Abstract

The present study illustrates enhanced removal of methylene blue (MB) and malachite green (MG) from water using alkali-activated coconut fiber (ACF) as adsorbent. Alkali activation effectively reduces the lignocellulosic components present within coco-fiber which in turn reinforces the coco-fiber to become more water-stable. The material was characterized by FTIR, SEM-EDS, BET, XRD, and pH_ZPC. BET surface area was found to be 10.901 m² g⁻¹, whereas pH_ZPC of the material is 6.05. FESEM images reveal rod-like morphology. Batch experiments were optimized with respect to contact time (0–120 min), temperature (288–308 K), pH (3–10), dose (1–5 g) and input dye concentration (10–50 mg L⁻¹). The maximum adsorption coefficient was found to be 133.11 and 110.74 mg g⁻¹ for MB and MG respectively. Adsorptions are best described by pseudo-second-order kinetics (k_MB = 1.712, R² = 0.999; k_MG = 1.399, R² = 0.999) and Langmuir isotherm model (R² = 0.999). Thermodynamic data suggests a spontaneous (ΔG, −14 kJ mol⁻¹) and feasible process. Spent material could be regenerated by using 0.5 M HCl. Up to 50% retention of activities was seen after five cycles. It can be concluded that alkali-activated coconut fiber is an economic and sustainable choice for dye removal.

Novelty statement: Spent coconut was converted into an effective biosorbent by simple alkali activation under ambient conditions to increase the hydrophobicity of the fibers by reducing the lignocellulosic components. Two cationic dyes; methylene blue and malachite green have been efficiently removed with adsorption capacities of 133.11 and 110.74 mg g⁻¹. The operation is simple, economically viable, and partially fulfills the principles of green engineering. Comparing with contemporary adsorbents, this material offers higher adsorption capacities with multi-cycle reusability and enhanced water stability.

摘要

本研究表明，使用碱活化椰子纤维 (ACF) 作为吸附剂，可以增强从水中去除亚甲蓝 (MB) 和孔雀石绿 (MG) 的能力。碱活化有效地减少了存在于可可纤维中的木质纤维素成分，这反过来增强了可可纤维以变得更加水稳定。该材料通过 FTIR、SEM-EDS、BET、XRD 和 pH _{ZPC 进行表征}。发现BET表面积为10.901 m ² g ^-1，而材料的pH _ZPC为6.05。FESEM 图像显示棒状形态。针对接触时间（0-120 分钟）、温度（288-308 K）、pH（3-10）、剂量（1-5 g）和输入染料浓度（10-50 mg L ^-1）。MB和MG的最大吸附系数分别为133.11和110.74 mg g ^-1。吸附最好通过伪二级动力学（k _MB = 1.712，R ² = 0.999；k _MG = 1.399，R ² = 0.999）和朗缪尔等温线模型（R ² = 0.999）来描述。热力学数据表明自发 (Δ G , -14 kJ mol ^-1) 和可行的过程。用过的材料可以通过使用 0.5 M HCl 进行再生。五个周期后，活动的保留率高达 50%。可以得出结论，碱活化椰子纤维是去除染料的经济且可持续的选择。

新颖性声明：废椰子在环境条件下通过简单的碱活化转化为有效的生物吸附剂，通过减少木质纤维素成分来增加纤维的疏水性。两种阳离子染料；亚甲基蓝和孔雀石绿已被有效去除，吸附容量分别为 133.11 和 110.74 mg g ^-1。操作简单，经济可行，部分符合绿色工程的原则。与现代吸附剂相比，这种材料具有更高的吸附能力、多循环可重复使用性和增强的水稳定性。