TY - JOUR

T1 - Halloysite nanoclay supported adsorptive removal of oxytetracycline antibiotic from aqueous media

AU - Ramanayaka, Sammani

AU - Sarkar, Binoy

AU - Cooray, Asitha T.

AU - Ok, Yong Sik

AU - Vithanage, Meththika

PY - 2020/2/15

Y1 - 2020/2/15

N2 - Halloysite nanoclay was utilized to retain aqueous oxytetracycline (OTC) which is extensively used in the veterinary industry. The micro-structure and functionality of the nanoclay were characterized through spectroscopic techniques before and after adsorption. The OTC removal experiments were performed at different pH conditions (pH 3.0–9.0), ionic strengths (0.001, 0.01, 0.1 M NaNO3) and contact time (up to 32 h) at an initial 25 mg/L OTC concentration with 1.0 g/L halloysite. Oxytetracycline adsorption was pH dependent, and the best pH was observed in the range of pH 3.5–5.5 at a 0.001 M ionic strength. At pH 3.5, the maximum OTC adsorption amount was 21 mg/g which translated to 68% removal of the initial OTC loading. Positively charged inner lumen and negatively charged outer lumen of the tubular halloysite structure led to form inner-sphere complexes with the anionic and cationic forms of OTC, respectively. A rapid adsorption of OTC was observed in the kinetic study where 62% OTC was adsorbed in 90 min. Pseudo-second order equation obeyed by the kinetic data indicated that the adsorption was governed by chemisorption, whereas Hill isotherm equation was the most fitted with a maximum adsorption capacity of 52.4 mg/g indicating a cooperative adsorption phenomenon.

AB - Halloysite nanoclay was utilized to retain aqueous oxytetracycline (OTC) which is extensively used in the veterinary industry. The micro-structure and functionality of the nanoclay were characterized through spectroscopic techniques before and after adsorption. The OTC removal experiments were performed at different pH conditions (pH 3.0–9.0), ionic strengths (0.001, 0.01, 0.1 M NaNO3) and contact time (up to 32 h) at an initial 25 mg/L OTC concentration with 1.0 g/L halloysite. Oxytetracycline adsorption was pH dependent, and the best pH was observed in the range of pH 3.5–5.5 at a 0.001 M ionic strength. At pH 3.5, the maximum OTC adsorption amount was 21 mg/g which translated to 68% removal of the initial OTC loading. Positively charged inner lumen and negatively charged outer lumen of the tubular halloysite structure led to form inner-sphere complexes with the anionic and cationic forms of OTC, respectively. A rapid adsorption of OTC was observed in the kinetic study where 62% OTC was adsorbed in 90 min. Pseudo-second order equation obeyed by the kinetic data indicated that the adsorption was governed by chemisorption, whereas Hill isotherm equation was the most fitted with a maximum adsorption capacity of 52.4 mg/g indicating a cooperative adsorption phenomenon.

KW - Adsorption

KW - Emerging contaminants

KW - Nanomaterials

KW - Pharmaceuticals

KW - Water pollution

U2 - 10.1016/j.jhazmat.2019.121301

DO - 10.1016/j.jhazmat.2019.121301

M3 - Journal article

C2 - 31600698

AN - SCOPUS:85072854829

VL - 384

JO - Journal of Hazardous Materials

JF - Journal of Hazardous Materials

SN - 0304-3894

M1 - 121301

ER -