Removal of nano-sized polystyrene plastic from aqueous solutions using untreated coffee grounds
Journal
Chemosphere
Journal Volume
286
Date Issued
2022
Author(s)
Abstract
Nanoplastic (NP) pollution is an emerging global concern due to its adverse impact on aquatic ecosystems. Nevertheless, the removal of aqueous NPs from aquatic environments remains a significant challenge. This study aims to investigate whether polystyrene NP in aqueous solutions can be removed using coffee grounds. Due to the difficulty associated with directly measuring NP levels and monitoring the biosorption process, we used fluorescent-orange amine-modified polystyrene beads (fluo-NP, 100 nm) to evaluate the efficacy of the biosorption process. The factors including pH, coffee grounds concentration, initial fluo-NP concentration, and contact time were optimized on batch experiments. In addition, the isotherm and kinetic models were employed to clarify the adsorption behaviors and mechanisms. It was found that aqueous fluo-NP particles were effectively adsorbed onto the coffee grounds over a wide pH range (pH 2–12), with a coffee ground concentration of 25 g/L leading to the maximum adsorption efficiency (74%). The equilibrium adsorption capacity of the coffee grounds was 4 mg/g for a reaction time of 40 min. Coffee grounds demonstrated the highest removal efficiency when the initial fluo-NP concentration was 100–125 mg/L. The Dubinin-Radushkevich model and pseudo-second-order model described the adsorption isotherm and kinetics well, respectively, and the adsorption at high fluo-NP concentration range was favorable. Moreover, the results suggest that the mechanism lies in the electrostatic interactions and hydrogen bonding between surface functional groups of the coffee grounds and the fluo-NP particles. Given that there is an urgent need to remove NPs from aqueous systems, this study illustrates that it is possible to use coffee ground biowaste for this purpose. ? 2021 Elsevier Ltd
Subjects
Biosorption
Biowaste
Coffee grounds
Nanoplastics
Adsorption
Aquatic ecosystems
Efficiency
Hydrogen bonds
Polystyrenes
Aquatic environments
Biosorption process
Biowastes
Concentration-time
Ground concentrations
Nano-sized polystyrenes
Polystyrene beads
Polystyrene plastics
adsorption
aquatic ecosystem
aqueous solution
coffee
isotherm
nanoparticle
polymer
removal experiment
Citrus sinensis
plastic
polystyrene derivative
ecosystem
kinetics
pH
solution and solubility
thermodynamics
water pollutant
Coffee
Ecosystem
Hydrogen-Ion Concentration
Kinetics
Plastics
Solutions
Thermodynamics
Water Pollutants, Chemical
Type
journal article