Sorption of synthetic dyes on low-cost solid sorbents is a simple technique for their removal from wastewater. Recent initiatives in the sorption process have sought the use of activated carbon derived from agricultural wastes as it provides an attractive and cheaper alternative to commercial activated carbon, which is usually expensive. This research investigates the sorption kinetics and equilibrium of two synthetic cationic dyes, crystal violet and methylene blue from aqueous media using activated carbon prepared from an agro-waste, Millettia thonningii seed pods. Sorption experiments were carried out using the batch process. The kinetic data were analyzed using the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models while the equilibrium data were analyzed using the Langmuir, Freundlich, and Redlich–Peterson isotherm models. Nonlinear regression method was used to fit the data to the isotherm models in order to determine model parameters and the best-fit isotherms. Thus, three error functions; coefficient of determination, Chi-square statistic test, and the sum of error squares were applied to evaluate the sorption data. The pseudo-second-order model best described the sorption kinetics of both dyes while the Redlich–Peterson model described the equilibrium data the most, followed closely by the Freundlich isotherm model indicating a heterogeneous sorbent surface. The experimental results indicate that the agro-waste derived activated carbon is a viable adsorbent for the remediation of dye-contaminated water.

中文翻译：

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水溶液中结晶紫和亚甲基蓝在农残衍生活性炭上的吸附的非线性回归分析

在低成本固体吸附剂上吸附合成染料是从废水中去除它们的简单技术。吸附过程中的最新举措已寻求使用源自农业废物的活性炭，因为它提供了通常价格昂贵的商业活性炭的诱人且便宜的替代品。这项研究调查了两种合成阳离子染料的吸附动力学和平衡性，这些阳离子染料是使用农业废料米勒蒂娜制得的活性炭从水性介质中提取的结晶紫和亚甲基蓝。种子荚。吸附实验使用分批过程进行。使用伪一级，伪二级和粒子内扩散模型分析了动力学数据，同时使用Langmuir，Freundlich和Redlich-Peterson等温模型分析了平衡数据。为了确定模型参数和最佳拟合等温线，使用了非线性回归方法将数据拟合等温线模型。因此，三个误差函数；测定系数，卡方统计检验和误差平方和用于评估吸附数据。伪二级模型最能描述两种染料的吸附动力学，而Redlich-Peterson模型最能描述平衡数据，紧随其后的是Freundlich等温模型，表明吸附剂表面非均质。