Removal of hexavalent chromium from impaired water: Polyethylenimine-based sorbents − A review

Optimization of batch and packed-bed column Cr(vi) adsorption of an amine-rich chitosan/polyethyleneimine composite: application in electroplating wastewater treatment

“…1,6,7,9 The environmental threat of Cr(VI) has attracted many scientists to work on innovative approaches to remove Cr(VI) from water for the past 20 years, as indicated by the high number of publications. 4,5 Furthermore, many studies have favored adsorption over other methods, mainly because it is simple, cost-effective, and reusable. 1,[3][4][5]10 Another advantage of the adsorption process is the possibility of using sustainable materials to produce the adsorbent.…”

“…Chromium is mainly present in the environment as Cr(III) and Cr(VI). [1][2][3][4][5] Cr(III) is a micronutrient, but it can be toxic at high concentrations. On the other hand, chromium compounds like chromate (CrO 4 − ), dichromate (Cr 2 O 7 2− ), and hydrogen chromate (HCrO 4 ) are carcinogenic and toxic even at ppb levels since they are highly soluble and can easily diffuse through the cell membranes in the tissues.…”

“…4,5 Furthermore, many studies have favored adsorption over other methods, mainly because it is simple, cost-effective, and reusable. 1,[3][4][5]10 Another advantage of the adsorption process is the possibility of using sustainable materials to produce the adsorbent. Several agricultural by-products have been reported in the literature as viable biosorbents for chromium removal, including fruit shells, 11,12 water caltrop, 13 and nanocellulose.…”

“…19 That could be the reason why most research articles limit the evaluation of their adsorbents to batch conditions instead of continuous conditions, such as in a column reactor. To put this fact into numbers, in a review article focusing on polyethyleneimine (PEI) composites, 5 out of 136 studies on chromium adsorption, only six had studied continuous flow conditions in a column reactor. While the authors highlight the value of batch studies as an essential first step to understand the adsorption process, they emphasize the importance of investigations in flow conditions to bring adsorption technologies to real-world applications.…”

N-type silver ammonia-polyethyleneimine/single-walled carbon nanotube composite films with enhanced thermoelectric properties

“…PEI can form stable complexes with metal ions, as reported in the literature. 29,30 Therefore, this work was performed to improve the thermoelectric performance and air stability of PEI/SWCNT by alleviating the activity of PEI via ligand exchange between PEI and silver ammonia and reduction treatment.…”