Hybrid polysaccharide beads for enhancing adsorption of Cr(VI) ions

Abstract

Alginate (Alg) beads were modified by the adsorption of poly(4-vinyl-N-pentyl pyridinium bromide (QVPV) polycation, aiming towards the adsorption of Cr(VI) ions from aqueous solution. The adsorption isotherm of QPVP onto Alg beads fitted well the Langmuir adsorption model, yielding maximum adsorption capacity (q max) of 91 mg g −1 and high constant affinity of 7.53 × 10 7 L mol −1. X-ray photoelectron spectroscopy and elemental analysis indicated that the QPVP chains were mainly on the Alg beads surface. The adsorption of Cr(VI) in the dilute range (0.5 mg L −1 to 10 mg L −1) on Alg-QPVP beads in batch system was investigated by means of flame atomic absorption spectrometry. Under optimal adsorption conditions (HNO 3 , pH 2, 6 mg of dried beads, 15 mL of solution, 30 min contact time) the nonlinear fitting with Langmuir model yielded q max of 18 mg g −1 and constant affinity of 124 L mol −1 , whereas the q max of 156 mg g −1 and adsorption energy of 9.8 kJ mol −1 were obtained from linear fitting with Dubinin-Radushkevitch model. The breakthrough curves obtained for Cr(VI) at 100 mg L −1 in the fixed bed column system were fitted to the Adams-Bohart and Thomas models. Fitting parameters indicated a fast dynamic adsorption process, which takes place mainly on the beads surface. The reduction of adsorbed Cr(VI) ions to Cr(III) by ascorbic acid, a non-toxic biological reductant, allowed the fast and complete recycling of the Alg-QPVP beads for at least 20 times without losing performance. Novel Alg-QPVP beads presented attractive features for dynamic process, such as quickness (k > 1 × 10 −3 L mg −1 min −1) and high adsorption capacity in the dilute range, low cost and recycling possibility.

Functionalized Titanium-Based MOF for Cr(VI) Removal from Wastewater

“…Among these methods, adsorption is considered the most promising removal method of Cr(VI) due to its low cost and removal efficiency. 17,18 Therefore, various materials have been employed for Cr(VI) removal, including organic materials, 19 biological materials, 20,21 inorganic materials, 3 and composites. 22 Recently, metal−organic frameworks (MOFs) have attracted significant research attention due to their large specific surface area, porosity, and ability to introduce varieties of functional groups, and hence are considered promising candidates for heavy metal adsorption.…”

“…The current removal methods for Cr­(VI) include chemical precipitation, electrochemical process, ion exchange method, , membrane separation technique, , biological treatment, adsorption method, − and so on. Among these methods, adsorption is considered the most promising removal method of Cr­(VI) due to its low cost and removal efficiency. , Therefore, various materials have been employed for Cr­(VI) removal, including organic materials, biological materials, , inorganic materials, and composites …”

Removal of chromium ions by a bionanocomposite hydrogel based on starch-g-poly(acrylic acid) reinforced by cellulose nanofibers through a fix-bed adsorption column

“…On the other hand, Cr(VI) might cause intense health problems such as carcinogenesis, liver and kidney failure (Arantes de Carvalho et al 2018). Cr(VI) occurs in the forms of chromate (CrO4 2-) at pH more prominent than 6, hydrogen chromate (HCrO 4-) at pH 1-6, dichromate (Cr2O7 2-) at concentrations greater than one g/L, and dihydrogen chromate (H2Cr2O7) at pH was less than 1 (Jiang et al 2018).…”

“…Cr(VI) occurs in the forms of chromate (CrO4 2-) at pH more prominent than 6, hydrogen chromate (HCrO 4-) at pH 1-6, dichromate (Cr2O7 2-) at concentrations greater than one g/L, and dihydrogen chromate (H2Cr2O7) at pH was less than 1 (Jiang et al 2018). Unfortunately, Cr(VI) ions build and hurt the lungs and kidneys, thus eliminating them from industrial effluent (Arantes de Carvalho et al 2018). According to the World Health Organization, wastewater's Cr(VI) level should not exceed 0.1 mg/g and 0.05 mg/g in surface and potable water, respectively (Hsini et al 2021).…”

Evaluation of calcium alginate microparticles for copper preconcentration prior to F AAS measurements in fresh water

“…Alginic acid, a biopolymer extracted from brown seaweeds comprising of α-L-guluronic acid (G) and β-D-mannuronic acid (M) groups has been frequently used for the separation of metallic cations (e.g., Ni [24], Zn [24], Pb [24,25], Cu [26,27]) from aqueous media via a cation-exchange reaction. This substrate has been also used aiming towards the adsorption of Cr(VI) ions from aqueous solution after chemical modification [28]. Calcium alginate (CA) beads were used in batch mode for Cu preconcentration from fresh waters prior to F AAS measurements [29].…”