The structural changes of silicate anions in the desilication process with the addition of calcium hydrate alumino-carbonate were studied by measuring Raman spectra, infrared spectra and corresponding second derivativ...The structural changes of silicate anions in the desilication process with the addition of calcium hydrate alumino-carbonate were studied by measuring Raman spectra, infrared spectra and corresponding second derivative spectra. The results show that the desilication ratio in the solution prepared by the addition of sodium silicate(solution-SS) is much greater than that in the solution by the addition of green liquor(solution-GL), and low alumina concentration in the sodium aluminate solutions facilitates the desilication process. It is also shown that alumino-silicate anions in the solution-GL, and Q^3 polymeric silicate anions in solution-SS are predominant, respectively. In addition, increasing the concentration of silica favors respectively the formation of the alumino-silicate or the Q^3 silicate anions in the solution-GL or the solution-SS. Therefore, it can be inferred that the low desilication ratio in the silicate-bearing aluminate solution is mainly attributed to the existence of alumino-silicate anions.展开更多
Micellar enhanced ultrafiltration （MEUF） is a new effective treatment technology for the filtration removal of organic pollutants through solubilization. The present paper is aimed to study the solubilization of org...Micellar enhanced ultrafiltration （MEUF） is a new effective treatment technology for the filtration removal of organic pollutants through solubilization. The present paper is aimed to study the solubilization of organic compounds such as chlorobenzene （CB）, pyrene and phenol by anionic, cationic and mixed anionic-nonionic surfactants such as sodium dodecyl sulfate （SDS）, cetyltrimethylammonium bromide （CTMAB） and Tween-80 （TW80） and the mixed SDS-TW80 with a batch equilibrium method. This study enables us to supply deeper investigation for MEUF. The results showed that solubilization capacity was not obvious below the critical micellar concentration （CMC）. The apparent solubilities of organic compounds were linearly related to surfactant concentrations over their CMCs. Solubilization capacity by single surfactants follow the order of TW80 〉 CTMAB 〉 SDS. The results also proved that the solubilization of the organic contaminants by the mixed surfactants can significantly be enhanced compared with the single anionic surfactant SDS. Whereas the CMC can be decreased, the solubility can be increased as long as the mass ratio of nonionic surfactant increases. The solubility enhancement efficiency of the different organic compounds follow the order of phenol 〉 CB 〉 pyrene. In addition, the solubilization ratio appears to be positively relative to the intrinsic water solubility of the organic contaminants and negatively correlates to octanol-water coefficients （Kow） of organic compounds and the hydrophile-lypophile balance values （HLB） of the surfactants.展开更多
Strongly acidic soils （pH 〈 5.0） are detrimental to tea （Camellia sinensis） production and quality. Little information exists on the ability of surface amendments to ameliorate subsoil acidity in the tea garden s...Strongly acidic soils （pH 〈 5.0） are detrimental to tea （Camellia sinensis） production and quality. Little information exists on the ability of surface amendments to ameliorate subsoil acidity in the tea garden soils. A 120-d glasshouse column leaching experiment was conducted using commonly available soil ameliorants. Alkaline slag （AS） and organic residues, pig manure （PM） and rapeseed cake （RC） differing in ash alkalinity and C/N ratio were incorporated alone and in combination into the surface （0-15 cm） of soil columns （10 cm internal diameter x 50 cm long） packed with soil from the acidic soil layer （15-30 cm） of an Ultisol （initial pH -- 4.4）. During the 120-d experiment, the soil columns were watered （about 127 mm over 9 applications） according to the long-term mean annual rainfall （1 143 mm） and the leachates were collected and analyzed. At the end of the experiment, soil columns were partitioned into various depths and the chemical properties of soil were measured. The PM with a higher C/N ratio increased subsoil pH, whereas the RC with a lower C/N ratio decreased subsoil pH. However, combined amendments had a greater ability to reduce subsoil acidity than either of the amendments alone. The increases in pH of the subsoil were mainly ascribed to decreased base cation concentrations and the decomposition of organic anions present in dissolved organic carbon （DOC） and immobilization of nitrate that had been leached down from the amended layer. A significant （P 〈 0.05） correlation between alkalinity production （reduced exchangeable acidity - N-cycle alkalinity） and alkalinity balance （net alkalinity production - N-cycle alkalinity） was observed at the end of the experiment. Additionally, combined amendments significantly increased （P ~ 0.05） subsoil cation concentrations and decreased subsoil A1 saturation （P 〈 0.05）. Combined applications of AS with organic amendments to surface soils are effective in reducing subsoil acidity in high-rainfall areas. Further investigations under field conditions and over longer timeframes are needed to fully understand their practical effectiveness in ameliorating acidity of deeper soil layers under naturally occurring leaching regimes.展开更多
基金Project(51274242)supported by the National Natural Science Foundation of ChinaProject(2015CX001)supported by the Innovation-driven Plan in Central South University,China
文摘The structural changes of silicate anions in the desilication process with the addition of calcium hydrate alumino-carbonate were studied by measuring Raman spectra, infrared spectra and corresponding second derivative spectra. The results show that the desilication ratio in the solution prepared by the addition of sodium silicate(solution-SS) is much greater than that in the solution by the addition of green liquor(solution-GL), and low alumina concentration in the sodium aluminate solutions facilitates the desilication process. It is also shown that alumino-silicate anions in the solution-GL, and Q^3 polymeric silicate anions in solution-SS are predominant, respectively. In addition, increasing the concentration of silica favors respectively the formation of the alumino-silicate or the Q^3 silicate anions in the solution-GL or the solution-SS. Therefore, it can be inferred that the low desilication ratio in the silicate-bearing aluminate solution is mainly attributed to the existence of alumino-silicate anions.
文摘Micellar enhanced ultrafiltration （MEUF） is a new effective treatment technology for the filtration removal of organic pollutants through solubilization. The present paper is aimed to study the solubilization of organic compounds such as chlorobenzene （CB）, pyrene and phenol by anionic, cationic and mixed anionic-nonionic surfactants such as sodium dodecyl sulfate （SDS）, cetyltrimethylammonium bromide （CTMAB） and Tween-80 （TW80） and the mixed SDS-TW80 with a batch equilibrium method. This study enables us to supply deeper investigation for MEUF. The results showed that solubilization capacity was not obvious below the critical micellar concentration （CMC）. The apparent solubilities of organic compounds were linearly related to surfactant concentrations over their CMCs. Solubilization capacity by single surfactants follow the order of TW80 〉 CTMAB 〉 SDS. The results also proved that the solubilization of the organic contaminants by the mixed surfactants can significantly be enhanced compared with the single anionic surfactant SDS. Whereas the CMC can be decreased, the solubility can be increased as long as the mass ratio of nonionic surfactant increases. The solubility enhancement efficiency of the different organic compounds follow the order of phenol 〉 CB 〉 pyrene. In addition, the solubilization ratio appears to be positively relative to the intrinsic water solubility of the organic contaminants and negatively correlates to octanol-water coefficients （Kow） of organic compounds and the hydrophile-lypophile balance values （HLB） of the surfactants.
基金This study was supported by the National Natural Science Foundation of China （No. 41401336）, the Na- tural Science Foundation of Jiangsu Province, China （No. BK20130105）, the State Key Laboratory of Soil and Sustainable Agriculture, Chinese Academy of Sci-ence （No. Y412201452）, and the Environmental Pro- tection Public Benefit Research Foundation of China （No. 201309036）. We thank the three anonymous refe- rees for their helpful comments.
文摘Strongly acidic soils （pH 〈 5.0） are detrimental to tea （Camellia sinensis） production and quality. Little information exists on the ability of surface amendments to ameliorate subsoil acidity in the tea garden soils. A 120-d glasshouse column leaching experiment was conducted using commonly available soil ameliorants. Alkaline slag （AS） and organic residues, pig manure （PM） and rapeseed cake （RC） differing in ash alkalinity and C/N ratio were incorporated alone and in combination into the surface （0-15 cm） of soil columns （10 cm internal diameter x 50 cm long） packed with soil from the acidic soil layer （15-30 cm） of an Ultisol （initial pH -- 4.4）. During the 120-d experiment, the soil columns were watered （about 127 mm over 9 applications） according to the long-term mean annual rainfall （1 143 mm） and the leachates were collected and analyzed. At the end of the experiment, soil columns were partitioned into various depths and the chemical properties of soil were measured. The PM with a higher C/N ratio increased subsoil pH, whereas the RC with a lower C/N ratio decreased subsoil pH. However, combined amendments had a greater ability to reduce subsoil acidity than either of the amendments alone. The increases in pH of the subsoil were mainly ascribed to decreased base cation concentrations and the decomposition of organic anions present in dissolved organic carbon （DOC） and immobilization of nitrate that had been leached down from the amended layer. A significant （P 〈 0.05） correlation between alkalinity production （reduced exchangeable acidity - N-cycle alkalinity） and alkalinity balance （net alkalinity production - N-cycle alkalinity） was observed at the end of the experiment. Additionally, combined amendments significantly increased （P ~ 0.05） subsoil cation concentrations and decreased subsoil A1 saturation （P 〈 0.05）. Combined applications of AS with organic amendments to surface soils are effective in reducing subsoil acidity in high-rainfall areas. Further investigations under field conditions and over longer timeframes are needed to fully understand their practical effectiveness in ameliorating acidity of deeper soil layers under naturally occurring leaching regimes.
