The electrochemical deposition technique was applied to achieve porous silicon （PS） surface passivated with Ag deposition for improving the properties of PS photoluminescence. The relation of Ag depositing forms to ...The electrochemical deposition technique was applied to achieve porous silicon （PS） surface passivated with Ag deposition for improving the properties of PS photoluminescence. The relation of Ag depositing forms to current density and the effect of PS hydrophilic surface on deposition uniformity were investigated. The experimental results indicated that there were two critical current densities （maximum and minimum） in which Ag was absent and electroplated on PS surface correspondingly, and the range of current density for deposition of Ag on porous silicon was from 50 μA/cm^2 to 400 μA/cm^2. The process of changing PS surface from hydrophobic into hydrophilic had positive effect on Ag deposition uniformity. Under the same experimental conditions, PS hydrophobic surface presented uneven Ag deposition.However, hydrophilic surface treated with SC-1 solution was even. Finally, the effect of PS surface passivation with Ag even deposition on photoluminescence intensity and stabilization of PS was studied. It was discovered that Ag passivation inhibited the degradation of PL intensity effectively. In addition, excessive Ag deposition had a quenching effect on room-temperature visible photoluminescence of PS.展开更多
Changes in the regulatory requirements and the forthcoming Disinfectant/Disinfection By-Products （D/DBP） Rule will require that drinking water treatment facilities be operated to achieve maximum removals of particle...Changes in the regulatory requirements and the forthcoming Disinfectant/Disinfection By-Products （D/DBP） Rule will require that drinking water treatment facilities be operated to achieve maximum removals of particles and disinfectant tolerant microorganisms as well as natural organic matter （NOM）. For drinking water production, the use of membrane filtration processes such as microfiltration and ultrafiltration （MF/UF） alone to satisfy the turbidity, particle and microorganism removal a requirement of the surface water treatment regulation （SWTR） is not enough. MF/UF treatment processes can achieve only nominal （10 percent） removal of disinfection by-products （DBP） precursors （James, et al., 1995）. On the other hand, too fast fouling can make the filtration processes more difficult to carry on. To solve these problems, many authors have been interested in installing coagulation pretreatment before membrane filtration to improve membrane performance. However, previous studies reported conflicting results. Some supported the effectiveness of coagulation pretreatment, while others contended that coagulation aggravated membrane performance. This research aims to identify the effects of coagulation pretreatment on membrane filtration through a pilot study using PVDF membrane in combination with analyzing the rationale of coagulation. Another objective of this research was to evaluate the different impacts on membrane performance of using different membrane modules （the submerged module and pressured module）. The results showed that coagulation pretreatment greatly improved the membrane performance, extending the filtration time as well as reducing the permeated organic level, and that the submerged module is much more efficient than the pressured module.展开更多
Several macroporous polymeric adsorbents (NDA-999, XAD-8, X-5 and XAD-2) were employed in the study to adsorb phenylacetic acid from aqueous solution. Effect of salt and ambient temperature on adsorption was studied u...Several macroporous polymeric adsorbents (NDA-999, XAD-8, X-5 and XAD-2) were employed in the study to adsorb phenylacetic acid from aqueous solution. Effect of salt and ambient temperature on adsorption was studied using NDA-999 adsorbent and the adsorption process conforms to Freundlich抯 model reasonably. Adsorption dynamics were conducted in batch experiments in order to make clear the mechanism of adsorption process. It is proved that the squared driving force mass transfer model can be adopted to elucidate the process. The treatment process of industrial wastewater containing high strength of phenylacetic acid was proposed for cleaner production of phenylacetic acid.展开更多
Leaching behavior of individual ions from three saline soils （S1 = 85.0 dS/m, S2 = 53.92 dS/m and S3 = 38.14 dS/m） under magnetic water （MW） treatment or non-magnetized well water （WW） was investigated in column...Leaching behavior of individual ions from three saline soils （S1 = 85.0 dS/m, S2 = 53.92 dS/m and S3 = 38.14 dS/m） under magnetic water （MW） treatment or non-magnetized well water （WW） was investigated in column study. After five pore volumes, soil electrical conductivity （EC） decreased to a range between 2.99-3.29 dS/m under the two water treatments. The rate of soluble cations leached was Na＋ 〉 Ca2＋ 〉 Mg2＋ 〉 K＋ and CI- 〉 SO42- 〉 HCO3- for anions under the two water treatments. The greater amount of salt leached was during the first two pore volumes and was higher under MW treatment. Among soils, the higher the initial EC, the greater the amount of the salt leached. Measurements of the exchangeable Na~ performed at the end of leaching experiment showed a high decrease in soil exchangeable Na＋ compared to the initial values of sodium adsorption ratio （SAR） and exchangeable sodium percentage （ESP） in the soil indicated that there was no prospects of soil sodification after leaching with five pore volumes.展开更多
文摘The electrochemical deposition technique was applied to achieve porous silicon （PS） surface passivated with Ag deposition for improving the properties of PS photoluminescence. The relation of Ag depositing forms to current density and the effect of PS hydrophilic surface on deposition uniformity were investigated. The experimental results indicated that there were two critical current densities （maximum and minimum） in which Ag was absent and electroplated on PS surface correspondingly, and the range of current density for deposition of Ag on porous silicon was from 50 μA/cm^2 to 400 μA/cm^2. The process of changing PS surface from hydrophobic into hydrophilic had positive effect on Ag deposition uniformity. Under the same experimental conditions, PS hydrophobic surface presented uneven Ag deposition.However, hydrophilic surface treated with SC-1 solution was even. Finally, the effect of PS surface passivation with Ag even deposition on photoluminescence intensity and stabilization of PS was studied. It was discovered that Ag passivation inhibited the degradation of PL intensity effectively. In addition, excessive Ag deposition had a quenching effect on room-temperature visible photoluminescence of PS.
文摘Changes in the regulatory requirements and the forthcoming Disinfectant/Disinfection By-Products （D/DBP） Rule will require that drinking water treatment facilities be operated to achieve maximum removals of particles and disinfectant tolerant microorganisms as well as natural organic matter （NOM）. For drinking water production, the use of membrane filtration processes such as microfiltration and ultrafiltration （MF/UF） alone to satisfy the turbidity, particle and microorganism removal a requirement of the surface water treatment regulation （SWTR） is not enough. MF/UF treatment processes can achieve only nominal （10 percent） removal of disinfection by-products （DBP） precursors （James, et al., 1995）. On the other hand, too fast fouling can make the filtration processes more difficult to carry on. To solve these problems, many authors have been interested in installing coagulation pretreatment before membrane filtration to improve membrane performance. However, previous studies reported conflicting results. Some supported the effectiveness of coagulation pretreatment, while others contended that coagulation aggravated membrane performance. This research aims to identify the effects of coagulation pretreatment on membrane filtration through a pilot study using PVDF membrane in combination with analyzing the rationale of coagulation. Another objective of this research was to evaluate the different impacts on membrane performance of using different membrane modules （the submerged module and pressured module）. The results showed that coagulation pretreatment greatly improved the membrane performance, extending the filtration time as well as reducing the permeated organic level, and that the submerged module is much more efficient than the pressured module.
文摘Several macroporous polymeric adsorbents (NDA-999, XAD-8, X-5 and XAD-2) were employed in the study to adsorb phenylacetic acid from aqueous solution. Effect of salt and ambient temperature on adsorption was studied using NDA-999 adsorbent and the adsorption process conforms to Freundlich抯 model reasonably. Adsorption dynamics were conducted in batch experiments in order to make clear the mechanism of adsorption process. It is proved that the squared driving force mass transfer model can be adopted to elucidate the process. The treatment process of industrial wastewater containing high strength of phenylacetic acid was proposed for cleaner production of phenylacetic acid.
文摘Leaching behavior of individual ions from three saline soils （S1 = 85.0 dS/m, S2 = 53.92 dS/m and S3 = 38.14 dS/m） under magnetic water （MW） treatment or non-magnetized well water （WW） was investigated in column study. After five pore volumes, soil electrical conductivity （EC） decreased to a range between 2.99-3.29 dS/m under the two water treatments. The rate of soluble cations leached was Na＋ 〉 Ca2＋ 〉 Mg2＋ 〉 K＋ and CI- 〉 SO42- 〉 HCO3- for anions under the two water treatments. The greater amount of salt leached was during the first two pore volumes and was higher under MW treatment. Among soils, the higher the initial EC, the greater the amount of the salt leached. Measurements of the exchangeable Na~ performed at the end of leaching experiment showed a high decrease in soil exchangeable Na＋ compared to the initial values of sodium adsorption ratio （SAR） and exchangeable sodium percentage （ESP） in the soil indicated that there was no prospects of soil sodification after leaching with five pore volumes.
