Adsorption of tetracycline antibiotics by nitrilotriacetic acid modified magnetic chitosan-based microspheres from aqueous solutions

With the abuse of tetracycline antibiotics and their high detection rate in the water environment, causing non-negligible environmental hazards and health risks, the treatment of tetracycline wastewater has been paid much attention. Herein, a noval magnetic adsorbent, nitrilotriacetic acid-modified magnetic chitosan microspheres (NDMCMs) was successfully prepared and applied to remove tetracycline antibiotics (TC) from wastewater. The results found that the solution pH and ion strength greatly affected the adsorption capacity of TC by NDMCMs. Additionally, the adsorption capacity of NDMCMs (373.5 mg g −1 ) was four times higher than that of MCMs (92 mg g −1 ) at pH 8.0, attributed to the various amino and carboxyl groups in the grafted chain. The experiment data were better correlated with the Freundlich isotherm model and the pseudo-second-order kinetic model, indicating that the adsorption between TC and adsorbent surfaces occurred as multilayer adsorption, and the chemical interaction played as a rate-limiting step in the adsorption process. The thermodynamic parameter calculation results demonstrated that the adsorption of TC by NDMCMs followed a spontaneous, endothermic, and orderly process. Besides, the regeneration performance of NDMCMs showed that it is fully qualified for practical application of TC adsorption. The adsorption mechanism proposed by the FT-IR spectroscopic analysis of the adsorbent before and after the adsorption of TC was mainly through π - π interaction, cation- π bond, hydrogen bond, and amidation reaction. Based on all experimental results, NDMCMs is an efficient and sustainable magnetic adsorbent, which can be used to remove TC from wastewater. • Chitosan-based magnetic adsorbent with NTA modified are synthesized. • NDMCMs showed excellent adsorption capacities for tetracycline. • NDMCMs could be efficiently separated from aqueous solutions with magnetic force. • TC-loaded NDMCMs could be easily regenerated and reused more than five-times. • The good reusability of adsorbent indicated its practical application.