High-capacity adsorption of benzotriazole from aqueous solution by calcined Zn-Al layered double hydroxides

The increasing presence of the toxic compound benzotriazole (BTA) in water bodies makes it an emerging environmental pollutant of concern; thus, there is an urgent need for a method to remove BTA efficiently. Herein, calcined Zn-Al layered double hydroxides (LDHs) were prepared and used as novel adsorbents for removing BTA from aqueous solution. The adsorption isotherms and kinetics were studied, and the factors that affect the adsorption, such as adsorbent dosage, ion strength and solution pH, were investigated. The maximum adsorption capacity of calcined LDH for BTA was as high as 1910 mg/g, which is the highest capacity for a BTA adsorbent reported to date. Calcined LDH also exhibited stable adsorption capacity in the presence of NaCl or MgSO4; moreover, it can be reused for at least 4 cycles without obvious loss of its capacity. The structural recovery of calcined LDH with incorporation of BTA ions was found to be the main reason for such high adsorption capacity.