Phosphate uptake from water on a Surfactant-Modified Zeolite and Ca-zeolites

Abstract

The phosphate adsorption kinetics are determined in batch-wise (noted B) and fixed-bed column (noted C) experiments on a Surfactant-Modified Zeolite (SMZ) and various Ca-zeolites. The influence of phosphate concentration (0.08 or 0.8 mmol/L), presence of NO 3 -, HCO 3 -, SO 4 2-and Cl -competing anions (individual concentration = 0.8 meq/L) and flow rate Q (1-30 mL/min) is studied. Preliminary experiments lead to the selection of the most efficient Ca-LTA and SMZ samples for the subsequent studies. In B experiments, the nature of the used system does not influence the equilibrium removal rate R (&80%) but affects the adsorption kinetics. The equilibrium times are shorter on SMZ than on Ca-LTA, increasing with the phosphate concentration and the presence of competing anions, respectively in the *0.5-6 or *3-24 h ranges. In C experiments, the phosphate uptake performances on SMZ are higher than in the corresponding B experiments, with in particular higher final q/q m values. The deterioration of the performances on SMZ in presence of competing anions or with increase of Q is due to the effect of the slow phosphate ion-exchange kinetics and the short used contact time. For similar reasons, sorption on Ca-LTA is lower than on SMZ. For instance, with a 0.8 mmol/L phosphate concentration and a 10 mL/min flow rate, the time-decreasing R values become close to 50 and 10% after filtration of 10 bed-volumes respectively in presence of SMZ and Ca-LTA. Globally, SMZ is clearly more efficient than Ca-LTA, being furthermore a versatile and easily regenerable material.

Simultaneous recovery of ammonium and phosphate from simulated treated wastewater effluents by activated calcium and magnesium zeolites

“…Therefore, to improve phosphate sorption performance as well as to provide higher selectivity towards oxyanions sorption, the incorporation of divalent or trivalent metallic ions such as Ca 2+ , Mg 2+ , Fe 3+ and La 3+ through ion exchange in a salt modification pretreatment of zeolites was studied. Pretreatment was carried out mainly at high temperature in order to favor the ion exchange as zeolites present more affinity towards monovalent ions …”

Tailored zeolites for the removal of metal oxyanions: Overcoming intrinsic limitations of zeolites

“…compounds such as clays. This process enables not only the adsorption of metal oxyanions; sulfate, nitrate and phosphate [48,49], organic and aromatic compounds [45,50], pharmaceutical drugs [51], bacteria [52] or even viruses [53] have been reported to be adsorbed on SMZs.…”

Mechanisms of CPB Modified Zeolite on Mercury Adsorption in Simulated Wastewater

“…Generally, in order to improve the contaminant elimination rate of zeolites, modification should be taken into consideration. Former studies focused on the choices of zeolite modification methods (Lei et al, 2008;Jimenze et al, 2011;Xie et al, 2012), the optimum operating conditions for adsorption reaction (Li et al, 2011;Sun et al, 2011), the analysis of the effects of competing ions (Schick et al, 2012), and fitting of the adsorption kinetics and thermodynamics models (Hao et al, 2012;Alver and Metin, 2012). There are few detailed discussions of Hg(II) adsorption mechanisms by the structure transformation and properties of modified zeolites.…”