Nitrogen recovery and valorization is gaining interest due to the current need for nitrogen removal, so it is of great interest that ammonium-selective sorbents be evaluated. In this study, a zeolitic material synthesized from coal fly ash (Ze–Na) in sodium form as well as its modification to potassium form (Ze–K) were evaluated as sorbent materials for the recovery of ammonium from wastewater effluents. The sorption performance was assessed through three consecutive sorption-desorption cycles reporting opposite behavior in terms of ammonium sorption capacity. Decreasing in the case of Ze–Na and to slightly increase for Ze–K due to alkaline activation of zeolite surface. The maximum sorption capacities obtained were 109 ± 4 mg NH4/g and 33 ± 1 mg NH4/g for Ze–Na and Ze–K, respectively. It is important to point out that in the case of Ze–Na, the maximum sorbent capacity was obtained during the first sorption cycle whereas in the case of Ze–K, it was obtained during the last working cycle due to the alkaline regeneration. Kinetic studies showed that after every regeneration step, the sorption kinetics turn faster as alkaline desorption increased the zeolite-specific surface, thus increasing the size of porous and enhancing the diffusion through the particle. Results obtained indicate that sorption capacity decreased significantly after every working cycle using Ze–Na whereas Ze–K followed the opposite behavior despite its initial lower sorption capacity.
You, X.; Guaya, D.; Farran, A.; Valderrama, C.; Cortina, J. Journal of chemical technology & biotechnology Vol. 91, num. 3, p. 693-704 DOI: 10.1002/jctb.4629 Data de publicació: 2016-03-01 Article en revista
BACKGROUND: This study evaluated a polymeric ion exchanger impregnated with nanoparticles of hydrated ferric oxide as a selective sorbent for anionic P(V) species. The hybrid impregnated anion exchanger (HAIX) employed as sorbent combines the durability and mechanical strength of a polymeric weak base anion exchange resin with the high sorption affinity of hydrated ferric oxide towards P(V) species.; RESULTS: The P(V) loading capacity of the sorbent at a pH simulating the expected conditions in treated wastewaters was 92+/-3mg P-PO4 g(-1) in single component solutions. The sorption of P(V) is affected slightly by the common ions typically present in these effluents such as Cl-, SO42- and NO3-, and a reduction of only 5% was observed (89+/-2 mg P-PO4 g(-1)) in multicomponent solutions. The sorbent can be regenerated (95+/-3%) using 4% (w/w) sodium hydroxide solution.; CONCLUSIONS: HAIX displays high selectivity for phosphate and small affinity for SO42-, NO3- and Cl- ions, which provides excellent conditions for its application at pH values typical of secondary wastewater effluents. HAIX exhibits higher and competitive phosphate removal capacity compared with data reported in the literature for materials based on HFO and for adsorbents prepared by impregnation of HFO onto polymeric supports. (C) 2015 Society of Chemical Industry
You, X.; Farran, A.; Guaya, D.; Valderrama, C.; Cortina, J.; Soldatov, V. Journal of Environmental Chemical Engineering Vol. 4, num. 1, p. 388-397 DOI: 10.1016/j.jece.2015.11.032 Data de publicació: 2016 Article en revista
This study presents the evaluation of a fibrous ion exchanger impregnated with nanoparticles of hydrated ferric oxide (HFO) as a selective sorbent for phosphate. The hybrid impregnated anion exchanger (FIBAN-As) combines the durability and mechanical strength of a polymeric weak base anion exchange resin with the high sorption affinity of HFO towards phosphate species. The phosphate loading capacity at the common pH of waste waters treatment plant secondary effluents was 162 ± 12 mg PO43-/g sorbent. Dynamic experiments were carried out and data obtained was fitted to fixed-bed sorption models. The theoretical sorption capacities reported by the Thomas model were in good agreement to the breakthrough experimental capacities determined from the sorption data. The sorption capacity decreased in multicomponent system due to the faster ion exchange of competing anions compared to phosphate ions. The loaded FIBAN-As was efficiently regenerated by using a sodium hydroxide solution, reporting up to 90% of recovery. Finally, reuse of FIBAN-As was evaluated in three successively sorption–desorption cycles by using two regeneration solutions. A sorption capacity reduction of 23% and 30% was observed for acid and alkaline solutions, respectively after the third cycle