载Ca磁性碳纳米管对水中腐殖酸的去除

Removal of humic acid from aqueous solutions by magnetic MWCNTs coated calcium

采用化学共沉淀一步法以钙盐和铁盐对多壁碳纳米管(MWCNTs)改性以制备具有去除水中微污染物腐殖酸的磁性碳纳米管复合材料。X射线能谱分析表明改性MWCNTs上载有Ca和Fe元素。通过振动样品磁强计测得该复合材料具有较强磁性。改性后的MWCNTs 30 min对水中腐殖酸的去除率由改性前的63.89%提高到90.27%。研究了改性MWCNTs投加量、腐殖酸初始浓度、吸附时间、振荡速度、pH及温度对水中腐殖酸去除的影响。结果表明,腐殖酸去除率随着载Ca磁性MWCNTs投加量增大而提高。吸附量随着腐殖酸初始浓度的增大而增加,但去除率却减小。吸附初期腐殖酸去除速率快,0.5 g·L^(-1)的载Ca磁性多壁碳纳米管在腐殖酸初始浓度为20 mg·L^(-1)时,5 h达到吸附平衡,平衡吸附量为39.41mg·g^(-1)。腐殖酸去除率随着振荡速度的增大而增大,在225 r·min^(-1)时达最大,随后随着振荡速度的增大而缓慢下降。在弱酸性下,腐殖酸去除率较高,当pH为5时,腐殖酸去除率达到92.24%;当pH<5时,酸性加强,腐殖酸去除率下降;当pH>5时,腐殖酸去除率随pH增大呈下降趋势。腐殖酸去除率随着温度的升高而降低。

Multiwalled carbon nanotubes（ MWCNTs） were modified using a one-step chemical coprecipitation method with calcium and ferric salt to prepare magnetic MWCNTs coated in calcium for the purpose of removing micro-polluted humic acid（ HA） from an aqueous solution. The components of the modified MWCNTs were analyzed by an X-ray energy dispersive spectrometer（ EDS）,and the results showed the presence of Ca and Fe on the modified MWCNTs. Magnetism detection showed that the magnetism of the composite material was higher. The rate of HA removal in 30 minutes increased from 63. 89% for raw MWCNTs to 90. 27% for modified MWCNTs.In addition,the effects of modified MWCNT dosage,HA initial concentration,adsorption time,oscillation velocity,p H,and temperature on HA removal rate in micro-polluted water were studied. The results showed that the removal rate increased with the increase of the dosage. The adsorption quantity increased with an increase in the initial concentration of HA,but the removal rate decreased. The removal speed was very fast during the initial period of adsorption. After 5 hours,it reached adsorption equilibrium,in which the adsorption quantity was 39. 41mg·g^-1at a HA concentration of 20 mg·L^-1and modified MWCNTs dosage of 0. 5 g·L^-1. The HA removal rate increased with the increase in vibration speed,and reached a maximum at 225 r ·min^-1,and decreased subsequently. The removal rate of HA was high in weak acid conditions,and reached a maximum of 92. 24% at pH 5 and decreased on either side of pH 5. The HA removal rate decreased with an increase in temperature.