Zhang Liming, Ren Yanfang, Xue Yuhao, Cui Zhiwen, Wei Qihang, Han Chuan, He Junyu
School of Environmental and Safety Engineering, Changzhou University Changzhou 213164 PR China
Jiangsu Petrochemical Safety and Environmental Engineering Research Center Changzhou 213164 PR China.
RSC Adv. 2020 Sep 30;10(59):35878-35888. doi: 10.1039/d0ra06586b. eCollection 2020 Sep 28.
Biochars were prepared by pyrolyzing mango peel waste at 300, 400, 500, 600 and 700 °C. Various characterizations were carried out to explore the effect of pyrolysis temperature on the biochars. The data indicated that the physical and chemical properties of biochar such as pH, element ratio, specific surface area and functional groups changed with the increase of pyrolysis temperature. The yield and contents of hydrogen, nitrogen and oxygen decreased, while contents of the ash and carbon, pH and specific surface area of the biochars increased. In addition, the molar ratios of H/C, O/C and (O + N)/C decreased. In this study, batch adsorption experiments for Cd(ii) adsorption were performed with initial Cd(ii) concentrations of 10-300 mg L, contact times of 0-2880 min, various pH (2-8) and biochar dose (1-20 g L). Langmuir isotherm and pseudo-second-order kinetics models were better fits than other models, suggesting the dominant adsorption of mango peel biochars is monolayer adsorption. Biochar derived at 500 °C was found to have the highest adsorption capacity of 13.28 mg g among all biochars and the adsorption efficiency was still 67.7% of the initial adsorption capacity after desorption for 4 times. Based on adsorption kinetics and isotherm analysis in combination with EDS, FTIR and XRD analysis, it was concluded that cation exchange, complexation with surface functional groups and precipitation with minerals were the dominant mechanisms responsible for Cd adsorption by mango peel biochar. The study suggested that mango peel can be recycled to biochars and can be used as a low-cost adsorbent for Cd(ii) removal from wastewater.
通过在300、400、500、600和700℃下热解芒果皮废料制备生物炭。进行了各种表征以探究热解温度对生物炭的影响。数据表明，生物炭的物理和化学性质，如pH值、元素比例、比表面积和官能团，随着热解温度的升高而变化。生物炭的产率以及氢、氮和氧的含量降低，而灰分、碳含量、pH值和比表面积增加。此外，H/C、O/C和(O + N)/C的摩尔比降低。在本研究中，进行了Cd(ii)吸附的批量实验，初始Cd(ii)浓度为10 - 300 mg/L，接触时间为0 - 2880分钟，不同pH值(2 - 8)和生物炭剂量(1 - 20 g/L)。Langmuir等温线和准二级动力学模型比其他模型拟合效果更好，表明芒果皮生物炭的主要吸附方式是单层吸附。发现在500℃下制备的生物炭在所有生物炭中具有最高吸附容量，为13.28 mg/g，解吸4次后吸附效率仍为初始吸附容量的67.7%。基于吸附动力学和等温线分析，并结合EDS、FTIR和XRD分析，得出阳离子交换、与表面官能团络合以及与矿物质沉淀是芒果皮生物炭吸附Cd的主要机制。该研究表明，芒果皮可以回收制成生物炭，并可作为一种低成本吸附剂用于去除废水中的Cd(ii)。
