Zn/Fe bimetallic modified Spartina alterniflora-derived biochar heterostructure with superior catalytic performance for the degradation of malachite green

Abstract

In this study, the synchronous magnetized carbonization method was utilized for preparing photocatalysis ZnO-Fe@SC heterostructure, which exhibited degradation efficiency 99.14% (60 min) for malachite green (200 mg/L) and could still maintain good performance after 5 cycles. The prepared ZnO-Fe@SC was analyzed using UV–Vis DRS, PL, SEM, TEM, BET, FTIR, XPS and VSM, and LC–MS for degradation products. The results indicate that photocatalyst has favorable magnetic properties, chemical stability and low charge carriers (e⁻/h⁺) recombination rate. The modification of bimetals enables the composite photocatalyst to enhance the intensity of photogenerated electron transition. Moreover, quenching experiment revealed that the photo-generated holes (h⁺) and superoxide radicals (·O²⁻) were the dominant active species during the photocatalytic process, which degraded malachite green into small molecules by demethylation, deamination, ring-opening reactions as deducted from LC–MS analysis. ZnO-Fe@SC was prepared using a green, safe, low cost and operable synthetic method, which has a broad market potential in the field of environmental remediation.

Graphical Abstract

Highlight

•	ZnO-Fe@SC was prepared via simultaneous magnetized carbonization method using Spartina alterniflora-derived biochar.
•	ZnO-Fe@SC was a heterojunction composite photocatalyst that could achieve up to 99.14% degradation performance of MG in 60 min.
•	ZnO-Fe@SC could be effectively recycled to avoid the leaching of Nano-ZnO.

Funding

the Fundamental Research Funds for Zhejiang Provincial Universities and Research Institutes(2021J004)