Gelaw Yenewa Bewket, Dagne Henok, Adane Balew, Yirdaw Getasew, Moges Mekonnen, Aneley Zelalem, Kumlachew Lake, Aschale Abebaw, Deml Yikeber Argachew, Tegegne Eniyew, Birhan Tsegaye Adane
Environmental Health Department, College of Medicine and Health Science, Debre Markos University, Debre Markos, Ethiopia.
Environmental and Occupational Health and Safety Department, Institute of Public Health, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia.
Heliyon. 2024 Nov 14;10(22):e40389. doi: 10.1016/j.heliyon.2024.e40389. eCollection 2024 Nov 30.
Cadmium is among the most hazardous heavy metals, posing the greatest risk to human beings and the environment. Adsorption with activated carbon prepared from agricultural waste is the most effective way to remove cadmium (II) from wastewater. In this study, activated carbon prepared from the stem of Khat ( plant was used for the removal of cadmium (II) from wastewater.
To evaluate the efficiency and mechanism of the removal of cadmium (II) from wastewater using Khat (Catha edulis) stem activated carbon at different operating parameters.
Proximate and Fourier transform infrared analyses were conducted to characterise the prepared Khat stem-activated carbon. The effects of initial cadmium concentration, adsorbent dose, pH, contact time, and agitation speed on the cadmium removal efficiency of Khat stem-activated carbon were evaluated. Furthermore, isotherm and kinetic models of adsorption were used to evaluate the mechanism of cadmium removal.
The proximate analysis indicated that the activated carbon derived from Khat stems possesses a bulk density of 0.58 g/cm and surface area of 615 m/g. Additionally, the prepared Khat stem activated carbon has 4 %, 14 %, and 22 % of moisture content, ash content, and volatile matter, respectively. Furthermore, the proximate analysis indicated that the Khat stem activated carbon has a porosity of 55 %. The Fourier transformed infrared spectroscopy result indicated the presence of phenolic, alcoholic, and carboxylic acid functional groups on the surface of Khat stem activated carbon. The experimental data showed a better fit with the Langmuir isotherm model (R-squared and chi-square value of 0.9727 and 1.3936, respectively) and the pseudo-second-order kinetic model (R-squared and chi-square values of 0.9032 and 0.2179, respectively). The highest adsorption efficiency of cadmium (97 %) was attained at an adsorbent dose of 0.125 g, a contact time of 30 min, an initial cadmium concentration of 20 mg/L, a pH of 5, and an agitation speed of 100 rpm at room temperature (25 °C).
The results obtained in this research demonstrated that activated carbon from Khat stems can be employed as an economical, ecologically friendly, easily accessible and efficient activated carbon to remove Cd (II) from wastewater.
镉是危害最大的重金属之一，对人类和环境构成极大风险。用农业废弃物制备的活性炭吸附是从废水中去除镉（II）的最有效方法。在本研究中，用巧茶（Catha edulis）茎制备的活性炭用于从废水中去除镉（II）。
评估在不同操作参数下，使用巧茶（Catha edulis）茎活性炭从废水中去除镉（II）的效率和机制。
进行了近似分析和傅里叶变换红外分析，以表征制备的巧茶茎活性炭。评估了初始镉浓度、吸附剂剂量、pH值、接触时间和搅拌速度对巧茶茎活性炭去除镉效率的影响。此外，使用吸附等温线模型和动力学模型来评估镉的去除机制。
近似分析表明，源自巧茶茎的活性炭堆积密度为0.58 g/cm，表面积为615 m²/g。此外，制备的巧茶茎活性炭的水分含量、灰分含量和挥发物含量分别为4%、14%和22%。此外，近似分析表明巧茶茎活性炭的孔隙率为55%。傅里叶变换红外光谱结果表明巧茶茎活性炭表面存在酚类、醇类和羧酸官能团。实验数据与朗缪尔等温线模型（决定系数和卡方值分别为0.9727和1.3936）和伪二级动力学模型（决定系数和卡方值分别为0.9032和0.2179）拟合得更好。在室温（25°C）下，吸附剂剂量为0.125 g、接触时间为30分钟、初始镉浓度为20 mg/L、pH值为5和搅拌速度为100 rpm时，镉的最高吸附效率（97%）得以实现。
本研究获得的结果表明，巧茶茎活性炭可作为一种经济、生态友好、易于获取且高效的活性炭用于从废水中去除Cd（II）。
