Magnesium–aluminum layered double hydroxide/graphitic carbon nitride/zeolitic imidazolate framework-8 nanocomposite for enhanced tetracycline removal from aqueous solution

Abstract

During the last decade, tetracycline (TC) has been employed for the treatment of bacterial infections. While it offers benefits in the field of medicine care, its presence in water media leads to the pollution of the ecological systems and poses risks to public health. A ternary nanocomposite of magnesium-aluminum layered double hydroxide/graphitic carbon nitride/zeolitic imidazolate framework-8 (Mg-Al LDH/g-C₃N₄/ZIF-8) was fabricated to effectively adsorb TC from polluted media. The nanocomposite was analyzed using N₂ adsorption/desorption, FT-IR, FESEM, XRD, and EDS techniques. The effects of different factors including adsorbent dosage (5–15 mg), TC concentration (10–150 mg/L), initial pH of solution (4–10) and adsorption time (5–90 min) on TC removal efficiency were investigated. The optimization of parameter values for removing of TC with the Mg-Al LDH/g-C₃N₄/ZIF-8 nanocomposite was performed through response surface methodology (RSM) via central composite design method (CCD) approach. Different models have been tested to find an appropriate fit based on real data, by checking the analysis of variance (R²= 0.96, R_adj= 0.94). The maximum value for adsorption capacity was obtained at dosage of 10 mg, contact time of 15 min, and pH =6. A maximum value of 454.55 mg/g for adsorption capacity was achieved via Langmuir model. In addition, the adsorbent maintained its optimal performance for TC removal after four reuses with about 4.5 % reduction in efficiency. According to obtained data, the nanocomposite has promising potential and effectiveness to eliminate TC antibiotic from aqueous solution.