Mortazavian Soroosh, Murph Simona E Hunyadi, Moon Jaeyun
Department of Mechanical Engineering, University of Nevada Las Vegas, Las Vegas, NV 89154, USA.
Savannah River National Laboratory (SRNL), Aiken, SC 29808, USA.
Materials (Basel). 2022 Sep 1;15(17):6055. doi: 10.3390/ma15176055.
Biochar is commonly used for soil amendment, due to its excellent water-holding capacity. The Cr(VI) contamination of water is a current environmental issue in industrial regions. Here, we evaluated the effects of two-step modifications on boosting biochar's performance in terms of the removal of aqueous hexavalent chromium (Cr(VI)), along with investigating the alterations to its surface properties. The first modification step was heat treatment under air at 300 °C, producing hydrophilic biochar (HBC). The resulting HBC was then impregnated with zero-valent iron nanoparticles (nZVI), creating an HBC/nZVI composite, adding a chemical reduction capability to the physical sorption mechanism. Unmodified biochar (BC), HBC, and HBC/nZVI were characterized for their physicochemical properties, including surface morphology and elemental composition, by SEM/EDS, while functional groups were ascertained by FTIR and surface charge by zeta potential. Cr(VI) removal kinetic studies revealed the four-time greater sorption capacity of HBC than BC. Although unmodified BC showed faster initial Cr(VI) uptake, it rapidly worsened and started desorption. After nZVI impregnation, the Cr(VI) removal rate of HBC increased by a factor of 10. FTIR analysis of biochars after Cr(VI) adsorption showed the presence of Cr(III) oxide only on the used HBC/nZVI and demonstrated that the carbonyl and carboxyl groups were the main groups involved in Cr(VI) sorption. Modified biochars could be considered an economical substitute for conventional methods.
生物炭因其出色的持水能力而常用于土壤改良。水体中的六价铬（Cr(VI)）污染是工业区当前面临的一个环境问题。在此，我们评估了两步改性对提高生物炭去除水中六价铬（Cr(VI)）性能的影响，并研究了其表面性质的变化。第一步改性是在300℃的空气中进行热处理，制得亲水性生物炭（HBC）。然后将所得的HBC用零价铁纳米颗粒（nZVI）浸渍，制成HBC/nZVI复合材料，为物理吸附机制增添了化学还原能力。通过扫描电子显微镜/能谱仪（SEM/EDS）对未改性生物炭（BC）、HBC和HBC/nZVI的物理化学性质（包括表面形态和元素组成）进行了表征，通过傅里叶变换红外光谱仪（FTIR）确定了官能团，通过zeta电位测定了表面电荷。Cr(VI)去除动力学研究表明，HBC的吸附容量是BC的四倍。尽管未改性的BC最初对Cr(VI)的吸收较快，但很快就变差并开始解吸。在浸渍nZVI后，HBC对Cr(VI)的去除率提高了10倍。对吸附Cr(VI)后的生物炭进行FTIR分析表明，仅在使用过的HBC/nZVI上存在三氧化二铬（Cr(III)）氧化物，并证明羰基和羧基是参与Cr(VI)吸附的主要基团。改性生物炭可被视为传统方法的一种经济替代物。
