Sankararamakrishnan Nalini, Sharma Ajit Kumar, Sanghi Rashmi
Facility for Ecological and Analytical Testing, 302 Southern Laboratories, Indian Institute of Technology, Kanpur, U.P. 208016, India.
J Hazard Mater. 2007 Sep 5;148(1-2):353-9. doi: 10.1016/j.jhazmat.2007.02.043. Epub 2007 Feb 23.
Chitosan was chemically modified by introducing xanthate group onto its backbone using carbondisulfide under alkaline conditions. The chemically modified chitosan flakes (CMC) was used as an adsorbent for the removal of cadmium ions from electroplating waste effluent under laboratory conditions. CMC was found to be far more efficient than the conventionally used adsorbent activated carbon. The maximum uptake of cadmium by CMC in batch studies was found to be 357.14 mg/g at an optimum pH of 8.0 whereas for plain chitosan flakes it was 85.47 mg/g. Since electroplating wastewater contains cyanide in appreciable concentrations, interference of cyanide ions in cadmium adsorption was found to be very significant. This problem could be easily overcome by using higher doses of CMC, however, activated carbon was not found to be effective even at higher doses. Due to the high formation constant of cadmium with xanthate and adsorption was carried out at pH 8, cations like Pb(II), Cu(II), Ni(II) and Zn(II) did not interfere in the adsorption. Dynamics of the sorption process were studied and the values of rate constant of adsorption were calculated. Desorption of the bound cadmium from CMC was accomplished with 0.01 N H(2)SO(4). The data from regeneration efficiencies for 10 cycles evidenced the reusability of CMC in the treatment of cadmium-laden wastewater.
在碱性条件下，通过二硫化碳将黄原酸酯基团引入壳聚糖主链对其进行化学改性。在实验室条件下，将化学改性的壳聚糖薄片（CMC）用作吸附剂，用于去除电镀废水中的镉离子。结果发现，CMC的效率远高于传统使用的吸附剂活性炭。在分批研究中，CMC对镉的最大吸附量在最佳pH值8.0时为357.14 mg/g，而普通壳聚糖薄片为85.47 mg/g。由于电镀废水中含有相当浓度的氰化物，发现氰离子对镉吸附的干扰非常显著。然而，通过使用更高剂量的CMC可以轻松克服这个问题，而即使在更高剂量下，活性炭也未发现有效。由于镉与黄原酸酯的形成常数很高，且吸附在pH 8下进行，Pb(II)、Cu(II)、Ni(II)和Zn(II)等阳离子不会干扰吸附。研究了吸附过程的动力学，并计算了吸附速率常数的值。用0.01 N H₂SO₄实现了从CMC上解吸结合的镉。10个循环的再生效率数据证明了CMC在处理含镉废水方面的可重复使用性。
