Adsorption of Divalent Cadmium (Cd(II)) from Aqueous Solutions onto Chitosan-Coated Perlite Beads

Abstract

Chitosan-coated perlite beads were prepared in the laboratory via the phase inversion of a liquid slurry of chitosan dissolved in oxalic acid and perlite to an alkaline bath for better exposure of amine groups (NH 2 ). The NH 2 groups in chitosan are considered active sites for the adsorption of heavy metals. The beads were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) microanalysis, which revealed their porous nature. The chitosan content of the beads was 32%, as determined using a thermogravimetric method. The adsorption of Cd 2+ from an aqueous solutions on chitosan-coated perlite beads was studied under both equilibrium and dynamic conditions in the concentration range of 100-5000 ppm. The pH of the solution was varied over a range of 2-8. The adsorption of Cd 2+ on chitosan was determined to be pH-dependent, and the maximum adsorption capacity of chitosan-coated perlite beads was determined to be 178.6 mg/g of bead at 298 K when the Cd(II) concentration was 5000 mg/L and the pH of the solution was 6.0. On a chitosan basis, the capacity was 558 mg/g of chitosan. The XPS data suggests that cadmium was mainly adsorbed as Cd 2+ and was attached to the NH 2 group. The adsorption data could be fitted to a two-site Langmuir adsorption isotherm. The data obtained at various temperatures provided a single characteristic curve when correlated according to a modified Polanyi's potential theory. The heat of adsorption data calculated at various loadings suggests that the adsorption was exothermic in nature. It was noted that a 0.1 N solution of HCl could remove the adsorbed cadmium from the beads, but a bed volume of approximately three times the bed volume of treated solution was required to completely remove Cd(II) from the beads. However, one bed volume of 0.5 M ethylenediamine tetra acetate (EDTA) solution can remove all of the adsorbed cadmium after the bed became saturated with Cd(II) during dynamic study with a solution containing 100 mg/L of cadmium. The diffusion coefficient of Cd(II) onto chitosan-coated beads was calculated from the breakthrough curve, using Rosen's model, and was determined to be 8.0 × 10 -13 m 2 /s.

Identification of potential soil adsorbent for the removal of hazardous metals from aqueous phase

“…Among the above-mentioned processes, adsorption plays a pivotal role in removing metals from the aqueous phase using various biomaterial sorbents, algae (Holan et al 1993), fungi, sugar cane bagasse (Cerino Córdova et al 2011;Peterlene et al 1999), rice husk, wheat barn (Nouri et al 2007), pine bark, olive cake (Doyurum and Celik 2006), coconut husk, chitin (Benguella and Benaissa 2002), ash, activated carbon (Jusoh et al 2007;Onundi et al 2011;Zavvar Mousavi and Seyedi 2011), etc. Clays, zeolite, calcite, manganese nodule residue (Agrawal and Sahu 2006;Tashauoei et al 2010), perlite (Hasan et al 2006) and peat (Gabaldon et al 2006) have also been employed to remove metals from the water phase. Also, low-cost natural clay/soil is used to develop highthroughput inorganic adsorbent as well as membrane filter in removing heavy metals from aqueous phase.…”

Chitosan Based Membranes for Separation, Pervaporation and Fuel Cell Applications: Recent Developments

“…The maximum adsorption capacity of Cd(II) on chitosan-coated perlite beads at pH: 6 was found to be 78 and 178.6 mg g -1 of beads from a solution containing 1000 and 5000 mg l -1 of Cd(II), respectively, at 298 K. Breakthrough data from a column were used to calculate the diffusion coefficients for Cd(II) into the chitosan coated perlite beads, and the diffusion coefficient was found to be 8×10 -13 m 2 s -1 [39]. The modification of −OH groups on CS chemical reactions using ehtylenediamine and carbodiimide (CR) were also studied [40].…”

Synthesis of Pb(II) Imprinted Carboxymethyl Chitosan and the Application as Sorbent for Pb(II) Ion

“…Chitosan has biological and chemical properties such as biocompatibility, nontoxicity, high chemical reactivity, chelation and adsorption [7][8]. Chitosan has high sorption capacity for several metal ions because it possess a number of functional groups such as hydroxyl and amine groups that can bind metal ions by chemisorption and physisorption [9][10].…”