Liu Yang, Sun Changbin, Xu Jin, Li Youzhi
College of Life Science and Technology, Guangxi University, Nanning, Guangxi, PR China.
J Hazard Mater. 2009 Aug 30;168(1):156-62. doi: 10.1016/j.jhazmat.2009.02.009. Epub 2009 Feb 12.
Heavy metal removal from industrial wastewater is not only to protect living organisms in the environment but also to conserve resources such as metals and water by enabling their reuse. To overcome the disadvantage of high cost and secondary pollution by the conventional physico-chemical treatment techniques, environmentally benign and low-cost adsorbents are in demand. In this study, the use of raw and acid-pretreated bivalve mollusk shells (BMSs) to remove metals from aqueous solutions with single or mixed metal was evaluated at different BMSs doses, pH and temperatures in batch shaking experiments in laboratory conditions. When the BMSs were used to treat CuSO(4)x5H(2)O solution, the copper sorption capacities of the raw and acid-pretreated BMSs were approximately 38.93 mg/g and 138.95 mg/g, respectively. The copper removal efficiency (CRE) of the raw BMSs became greatly enhanced with increasing initial pH, reaching 99.51% at the initial pH 5. Conversely, the CRE of the acid-pretreated BMSs was maintained at 99.48-99.52% throughout the pH range of 1-5. Furthermore, the CRE values of the raw and acid-pretreated BMSs were not greatly changed when the temperature was varied from 15 degrees C to 40 degrees C. In addition, the CRE value of the raw BMSs was maintained for 12 cycles of sorption-desorption with a CRE of 98.4% being observed in the final cycle. Finally, when the BMSs were used to treat electroplating wastewater, the removal efficiencies (REs) of the raw BMSs were 99.97%, 98.99% and 87% for Fe, Zn and Cu, respectively, whereas the REs of the acid-pretreated BMSs were 99.98%, 99.43% and 92.13%, respectively. Ion exchange experiments revealed that one of mechanisms for metal sorption by the BMSs from aqueous solution is related to ion exchange, especially between the metal ions in the treated solution and Ca(2+) from BMSs. Infrared absorbance spectra analysis indicated that the acid pretreatment led to occurrence of the groups (i.e. -OH, -NH, C=O and S=O) of negative charge in treated BMSs. Scanning electron microscopy revealed that acid pretreatment enabled the used BMSs to form the flake-shaped structure with smooth surfaces that can supply a better interface for binding metal ions.
从工业废水中去除重金属不仅是为了保护环境中的生物，还能通过实现金属和水的再利用来节约资源。为了克服传统物理化学处理技术成本高和产生二次污染的缺点，对环境无害且低成本的吸附剂有需求。在本研究中，在实验室条件下通过分批振荡实验，评估了使用生的和酸预处理的双壳贝类贝壳（BMSs）在不同BMSs剂量、pH值和温度下从单一或混合金属水溶液中去除金属的效果。当使用BMSs处理CuSO₄·5H₂O溶液时，生的和酸预处理的BMSs对铜的吸附容量分别约为38.93mg/g和138.95mg/g。生的BMSs对铜的去除效率（CRE）随着初始pH值的增加而大幅提高，在初始pH值为5时达到99.51%。相反，酸预处理的BMSs在1 - 5的整个pH范围内CRE保持在99.48% - 99.52%。此外，当温度在15℃至40℃之间变化时，生的和酸预处理的BMSs的CRE值变化不大。另外，生的BMSs的CRE值在12次吸附 - 解吸循环中保持稳定，在最后一个循环中观察到的CRE为98.4%。最后，当使用BMSs处理电镀废水时，生的BMSs对铁、锌和铜的去除效率（REs）分别为99.97%、98.99%和87%，而酸预处理的BMSs的REs分别为99.98%、99.43%和92.13%。离子交换实验表明，BMSs从水溶液中吸附金属的机制之一与离子交换有关，特别是处理溶液中的金属离子与BMSs中的Ca²⁺之间的离子交换。红外吸收光谱分析表明，酸预处理导致处理后的BMSs中出现带负电荷的基团（即 -OH、-NH、C = O和S = O）。扫描电子显微镜显示，酸预处理使使用过的BMSs形成表面光滑的片状结构，可为结合金属离子提供更好的界面。
