Electrospun hematite nanofiber/mesoporous silica core/shell nanomaterials as an efficient adsorbent for heavy metals

Abstract

Functionalized nanomaterials hold tremendous promise for water treatment because their high surface area makes them ideal sorbents for pollutants like heavy metal ions that are pervasive in global water supplies.

Chromium removal from contaminated waters using nanomaterials – A review

“…Among the various materials used for chromium removal, nanoparticles have been the most common, either using just the core nanoparticles [9,[40][41][42][43][44][45][46], nanoparticles with functionalization [35,[47][48][49], or modified nanoparticles incorporated on substrates [36,50]. Other type of materials have been used, such as nanocomposites [37,51,52], nanofibers [38] and carbon nanotubes [39]. In present review, nanomaterials like zero-valent iorn nanoparticels (nZVI) were not found.…”

“…Numerous studies have been published on chromium sorption in aqueous phase using various materials and in particular synthetic nanomaterials [9,[35][36][37][38][39]. To select the articles For each selected article, it was extracted the information related to the parameters considered relevant in sorption [7][8][9]: name and nature of the sorbent, mass of the sorbent with respect to the water volume, type of water used in the experiment, type of experiment (single or other contaminants besides chromium), pH, temperature, contact time between the sorbent and the solution, initial concentration of chromium, chromium species initially present in solution, and removal efficiency.…”

“…Removal of Cr(VI) was tested at pH from 2 to 3 [9,39,[42][43][44]66,69], although some authors have been studied the removal at more realist pH interval, 5-8 [40,70], which is the pH found in actual industrial effluent. Values of optimal pH in the removal of Cr(III) were between 5 and 7 [9,38,42,48,51,71].…”

“…Chromium speciation. Cr(VI) have been the most investigated species, although some researchers have run experiments with Cr(III) forms [38,47,48,51,71]. Others studies used with both Cr(III) and Cr(VI) [9,42,69,77,78].…”

“…Regarding the reaction of Cr(III) with the different materials, the binding is through an ion or molecular exchange mechanism combined with some kind of physisorption [69,77]. Egodawatte et al [38] proposed that the binding mechanism between the nanofibers and Cr(III) involves the sorption of a positive complex on the surface of the materials. Arthy et al [51] suggested a chemisorption mechanism.…”