Adsorption characteristics of diclofenac and sulfamethoxazole to graphene oxide in aqueous solution.
The adsorptive properties of graphene oxide (GO) were characterized, and the binding energies of diclofenac (DCF) and sulfamethoxazole (SMX) on GO adsorption were predicted using molecular modeling. The adsorption behaviors of DCF and SMX were investigated in terms of GO dosage, contact time, and pH. Additionally, the effects of sonication on GO adsorption were examined. GO adsorption involves "oxygen-containing functional groups" (OCFGs) such as COOH, which exhibit negative charges over a wide range of pH values (pH 3-11). DCF (-18.8 kcal mol(-1)) had a more favorable binding energy on the GO surface than SMX (-15.9 kcal mol(-1)). Both DCF and SMX were removed from solution (adsorbed to GO), up to 35% and 12%, respectively, within 6h, and an increase in GO dosage enhanced the removal of DCF. Electrostatic repulsion occurred between dissociated DCF/SMX and the more negatively charged GO at basic pH (>pKa). The sonication of GO significantly improved the removal of DCF (75%) and SMX (30%) due to dispersion of exfoliated GO particles and the reduction of OCFGs on the GO surface. Both DCF and SMX in the adsorption isotherm were explained well by the Freundlich model. The results of this study can be used to maximize the adsorption capacities of micropollutants using GO in water treatment processes.
Department of Environmental Health, Graduate School of Public Health, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 157-742, South Korea; Department of Civil and Environmental Engineering, University of South Carolina, Columbia, 300 Main Street, Columbia, SC 29208, USA.
Seung-Woo
SW
Nam
Department of Civil and Environmental Engineering, University of South Carolina, Columbia, 300 Main Street, Columbia, SC 29208, USA.
Chanil
C
Jung
Department of Chemical Engineering, University of South Carolina, 300 Main Street, Columbia, SC 29208, USA.
Hang
H
Li
Department of Chemical Engineering, University of South Carolina, 300 Main Street, Columbia, SC 29208, USA.
Miao
M
Yu
Department of Civil and Environmental Engineering, University of South Carolina, Columbia, 300 Main Street, Columbia, SC 29208, USA.
Joseph R V
JR
Flora
Department of Civil and Environmental Engineering, University of South Carolina, Columbia, 300 Main Street, Columbia, SC 29208, USA.
Linkel K
LK
Boateng
Department of Civil and Environmental Engineering, Korea Army Academy at Young-Cheon, 135-1 Changhari, Kokyungmeon, Young-Cheon, Gyeongbuk 770-849, South Korea.
Namguk
N
Her
Department of Environmental Health, Graduate School of Public Health, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 157-742, South Korea. Electronic address: zohkd@snu.ac.kr.
Kyung-Duk
KD
Zoh
Department of Civil and Environmental Engineering, University of South Carolina, Columbia, 300 Main Street, Columbia, SC 29208, USA. Electronic address: yoony@cec.sc.edu.
Yeomin
Y
Yoon
D000327:Adsorption; D004008:Diclofenac / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D010087:Oxides; D012996:Solutions; D013010:Sonication; D013420:Sulfamethoxazole / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods
D010087:Oxides; D012996:Solutions; D014874:Water Pollutants, Chemical; D004008:Diclofenac; D006108:Graphite; D013420:Sulfamethoxazole
Adsorption; Diclofenac; Graphene oxide; Molecular modeling; Sonication; Sulfamethoxazole