Tho P T, Van Huu Tap, Nguyen Lan Huong, Hoang Trung Kien, Ha Tran Thi Ngoc, Nguyen Thi Tuyet, Hanh Nguyen Thi Bich, Nguyen Van Quang, Le Sy Hung, Thai Van Nam, Tran Quoc Ba, Sadeghzadeh Seyed Mohsen, Asadpour Robabeh, Thang Phan Quang
Laboratory of Magnetism and Magnetic Materials, Advanced Institute of Materials Science, Ton Duc Thang University Ho Chi Minh City Vietnam
Faculty of Applied Sciences, Ton Duc Thang University Ho Chi Minh City Vietnam.
RSC Adv. 2021 May 25;11(31):18881-18897. doi: 10.1039/d1ra01599k. eCollection 2021 May 24.
This study presents the modification of cassava root husk-derived biochar (CRHB) with ZnO nanoparticles (ZnO-NPs) for the simultaneous adsorption of As(iii), Cd(ii), Pb(ii) and Cr(vi). By conducting batch-mode experiments, it was concluded that 3% w/w was the best impregnation ratio for the modification of CRHB using ZnO-NPs, and was denoted as CRHB-ZnO3 in this study. The optimal conditions for heavy metal adsorption were obtained at a pH of 6-7, contact time of 60 min, and initial metal concentration of 80 mg L. The heavy metal adsorption capacities onto CRHB-ZnO3 showed the following tendency: Pb(ii) > Cd(ii) > As(iii) > Cr(vi). The total optimal adsorption capacity achieved in the adsorption of the 4 abovementioned metals reached 115.11 and 154.21 mg g for CRHB and CRHB-ZnO3, respectively. For each Pb(ii), Cd(ii), As(iii), and Cr(vi) metal, the maximum adsorption capacities of CRHB-ZnO3 were 44.27, 42.05, 39.52, and 28.37 mg g, respectively, and those of CRHB were 34.47, 32.33, 26.42 and 21.89 mg g, respectively. In terms of kinetics, both the pseudo-first-order and the pseudo-second-order fit well with metal adsorption onto biochars with a high correlation coefficient of , while the best isothermal description followed the Langmuir model. As a result, the adsorption process of heavy metals onto biochars was chemisorption on homogeneous monolayers, which was mainly controlled by cation exchange and surface precipitation mechanisms due to enriched oxygen-containing surface groups with ZnO-NP modification of biochar. The FTIR and EDS analysis data confirmed the important role of oxygen-containing surface groups, which significantly contributed to removal of heavy metals with extremely high adsorption capacities, comparable with other studies. In conclusion, due to very high adsorption capacities for metal cations, the cassava root husk-derived biochar modified with ZnO-NPs can be applied as the alternative, inexpensive, non-toxic and highly effective adsorbent in the removal of various toxic cations.
本研究介绍了用氧化锌纳米颗粒（ZnO-NPs）对木薯根壳衍生生物炭（CRHB）进行改性，以同时吸附As(iii)、Cd(ii)、Pb(ii)和Cr(vi)。通过进行批量模式实验得出，3% w/w是使用ZnO-NPs改性CRHB的最佳浸渍比例，在本研究中记为CRHB-ZnO3。重金属吸附的最佳条件为pH值6 - 7、接触时间60分钟以及初始金属浓度80 mg/L。CRHB-ZnO3对重金属的吸附容量呈现以下趋势：Pb(ii) > Cd(ii) > As(iii) > Cr(vi)。上述4种金属吸附时，CRHB和CRHB-ZnO3的总最佳吸附容量分别达到115.11和154.21 mg/g。对于每种Pb(ii)、Cd(ii)、As(iii)和Cr(vi)金属，CRHB-ZnO3的最大吸附容量分别为44.27、42.05、39.52和28.37 mg/g，CRHB的最大吸附容量分别为34.47、32.33、26.42和21.89 mg/g。在动力学方面，准一级和准二级模型都能很好地拟合生物炭对金属的吸附，相关系数较高，而最佳等温线描述符合朗缪尔模型。因此，重金属在生物炭上的吸附过程是均匀单层上的化学吸附，主要受阳离子交换和表面沉淀机制控制，这是由于生物炭经ZnO-NP改性后富含含氧表面基团。傅里叶变换红外光谱（FTIR）和能谱分析（EDS）数据证实了含氧表面基团的重要作用，其对重金属的去除有显著贡献，吸附容量极高，与其他研究相当。总之，由于对金属阳离子具有非常高的吸附容量，用ZnO-NPs改性的木薯根壳衍生生物炭可作为去除各种有毒阳离子的替代、廉价、无毒且高效的吸附剂。
