Green Synthesis of a Biochar‐Based Iron Oxide Catalyst for Efficient Degradation of Pesticides: Kinetics and Photoactivity

Abstract

Photocatalysis is considered as promising methodology for the removal of pesticides from wastewater given its cost‐effective and environmental benignity. Pesticide toxicity and bioaccumulation have brought up environmental issues, underlining the necessity for efficient removal techniques based on novel nanomaterials. Herein, biochar (BC) synthesized by using waste peels of citrus limetta embedded with green synthesized Fe2O3 nanoparticle by using green tea extract. By using PXRD analysis, the α phase of Fe2O3 confirmed. Endosulfan (ES) and Ethion (ET) pesticides are degraded photocatalytically using a sequential, BC@ Fe2O3 nanohybrid. At the pollutant concentration (50 mg L−1), with catalytic dose (25 mg) in acidic condition under natural sunlight, BC@ Fe2O3 showed to be extremely effective in the breakdown of pesticides. The higher removal of pesticides by BC@ Fe2O3 supported by higher value of zeta potential (−22.5 mV), enhanced surface area (74 m2 g−1) and lower value of band gap (1.8 eV) as an effect of interactive characteristic and semiconducting behaviour. The fast decline in pesticide concentration followed by a gradual decrease demonstrated Ist order kinetics triggered by Langmuir adsorption. The availability of active species such as oxygen, hydroxyl radicals and holes, which are liable for pesticide breakdown, proved by scavenger analysis. Formation of safer metabolites during the photocatalytic studies confirmed by the LC‐MS studies. Finally, modified BC@ Fe2O3 nanohybrid may prove to be a viable alternative catalyst for industrial applications due to their reusability (n=7), charge separation, stability and high surface activity.

Highly efficient sunlight-driven photo-adsorptive degradation of organic pollutants by green synthesized Z-scheme heterojunction CeO2@ZnO nanocomposite

“…Accordingly, hydroxyl (˙OH) and holes (h + ) play complementary roles, while superoxide ions (˙O 2 − ) play a dominant role as the active species in the photocatalytic degradation. [54][55][56] A significantly lower degradation rate was observed in the case of pBZQ. Next, the percentage degradation of both pollutants is shown as a bar diagram in Fig.…”

“…53 Adsorption typically goes through four stages: medium resistance, particle diffusion, mass transfer, and adherence to the photocatalyst surface. 54 The removal process consisted of mass transfer, which was limited by diffusion resistance, and adsorption on the active sites of the nanocatalyst. Adsorption, light absorption, and charge transfer are the processes in photocatalytic degradation that result in dynamic species like hydroxyl radicals.…”

“…Afterward, the hydroperoxyl radical (HO 2 ˙) is formed when ˙O2 − reacts with H + and superoxide anion formation due to interaction with ˙OH radicals. [54][55][56] For the quenching of holes, ˙OH radical and ˙O2 − , different quenchers were used, namely ethylenediaminetetraacetic acid disodium salt (Na 2 EDTA), tert-butyl alcohol (t-BuOH) and para-benzoquinone (pBZQ). 63 Na 2 EDTA or any hole scavenger can interact with a photocatalyst and ensure reduction of a target pollutant either by direct injection of electrons or by indirect injection of electrons.…”

Biosynthesized Metallic Nanoarchitecture for Photocatalytic Degradation of Emerging Organochlorine and Organophosphate Pollutants: A Review

“…Several eluents have been studied to help [99] (b) PXRD data of reused biogenic GG-CdMgFe 2 O 4 @TiO 2 nanocomposite, [100] (c) Recyclability test of biogenic GG-CdMgFe 2 O 4 @TiO 2 nanocomposite, [100] (d) Recyclability test of biogenic nanocomposite, [98] (e) PXRD data of reused biogenic nanocomposite. [98] desorb OP and OC from used nanophotocatalysts Among these are ethanol, [126] distilled water and acetone, [93,98] distilled water and n-hexane, [130] and centrifugation, water and acetone. [131] However, the most frequently used eluent is distilled water and n-hexane.…”

“…After the nth cycle, a nanonanophotocatalyst's average degradation capacity is higher than 78 %. Several eluents have been studied to help desorb OP and OC from used nanophotocatalysts Among these are ethanol, [126] distilled water and acetone, [93,98] distilled water and n‐hexane, [130] and centrifugation, water and acetone [131] . However, the most frequently used eluent is distilled water and n‐hexane.…”