Cost-Effective Preparation of Gold Tailing-Based Aerogels for Efficient Adsorption of Copper Ions from Wastewater

Abstract

Water pollution caused by heavy metal ions has attracted worldwide attention. In this work, gold tailings were used as raw materials and the sol–gel method combined with the atmospheric pressure drying method were used to achieve the low-cost preparation of a silica aerogel. (3-Aminopropyl) triethoxysilane (APTES), ethylenediaminetetraacetic acid disodium salt (EDTA-2Na), and chitosan were used to modify the silica aerogel, which was then used as an adsorbent for the adsorption of copper ions in wastewater. The adsorbent type, adsorption time, copper ion concentration, and pH value were investigated as variables to explore the best adsorption conditions. The adsorption mechanism was also elaborated on. The crystal structure, surface morphology, surface functional groups, chemical composition, and specific surface area of the aerogels and the modified aerogels were characterized by various physiochemical characterizations such as XRD, SEM, FT-IR, XRF, and BET. The results showed that the prepared silica aerogel contained 91.1% SiO2, mainly amorphous SiO2, and amino and carboxyl groups. Other functional groups were successfully grafted onto the silica aerogels. The original silica aerogels and modified silica aerogels had a large specific surface area, total pore volume, and pore diameter. When copper ions were adsorbed by the chitosan-modified silica aerogels, the adsorption capacity of the copper ions was the highest (33.51 mg/g) under the conditions of a copper ion concentration of 100 mg/L, a pH value of 7, and an adsorption time of 2 h. The adsorption of Cu2+ was mainly due to the ion exchange and electrostatic gravity.