We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Comparison of Hexavalent Chromium Adsorption Behavior on Conventional and Biodegradable Microplastics
Summary
Researchers compared hexavalent chromium adsorption behavior on conventional versus biodegradable microplastics, finding that polymer chemistry and surface aging significantly affect chromium binding capacity and the risk of co-transport in contaminated environments.
Microplastics are omnipresent in aquatic environments and can act as vectors to carry other pollutants, modifying their pathway through the systems. In this study, the differences in the adsorption capacity and mechanism for Cr(VI) sorption with polyethylene (PE, a conventional microplastic) and polylactic acid (PLA, a biodegradable microplastic) were investigated via characterization of the MPs, the determination of kinetic behavior (pseudo-first- and second-order model, the Elovich model), and the degree of fit to Langmuir and Freundlich isothermal models; the adsorption behavior was also studied under different solution conditions. The results indicated that when the dose of MPs was 1 g/L, the adsorption capacity of Cr(VI) on MPs reached the highest value, the adsorption capacities were PLA(0.415 mg/g) > PE(0.345 mg/g). The adsorption of Cr(VI) on PE followed the Langmuir isotherm model, while PLA had a stronger fit with the Freundlich model. Sorption in both cases followed a pseudo-first-order kinetics model. The maximum adsorption capacity of Cr(VI) on PLA (0.54 mg/g) is higher than that on PE (0.38 mg/g). In addition, PLA could reach adsorption equilibrium in about 8 h and can adsorb 72.3% of the total Cr(VI) within 4 h, while PE required 16 h to reach equilibrium, suggesting that PLA adsorbs at a significantly faster rate than PE. Thus, biodegradable MPs like PLA may serve as a superior carrier for Cr(VI) in aquatic environments. When the pH increased from 2 to 6, the adsorption of Cr(VI) by PE and PLA decreased from 0.49 mg/g and 0.52 mg/g to 0.27 mg/g and 0.26 mg/g, respectively. When the concentration of sodium dodecyl sulfate in the Cr(VI) solution was increased from nil to 300 mg/L, the adsorption of Cr(VI) by PE and PLA increased by 3.66 and 3.05 times, respectively. In addition, a higher temperature and the presence of Cu2+ and photoaging promoted the adsorption of Cr(VI) by MPs, while higher salinity inhibited the adsorption. The desorption efficiencies of Cr(VI) on MPs were PLA(57.8%) > PE(46.4%). The characterization results further confirmed that the adsorption mechanism could be attributed to electrostatic attraction, hydrogen bonding, and surface complexation. In sum, PLA could potentially serve as better vectors for Cr(VI) than PE, but the risk associated with PLA might be higher than that with PE.
Sign in to start a discussion.
More Papers Like This
Microplastics as an emerging vector of Cr(VI) in water: Correlation of aging properties and adsorption behavior
Researchers studied the correlation between aging properties and adsorption of hexavalent chromium Cr(VI) onto polyethylene microplastics under accelerated UV aging conditions, finding that aging-induced changes in surface chemistry increased the adsorption capacity. Aged microplastics may act as more effective vectors for toxic heavy metals in aquatic environments.
Adsorption mechanism of hexavalent chromium on electron beam-irradiated aged microplastics: Novel aging processes and environmental factors
Researchers used electron beam irradiation as a novel method to age polypropylene microplastics and then studied how these aged particles adsorb hexavalent chromium from water. They found that aging dramatically increased the microplastics' ability to bind chromium by generating oxygen-containing functional groups on their surfaces. The study highlights that weathered microplastics in the environment may have a significantly greater capacity to concentrate heavy metal pollutants than fresh plastic particles.
Adsorption behaviour of microplastics on the heavy metal Cr(VI) before and after ageing
Researchers studied how UV aging affects the adsorption of hexavalent chromium onto PE, PS, and PA microplastics, finding that aged microplastics had significantly enhanced adsorption capacity due to increased surface area and functional group changes from weathering.
Aging properties of polyethylene and polylactic acid microplastics and their adsorption behavior of Cd(II) and Cr(VI) in aquatic environments
Researchers compared how polyethylene and polylactic acid (PLA) microplastics age in the environment and how that aging affects their ability to absorb heavy metals like cadmium and chromium from water. They found that aging changed the surface chemistry of both plastic types, increasing their capacity to pick up these toxic metals. The findings matter because aged microplastics in the environment may concentrate and transport more pollutants than fresh plastic particles.
Polyamide microplastics as better environmental vectors of Cr(VI) in comparison to polyethylene and polypropylene microplastics
Researchers found that polyamide microplastics adsorb more hexavalent chromium (Cr(VI)) than polyethylene or polystyrene microplastics, with UV aging increasing adsorption capacity, making polyamide particles potentially more dangerous environmental vectors for this toxic heavy metal.