Abstract

Herein, we report the preparation of a novel biosorbent; a citric acid modified red-seaweed for crystal violet (CV) removal from water. Surface characterization and basic biosorption characteristics of pristine red seaweed (RS) and its citric acid-modified form (RS@CA) were critically evaluated through scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transformed infrared (FTIR) spectroscopy, and BET surface analysis. Batch experiments were, then, performed to evaluate the biosorption performance of adsorbent under various operational parameters. The CV biosorption kinetics and equilibrium data were fitted well by pseudo second order and Langmuir model for both RS and RS@CA, respectively. Optimum monolayer uptakes of RS and RS@CA for CV dye were 142.86 and 217.38 mg g⁻¹, respectively. Thermodynamically, the biosorption process was found to be endothermic (ΔH° > 0) and spontaneous (ΔG° ˂ 0). The CV binding mechanism toward RS@CA surface sites was mainly manifested by the electrostatic driving force pathway. Response surface methodology calculations showed a maximum CV biosorption efficiency of 93.40% at optimum biosorption conditions: pH 7, biosorbent dose of 1.5 g L⁻¹, initial CV concentration of 20 mg L⁻¹, and adsorption time of 90 minutes at 20 °C. The regeneration data further indicated that RS@CA could be effectively reused up to five cycles, losing only 6.7% of the original CV removal efficiency. Finally, it was concluded that RS@CA could be used as a cost-effective, eco-friendly and recyclable biosorbent to remove CV dye from water.

摘要

在此，我们报告了一种新型生物吸附剂的制备；一种柠檬酸改性的红海藻，用于从水中去除结晶紫 (CV)。通过扫描电子显微镜 (SEM)、能量色散 X 射线光谱 (EDS)、傅里叶变换红外对原始红海藻 (RS) 及其柠檬酸改性形式 (RS@CA) 的表面表征和基本生物吸附特性进行了严格评估(FTIR) 光谱和 BET 表面分析。然后，进行批量实验以评估吸附剂在各种操作参数下的生物吸附性能。RS 和 RS@CA 的 CV 生物吸附动力学和平衡数据分别通过伪二阶和 Langmuir 模型很好地拟合。CV 染料对 RS 和 RS@CA 的最佳单层吸收分别为 142.86 和 217.38 mg g ^-1， 分别。在热力学上，发现生物吸附过程是吸热的（ΔH°> 0）和自发的（ΔG°˂0）。CV对RS@CA表面位点的结合机制主要表现为静电驱动力途径。响应面法计算表明，在最佳生物吸附条件下，最大 CV 生物吸附效率为 93.40%：pH 7，生物吸附剂剂量为 1.5 g L ^-1，初始 CV 浓度为 20 mg L ^-1，吸附时间为 90 分钟，20 °C . 再生数据进一步表明，RS@CA 最多可有效重复使用五个循环，仅损失原始 CV 去除效率的 6.7%。最后得出结论，RS@CA 可作为一种经济高效、环保且可回收的生物吸附剂从水中去除 CV 染料。