Antibiotics adsorption from contaminated water by composites of ZSM-5 zeolite nanocrystals coated carbon

The presence of antibiotic residues such as ciprofloxacin (CIPR) in an aqueous environment is dangerous when their concentrations exceed the allowable. Therefore, eliminating these residues from the wastewater becomes an essential issue to prevent their harm. In this work, the potential of efficient adsorption of ciprofloxacin antibiotics was studied using eco-friendly ZSM-5 nanocrystals‑carbon composite (NZC). An inexpensive effective natural binder made of the sucrose-citric acid mixture was used for preparing NZC. The characterization methods revealed the successful preparation of NZC with a favorable surface area of 103.739 m2/g, and unique morphology and functional groups. Investigating the ability of NZC for adsorbing CIPR antibiotics conducted at different conditions showed that 0.3 g of NZC achieved outstanding adsorption for 150 ppm CIPR antibiotic from 100 mL solutions at mixing speed of 200 rpm, solution pH of 4–6, and solution temperature of 25–30 °C. Estimating the values of ∆H°, ∆S°, and ∆G° confirmed that the adsorption process of CIPR antibiotics by NZC was feasible, exothermic and spontaneous. The Freundlich and pseudo-second-order models well fitted the adsorption process's experimental data. The results of both the kinetic and isotherm studies showed that the adsorption process of CIPR antibiotics by NZC is simultaneously composed of physical and chemical adsorption on the heterogeneous adsorption sites in multilayers. Also, the intra-particle diffusion was not the controlling step and the external surface adsorption influenced the adsorption of CIPR. From the abovementioned results, NZC is recommended as a highly efficient adsorbent for the removal of CIPR-loaded effluents. [Display omitted] •Carbon coated by ZSM-5 zeolite nanocrystals was synthesized by low-cost binder.•Carbon coated by ZSM-5 zeolite nanocrystals is a promising adsorbent for ciprofloxacin.•Adsorption of ciprofloxacin was not controlled by the intra-particle diffusion.•Adsorption of ciprofloxacin was influenced by the external film adsorption.•The process mechanism was chemi-/physisorption, exothermic, and spontaneous.