Design of nanostructured SnFe2O4 decorated on bentonite substrate for water remediation in removal of amoxycillin, statistical optimisation, operational functions and mechanism

Abstract

ABSTRACT The presence of drug residue compounds such as antibiotics in the aquatic environment is an enhancing concern due to their toxicity and resistance of these pollutants. The fabrication of new eco-friendly catalyst and simple method for removal of antibiotics in water remediation has become an important challenge. In this work, we show that nanostructured SnFe2O4 decorated on bentonite could be conducted as an impressive catalyst in degradation of amoxycillin (AMX) from water under UV light irradiation. The prepared SnFe2O4/bentonite was instrumentally characterised using different techniques. The average particle sizes for the SnFe2O4 nanoparticles and SnFe2O4/bentonite nanocomposites were 45.00 and 51.00 nm, respectively. It can be seen that the pure SnFe2O4 nanoparticles and SnFe2O4/bentonite nanocomposites have a band gap of about 2.37 eV and 2.08 eV, respectively. The active surface of the SnFe2O4/bentonite nanocomposites increases due to the presence of bentonite. The AMX was degraded after 40 min using the SnFe2O4/bentonite nanocomposites about 98.00%. The SnFe2O4 nanoparticles show the lowest photocatalytic activity (77.4%) compared to the composite sample. The order roles of active species in the AMX degradation were as follows: •O2 − > •OH > e− > h+. The operational functions including pH of solution, reaction time and catalyst dosage that influence the degradation were optimised. The statistical optimisation was performed using Box–Behnken design of response surface methodology. The best AMX degradation (98.0%) was observed at pH: 5.00 with 0.500 g/L of SnFe2O4/bentonite nanocomposites in 40 min under UV light irradiation. At acidic pH, the catalyst has a negative charge and amoxycillin has a positive charge, and, hence, the degradation is completed on the catalyst surface. Validation model of this process shows the negligible difference response and was 97.62% at this condition.