Department of NREM, CSIR-CIMFR, Dhanbad, India.
Department of Chemistry, IIT(ISM), Dhanbad, India.
Int J Phytoremediation. 2021;23(8):791-808. doi: 10.1080/15226514.2020.1858399. Epub 2020 Dec 21.
In this study mixture of coconut shell and coir was used for Cr (VI) removal from synthetic wastewater and statistical tool Response Surface Modeling RSM) was applied to optimize process parameters. The solution pH (2-6), reaction time (20-100 minutes) and adsorbent quantity (0.03-0.2 g) was optimized to find the maximum response of Cr (VI) removal using statistical Box-Behnken design (BBD) software. The equilibrium data obtained by the batch experiment were analyzed by ANOVA and found fitted in a second-order polynomial equation through multiple regression analysis. The optimum value of pH, adsorbent quantity and reaction time for 99% of Cr(VI) was found as 2, 0.1 g and 100 minutes, respectively. By using non-linear regression method it was found that Freundlich isotherm and Pseudo-second-order kinetic with high correlation coefficient (), low Chi-square () and root mean squares errors (RMSE), best describe the adsorption of Cr (VI) on mixture of coconut shell and coir (MCSC) surface. Positive enthalpy (ΔH°) and negative Gibbs free energy (ΔG) values confirm the endothermic and spontaneous nature of adsorption process. Pre and post adsorption phenomenon was confirmed by characterization of adsorbent using AFM, FTIR, SEM, and EDX analysis. The adsorbent MCSC has regenerative property and can be reused 3-4 times after treating with alkaline medium (0.2 N NaOH) and offered more than 60% removal of Cr (VI) at the fourth cycle. It can be inferred based on this study that MCSC is an effective adsorbent for Cr (VI) removal and can be used on an industrial scale for social and environmental benefit. An agriculture waste mixture of coconut shell and coir (MCSC) without the addition of any chemical reagent, was used for Cr(VI) removal. As per literature survey and best of our knowledge, the adsorbent MCSC has not been reported for Cr (VI) removal. In the previous study, authors reported either coconut coir pith or coconut shell or coconut charcoal as adsorbent for Cr (VI) removal. The adsorbent MCSC is efficient even at very low doses (0.1 g) as compared to the reported adsorbent.
在这项研究中，椰壳和椰糠的混合物被用于从合成废水中去除六价铬，并应用统计工具响应面建模（RSM）来优化工艺参数。优化了溶液 pH 值（2-6）、反应时间（20-100 分钟）和吸附剂用量（0.03-0.2 克），以使用统计 Box-Behnken 设计（BBD）软件找到六价铬去除的最大响应。通过方差分析对批量实验获得的平衡数据进行了分析，并通过多元回归分析发现，这些数据符合二阶多项式方程。对于 99%的 Cr(VI)，最佳的 pH 值、吸附剂用量和反应时间值分别为 2、0.1g 和 100 分钟。通过使用非线性回归方法，发现 Freundlich 等温线和准二级动力学模型与高相关系数（）、低卡方（）和均方根误差（RMSE）最能描述 Cr(VI)在椰壳和椰糠混合物（MCSC）表面的吸附。正焓（ΔH°）和负吉布斯自由能（ΔG°）值证实了吸附过程的吸热和自发性质。通过 AFM、FTIR、SEM 和 EDX 分析对吸附剂进行表征，证实了吸附前后的现象。吸附剂 MCSC 具有再生性能，经碱性介质（0.2N NaOH）处理后可重复使用 3-4 次，在第 4 次循环时仍能去除超过 60%的 Cr(VI)。根据这项研究可以推断，MCSC 是一种有效的 Cr(VI)去除吸附剂，可在工业规模上用于社会和环境效益。一种农业废弃物混合物，由椰壳和椰糠组成，没有添加任何化学试剂，被用于去除六价铬。根据文献调查和我们的了解，这种吸附剂 MCSC 尚未被报道用于去除六价铬。在之前的研究中，作者曾报道过椰子纤维或椰子壳或椰子炭作为吸附剂用于去除六价铬。与报道的吸附剂相比，MCSC 即使在非常低的剂量（0.1g）下也非常有效。
