Three-dimensional(3D)porous absorbents have attracted significant attention in the oily wastewater treatment technology due to their high porosity and elasticity.Given their amphiphilic surface,they have a propensity ...Three-dimensional(3D)porous absorbents have attracted significant attention in the oily wastewater treatment technology due to their high porosity and elasticity.Given their amphiphilic surface,they have a propensity to simultaneously absorb water and oil,which restricts their range of applications.In this study,a reduced graphene oxide and titanium dioxide nanocomposite(rGO/TiO_(2))was used to fabricate an ultra-hydrophobic melamine sponge(MS)through interfacial modification using a solution immersion technique.To further modify it,poly-dimethylsiloxane(PDMS)was grafted onto its surface to establish stronger covalent bonds with the composite.The water contact angle of the sponge(rGO/TiO_(2)/PDMS/MS)was 164.2°,which satisfies the condition for ultrahydrophobicity.The evidence of its water repellency was demonstrated by the Cassie-Baxter theory and the lotus leaf effect.As a result of the increased density of rGO/TiO_(2)/PDMS/MS,it recorded an initial capacity that was 2 g/g lower than the raw MS for crude oil absorption.The raw MS retained 53% of its initial absorption capacity after 20 cycles of absorption,while rGO/TiO_(2)/PDMS/MS retained 97%,suggesting good recyclability.Excellent oil and organic solvent recovery(90%-96%)was demonstrated by rGO/TiO_(2)/PDMS/MS in oil-water combinations.In a continuous separation system,it achieved a remarkable separation efficiency of 2.4×10^(6)L/(m^(3)·h),and in turbulent emulsion separation,it achieved a demulsification efficiency of 90%-91%.This study provides a practical substitute for massive oil spill cleaning.展开更多
Ultrasonic field was applied in the treatment of oil emulsification wastewater by ZrO2 ceramic mem-brane. The permeate flux, rejection ratio in the filtration process and recovery ratio of flux in the membrane cleanin...Ultrasonic field was applied in the treatment of oil emulsification wastewater by ZrO2 ceramic mem-brane. The permeate flux, rejection ratio in the filtration process and recovery ratio of flux in the membrane cleaning process were measured. Great improvement in the permeate flux and rejection ratio have been observed for the membrane process enhanced by the ultrasonic field. The permeate flux of water through the membrane was about 210L.m^-2.h^-1 and the oil rejection ratio was over 99.9% under the optimal ultrasonic treatment conditions, which were 8W of ultrasonic power, 7cm of ultrasonic probe length introduced into the membrane channel and the same ultrasonic radiation direction as the wastewater flow. The resistance of the membrane process was compared between the cases with and without ultrasound, and the total resistance was reduced 68% by the use of ultrasound, Four methods including water cleaning, water cleaning under sonication, chemical cleaning and chemical cleaning under sonication were used to recover membrane flux. It was found that the flux recovery ratio increased with the increase of ultrasonic cleaning power. In addition, the use of chemical agents combining with ultrasonic irradiation showed a synergistic effect, which resulted in the highest cleaning efficiency and the shorter cleaning time.展开更多
Two nonfoaming bubble separation techniques, air stripping and solvent sublation, are presented and discussed in order to recover butyl acetate (BA) from discharged wastewater after solvent extraction of penicillin. R...Two nonfoaming bubble separation techniques, air stripping and solvent sublation, are presented and discussed in order to recover butyl acetate (BA) from discharged wastewater after solvent extraction of penicillin. Results show air stripping is not suitable for the recovery of BA from the wastewater. Axial concentration of BA had a noted maximum point along the column. In contrast, solvent sublation is very effective to recover BA from the wastewater. In solvent sublation experiments, axial concentration of BA along the column first increased and then decreased from the bottom to the top because of two primary mass transport processes. One is the transport by adsorption or attachment to ascending bubbles, and the other is by dispersion at water-solvent interface and by water film in organic solvent layer. In order to elucidate the high removal efficiency in solvent sublation, the microstructure of the wastewater was studied with optic microscope, which was showed to be an emulsion of BA in water at large concentration of BA. Solvent sublation can be successfully used in the removal of BA from its emulsion in the wastewater. The surface tension of simulated solution composed of lysozyme and BA was studied to understand mutual effect of biological materials and BA. Results show that lysozyme affects the adsorption of BA at air-water interface and they may form a complex between BA and lysozyme molecules.展开更多
Two new integrated processes, gas-energy-management （GEM）—electrochemical catalytic oxidation （ECO）—membrane bioreactor （MBR） and ultrafiltration （UF）—ECO—MBR, in industrial-scale test for treating cold-ro...Two new integrated processes, gas-energy-management （GEM）—electrochemical catalytic oxidation （ECO）—membrane bioreactor （MBR） and ultrafiltration （UF）—ECO—MBR, in industrial-scale test for treating cold-rolling mill emulsion wastewater with water quantity of 200 L/h to 3000 L/h were studied. The former was put forward firstly and the latter was applied initially in this field. The operation conditions and mechanisms of each module in the integrated processes were analyzed and the influences of operational parameters of two processes on chemical oxygen demand （CODCr） removal efficiency were comparatively investigated. The test results showed that the ultimate water quality from the two processes after treatment could meet the requirement for reuse.However, the quality of effluent treated by GEM—ECO—MBR was more stable than that of UF—ECO—MBR.展开更多
基金supported by the Universiti Brunei Darussalam Research Funding(Grant No.UBD/OAVCRI/CRGWG(022)/171001).
文摘Three-dimensional(3D)porous absorbents have attracted significant attention in the oily wastewater treatment technology due to their high porosity and elasticity.Given their amphiphilic surface,they have a propensity to simultaneously absorb water and oil,which restricts their range of applications.In this study,a reduced graphene oxide and titanium dioxide nanocomposite(rGO/TiO_(2))was used to fabricate an ultra-hydrophobic melamine sponge(MS)through interfacial modification using a solution immersion technique.To further modify it,poly-dimethylsiloxane(PDMS)was grafted onto its surface to establish stronger covalent bonds with the composite.The water contact angle of the sponge(rGO/TiO_(2)/PDMS/MS)was 164.2°,which satisfies the condition for ultrahydrophobicity.The evidence of its water repellency was demonstrated by the Cassie-Baxter theory and the lotus leaf effect.As a result of the increased density of rGO/TiO_(2)/PDMS/MS,it recorded an initial capacity that was 2 g/g lower than the raw MS for crude oil absorption.The raw MS retained 53% of its initial absorption capacity after 20 cycles of absorption,while rGO/TiO_(2)/PDMS/MS retained 97%,suggesting good recyclability.Excellent oil and organic solvent recovery(90%-96%)was demonstrated by rGO/TiO_(2)/PDMS/MS in oil-water combinations.In a continuous separation system,it achieved a remarkable separation efficiency of 2.4×10^(6)L/(m^(3)·h),and in turbulent emulsion separation,it achieved a demulsification efficiency of 90%-91%.This study provides a practical substitute for massive oil spill cleaning.
基金Supported by the Special Funds for Major State Basic Research Program of China （973 Program, No.2003CB615707） and the National Natural Science Foundation of China （No.20436030）.
文摘Ultrasonic field was applied in the treatment of oil emulsification wastewater by ZrO2 ceramic mem-brane. The permeate flux, rejection ratio in the filtration process and recovery ratio of flux in the membrane cleaning process were measured. Great improvement in the permeate flux and rejection ratio have been observed for the membrane process enhanced by the ultrasonic field. The permeate flux of water through the membrane was about 210L.m^-2.h^-1 and the oil rejection ratio was over 99.9% under the optimal ultrasonic treatment conditions, which were 8W of ultrasonic power, 7cm of ultrasonic probe length introduced into the membrane channel and the same ultrasonic radiation direction as the wastewater flow. The resistance of the membrane process was compared between the cases with and without ultrasound, and the total resistance was reduced 68% by the use of ultrasound, Four methods including water cleaning, water cleaning under sonication, chemical cleaning and chemical cleaning under sonication were used to recover membrane flux. It was found that the flux recovery ratio increased with the increase of ultrasonic cleaning power. In addition, the use of chemical agents combining with ultrasonic irradiation showed a synergistic effect, which resulted in the highest cleaning efficiency and the shorter cleaning time.
基金Supported by the National Natural Science Foundation of China (No. 20406021, No. 20236050 and No. 20221603).
文摘Two nonfoaming bubble separation techniques, air stripping and solvent sublation, are presented and discussed in order to recover butyl acetate (BA) from discharged wastewater after solvent extraction of penicillin. Results show air stripping is not suitable for the recovery of BA from the wastewater. Axial concentration of BA had a noted maximum point along the column. In contrast, solvent sublation is very effective to recover BA from the wastewater. In solvent sublation experiments, axial concentration of BA along the column first increased and then decreased from the bottom to the top because of two primary mass transport processes. One is the transport by adsorption or attachment to ascending bubbles, and the other is by dispersion at water-solvent interface and by water film in organic solvent layer. In order to elucidate the high removal efficiency in solvent sublation, the microstructure of the wastewater was studied with optic microscope, which was showed to be an emulsion of BA in water at large concentration of BA. Solvent sublation can be successfully used in the removal of BA from its emulsion in the wastewater. The surface tension of simulated solution composed of lysozyme and BA was studied to understand mutual effect of biological materials and BA. Results show that lysozyme affects the adsorption of BA at air-water interface and they may form a complex between BA and lysozyme molecules.
基金Item Sponsored by Preferred Scientific Research Foundation for Returned Overseas Chinese Scholars,Ministry of Human Resources and Social Security of China ([2007]170)
文摘Two new integrated processes, gas-energy-management （GEM）—electrochemical catalytic oxidation （ECO）—membrane bioreactor （MBR） and ultrafiltration （UF）—ECO—MBR, in industrial-scale test for treating cold-rolling mill emulsion wastewater with water quantity of 200 L/h to 3000 L/h were studied. The former was put forward firstly and the latter was applied initially in this field. The operation conditions and mechanisms of each module in the integrated processes were analyzed and the influences of operational parameters of two processes on chemical oxygen demand （CODCr） removal efficiency were comparatively investigated. The test results showed that the ultimate water quality from the two processes after treatment could meet the requirement for reuse.However, the quality of effluent treated by GEM—ECO—MBR was more stable than that of UF—ECO—MBR.
