LTA and FAU-X Iron-Enriched Zeolites: Use for Phosphate Removal from Aqueous Medium

Abstract

Hydrothermally synthesized Linde type A (LTA) and faujasite X (FAU-X) zeolites are low-cost and environmentally benign inorganic carriers for environmental applications. In this study, (oxy)hydroxides were incorporated onto LTA and FAU-X zeolites to promote the phosphate adsorption. The performance of LTA-Fe and FAU-X-Fe was evaluated through batch adsorption assays. A complete evaluation was performed to recover phosphate from synthetic wastewater. The effect of pH, concentration, equilibrium, and kinetic parameters on phosphate adsorption and its further reuse in sorption–desorption cycles were evaluated. LTA-Fe and FAU-X-Fe are effective for adsorption of phosphate at neutral (e.g., pH 7.0 ± 0.2) and in a broad range of phosphate concentrations. Higher ratios of adsorption capacities were obtained by synthetic zeolites enriched with iron in comparison to their parent forms. The phosphate adsorption occurred through hydrogen bonding and complexation reactions between protonated iron hydroxyl groups and phosphate anions. The phosphate monolayer adsorption was followed by diffusion through the internal pores and 80% of the equilibrium adsorption was reached within 50 min. The LTA-Fe and FAU-X-Fe can be used for phosphate recovery from wastewater treatment plants. The use of LTA-Fe and FAU-X-Fe in a tertiary wastewater treatment stage could allow to reduce the phosphate–phosphorous content, reaching the regulatory levels (equal 1 mg L−1 total phosphorous). The phosphate adsorption using LTA-Fe and FAU-X-Fe does not require pH adjustment, and it is endothermic. The reusability of both iron zeolites is limited, and they can be finally disposed for soil amendment applications.

Fe3+/Mn2+ (Oxy)Hydroxide Nanoparticles Loaded onto Muscovite/Zeolite Composites (Powder, Pellets and Monoliths): Phosphate Carriers from Urban Wastewater to Soil

“…The basal space d 110 plane was calculated as 6.43 Å for the sodalite at 2 : 13.8, which is comparable to the d 110 value of the sodalite pattern 6.40 Å. The incorporation of Fe 3+ and Mn 2+ cations in the sodalite zeolite occurred in the extra-framework octahedral and in the framework tetrahedral sites as has been reported for other zeolites [ 14 ]. The information provided by the crystallographic parameters of the obtained sodalite suggest the partial incorporation of iron and manganese into the sodalite structure.…”

“…The kinetical parameters determined for powder raw muscovite MC and muscovite/sodalite composites LMC suggest the application in stirred reactor-based arrangements. Even though, higher phosphate removal efficiencies have been reported for powder clays and zeolites [ 5 , 14 ]. The fixed-bed column adsorption arrangement is conventionally limited for powders, but viable for muscovite/analcime composites PLMCT 3 and SLMCT 2 .…”

“…However, the main restriction is their final disposal which is not environmentally friendly. Thereby, the use minerals (e.g., aluminosilicates) are preferred by the opportunity of final soil amendment application because they do not represent a risk by the release of toxic pollutants [ 14 ]. Conventionally, the use of layered aluminosilicates minerals is reported as an efficient method for water remediation applications.…”

“…Particularly in the environmental field, the nanoparticles highly improve the adsorption efficiency of pollutants due to the high specific surface area [ 24 ]. However, the major concern of using nanoparticles is the rapidly aggregation effect which can be avoided by supporting them onto templates [ 14 ]. The aggregation of nanoparticles can affect their physicochemical properties and the effectiveness of adsorbents.…”

Effect of Mn2+/Zn2+/Fe3+ Oxy(Hydroxide) Nanoparticles Doping onto Mg-Al-LDH on the Phosphate Removal Capacity from Simulated Wastewater

“…The use of wastewater seems to be the most important source for nutrient recycling since common wastewater treatment systems have a limited nutrient removal efficiency. Conventionally, phosphate removal includes biological, chemical, and physical treatment processes; however, they are expensive and non-effective in removing traces [ 5 ]. The adsorption treatment for wastewater has attracted scientists’ attention as one of the most promising strategies for wastewater purification.…”