Metal-Anion Sorption by Chitosan Beads:  Equilibrium and Kinetic Studies

Abstract

Chitosan is a well-known biopolymer, whose high nitrogen content confers remarkable ability for the sorption of metal ions from dilute effluents. However, its sorption performance in both equilibrium and kinetic terms is controlled by diffusion processes. Gel bead formation allows an expansion of the polymer network, which improves access to the internal sorption sites and enhances diffusion mechanisms. Molybdate and vanadate recovery using glutaraldehyde cross-linked chitosan beads reaches uptake capacities as high as 7−8 mmol g-1, depending on the pH. The optimum pH (3−3.5) corresponded to the predominance range of hydrolyzed polynuclear metal forms and optimum electrostatic attraction. While for beads, particle size does not influence equilibrium, for flakes, increasing sorbent radius significantly decreases uptake capacities to 1.5 mmol g-1. Sorption kinetics are mainly controlled by intraparticle diffusion for beads, while for flakes the controlling mechanisms are both external and intraparticle diffusions. The gel conditioning increases the intraparticle diffusivity by 3 orders of magnitude: intraparticle diffusivities range between 10-13 and 10-10 m2 min-1, depending on the sorbent size and the conditioning.

Removal of airborne hexavalent chromium mist using chitosan gel beads as a new control approach

“…The slight effect of agitation implies that external mass transfer is not the sole rate limiting phase of sorption. However, Findon et al reported that, copper and mercury sorption is not dependent on the agitation speed (Guibal et al, 1998). The results demonstrated that, Chitosan is an effective sorbent of Cr (VI) and the sorption is significantly influenced by parameters such as sorbent concentration, temperature, air pollution concentration, and air velocity.…”

“…In the alkaline solution, the beads kept their initial spherical forms and formed chitosan beads ( Fig. 1) (Guibal et al, 1998 andGuibal et al, 1999). The beads were stirred in NaOH solution on the orbital shaker at 250 rpm for 24 h. Then, they were washed three times with distilled water and kept in a 2.5 M NaOH solution at 4 °C.…”

Adsorption Characteristics of Copper (II) Ions from Aqueous Solution onto Ionic Cross-linked Pva/P(Aam-Nipaam) Core-shell Nanogels

“…5 ), C: is the intercept of straight lines, which gives information about the boundary layer thickness [39,40]. On fitting data to the above equation, if the linear correlation value is close to unity, then intraparticle diffusion process is effective onto nanogels.…”

Arsenic Sorption Using Mixtures of Ion Exchange Resins Containing N-Methyl-D-Glucamine and Quaternary Ammonium Groups

“…A number of these studies have developed sorption processes including adsorption and ion-exchange mechanisms, precipitation, solvent extraction, conjunction of membranes and polymers using simple materials such as activated carbon or more sophisticated materials such as especially tailored polymers as well as biosorbents, such as fungal or bacterial biomass, and materials of biological origin, including alginate and chitosan [2][3][4][5][6][7][8][9][10][11][12][13][14] .…”