Preparation of PEI/CS aerogel beads with a high density of reactive sites for efficient Cr(vi) sorption: batch and column studies

Abstract

In view of the sustainable character and high-density of reactive sorption sites, a new kind of poly(ethylenimine)/chitosan (PEI/CS) aerogel beads were successfully synthesized using controllable sol-gel and freeze drying methods, with the aim of using them for efficient Cr(VI) removal from aqueous acid solutions. Compared with the reported CS-based sorbents for hexavalent chromium [Cr(VI)], not only is the synthetic process used simple but the bead-like samples could be easily separated from solutions for recycling. Structural characterization and batch experiments were compared to illustrate the adsorption performance of the aerogel beads which were synthesized using various processes. Out of the three samples (CS-glutaraldehyde (GA), CS-GA-PEI and CS/PEI-GA beads), the one referred to as CS-GA-PEI exhibited the highest adsorption capacity and the maximum amount of Cr(VI) removal was 402.9 mg g À1 at pH 2.0 and 298 K. The pseudo-second-order and Langmuir model preferably fitted the adsorption process best. After five cycles of desorption-regeneration tests, more than 80% of Cr(VI) could still be removed by these newly designed CS-GA-PEI beads. Adsorption mechanisms could be explained using electrostatic attraction and reduction reaction theories, on the basis of comprehensive analysis. More importantly, taking advantage of the micrometer sized particles and three-dimensional network that developed, fixed-bed column tests were also conducted on the resultant bead-like sample, which also exhibited excellent sorption performance under testing conditions. These superiorities of CS-GA-PEI beads make them a potential candidate for use in remediating the pollution caused by Cr(VI) ions.

Polyethylenimine-functionalized cellulose aerogel beads for efficient dynamic removal of chromium(vi) from aqueous solution

“…Those results were consistent with the previous works. 3,21 As can be seen from the Fig. 5b, the uptake capacity of Cr(VI) decreased with the increase of TOC.…”

“…Amongst them, using low-cost biomass as adsorbent to remove Cr(VI) has received great attention, such as rice husk, 17 cellulose, 18 lignin, 19 sodium alginate 20 and chitosan. 21 Among these materials, cellulose has received increasing attentions owing to its properties which contain inexpensive, abundant, non-toxic, low weight, renewable and biodegradable. There are many -OH groups on the surface of cellulose that can provide some adsorption capacity.…”

Review on the Production of Polysaccharide Aerogel Particles

“…Further application fields embrace environmental remediation and catalysis, both of them have been comprehensively reviewed very recently [210,211]. Functionalized nanofibrillar network of polysaccharide aerogel beads have been utilized as promising reusable filter materials for the applications in environment control system [172,230,231]. High specific surface area of nano-network and chelating functional groups of polysaccharide aerogels offer hosting property and they can be utilized for catalysis applications [65,66,67,68].…”

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

“…25–45 Previous studies have identified two main problems in CS/PEI adsorbents used for metal removal: (1) complicated synthesis process 46,47 and (2) reduction in adsorption capacity at pH values above 3 that would lead to low adsorption capacity at neutral pH value. 46–50 To use an adsorbent for chromium removal in industry, the production process should be robust to facilitate scale-up and the adsorbent should be effective at pH values close to real wastewater, instead of highly acidic water.…”