisms could be the combined action of electrostatic interaction, complexation and ion-exchange between functional groups and metal ions.
基金the Ministry of Higher Education,Malaysia(MOHE)for the financial supports received under University Grant(08H05)and Fundamental Research Grant Scheme(4F872)Universiti Teknologi Malaysia for the GUP grant No.17H65the support to the main author,Wong Syie Luing,in the form of Post-Doctoral Fellowship Scheme for the project"Catalytic Cracking of Low Density Polyethylene Waste to Liquid Fuels in Fixed Bed Reactor"
文摘Adsorption is an important process in wastewater treatment,and conversion of waste materials to adsorbent offers a solution to high material cost related to the use of commercial activated carbon.This study investigated the adsorption behaviour of Reactive Black 5（RB5）and methylene blue（MB）onto activated carbon produced from textile sludge（TSAC）.The activated carbon was synthesized through chemical activation of precursor followed with carbonization at 650℃ under nitrogen flow.Effects of time（0–200 min）,pH（2–10）,temperature（25–60℃）,initial dye concentration（0–200 mg·L^-1）,and adsorbent dosage（0.01–0.15 g）on dye removal efficiency were investigated.Preliminary screening revealed that TSAC synthesized via H2SO4activation showed higher adsorption behaviour than TSAC activated by KCl and ZnCl2.The adsorption capacity of TSAC was found to be 11.98 mg·g^-1（RB5）and 13.27 mg·g^-1（MB）,and is dependent on adsorption time and initial dye concentration.The adsorption data for both dyes were well fitted to Freundlich isotherm model which explains the heterogeneous nature of TSAC surface.The dye adsorption obeyed pseudo-second order kinetic model,thus chemisorption was the controlling step.This study reveals potential of textile sludge in removal of dyes from aqueous solution,and further studies are required to establish the applicability of the synthesized adsorbent for the treatment of waste water containing toxic dyes from textile industry.
基金supported by the National Hi-Tech Research and Development Program (973) of China (No.2011CB201505, 2010CB732206)the National Natural Science Foundation of China (No.20907008)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education (No.20090092120010)support of the Foundation for Southeast University Excellent Young Teacher
文摘Sewage sludge with the additive corn cob was used as prescusor to prepare sludge-based carbon adsorbents by pyrolysis method. And then, the carbonizated products were activated with potassium hydroxide. The mixing ratio of the corn cob to sewage sludge was investigated. The surface area and pore size distribution, elemental composition, surface chemistry structure and the surface physical morphology were determined and compared. The results demonstrated that the addition of corn cob into the sewage sludge sample could effectively improve the surface area （from 287 to 591 m 2 /g） and the microporosity （from 5% to 48%） of the carbon based adsorbent, thus enhancing the adsorption behavior. The sulfur dioxide adsorption capacity was measured according to breakthrough test. It was found that the sulfur dioxide adsorption capacity of the adsorbents was obviously enhanced after the addition of the corn cob. It is presumed that not only highly porous adsorbents, but also a high metallic content of these materials are required to achieve good performances.
基金supported by the Important Project of Science and Technology for Water Pollution Control and Treatment (No:2009ZX07424-005-01)
文摘Drinking water treatment sludge,characterized as accumulated suspended solids and organic and inorganic matter,is produced in large quantities during the coagulation process.The proper disposal,regeneration or reuse of sludge is,therefore,a significant environmental issue.Reused sludge at low temperatures is an alternative method to enhance traditional coagulation efficiency.In the present study,the recycling mass of mixed sludge and properties of raw water （such as pH and turbidity） were systematically investigated to optimize coagulation efficiency.We determined that the appropriate dosage of mixed sludge was 60 mL/L,effective initial turbidity ranges were below 45.0 NTU,and optimal pH for DOMs and turbidity removal was 6.5-7.0 and 8.0,respectively.Furthermore,by comparing the flocs characteristics with and without recycling sludge,we found that floc structures with sludge were more irregular with average size growth to 64.7 μm from 48.1 μm.Recycling sludge was a feasible and successful method for enhancing pollutants removal,and the more irregular flocs structure after recycling might be caused by breakage of reused flocs and incorporation of powdered activated carbon into larger flocs structure.Applied during the coagulation process,recycling sludge could be significant for the treatment of low temperature and micro-polluted source water.
基金Supported by the National Natural Science Foundation of China(No.21376167)
文摘Solid–liquid separation is a vital step in drilling sludge disposal, and the filterability and settleability of drilling sludge are the main evaluating indicators for the separation process. The influence of Na^+,K^+,Mg^(2+),Ca^(2+),and Fe^(3+) on drilling sludge filterability and settleability was investigated in our research. The water content,filtration rate, supernatant volume and supernatant turbidity were measured to evaluate the filterability and settleability of drilling sludge. Meanwhile, the zeta potential, specific surface area of sludge flocs, particle size distribution and Fourier-transformed infrared spectra were employed to clarify the influencing mechanism.The experimental results showed that the filterability and settleability of drilling sludge were related to concentration and types of cations. Mg^(2+),Ca^(2+),and Fe^(3+) performed better than Na^+, K^+, and the cations with smaller hydrated radius got superior solid–liquid separation behavior at same valence. Finally, the spectra indicated that no chemical adsorption occurred between inorganic cations and drilling sludge flocs. The variation of surface charge and flocs growth after adding different inorganic cations were the reasons for the changes of the filterability and settleability.
基金supported by the National Key Technologies R&D Program of China(No.2012BAJ25B02)
文摘Low-cost but high-efficiency composites of iron-containing porous carbons were prepared using sewage sludge and ferric salts as raw materials. Unlike previous time- and energy-consuming manufacturing procedures, this study shows that pyrolyzing a mixture of sludge and ferric salt can produce suitable composites for lead adsorption. The specific surface area, the total pore volume and the average pore width of the optimal composite were 321 m^2/g, 0.25 cm^3/g, and 3.17 nm, respectively. X-ray diffraction analysis indicated that ferric salt favored the formation of metallic iron, while Fourier transform infrared spectroscopy revealed the formation of hydroxyl and carboxylic groups. The result of batch tests indicated that the adsorption capacity of carbons activated with ferric salt could be as high as 128.9 mg/g, while that of carbons without activation was 79.1 mg/g. The new manufacturing procedure used in this study could save at least 19.5 k J of energy per gram of activated carbon.
基金Special Project for Social Development of Yunnan Province(202103AC100001)Double-First Class University Plan(C176220100042)+1 种基金Scientific Research Fund Project of Yunnan Provincial Department of Education(2023Y0210)Graduate Student Funding of School of Ecology and Environmental Science,Yunnan University(Y2000229).
文摘Excess phosphorus(P)in water can lead to eutrophication and upset ecological balance.In this study,biochar with ultrathin two-dimensional nanosheets from the natural mesocarp of shaddock was chosen as the carrier.The highly dispersed and small particle size of La(OH)_(3) on the surface of the nanosheets(MSBL3)was successfully achieved using chemical impregnation for the adsorption of P in aqueous solution,and the maximum adsorption capacity was 260.0 mg P g^(−1)[La].The differences in surface crystallization of La(OH)_(3) on biochar at different La loadings were analyzed using the high-precision characterization methods.After six adsorption-desorption cycles,MSBL3 retained 76.7%of its initial performance in terms of the P adsorption capacity.The preparation of 1 g of MSBL3 costs about RMB 1,and it could reduce the P concentration in 2.6 ton of Laoyu River water to below the eutrophication threshold;and the inhibitory effect of MSBL3 on the eutrophication of water bodies was confirmed by the growth state of water hyacinth.Furthermore,0.1 M MSBL3 could inhibit Escherichia coli and Staphylococcus aureus up to 98.7%and 85.0%,respectively,which indicates that MSBL3 can be used to recover P from water and also to improve water quality.In addition,the growth of the maize seedlings verified that the P-absorbed MSBL3 waste is a good soil fertilizer and can solve the problem of post-treatment of the adsorbent.In conclusion,MSBL3 prepared in this study is a promising P sorbent for application.
