College of Chemistry and Environment Protection Engineering, Southwest Minzu University, Chengdu, 610041, PR China; School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Rd., Shanghai, 200240, PR China.
College of Chemistry and Environment Protection Engineering, Southwest Minzu University, Chengdu, 610041, PR China.
Environ Res. 2019 Dec;179(Pt A):108779. doi: 10.1016/j.envres.2019.108779. Epub 2019 Sep 26.
Graphene adsorbents have been applied to remove diverse pollutants from aqueous systems. However, the mechanical strength of most graphene adsorbents is low and the fragile graphene sheets are released into the environment. In this study, we prepared carboxylated graphene oxide/chitosan/cellulose (GCCSC) composite beads with good mechanical strength for the immobilization of Cu from both water and soil. The proportional limit of GCCSC beads was 3.2 N, a much larger value than graphene oxide beads (0.2 N). The largest pressure for GCCSC beads recorded before brittle failure was 26 N. The Cu adsorption capacity of GCCSC beads was 22.4 mg/g in aqueous systems at initial Cu concentration of 40 μg/mL, which is competitive with many efficient adsorbents. The partition coefficient (PC) for the Cu adsorption onto GCCSC beads was 1.12 mg/g/μM at C of 0.83 mg/L and q of 14.3 mg/g. The PC decreased to 0.055 mg/g/μM at C of 26.0 mg/L and q of 22.4 mg/g. The adsorption kinetics of Cu on GCCSC beads were moderately fast and required approximately 3 h to reach equilibrium with a k of 0.0021 g/(mg·min). A lower temperature and higher pH slightly increased the adsorption capacity of GCCSC beads. The ionic strength did not influence the adsorption. The porous structure of GCCSC beads blocked the direct contact between soil and the graphene surface; thus, a high Cu immobilization efficiency was achieved by GCCSC beads applied to soil. The implications for the design of high-performance graphene adsorbents for water and soil remediation are discussed.
石墨烯吸附剂已被应用于从水系统中去除各种污染物。然而，大多数石墨烯吸附剂的机械强度较低，易碎的石墨烯片体会释放到环境中。在这项研究中，我们制备了具有良好机械强度的羧基化氧化石墨烯/壳聚糖/纤维素（GCCSC）复合珠，用于固定水中和土壤中的铜。GCCSC 珠的比例极限为 3.2 N，远大于氧化石墨烯珠（0.2 N）。GCCSC 珠记录到的脆性失效前的最大压力为 26 N。GCCSC 珠在初始铜浓度为 40 µg/mL 的水溶液中的铜吸附量为 22.4 mg/g，与许多高效吸附剂相当。GCCSC 珠对铜的分配系数（PC）在 C 为 0.83 mg/L 和 q 为 14.3 mg/g 时为 1.12 mg/g/µM。当 C 为 26.0 mg/L 和 q 为 22.4 mg/g 时，PC 降低至 0.055 mg/g/µM。Cu 在 GCCSC 珠上的吸附动力学适中，达到平衡约需 3 h，k 值为 0.0021 g/（mg·min）。较低的温度和较高的 pH 值略微增加了 GCCSC 珠的吸附容量。离子强度对吸附没有影响。GCCSC 珠的多孔结构阻止了土壤与石墨烯表面的直接接触；因此，GCCSC 珠在土壤中的应用实现了较高的铜固定效率。讨论了用于水和土壤修复的高性能石墨烯吸附剂的设计意义。
