We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Adsorption of a diverse range of pharmaceuticals to polyethylene microplastics in wastewater and their desorption in environmental matrices
Summary
Researchers investigated how polyethylene microplastics adsorb pharmaceuticals in municipal wastewater and release them in environmental and biological fluids. They found that drug adsorption depended heavily on the compound's charge and hydrophobicity, with cationic and hydrophobic drugs adsorbing most readily. The study suggests that microplastics could act as vectors for certain pharmaceuticals, potentially transporting them through waterways and into organisms.
It is proposed that microplastics discharged from wastewater treatment plants act as a vector of pharmaceuticals. In this study, adsorption of pharmaceuticals to polyethylene microplastics was investigated in municipal wastewater. Pharmaceuticals for study were selected to represent different speciation (anionic, cationic, and neutral) and a range of pH dependant octanol-water distribution coefficients (log D). Findings revealed adsorption favoured those in cationic form with the greatest hydrophobicity (e.g., fluoxetine log D 2.0 at pH 7.8). Adsorption of anionic pharmaceuticals was restricted due to repulsion with the microplastic's negatively charged surface. Only atorvastatin had any appreciable adsorption due to its comparatively high log D value (2.9). Those pharmaceuticals predominantly in neutral form (carbamazepine and ketamine) with log D values ≥2.4 had similar adsorption. Freundlich K values were 3400, 386, 284, 259 and 218 (mg kg)(mg L) for fluoxetine, propranolol, atorvastatin, ketamine, and carbamazepine, respectively. All pharmaceuticals with log D values <1.0 (atenolol, gliclazide, bezafibrate, and ifosfamide) did not adsorb to microplastics, irrespective of their speciation. Changing composition of wastewater (pH, dilution with stormwater and NaCl addition) within the range expected for municipal wastewater had limited influence on adsorption. Pharmaceutical desorption from microplastics was assessed in river water and simulated gastric and intestinal fluids. Solution pH was considered the most important factor for pharmaceutical desorption, influencing both pharmaceutical speciation and microplastic surface charge. Greatest desorption was observed for the cationic pharmaceuticals in gastric fluids due to a reduced surface charge of the microplastics under low pH conditions. Up to 50% desorption of fluoxetine occurred in gastric fluid at 37 °C. These findings show that pharmaceuticals adsorbed to microplastics are 'bioavailable'. However, this is often overlooked as an exposure route to aquatic organisms because water samples are normally pre-filtered prior to chemical analysis.
Sign in to start a discussion.
More Papers Like This
Sorption of pharmaceuticals on the surface of microplastics
Researchers tested the ability of four common microplastic types to adsorb nine pharmaceutical compounds frequently found as water pollutants. They found that sorption involved both hydrophobic and electrostatic interactions, but under natural environmental conditions the binding was relatively weak. The study suggests that while microplastics can interact with pharmaceutical residues, their role as carriers of these contaminants in real aquatic environments may be more limited than previously assumed.
Sorption of selected pharmaceutical compounds on polyethylene microplastics: Roles of pH, aging, and competitive sorption
Researchers found that polyethylene microplastics adsorb pharmaceutical compounds including an antibiotic, a beta-blocker, and an antidepressant, with sorption capacity influenced by pH, aging of the plastic, and competition between compounds — raising concern about microplastics as carriers of pharmaceuticals in aquatic environments.
Sorption and desorption of selected pharmaceuticals by polyethylene microplastics
Researchers tested the sorption and desorption of three pharmaceuticals — sulfamethoxazole, propranolol, and sertraline — onto polyethylene microplastics in water, finding that all three compounds sorbed to the plastic surface and were only partially released over time. The results suggest microplastics can act as vectors for pharmaceutical compounds in aquatic environments, potentially affecting their bioavailability.
Polyamide microplastics in wastewater as vectors of cationic pharmaceutical drugs
Researchers investigated whether polyamide microplastics in wastewater can adsorb pharmaceutical drugs and transport them into the environment. They found significant adsorption of hydrophobic pharmaceuticals like propranolol, amitriptyline, and fluoxetine, with limited desorption in river water but increased release in simulated gastric fluids. The findings suggest that microplastics discharged from wastewater treatment could carry adsorbed medications over long distances and release them if ingested by wildlife or humans.
Sorption of pharmaceuticals over microplastics’ surfaces: interaction mechanisms and governing factors
Researchers reviewed the sorption mechanisms by which pharmaceuticals interact with microplastic surfaces in the environment. The study found that electrostatic interactions, hydrogen bonding, and hydrophobic forces are the primary mechanisms governing pharmaceutical adsorption onto microplastics, suggesting that microplastics can serve as vectors for transporting pharmaceutical contaminants through ecosystems.