Chromium(VI) adsorption–reduction using a fibrous amidoxime-grafted adsorbent

Green fluorescent nanomaterials for rapid detection of chromium and iron ions: wool keratin-based carbon quantum dots

“…The global industrial revolution and rapid urbanization have escalated rapidly and resulted in the generation of huge quantities of wastewater all over the world. 1 In various industrial processes, such as electroplating, leather tanning, pigment production, 2–5 etc. , diverse heavy metal ions are discharged with the produced wastewater, leading to the risk of causing irreversible damage to the environment and human body.…”

“…, diverse heavy metal ions are discharged with the produced wastewater, leading to the risk of causing irreversible damage to the environment and human body. 2,6–8 The detection and treatment of heavy metal ions in water has become a serious issue that needs to be solved urgently. The common detection methods for heavy metal ions usually relied on large instruments such as atomic absorption spectrometry (AAS) and inductively coupled plasma-mass spectrometry (ICP-MS), 9,10 which are expensive and have complicated in sample pre-treatment.…”

Functionalized Titanium-Based MOF for Cr(VI) Removal from Wastewater

“…These results suggest that the reduction of Cr(VI) could be attributed to the oxidation of amidoxime groups, which could be oxidized into −C(NH 2 )O or further into −COOH (Figure S3). , The reduction process of Cr(VI) to Cr(III) was as follows, as shown by equations (eqs 10 and 11) below Cr 2 normalO 7 2 − + 14 normalH + + 6 normale − → 2 Cr 3 + + 7 normalH 2 normalO HCrO 4 − + 7 normalH + + 3 normale − → Cr 3 + + 4 normalH 2 normalO To further demonstrate that hexavalent chromium could be reduced by the amidoxime group to trivalent chromium, the thermodynamic free energy change before and after the reaction was calculated based on coordination chemistry and chemical reactions, as suggested by the previous literature. , The results (Figure S3) show that the Gibbs free energy changes of two reactions, as shown in Figure S3a, are −616.2 and −2043.4 kcal·mol –1 , respectively, which indicates that both reactions are thermodynamically feasible. This calculation further demonstrated that the reduction of Cr(VI) could be attributed to the oxidation of the amidoxime group.…”

“…These results suggest that the reduction of Cr(VI) could be attributed to the oxidation of amidoxime groups, which could be oxidized into −C(NH 2 )� O or further into −COOH (Figure S3). 52,53 The reduction process of Cr(VI) to Cr(III) was as follows, as shown by equations (eqs 10 and 11) below 36…”

“…To further demonstrate that hexavalent chromium could be reduced by the amidoxime group to trivalent chromium, the thermodynamic free energy change before and after the reaction was calculated based on coordination chemistry and chemical reactions, as suggested by the previous literature. 52,53 The results (Figure S3) show that the Gibbs free energy changes of two reactions, as shown in Figure S3a The cycling experiments of MIL-125(Ti)-AO for removal were also conducted. As shown in Figure S4, the relative removal ratio decreased about 53% in the first cycle and then decreased to 28% after five cycles.…”