Green synthesis of activated carbon-ZIF-8 nanocomposites from pistachio hulls for efficient antibiotic adsorption in water remediation

Water contamination by antibiotics like tetracycline (TC) and amoxicillin (AMX) poses serious environmental and health risks, necessitating effective removal techniques. This study synthesized activated carbon (AC) from pistachio hull powder (P) and used it as a support for Zeolitic Imidazolate Framework-8 (ZIF-8) to create green-synthesized nanocomposites with a synergistic structure of ZIF-8@(pistachio hull powder) activated carbon (Z@ACP) named ZP-0.01, ZP-0.02, and ZP-0.04, with varying weight percentages. These materials were characterized by FE-SEM, FT-IR, XRD, EDX, and BET analyses, confirming the successful integration of ZIF-8 nanoparticles on ACP, resulting in enhanced physicochemical properties and a high surface area (521 m²/g for ZP-0.01). Batch adsorption experiments showed that the ZP-0.01 nanocomposite exhibited excellent adsorption capacities for TC and AMX (up to 38.3 mg/g and 137 mg/g, respectively) under optimized pH, dosage, initial concentration, contact time, and temperature. Adsorption followed a pseudo-second-order kinetic model and fit the Langmuir isotherm, indicating monolayer chemisorption. The ZP-0.01 nanocomposite demonstrated strong reusability, maintaining over 93% capacity after five cycles. The main mechanisms involved in TC and AMX removal by the ZP-0.01 nanocomposite include hydrogen bonding, pore filling, chemisorption, π-π stacking, and electrostatic attraction. These findings highlight the potential of eco-friendly ZIF-8/AC nanocomposites as advanced adsorbents for sustainable antibiotic removal from water.