Department of Hydraulics Geotechnics and Environmental Engineering, University of Naples Federico II, Via Claudio 21, 80125 Naples, Italy.
J Environ Manage. 2013 Mar 15;117:1-6. doi: 10.1016/j.jenvman.2012.12.012. Epub 2013 Jan 17.
Results of a lab-scale experimental study are presented that aim to verify the use of ground shrimp shells, not otherwise conditioned, as an adsorbent material to remove chromium(III) from tannery wastewater. The obtained removal efficiency is found to be always over 90%, confirming the capacity of the tested materials to remove chromium(III). The adsorption process is well described by the Brauner-Emmett-Teller isotherm, indicating the existence of both weak and strong adsorption sites inside the shells. Kinetic tests allow to verify that the removal process takes place rapidly during the first 2 h and then tends to reach a plateau: the pseudo second-order model is found to be able to simulate with good approximation, the adsorption process. Analyses comparing the treatment process using shrimp shells vs. other chemical products frequently used for chromium removal, supported by microscopic observations, indicate that the efficiency obtained using shrimp shell is comparable to the efficiency obtained using sodium bicarbonate and sodium hydroxide, but the removal mechanism is different as the adsorption on the polysaccharidic matrix of the shells prevails over the precipitation of chromium salts. The skin tanned with recovered chromium is found to be of low quality; on the contrary satisfying tanning results are obtained using, as tanning agent, the sludge produced by the adsorption process without any further treatment, except for pH correction.
本文介绍了一项实验室规模的实验研究结果，旨在验证未经预处理的虾壳作为吸附材料从制革废水中去除三价铬的应用潜力。研究发现，三价铬的去除效率始终超过 90%，证实了所测试材料去除三价铬的能力。吸附过程可用 Brunauer-Emmett-Teller 等温线很好地描述，表明壳内存在弱和强吸附位。动力学测试表明，去除过程在前 2 小时内迅速发生，然后趋于达到平台：发现准二级模型能够很好地模拟吸附过程。通过微观观察支持的分析比较了使用虾壳与其他常用于去除铬的化学产品的处理工艺，表明使用虾壳获得的效率可与使用碳酸氢钠和氢氧化钠获得的效率相媲美，但去除机制不同，因为壳多糖基质上的吸附作用超过了铬盐的沉淀。使用回收的铬鞣制的皮革质量较低；相反，使用吸附过程产生的污泥作为鞣剂，无需进一步处理，除了 pH 值校正外，可获得令人满意的鞣制效果。
