Castro David, Rosas-Laverde Nelly Ma, Aldás María Belén, Almeida-Naranjo Cristina E, Guerrero Víctor H, Pruna Alina Iuliana
Department of Materials, Escuela Politécnica Nacional, Quito 170524, Ecuador.
Department of Civil and Environmental Engineering, Escuela Politécnica Nacional, Quito 170524, Ecuador.
Materials (Basel). 2021 Apr 22;14(9):2134. doi: 10.3390/ma14092134.
Contamination of water by heavy metals is a major environmental concern due to the potential ecological impact on human health and aquatic ecosystems. In this work, we studied the chemical modification of various fruit peels such as banana (BP), granadilla (GP), and orange ones (OP) in order to obtain novel bio-adsorbents to improve the removal of Zn(II) ions from 50 mg·L synthetic aqueous solutions. For this purpose, sodium hydroxide and calcium acetate were employed to modify the fruit peels. The moisture, extractives, lignin, hemicellulose, and cellulose contents of the raw materials were determined according to ASTM standards. The obtained bio-adsorbents were characterized by scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetric analysis (TGA). The results showed the OP bio-adsorbents performed better, especially when the concentration of the modifier solutions increased, e.g., the OP particles modified using 0.8 M NaOH and Ca(CHCOO) solutions resulted in 97% removal of Zn(II) contaminating ions and reached a maximum adsorption capacity of 27.5 mg Zn per gram of bio-adsorbent. The adsorption processes were found to follow a pseudo-second order model. The error function sum of square error indicated the Freundlich isotherm (non-linear regression) as best fit model. The obtained results are particularly interesting for material selection in wastewater treatment technologies based on contaminant adsorption.
重金属对水的污染是一个重大的环境问题，因为它可能对人类健康和水生生态系统产生生态影响。在这项工作中，我们研究了各种果皮（如香蕉皮（BP）、百香果壳（GP）和橙皮（OP））的化学改性，以获得新型生物吸附剂，用于提高从50 mg·L合成水溶液中去除Zn(II)离子的效果。为此，使用氢氧化钠和醋酸钙对果皮进行改性。根据ASTM标准测定了原材料的水分、提取物、木质素、半纤维素和纤维素含量。通过扫描电子显微镜（SEM）、傅里叶变换红外光谱（FTIR）和热重分析（TGA）对所得生物吸附剂进行了表征。结果表明，OP生物吸附剂表现更好，特别是当改性剂溶液浓度增加时，例如，使用0.8 M NaOH和Ca(CHCOO)溶液改性的OP颗粒对Zn(II)污染离子的去除率达到97%，每克生物吸附剂的最大吸附容量达到27.5 mg Zn。发现吸附过程遵循准二级模型。误差函数平方和表明Freundlich等温线（非线性回归）是最佳拟合模型。所得结果对于基于污染物吸附的废水处理技术中的材料选择特别有意义。
