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Application of Zn/Al layered double hydroxides for the removal of nano-scale plastic debris from aqueous systems

Journal of Hazardous Materials 2020 198 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Ekta Tiwari, Nisha Singh, Nitin Khandelwal, Fazel Abdolahpur Monikh, Gopala Krishna Darbha

Summary

Researchers demonstrated that zinc-aluminum layered double hydroxide (LDH) can efficiently adsorb nanoscale plastic debris from freshwater, achieving removal capacities exceeding 160 mg/g in deionized water, though performance dropped significantly under alkaline conditions and in the presence of competing ions like sulfate and phosphate — establishing LDH as a promising but condition-sensitive adsorbent for nanoplastic remediation.

Study Type Environmental

Nano-scale plastic debris (NPDs) are emerging as potential contaminants as they can be easily ingested by aquatic organisms and carry many pollutants in the environment. This study is aimed to remove NPDs from aqueous environment for the first time by using eco-friendly adsorption techniques. Initially, the interaction between NPDs and synthesized Zn-Al layered double hydroxide (LDH) was confirmed by pH titration of Zn-Al LDH against NPDs at varying mass ratio (50:1 to 50:7) and FTIR analysis for both before and after 2 h of contact time. Fast removal was observed in deionized water and synthetic freshwater with maximum sorption capacity (Q) of 164.49 mg/g,162.62 mg/g, respectively, according to Sips isotherm. Whereas, removal was least in synthetic hard water having a Q value of 53 mg/g. For 2 mM concentration of SO and PO, the adsorption capacity significantly decreased to 2%. The removal efficiency was found 100 % at pH 4, while at pH 9, it reached 37 % due to increased competitive binding and destabilization of LDH under alkaline conditions. The process of sorption was spontaneous in different types of water studied. The study reveals that Zn-Al LDH can be used as potential adsorbent for the removal of NPDs from freshwater systems.

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