High-performance adsorption of chromate by hydrazone-linked guanidinium-based ionic covalent organic frameworks: Selective ion exchange

Selective Chromium(VI) Trapping by an Acetate-Releasing Coordination Polymer

“…Although it is difficult to compare CPs to covalent-organic frameworks (COFs) in terms of total Cr uptake in milligrams per gram due to the heavy weight fraction of the metal in CPs, COFs comparatively suffer in their selectivity, particularly in the presence of polyvalent anions . Tp-DG Cl , for example, displays remarkable uptake of Cr (360 mg Cr/g), but the Cr uptake drops by approximately 60 and 80% in solutions containing sulfate in only 2-fold and 20-fold molar excess, respectively …”

“…Furthermore, Cr ranks among the top 20 toxic substances found within Superfund-controlled sites . Although Cr can be released from natural sources, modern Cr pollution stems largely from chemical and dye manufacturing, industrial energy production, leather industries, and mining. − The global release of Cr into water is reported to be as high as 157,000 t per year, making it the most common pollutant in groundwater among toxic trace elements. , Cr can exist in several oxidation states, but the two states most pertinent in natural bodies of water and wastewater are Cr­(III) and Cr­(VI). ,− …”

Subsurface and solid solution-type defect engineering in the CoCr2O4–Bi2WO4–NiS2 nanocomposite for the visible-light degradation of doxycycline and removal of chromium and its genotoxic evaluation in Allium cepa

“…According to the previous literature, several chromate-based nanocatalysts have been developed for environmental water treatment, such as Cr 2 S 3 , Cr 2 O 3 , NiCr 2 O 4 , and CoCr 2 O 3 , due to their enhanced photocatalytic activity under visible light irradiation. 19,20 Among these, metal chromates have been widely used due to their wide band gap range from 1.9 to 2.8 eV, which can efficiently utilize visible light for effective water treatment. 20 In addition, bismuth-based nanomaterials have been found to be one of the most effective photocatalytic active nanomaterial types that can utilize both UV and visible light for the effective removal of heavy metal and organic contaminants.…”

Guanidinium-Based Ionic Covalent-Organic Nanosheets for Sequestration of Cr(VI) and As(V) Oxoanions in Water

“…47 Success of small-molecule guanidinium-containing anion receptors 48,49 has alluded to great potential of guanidinium-based materials in oxoanion sequestration, yet this area is relatively underexplored. 32,38,50 Specifically, studies that examine the structure− activity relationship on the sequestration of oxoanions using guanidinium-based iCONs are still missing. The capability of these guanidinium-based framework materials in the adsorption and removal of chromate and arsenate in water hence remains poorly understood.…”

“…Ionic covalent-organic nanosheets (iCONs) − comprised of iminoguanidinium motifs have received increasing attention in many areas of research from energy storage and molecular separation, to CO 2 capture and conversion, as well as antimicrobial , and stimulus-responsive materials . Success of small-molecule guanidinium-containing anion receptors , has alluded to great potential of guanidinium-based materials in oxoanion sequestration, yet this area is relatively underexplored. ,, Specifically, studies that examine the structure–activity relationship on the sequestration of oxoanions using guanidinium-based iCONs are still missing. The capability of these guanidinium-based framework materials in the adsorption and removal of chromate and arsenate in water hence remains poorly understood.…”