Environmental Sciences Division, Instituto Potosino de Investigación Científica y Tecnológica, A.C., Camino a la Presa San José 2055, Col. Lomas 4ta. Sección, C.P. 78216, San Luis Potosí, S.L.P., Mexico.
Division of Engineering, Brown University, 182 Hope Street, Providence, RI, 02912, USA.
J Environ Manage. 2020 Apr 1;259:110044. doi: 10.1016/j.jenvman.2019.110044. Epub 2020 Jan 9.
Graphene oxide (GO) is a single-atom-thick sheet of carbon with oxygen-containing functional groups decorating its basal plane and edge sites. Most of its high surface area can be lost due to restacking of individual layers during the synthesis and drying of GO-based bulk sorbents. There is great interest to increase the specific surface area of graphene-based sorbents by introducing organic molecules as "pillaring agents" between GO sheets to hinder the stacking process and create sorbents with elevated surface area. This work synthesizes pillared GO by introducing chitosan (CS), a linear polysaccharide with various molecular weights. A composite of low molecular weight CS at a CS/GO ratio of 0.1 is shown to have the highest specific surface area (up to 70.5 m/g) in comparison to the medium and high CS molecular weight, pristine GO, and the CS/GO composite materials. The affinity of the optimized GO/CS composites towards benzene, toluene, and naphthalene was evaluated at 19.3 mg/L of organic matter content while altering pH. Sips and Langmuir adsorption isotherm models well described the adsorption behavior, and benzene adsorption performance was reduced at low pH. Related to the presence of dissolved organic matter (DOM) in solution, lower diffusivity constants (k) in hydrocarbon systems were recorded. Our results demonstrate the feasibility of CS as a potential pillaring agent in CS/GO composites to increase specific surface area and enhance the capture of soluble hydrocarbons from aqueous solutions.
氧化石墨烯（GO）是由单层碳原子组成的薄片，其基面和边缘位点上含有含氧官能团。在 GO 基 bulk sorbents 的合成和干燥过程中，由于各层的堆积，大部分高表面积会丢失。通过引入有机分子作为“支柱剂”在 GO 片之间来阻碍堆积过程，从而制造具有更高表面积的石墨烯基吸附剂，这引起了人们极大的兴趣。本工作通过引入壳聚糖（CS），一种具有各种分子量的线性多糖，合成了支柱化的 GO。与中分子量和高分子量 CS、原始 GO 以及 CS/GO 复合材料相比，在 CS/GO 比为 0.1 的低分子量 CS 复合中，具有最高的比表面积（高达 70.5 m/g）。在改变 pH 值的情况下，评估了优化后的 GO/CS 复合材料对苯、甲苯和萘的亲和力。Sips 和 Langmuir 吸附等温线模型很好地描述了吸附行为，并且在低 pH 值下，苯的吸附性能降低。与溶液中溶解有机物（DOM）的存在有关，在碳氢化合物体系中记录到较低的扩散常数（k）。我们的结果表明，CS 作为 CS/GO 复合材料中潜在的支柱剂，可用于增加比表面积并增强从水溶液中捕获可溶性碳氢化合物的能力。
