Aravindhan Rathinam, Madhan Balaraman, Rao Jonnalagadda Raghava, Nair Balachandran Unni, Ramasami Thirumalachari
Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India.
Environ Sci Technol. 2004 Jan 1;38(1):300-6. doi: 10.1021/es034427s.
The presence of chromium in the effluent is a major concern for the tanning industry. Currently, chemical precipitation methods are practiced for the removal of chromium from the effluent, but that leads to the formation of chrome-bearing solid wastes. The other membrane separation and ion exchange methods available are unfeasible due to their cost. In this study, the removal of chromium from tannery effluent has been carried out using abundantly available brown seaweed Sargassum wightii. Simulated chrome tanning solution was used for the standardization of experimental trials. Various factors influencing the uptake of chromium, viz., quantity of seaweed, concentrations of chromium, pH of the chrome-bearing wastewater, and duration of treatment, have been studied. Chemical modification of the seaweed through pretreatment with sulfuric acid, magnesium chloride, and calcium chloride showed improved uptake of chromium. Langmuir and Freundlich isotherms have been fitted for various quantities of seaweed. The dynamic method of treatment of protonated seaweed with simulated chrome tanning solution at a pH of 3.5-3.8 for a duration of 6 h gave the maximum uptake of about 83%. A similar uptake has been established for commercial chrome tanning wastewater containing the same concentration of chromium. The Sargassum species exhibited a maximum uptake of 35 mg of chromium per gram of seaweed. Fourier transform infrared spectroscopy, energy-dispersive X-ray analysis, and flame photometry studies have been carried out to understand the mechanistic pathway for the removal of chromium. The potential reuse of chromium-containing seaweed for the preparation of basic chromium sulfate (tanning agent) has been demonstrated.
废水中铬的存在是制革行业主要关注的问题。目前，采用化学沉淀法从废水中去除铬，但这会导致含铬固体废物的形成。其他可用的膜分离和离子交换方法因成本问题不可行。在本研究中，利用大量可得的褐藻半叶马尾藻从制革废水中去除铬。使用模拟铬鞣溶液对实验进行标准化。研究了影响铬吸收的各种因素，即海藻数量、铬浓度、含铬废水的pH值和处理时间。通过用硫酸、氯化镁和氯化钙进行预处理对海藻进行化学改性，显示出铬的吸收有所改善。对不同数量的海藻拟合了朗缪尔等温线和弗伦德利希等温线。在pH为3.5 - 3.8的条件下，用模拟铬鞣溶液对质子化海藻进行6小时的动态处理方法，铬的最大吸收量约为83%。对于含有相同铬浓度的商业铬鞣废水也得到了类似的吸收情况。半叶马尾藻每克海藻对铬的最大吸收量为35毫克。进行了傅里叶变换红外光谱、能量色散X射线分析和火焰光度法研究，以了解铬去除的机理途径。已证明含铬海藻在制备碱式硫酸铬（鞣剂）方面的潜在再利用价值。
