Efficient removal of pharmaceuticals from water using graphene nanoplatelets as adsorbent

Recently, pharmaceutical pollutants in water emerge as global concern as
they give threat to human health and environment. In this study, graphene
nanoplatelets (GNPs) were used to efficiently remove antibiotics
sulfamethoxazole (SMX) and analgesic acetaminophen (ACM) as pharmaceutical
pollutants from water by adsorption process. GNPs; C750, C300, M15, and M5
were characterized by high-resolution transmission electron microscopy,
Raman spectroscopy, X-Ray diffraction and Brunauer-Emmett-Teller. The
effects of several parameters; viz., solution pH, adsorbent amount,
initial concentration and contact time were studied. The parameters were
optimized by batch adsorption process and the maximum removal efficiency
for both pharmaceuticals were 99%. The adsorption kinetics and isotherms
model were employed, and the experimental data were best analysed with
pseudo-second kinetic and Langmuir isotherm with maximum adsorption
capacity (Qm) of 210.08 mg g-1 for sulfamethoxazole and
56.21 mg g-1 for acetaminophen. Regeneration study were applied
using different eluents; 5% ethanol-deionized water 0.005 M NaOH and HCl.
GNP C300 were able to remove most of both pollutants
from environmental water samples. Molecular docking was
used to simulate the adsorption mechanism of GNP C300 towards
sulfamethoxazole and acetaminophen with free binding energy of
-7.54 kcal mol-1 and -5.29 kcal mol-1 respectively which revealed
adsorption occurred spontaneously.