Li Yan, Gao Liangmin, Lu Zhongxiang, Wang Yuchen, Wang Yan, Wan Shunli
School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, China.
College of Life & Environmental Sciences, Huangshan University, Huangshan 245041, China.
ACS Omega. 2020 Oct 27;5(44):28702-28711. doi: 10.1021/acsomega.0c03893. eCollection 2020 Nov 10.
Biochar has become an attractive adsorbent for heavy metal removal, but its application potential is very limited because of the relatively low adsorption capacity and poor selectivity. In the present study, we decorated the biochar (BC) by impregnating hydrous ferric oxide (HFO) within the pore of biochar and consequently obtained a new hybrid adsorbent denoted as HFO-BC. The results show HFO-BC exhibited excellent performance to two representative heavy metals, i.e., Cd(II) and Cu(II), with maximal experimental sorption capacities of 29.9 mg/g for Cd(II) and 34.1 mg/g for Cu(II). HFO-BC showed satisfactory anti-interference ability for Cd(II) and Cu(II) removal in the presence of high levels of Ca(II) and Mg(II) owing to the specific inner-sphere complexation between the immobilized HFO and Cd(II) and Cu(II), which was probed by XPS analysis. Cd(II) and Cu(II) removal onto HFO-BC experienced two distinct stages prior to be adsorbed, i.e., migration from solution to the outside surface of adsorbent and pore diffusion and approached equilibrium within 100 min. In the laboratory-scale small column adsorption experiment, HFO-BC can generate ∼129 and 300 BV effluents for Cd(II) and Cu(II), equivalent to 774- and 1854-fold of its own weight, to meet their treatment standards. Moreover, the exhausted HFO-BC can be effectively regenerated using HCl-CaCl binary solution with a desorption rate more than 95%. All results validate that impregnating HFO inside the pores of BC is a promising approach to promote the practical applicability of BC for removing heavy metals from the polluted water.
生物炭已成为一种用于去除重金属的有吸引力的吸附剂,但其应用潜力非常有限,因为其吸附容量相对较低且选择性较差。在本研究中,我们通过在生物炭孔隙内浸渍水合氧化铁(HFO)来修饰生物炭(BC),从而获得一种新的混合吸附剂,记为HFO-BC。结果表明,HFO-BC对两种代表性重金属Cd(II)和Cu(II)表现出优异的性能,Cd(II)的最大实验吸附容量为29.9 mg/g,Cu(II)为34.1 mg/g。由于固定化HFO与Cd(II)和Cu(II)之间存在特定的内球络合作用,通过XPS分析证实,HFO-BC在高浓度Ca(II)和Mg(II)存在下对Cd(II)和Cu(II)的去除具有令人满意的抗干扰能力。Cd(II)和Cu(II)在被HFO-BC吸附之前经历两个不同阶段,即从溶液迁移到吸附剂外表面以及孔隙扩散,并在100分钟内达到平衡。在实验室规模的小柱吸附实验中,HFO-BC对Cd(II)和Cu(II)可产生约129和300床体积的流出液,相当于其自身重量的774倍和1854倍,以满足其处理标准。此外,使用HCl-CaCl二元溶液可有效再生耗尽的HFO-BC,解吸率超过95%。所有结果均证实,在BC孔隙内浸渍HFO是一种有前景的方法,可提高BC从污染水中去除重金属的实际适用性。