Chromium (VI) removal from aqueous solutions by purolite base anion-exchange resins with gel structure

Abstract

The removal of Cr (VI) from aqueous solution using two strong base anionic resins with gel structure, purolite A-400 (styrene-divinylbenzene matrix) and purolite A-850 (acrylic matrix) was investigated using a batch technique. The sorption efficiency was determined as a function of phases contact time, solution pH, resin dose, temperature and initial Cr (VI) concentration. The percentage of Cr (VI) removed reached maximum values (up to 99%) in the pH range 4.0-5.3 at a resin dose of 6 g/L and Cr (VI) concentration up to 100 mg/L. An increase in temperature had a positive effect on the Cr (VI) sorption process. The equilibrium sorption data were fitted with the Freundlich, Langmuir and Dubinin-Radushkevich isotherm models, using both linear and nonlinear regression methods. The Langmuir model verified the experimental data very well and gave a maximum sorption capacity of 120.55 and 95.82 mg Cr (VI)/g for the A-400 and A-850 resins, respectively. The thermodynamic study and mean free energy of sorption values calculated using Dubinin-Radushkevich equation indicated the sorption is a chemical endothermic process. The kinetic data were well described by the pseudo-second order kinetic equation and the sorption process is controlled by external (film) diffusion and intraparticle diffusion.

A preliminary batch study of sorption kinetics of Cr(VI) ions from aqueous solutions by a magnetic ion exchange (MIEX®) resin and determination of film/pore diffusivity

“…unloaded resin has become stronger and shifted to 937 cm -1 after Cr(VI) loading. Balan et al (2013) have reported that Cr=O vibrations appear around 948.96 cm -1 and this can result an enhancement in peak intensity in the spectrum of the loaded resin. The new peak at 771 cm -1 with a significant intensity is due to the Cr-O groups (Balan et al, 2013), which again confirms the Cr(VI) loading on MIEX resin.…”

Adsorption behavior of Cr(vi) from aqueous solution onto magnetic graphene oxide functionalized with 1,2-diaminocyclohexanetetraacetic acid

“…30 If the plot q t versus t 0.5 is linear and passes through the origin, the intraparticle diffusion is the only rate-limiting step; if the plot presents multilinearity, the adsorption process is controlled by two or more steps. 28 As can be seen from Fig. 4d, there are three processes controlling the adsorption rate: (i) the rst sharper portions may be attributed to the lm diffusion; (ii) the second linear portions are the gradual adsorption stages, where the intra-particle diffusion is rate-controlling step; and (iii) the third portions are nal equilibrium stages where intraparticle diffusion starts to slow down due to low adsorbate concentration in aqueous solution as well as less number of available adsorption sites.…”

Hexavalent chromium adsorption from aqueous solutions using nanoporous graphene/Fe3O4 (NPG/Fe3O4: modeling and optimization)

“…Adsorption is now viewed as a superior technique for its cost-effectiveness and flexibility. Many organic and inorganic adsorbents such as activated carbon [8], graphene [9], purolite [10], chitosan [11], metal oxides [12], and biological wastes [13] have been used for wastewater treatment procedures so far. Graphene has extraordinary physical and electrical *Corresponding author.…”