Removal of Cr(VI) from Acid Wastewater by BC/ZnFe₂O₄ Magnetic Nanocomposite via the Synergy of Absorption‐Photocatalysis

Abstract

Photocatalysis is a promising solar energy conversion technology due to its potential applications in water treatment, searching for highly efficient photocatalytic materials is highly desirable. Herein, we have prepared a series of biochar(BC)/ZnFe2O4 magnetic nanocomposites by the calcination‐hydrothermal two‐step method. BC/ZnFe2O4 owns improved photoabsorption from 400 to 1300 nm. PL spectra of BC/ZnFe2O4 shows a weaker intensity compared with BC and ZnFe2O4, and BC/ZnFe2O4 generates a stronger photocurrent density (∼0.08 μA cm−2) than that of BC (0) or ZnFe2O4 (0.03 μA cm−2) under the visible light irradiation, implying efficient separation efficiency of photogeneration carriers. The investigation of pH (3, 5, 7, 9, 11) sensitivity of BC/ZnFe2O4 demonstrates that removal efficiency of Cr(VI) achieves the highest rate at pH=3. Under visible light irradiation, BC/ZnFe2O4 as photocatalyst can remove 80 % Cr(VI), higher than that of BC (0) or ZnFe2O4 (44 %). In addition, BC/ZnFe2O4 composites exhibit excellent cycling stability and can be easily separated for recycling due to its stability and unique magnetic properties. This work has presented a promising strategy in adsorption‐photocatalytic treatment of acidic wastewater containing heavy metals.

g-C3N4 Modified by meso-Tetrahydroxyphenylchlorin for Photocatalytic Hydrogen Evolution Under Visible/Near-Infrared Light

“…Conversely, when turning off the light source, the photocurrents drop quickly (Luo et al, 2018 ; Li et al, 2021 ). The pattern can be repeated, indicating that photogenerated electrons can be transferred to the contact interface through the sample under light irradiation (Tian et al, 2017 ; Shen et al, 2020b ). Further observation found that the photocurrent value of mTHPC/pCN is higher than bCN, indicating that the charge separation efficiency of mTHPC/pCN has significantly enhanced (An et al, 2017 ).…”

Organic Moiety‐Regulated Photocatalytic Performance of Phosphomolybdate Hybrids for Hexavalent Chromium Reduction

“…In addition, the EPR spectrum of the reaction solution with 5,5‐dimethyl‐1‐pyrroline N‐oxide (DMPO) spin trap exhibited characteristic peaks related to the ⋅ O 2 − radical species (Figure S13), but the signal of ⋅ OH radical species was not detected. Both the produced electrons and ⋅ O 2 − species take part in the processes of Cr(VI) reduction and IPA oxidation, achieving the efficient photocatalytic performance toward Cr(VI) reduction (Figure S14) [43] . The possible reaction equations towards the whole photocatalytic process are as follows [46]…”

“…Among three organic components, bpe possesses the longest conjugated structure; bz has the biphenyl chromophore modified by auxochrome amino groups; while mbpy has the biphenyl fragment modified by non‐auxochrome methyl groups. Such different structural features of organic components will induce different light absorption capacities if they are assembled with polyoxoanions, [43] providing distinct photocatalyst models to study the structure‐activity relationship at the molecular level.…”

Highly efficient removal of Sb(V) from water by franklinite-containing nano-FeZn composites

“…Figure 8 shows XRD patterns for rGO/ NZV-FeZn (new), rGO/NZV-FeZn (after one year) and the used material of rGO/NZV-FeZn(Sb), and the numbers in brackets on the curve represent the crystal surface number (hkl) of XRD characterization material. The primary crystallite size of NZVs-FeZn microspheres were determined from the strongest XRD peak by Scherrer's formula 35 : …”