Capture and Release Recyclable Dimethylaminomethyl-Calixarene Functional Cloths for Point-of-Use Removal of Highly Toxic Chromium Water Pollutants

Abstract

Chromium(VI) contamination of drinking water arises from industrial activity wherever there is a lack of environmental legislation enforcement regarding the removal of such pollutants. Whilst it is possible to remove such harmful metal ions from drinking water through large scale facilities, there currently exists no safe and simple way to filter chromium(VI) oxoanions at point-of-use (which is potentially safer and necessary in remote locations or humanitarian scenarios). High surface area cloth substrates have been functionalized with calixarene molecules for the selective capture of aqueous chromium(VI) oxoanions in the presence of structurally similar anions. This is accomplished by pulsed plasmachemical deposition of a linker layer and subsequent functionalization with dimethylaminomethyl-calixarene (5,11,17,23tetrakis[(dimethylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene, DMAMcalixarene). Chromium(VI) oxoanions are captured by simply passing polluted water through the functionalised cloth, whilst other ions not harmful / beneficial to human health remain in the water. These cloth filters are simple to use, highly selective, and easily recyclable-thus making them attractive for point-of-use application in geographic regions lacking appropriate wastewater treatment plants or flawed environmental monitoring systems. Chromium(VI) pollutants have been successfully removed from real-world contaminated industrial wastewater streams using the dimethylaminomethyl-calixarene functionalised cloths.

“Functional upcycling” of polymer waste towards the design of new materials

“…42 Using this strategy, Badyal et al developed a multistage procedure for creating a composite material from PP fabric via pulsed plasma coating with poly(vinylbenzyl chloride), followed by covalent grafting of calixarene (Table 4(4)). 312 The prepared membrane is able to selectively entrap Cr 6+ oxoanions, making it attractive for point-of-use application in geographic regions lacking appropriate wastewater treatment plants or flawed environmental monitoring systems. Independently, PP fabric has been coated with electroconductive polyaniline (PANI) for adsorbing humic acid (Table 4(1)).…”

“…326,327 Despite the simplicity and convenience of noncovalent approaches, the leakage of active components to the surrounding media limits their widespread application, which can be resolved via covalent modification. Thus, the sulfonation of PP in concentrated sulfuric acid has been implemented to improve [307][308][309] (c) heteroradicals functionalisation; 167,310 (d) sulfonation; 311 (e) grafting under physical treatment; 312,313 (f) oxidation; 42,314,315 (g) grafting of C-centered radicals; 316 and (h) diazirine modification through carbene intermediate. 317 This journal is © The Royal Society of Chemistry 2023 their thermal, 328,329 adsorption performance 330 or electrochemical properties 311 (Fig.…”

“…10f and Table 4(5)). The formation of active sites using high-energy sources such as g-ray radiation, 331,332 electron beam, 313 UV 333 and plasma 312 allows for the covalently attachment of different organic molecules (e.g., acrylonitrile, polymethyl acrylate, PS, GMA, AA, and benzyl chloride) to the PP surface (Fig. 10e and Table 4(4)).…”

“…Fig. 10 Functionalisation of PP: (a) thermal xanthylation; 306 (b) radical grafting of polymers;[307][308][309] (c) heteroradicals functionalisation;167,310 (d) sulfonation;311 (e) grafting under physical treatment;312,313 (f) oxidation;42,314,315 (g) grafting of C-centered radicals; 316 and (h) diazirine modification through carbene intermediate 317. …”

Synthesis of BINOL–xylose-conjugates as “Turn-off” fluorescent receptors for Fe3+ and secondary recognition of cysteine by their complexes

“…[23][24][25][26][27][28] Therefore, the design of sensors for the detection of ions and biological molecules has attracted extensive attention. 29 It has been reported that rhodamine, 30,31 BODIPY, 32 calixarene, 33,34 cyclodextrin 35 and their derivatives can effectively identify metal ions, but it has not been found that they can perform secondary recognition for amino acids. It is well known that triazole compounds are used as corrosion inhibitors of organic copper, among which 1,2,4-triazole compounds are the most prominent.…”