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Abstract：
A novel approach to enhance the utilization of low-cost and sustainable chitosan for wastewater remediation is presented in this investigation. The study centers around the modification of chitosan beads using a deep eutectic solvent composed of choline chloride and urea at a molar ratio of 1:2, followed by treatment with sulfuric acid using an impregnation accessible methodology. The effectiveness of the modified chitosan beads as an adsorbent was evaluated by studying the removal of the azo dye Reactive Black 5 (RB5) from aqueous solutions. Remarkably, the modified chitosan beads demonstrated a substantial increase in adsorption efficiency, achieving excellent removal of RB5 within the concentration range of 25-250 mg/L, ultimately leading to complete elimination. Several key parameters influencing the adsorption process were investigated, including initial RB5 concentration, adsorbent dosage, contact time, temperature, and pH. Quantitative analysis revealed that the pseudo-second-order kinetic model provided the best fit for the experimental data at lower dye concentrations, while the intraparticle diffusion model showed superior performance at higher RB5 concentration ranges (150-250 mg/L). The experimental data were successfully explained by the Langmuir isotherm model, and the maximum adsorption capacities were found to be 116.78 mg/g at 298 K and 379.90 mg/g at 318 K. Desorption studies demonstrated that approximately 41.7% of the dye could be successfully desorbed in a single cycle. Moreover, the regenerated adsorbent exhibited highly efficient RB5 removal (80.0-87.6%) for at least five consecutive uses. The outstanding adsorption properties of the modified chitosan beads can be attributed to the increased porosity, surface area, and swelling behavior resulting from the acidic treatment in combination with the DES modification. These findings establish the modified chitosan beads as a stable, versatile, and reusable eco-friendly adsorbent with high potential for industrial implementation.
摘要：
在这项研究中，提出了一种新的方法来提高低成本和可持续的壳聚糖在废水修复中的利用率。该研究围绕使用由氯化胆碱和尿素以1：2的摩尔比组成的低共熔溶剂对壳聚糖珠进行改性，然后使用浸渍方法用硫酸处理。通过研究从水溶液中去除偶氮染料反应性黑5（RB5），评估了改性壳聚糖珠作为吸附剂的有效性。值得注意的是,改性壳聚糖珠显示了吸附效率的大幅增加，在25-250mg/L的浓度范围内实现对RB5的优异去除，最终导致彻底淘汰。研究了影响吸附过程的几个关键参数,包括初始RB5浓度，吸附剂用量,接触时间,温度,和pH。定量分析表明，伪二级动力学模型为较低染料浓度下的实验数据提供了最佳拟合，而颗粒内扩散模型在较高的RB5浓度范围（150-250mg/L）下显示出优异的性能。实验数据成功地解释了Langmuir等温线模型，发现在298K时的最大吸附容量为116.78mg/g，在318K时的最大吸附容量为379.90mg/g。解吸研究表明，大约41.7％的染料可以在单个循环中成功解吸。此外，再生吸附剂在至少五次连续使用中表现出高效的RB5去除率（80.0-87.6％）。改性壳聚糖珠的优异吸附性能可归因于孔隙率的增加，表面积,和由酸处理与DES改性组合产生的溶胀行为。这些发现建立了改性壳聚糖珠作为一种稳定的,多才多艺，和可重复使用的环保吸附剂，具有很高的工业实施潜力。
