Abstract

In the present study, batch experiments were carried out to elucidate the potential of apricot stone activated carbon ASAC to remove Pb²⁺ ions from aqueous solution. ASAC was characterized by Bruanauer, Emmett and Teller surface area S = 80.08 (m²/g), Fourier transform infrared spectroscopy and scanning electron microscopy. The effects of various process parameters such as initial pH (2–14), adsorbent dose (5–45 g/L) initial metal ion concentration (20–0 mg/L), contact time (0–90 min), agitation speed (100–700 rpm) and temperature (298–323 k) were investigated in their respective range and their optimum conditions were ascertained. The adsorption kinetics were analyzed by the pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion kinetic models. It was found that the adsorption of the metal ions followed pseudo-second-order kinetic model. The Adsorption isotherms were modeled with Langmuir, Freundlich, Temkin, Hasley and Harkins models and their isotherm constants were calculated. The Freundlich model fits the data with a monolayer adsorption capacity of 166.813 mg/g at pH 8. The thermodynamic parameters such as the Gibbs free energy, enthalpy and entropy were calculated to predict the nature of adsorption process. The calculated thermodynamic parameters showed that the adsorption of Pb²⁺ ions on ASAC is endothermic (ΔH⁰ = 121.38 kJ/mol) and not spontaneous (ΔG⁰ > 0) in nature.

中文翻译：

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杏石活性炭 (ASAC) 吸附铅 (Pb2+) 的传质过程：等温线建模和热力学研究

摘要

在本研究中，进行批量实验以阐明杏石活性炭ASAC从水溶液中去除Pb ²⁺离子的潜力。ASC 的特征在于 Bruanauer、Emmett 和 Teller 表面积S = 80.08 (m ²/g)、傅里叶变换红外光谱和扫描电子显微镜。各种工艺参数的影响，例如初始 pH (2-14)、吸附剂剂量 (5-45 g/L) 初始金属离子浓度 (20-0 mg/L)、接触时间 (0-90 分钟)、搅拌速度(100–700 rpm) 和温度 (298–323 k) 在各自的范围内进行了研究，并确定了它们的最佳条件。吸附动力学通过拟一级、拟二级、Elovich 和颗粒内扩散动力学模型进行分析。发现金属离子的吸附遵循准二级动力学模型。吸附等温线用 Langmuir、Freundlich、Temkin、Hasley 和 Harkins 模型建模，并计算了它们的等温线常数。Freundlich 模型以 166 的单层吸附容量拟合数据。在 pH 8 时为 813 mg/g。计算吉布斯自由能、焓和熵等热力学参数以预测吸附过程的性质。计算的热力学参数表明，Pb 的吸附ASAC 上的²⁺离子在本质上是吸热的（Δ H ⁰ = 121.38 kJ/mol）而不是自发的（Δ G ⁰ > 0）。