Potential Application of Discarded Natural Coal Gangue for the Removal of Tetracycline Hydrochloride (TC) from an Aqueous Solution

Abstract

The generation and accumulation of discarded coal gangue (CG) have severe environmental impacts. CG can adsorb other pollutants in the aquatic environment. However, previous studies have not assessed whether CG can adsorb the emerging contaminant tetracycline hydrochloride (TC). Here, discarded CG taken from a mine was pretreated by crushing, cleaning, and sieving and subsequently applied to the adsorption of TC. The adsorption studies were carried out by batch equilibrium adsorption experiments. Our findings indicated that the adsorption behavior could be accurately described using the quasi-first order kinetic and Langmuir adsorption isotherm models, indicating that monolayer adsorption was the main mechanism mediating the interaction between CG and TC. The adsorption process was classified as a thermodynamic endothermic and spontaneous reaction, which was controlled by chemical and physical adsorption, including electrostatic interaction and cation exchange. The pH of the solution had a great influence on the TC adsorption capacity of GC, with higher adsorption occurring in acidic environments compared to alkaline environments. This was attributed to the changes in CG Zeta potential and TC pKa at different pH conditions. Collectively, our findings demonstrated the potential applicability of discarded CG for the adsorption of TC and provided insights into the adsorption mechanisms.

Novel Adsorbents and Adsorption Methods for Pollutant Removal

“…In order to study the purification and detection technology of heavy metals in water, Dengpeng Wang, Chunlin He, and Yuling Zhao et al [ 13 , 14 , 15 ] discussed CdSe/CdS core–shell quantum dot tracing Cd 2+ in aqueous solutions, carbon adsorbent microwaves with waste amine–oxime removing Pb(II), and advanced Fe 3 O 4 @SFBC adsorbent removing As(III/V), respectively. Based on waste ore, two articles [ 16 ] studied the rational recovery process of radionuclides in tantalum–niobium slag and the adsorption effect of discarded coal gangue on the pollutant tetracycline hydrochloride, which reflected the important idea of turning waste into treasure.…”