Sorption and Transport of Antibiotic Ciprofloxacin in Soils Amended with Colloidal Biochar and Halloysite

Fluoroquinolones are one of the most frequently used antibiotics in the veterinary industry which shows tremendous mobility in soils after manure application. Colloidal biochar (CBC) amendments in soils facilitate the immobility and enhance physicochemical properties to retain contaminants in soils. Objectives of this study were to characterize the CBC halloysite composite, further to determine the sorption of ciprofloxacin (CPX), to evaluate the effect on CPX retainment when soil amended with CBC and halloysites. Biochar produced from Gliricidia sepiumwere taken to produce the CBC using ball-miller grinder and characterized using particle analyser and scanning electron microscope (SEM). The abilities to adsorb CPX at different pH in soil to retain the CPX were examined using batch sorption experiments and column studies. The particles analysed were in the range of 350- 400 nm and showed encapsulation of halloysite nanotubes within the biochar through SEM. Results showed a 40% increase in the CPX retention in soil with 2% amendments of CBC with halloysite and showed optimum adsorption at pH 5. Higher adsorption performance in the acidic pH and in the zwitterionic state of CPX could be attributed to both p-pelectron donor-acceptor interaction arising from CBC and CPX along with cation exchange and electrostatic interaction from the halloysite and CPX. Overall, CBC composites with halloysites could be utilised as an effective amendments to immobilise antibiotics from contaminated soils.