Adsorptive removal of Ciprofloxacin and Amoxicillin from single and binary aqueous systems using acid-activated carbon from Prosopis juliflora

Adsorptive removal of emerging contaminants like antibiotics from aqueous systems having one or more antibiotics using acid activated carbon have rarely been studied and reported. Current study deals with the adsorptive removal of individual antibiotic species i.e. Ciprofloxacin (CIP) and Amoxicillin (AMX) from single (CIP and AMX) and binary (CIP + AMX) adsorption systems using acid activated carbon prepared from Prosopis ftdiflora wood (PPJ). Binary adsorption system involved the synergistic and antagonistic influence of one antibiotic over the adsorption of other antibiotic. Physico-chemical alterations of PPJ surface due to acid activation and after adsorption were characterized for any surface modification. Parameters influencing the efficient adsorption of CIP and AMX viz. Initial pH of antibiotic solution, dosage of PPJ, sorbent-sorbate incubation temperature and initial concentration of antibiotic species were optimized. Sorbate-sorbent interaction studies for single system revealed sorbate's monolayer formation over adsorbent's surface and the involvement of chemisorption as verified by Langmuir isotherm model and pseudo-second order model respectively. For single system, Langmuir maximum adsorption capacity of PPJ was 250 mg/g for CIP and 714.29 mg/g for AMX. Meanwhile, competitive Langmuir model was used to investigate adsorption capacity of individual antibiotics in binary system i.e. 370.37 mg/g for CIP and 482.14 mg/g for AMX thus verifying CIP has antagonistic effect on AMX adsorption and AMX has synergistic effect on CIP adsorption on PPJ surface. Recyclability studies verified the PPJ can be used up to 4 cycles and co-existing cationic and anionic salts had minimal effect on the adsorption of antibiotics over PPJ surface. Conclusively PPJ proved efficient in eliminating emerging contaminants like that of antibiotics and thus it can be exploited for other grades of pollutants.