Affinity of Clinoptilolite‐based Zeolites towards Removal of Cd from Aqueous Solutions

Abstract

Cd removal from aqueous solutions using as-received and pretreated forms of two different clinoptilolite samples (denoted GC and BC) was investigated and dissimilar sorption affinities were revealed. Equilibrium behavior of systems were modeled using six different adsorption isotherms. The maximum sorption capacities, as obtained from the solubility-normalized Dubinin-Astakhov model for as-received samples, were determined as 0.18 meq/g and 0.12 meq/g for GC and BC, whereas 0.72 meq/g and 0.41 meq Cd/g was determined for their pretreated forms, respectively. Examination of the release of exchangeable cations into the solution at equilibrium and the change of pH were discussed in terms of varying prevalence of ion exchange, dissolution of the sorbent and adsorption.

Heat of adsorption, adsorption energy and activation energy in adsorption and ion exchange systems

“…Pb [47] Pb [47] Pb [47] Pb [38] Cd [47] Cd [47] Cd [47] Ni [33] Ni [33] Ni [33] Ni [33] Ni [33] Ni [39] Mn [35] Mn [35] Rb [16] Ag [43] Zr [40] Zr [40] Zr [40] Zr [40] Heat of adsorption (kJ/mol) Cd [30] Cd [30] Cd [30] Cd [30] Pb [11] Pb [11] Pb [26] Pb [37] Pb [37] Ni [11] Ni [11] Cu [11] Cu [11] Cu [11] Cu [31] Co [11] Co [11] Co [31] Zn [11] Zn [11] Zn [31] Mn [31] Cs [11] Cs [11] Cs [32] Cs [32] Cs [21] NH4 [11] NH4 [41] NH4 …”

Ion‐exchange adsorption of calcium ions from water and geothermal water with modified zeolite A

“…Although, the disparity between surface coverage and pore filling, monolayer and multilayer coverage is not clear for the ion exchange system, because the ion exchange is a stoichiometric phenomenon . Therefore, the maximum exchange capacity ( q m ) is corresponding to Q 0 in the Langmuir model, which also has been adopted in our adsorption systems …”

Adsorption of heavy metals on natural zeolites: A review

“…A significant increase in the surface area of natural clinoptilolite from 13 m 2 /g to 78 m 2 /g was reported after treatment with 2M HCl (Sprynskyy et al, 2006). The acid treatment was found to be more effective than other methods for the treatment (Bektas ¸ and Kara, 2004;Gedik and Imamoglu, 2008). Base and salt mediums for the treatment of natural zeolites have been mostly investigated and are reported by several authors (Al-Haj- Ali & Al-Hunaidi, 2010;Bektas ¸ and Kara, 2004;Gedik and Imamoglu, 2008;Mihaly-Cozmuta et al, 2014).…”