We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Pristine and modified biochar comparison for environmental micro(nano)plastic removal: adsorption dynamics, influencing factors, mechanisms, and regeneration potential
Summary
Tiny plastic particles called micro(nano)plastics are turning up in our water and soil, and scientists are studying charcoal-like material called biochar as a cheap, eco-friendly way to filter them out. This review of existing research found that "modified" biochar (treated with chemicals or heat to boost its plastic-trapping power) works significantly better than plain biochar at soaking up these particles. While this technology isn't yet ready for large-scale use, it's a promising step toward cleaning up the tiny plastics that end up in our drinking water and food supply, which is important since these particles have raised concerns about potential health risks.
Micro(nano)plastics (MNPs) are plastic particles ranging in size from < 1 µm to 5 mm, posing immense challenges owing to their ubiquitous and polydisperse nature, ecological and human health risks, and environmental remediation challenges. Biochar is a promising tool to remove legacy and emerging environmental pollutants, including MNPs, from aquatic and terrestrial matrices. This review systematically collates studies on pristine and modified biochar in terms of their potential to remove MNPs from laboratory and environmental samples (freshwater, seawater, wastewater, and soil), factors affecting MNP-biochar interactions, adsorption mechanisms, biochar regeneration methods, and research gaps. Our data analyses showed that the modified biochar (8.25–897.7 m 2 /g, p = 0.035) exhibited significantly higher surface area than that of pristine biochar (1.30–540.36 m 2 /g). Similarly, the adsorption capacity of modified biochar (10.92–1723 mg/g, p = 0.030) was significantly higher than that of the pristine biochar (0.56–80.3 mg/g). Pearson correlation analysis showed a significantly positive correlation between surface area and pyrolysis temperature for pristine biochar ( r = 0.81, p < 0.05); and adsorption capacity showed a significantly positive correlation with the size of MNPs ( r = 0.78, p < 0.05) for modified biochar. Further, properties of MNPs, biochar, and environmental conditions were the major factors affecting the MNP-biochar interface, plastic removal, and biochar regeneration. Removal mechanisms mainly involved pore filling, physical trapping, electrostatic interaction, hydrophobic interaction, hydrogen bonding, and π-π interactions. Depending on the type of MNPs and biochar, either single or multiple removal mechanisms can be involved in the adsorption of MNPs on biochar. Pyrolysis, ultrasonication, chemical methods, and hydrothermal degradation were mainly used individually or in combination to regenerate biochar with high reuse efficiencies. Lack of field studies; polymer mixture and environmental MNP removal; aging of biochar and MNPs; optimization and sustainable modification and regeneration of biochar; MNP-biochar-specific interaction mechanisms; scale-up applications; and fate of spent MNP-biochar complexes are the major research gaps and future research perspectives.