酸碱改性活性炭吸附微污染水源水中的Ni^(2+)

Adsorption of Ni^(2+) from micro-polluted source water by acid-alkali-modified activated carbon

通过HNO_3-KOH对活性炭进行改性,采用扫面电镜(SEM)、比表面积分析(BET)、红外光谱分析(FT-IR)和Boehm滴定法对改性前后的活性炭进行表征,研究了改性前后的活性炭在不同条件下对微污染水源水中Ni^(2+)的吸附能力和动力学。结果表明:改性活性炭表面含氧酸性官能团数量增加,比表面积和总孔容均略有降低,孔径变化不明显。在Ni^(2+)浓度为0.4 mg·L^(-1),改性活性炭投加量5.0 g·L^(-1),温度30℃时,反应1 h去除率可达95.55%,剩余Ni^(2+)浓度为0.017 8 mg·L^(-1),达到《生活饮用水卫生标准》(GB5749-2006)中的要求。相同条件下,改性前活性炭对Ni^(2+)的去除率仅为74.45%,剩余Ni^(2+)浓度达不到标准要求。活性炭对Ni^(2+)的等温吸附更符合Langmuir方程,吸附动力学数据符合准二级动力学方程。

Activated carbon（ AC） was modified by HNO3-KOH and characterized by scanning electron microscopy,N2 Brunauer-Emmett-Teller（ BET） adsorption analysis,Fourier transform infrared spectrometry,and Boehm titration. The adsorption behavior of Ni^2＋ obtained from micro-polluted source water by AC and modified AC,under different conditions,was studied. More acidic oxygen-containing functional groups were observed on the surface,and the BET surface area and the total pore volume decreased slightly,with no obvious change in pore size after modification. With the addition of 5. 0 g·L^-1of modified AC,the Ni^2＋ removal efficiency after 1 h of reaction was 95. 55%,with the Ni^2＋ concentration decreasing from 0. 4 mg·L^-1to 0. 017 8 mg·L^-1. This was below the standard for the Standards for Drinking Water Quality in 2006（ GB5749-2006）,and only 74. 45% of Ni^2＋ was removed by AC under the same condition. The kinetic data were well described by the pseudo-second order model,and the equilibrium adsorption data fit better to the Langmuir model.