Inefficient separation of inorganic salts and organic matters in crystallization mother liquor is still a problem to industrial wa stewater treatment since the high salinity significantly impedes organic pollutant deg...Inefficient separation of inorganic salts and organic matters in crystallization mother liquor is still a problem to industrial wa stewater treatment since the high salinity significantly impedes organic pollutant degradation by oxidation or incineration.In the study,acidification combined electrodialysis(ED)was attempted to effectively separate Cl-ions from organics in concentrate pulping wastewater.Membrane’s rejection rate to total organic carbon(TOC)was 85%at wastewater intrinsic pH=9.8 and enhanced to 93%by acidifying it to pH=2 in ED process.Negative-charged alkaline organic compounds(mainly lignin)could be liberated from their sodium salt forms and coagulated in acidification pretreatment.Neutralization of the organic substances also made their electro-migration less effective under electric driving force and in particular improved separation efficiency of chloride and organics.After acid-ED coupled treatment(pH=2 and J=40 mA·cm-2)[TOC]remarkably reduced from 1.315 g·L-1 to 0.048 g·L-1 and[Cl-]accumulated to 130 g·L-1 in concentrate solution.Recovery rate of NaCl was 89%and the power consumption was 0.38 kW·h·kg-1 NaCl.Irreversible fouling was not caused as electric resistance of membrane pile maintained stably.In conclusion,acidic-ED is a practical option to treat salinity organic wastewater when current techniques including thermal evaporation and pressure-driven membrane se paration present limitations.展开更多
In order to recover the SiO2 contained in the mother liquor in the course of NaY zeolite synthesis to minimize pollution, the influence of various preparation conditions on the filtering velocity of gel slurry was stu...In order to recover the SiO2 contained in the mother liquor in the course of NaY zeolite synthesis to minimize pollution, the influence of various preparation conditions on the filtering velocity of gel slurry was studied using the SiO2/Al2O3 gel recovered from the NaY mother liquor in the laboratory. The results of study had shown that at a SiO2/A12O3 ratio in the feed equating to 9:1 the SiO2 recovery rate and Al2O3utilization rate were high with a faster flow velocity of the filtrate. The pH value of the system had great impact on the flow velocity of filtrate. Between the two methods for regulating the pH value, the one for formation of silica/alumina gel slurry by addition of sulfuric acid prior to adding aluminium sulfate in the solution could secure a faster filtration velocity. The filtration velocity was decreased in tandem with increasing SiO2 concentration in mother liquor, meanwhile an increase in dry filter cake yield.展开更多
The mother liquor for preparing industrial HCN was investigated, to analyze the side-products’ structure and influence of molecular interactions of side-products with glycine and solvent on the glycine’s crystalliza...The mother liquor for preparing industrial HCN was investigated, to analyze the side-products’ structure and influence of molecular interactions of side-products with glycine and solvent on the glycine’s crystallization process. The side-products（SPs） were super-branched oligmers with plenty of hydrophilic groups, which could affect the crystallization process by interactions such as hydrogen bond. Alcohol-water mixed solvent with different polyols could be used to weaken the SPs-glycine interaction and strengthen the SPs-water interaction, which help to improve the crystallization efficiency and purity. After optimization, SPs’ mass fraction in glycine could be reduced by 80% and the morphology of crystal particles could also be improved.展开更多
Treatment to crystallization mother liquor containing high concentration of organic and inorganic substances is a challenge in zero liquid discharge of industrial wastewater.Acid precipitation coupled membrane-dispers...Treatment to crystallization mother liquor containing high concentration of organic and inorganic substances is a challenge in zero liquid discharge of industrial wastewater.Acid precipitation coupled membrane-dispersion advanced oxidation process(MAOP)was proposed for organics degradation before salt crystallization by evaporation.With acid-MAOP treatment CODCrin mother liquor of pulping wastewater was eliminated by 55.2%from ultrahigh initial concentration up to 12,500 mg·L^-1.The decolorization rate was 96.5%.Recovered salt was mainly NaCl(83.3 wt%)having whiteness 50 brighter than industrial baysalt of whiteness 45.The oxidation conditions were optimized as CO3=0.11 g·L^-1 and CH2O2=2.0 g·L^-1 with dispersing rate 0.53 ml·min^-1 for 100 min reaction toward acidified liquor of p H=2.Acidification has notably improved evaporation efficiency during crystallization.Addition of H2O2 made through membrane dispersion has eliminated hydroxyl radical"quench effect"and enhanced the degradation capacity,in particular,the breakage of carbon-chloride bonds(of both aliphatic and aromatic).As a result,the proposed coupling method has improved organic pollutant reduction so as the purity of salt from the wastewater mixture which can facilitate water and salt recycling in industry.展开更多
基金Supported by the Prosepective Joint Research Project of Jiangsu Province(BY2014005-06).
文摘Inefficient separation of inorganic salts and organic matters in crystallization mother liquor is still a problem to industrial wa stewater treatment since the high salinity significantly impedes organic pollutant degradation by oxidation or incineration.In the study,acidification combined electrodialysis(ED)was attempted to effectively separate Cl-ions from organics in concentrate pulping wastewater.Membrane’s rejection rate to total organic carbon(TOC)was 85%at wastewater intrinsic pH=9.8 and enhanced to 93%by acidifying it to pH=2 in ED process.Negative-charged alkaline organic compounds(mainly lignin)could be liberated from their sodium salt forms and coagulated in acidification pretreatment.Neutralization of the organic substances also made their electro-migration less effective under electric driving force and in particular improved separation efficiency of chloride and organics.After acid-ED coupled treatment(pH=2 and J=40 mA·cm-2)[TOC]remarkably reduced from 1.315 g·L-1 to 0.048 g·L-1 and[Cl-]accumulated to 130 g·L-1 in concentrate solution.Recovery rate of NaCl was 89%and the power consumption was 0.38 kW·h·kg-1 NaCl.Irreversible fouling was not caused as electric resistance of membrane pile maintained stably.In conclusion,acidic-ED is a practical option to treat salinity organic wastewater when current techniques including thermal evaporation and pressure-driven membrane se paration present limitations.
文摘In order to recover the SiO2 contained in the mother liquor in the course of NaY zeolite synthesis to minimize pollution, the influence of various preparation conditions on the filtering velocity of gel slurry was studied using the SiO2/Al2O3 gel recovered from the NaY mother liquor in the laboratory. The results of study had shown that at a SiO2/A12O3 ratio in the feed equating to 9:1 the SiO2 recovery rate and Al2O3utilization rate were high with a faster flow velocity of the filtrate. The pH value of the system had great impact on the flow velocity of filtrate. Between the two methods for regulating the pH value, the one for formation of silica/alumina gel slurry by addition of sulfuric acid prior to adding aluminium sulfate in the solution could secure a faster filtration velocity. The filtration velocity was decreased in tandem with increasing SiO2 concentration in mother liquor, meanwhile an increase in dry filter cake yield.
基金Supported by the National Natural Science Foundation of China(Nos.21006130,20806095)
文摘The mother liquor for preparing industrial HCN was investigated, to analyze the side-products’ structure and influence of molecular interactions of side-products with glycine and solvent on the glycine’s crystallization process. The side-products（SPs） were super-branched oligmers with plenty of hydrophilic groups, which could affect the crystallization process by interactions such as hydrogen bond. Alcohol-water mixed solvent with different polyols could be used to weaken the SPs-glycine interaction and strengthen the SPs-water interaction, which help to improve the crystallization efficiency and purity. After optimization, SPs’ mass fraction in glycine could be reduced by 80% and the morphology of crystal particles could also be improved.
基金Financial supports from the Prospective Joint Research Project of Jiangsu Province(BY2014005-06)National Natural Science Foundation of China(U1510202)the Jiangsu National Synergistic Innovation Center for Advanced Materials(SICAM)。
文摘Treatment to crystallization mother liquor containing high concentration of organic and inorganic substances is a challenge in zero liquid discharge of industrial wastewater.Acid precipitation coupled membrane-dispersion advanced oxidation process(MAOP)was proposed for organics degradation before salt crystallization by evaporation.With acid-MAOP treatment CODCrin mother liquor of pulping wastewater was eliminated by 55.2%from ultrahigh initial concentration up to 12,500 mg·L^-1.The decolorization rate was 96.5%.Recovered salt was mainly NaCl(83.3 wt%)having whiteness 50 brighter than industrial baysalt of whiteness 45.The oxidation conditions were optimized as CO3=0.11 g·L^-1 and CH2O2=2.0 g·L^-1 with dispersing rate 0.53 ml·min^-1 for 100 min reaction toward acidified liquor of p H=2.Acidification has notably improved evaporation efficiency during crystallization.Addition of H2O2 made through membrane dispersion has eliminated hydroxyl radical"quench effect"and enhanced the degradation capacity,in particular,the breakage of carbon-chloride bonds(of both aliphatic and aromatic).As a result,the proposed coupling method has improved organic pollutant reduction so as the purity of salt from the wastewater mixture which can facilitate water and salt recycling in industry.
