The presence of heavy metals in polluted water is known not only to cause severe harm to marine organisms, but also to terrestrial plants and animals including human beings. This research applied low-cost and environmentally benign adsorbent primed from waste orange peel (OP) for the removal of Cd(II) ions from aqueous solution via batch adsorption process. The surface properties of the orange peel powder were studied using scanning electron microscopy (SEM), X-ray spectroscopy (XRD) and Fourier transform infrared spectroscopy (FT-IR). Operational conditions like temperature, contact time, sorbent dosage, solution pH and initial adsorbate concentration were investigated. The utmost uptake of Cd(II) ion was obtained at a contact time of 120 min, initial metal concentration of 240 mg/L, adsorbent dosage of 0.04 g/L, temperature of 45 °C and solution pH of 5.5. Equilibrium results showed that the orange peel adsorbent has an adsorption capacity of 128.23 mg/g as obtained from the Langmuir isotherm. The adsorption kinetics data followed a pseudo-first-order kinetic model with correlation coefficient (R²) > 0.9 and low standard % error values. The adsorption process was found to be endothermic in nature with enthalpy of 0.0046 kJ mol⁻¹ and entropy of-636.865 Jmol⁻¹K⁻¹. Results from the optimization study indicated that higher adsorbent dosage and lower Cd(II) ion concentration increased the percentage of Cd(II) ion removal. Thus, orange peel could be used in the removal of Cd(II) ion from aqueous solutions.

中文翻译：

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桔皮作为消除Cd（II）离子的低成本吸附剂：动力学，等温线，热力学和优化评估

众所周知，污水中重金属的存在不仅会对海洋生物造成严重损害，而且还会对包括人类在内的陆地动植物造成严重伤害。这项研究应用了低成本，环保的，由废旧橙皮（OP）引发的吸附剂，通过分批吸附工艺从水溶液中去除Cd（II）离子。使用扫描电子显微镜（SEM），X射线光谱（XRD）和傅里叶变换红外光谱（FT-IR）研究了桔皮粉的表面性能。研究了温度，接触时间，吸附剂用量，溶液pH值和初始吸附物浓度等操作条件。在接触时间为120分钟，金属初始浓度为240 mg / L，吸附剂量为0.04 g / L的条件下，最大程度地吸收了Cd（II）离子。温度为45°C，溶液pH为5.5。平衡结果表明，从Langmuir等温线获得的橙皮吸附剂的吸附容量为128.23 mg / g。吸附动力学数据遵循具有相关系数（R²）> 0.9，且标准误差百分比值低。发现吸附过程本质上是吸热的，焓为0.0046 kJ mol ^-1，熵为-636.865 Jmol ^-1 K ^-1。优化研究的结果表明，较高的吸附剂量和较低的Cd（II）离子浓度会增加Cd（II）离子去除的百分比。因此，橙皮可用于从水溶液中去除Cd（II）离子。