The pretreatment for the removal of small molecules from poly(acrylic acid) sodium (PAAS) solution by continuous diafiltration was investigated using ultrafiltration membrane. The effects of PAAS concentration, pH, tr...The pretreatment for the removal of small molecules from poly(acrylic acid) sodium (PAAS) solution by continuous diafiltration was investigated using ultrafiltration membrane. The effects of PAAS concentration, pH, trans-membrane pressure and pretreatment time on the permeate concentration and permeate flux were studied. The results show that the necessary pretreatment time (NPT) increases with PAAS concentration, decreases with TMP. The change trend of permeate flux with time is affected by pH. The permeate fluxes rapidly decrease from the start, and then increase gradually to stable values at pH 5.0, pH 7.0 and pH 9.3. However, it decreases gradually with time till a state value at pH 3.0 (iso-electric point, IEP). The removal of small molecules is easy at pH greater than iso-electric point (IEP). The change of filtration potential with time indicates the similar trend to that of permeation concentration, but the former is more convenient for indication of NPT.展开更多
The flocculation tests of four pure minerals(diaspore,kaolinite,illite,pyrophyllite)and bauxite ore were investigated by the sedimentation.The dispersion behavior of the four pure minerals shows a very good consistenc...The flocculation tests of four pure minerals(diaspore,kaolinite,illite,pyrophyllite)and bauxite ore were investigated by the sedimentation.The dispersion behavior of the four pure minerals shows a very good consistency with the variation of zeta potential.The concentrate with the mass ratio of Al2O3 to SiO2(m(Al2O3)/m(SiO2))8.90 and the recovery of Al2O3 86.98%is obtained from bauxite ore(m(Al2O3)/m(SiO2)=5.68)in pH range of 9.5-10.0 by using sodium carbonate(5 kg/t)and sodium polyacrylate(7 g/t)as dispersant and flocculant respectively.Sodium carbonate acts as both pH modifier and favorable dispersant for aluminosilicates.The high performance of sodium polyacrylate on flocculation for diaspore is contributed to the carboxyl of sodium polyacrylate that interacts with active Al sites on diaspore by chemical absorption,and the hydrogen bond effects between hydroxyl group of macromolecule and surface Al—OH on diaspore to accelerate the sedimentation of diaspore.展开更多
基金Projects(21176264,21476265)supported by the National Natural Science Foundation of China
文摘The pretreatment for the removal of small molecules from poly(acrylic acid) sodium (PAAS) solution by continuous diafiltration was investigated using ultrafiltration membrane. The effects of PAAS concentration, pH, trans-membrane pressure and pretreatment time on the permeate concentration and permeate flux were studied. The results show that the necessary pretreatment time (NPT) increases with PAAS concentration, decreases with TMP. The change trend of permeate flux with time is affected by pH. The permeate fluxes rapidly decrease from the start, and then increase gradually to stable values at pH 5.0, pH 7.0 and pH 9.3. However, it decreases gradually with time till a state value at pH 3.0 (iso-electric point, IEP). The removal of small molecules is easy at pH greater than iso-electric point (IEP). The change of filtration potential with time indicates the similar trend to that of permeation concentration, but the former is more convenient for indication of NPT.
基金Project(2005CB623701)supported by the Major State Basic Research Development Program of China
文摘The flocculation tests of four pure minerals(diaspore,kaolinite,illite,pyrophyllite)and bauxite ore were investigated by the sedimentation.The dispersion behavior of the four pure minerals shows a very good consistency with the variation of zeta potential.The concentrate with the mass ratio of Al2O3 to SiO2(m(Al2O3)/m(SiO2))8.90 and the recovery of Al2O3 86.98%is obtained from bauxite ore(m(Al2O3)/m(SiO2)=5.68)in pH range of 9.5-10.0 by using sodium carbonate(5 kg/t)and sodium polyacrylate(7 g/t)as dispersant and flocculant respectively.Sodium carbonate acts as both pH modifier and favorable dispersant for aluminosilicates.The high performance of sodium polyacrylate on flocculation for diaspore is contributed to the carboxyl of sodium polyacrylate that interacts with active Al sites on diaspore by chemical absorption,and the hydrogen bond effects between hydroxyl group of macromolecule and surface Al—OH on diaspore to accelerate the sedimentation of diaspore.
