Phosphorus adsorption by a modified polyampholyte-diatomaceous earth material containing imidazole and carboxylic acid moieties: batch and dynamic studies.

VILLANUEVA, MARÍA EMILIA; DIEZ, ANA MARÍA DEL ROSARIO; GONZÁLEZ, JOAQUÍN ANTONIO; LÁZARO MARTÍNEZ, JUAN MANUEL; CAMPO DALL'ORTO, VIVIANA; COPELLO, GUILLERMO J

NEW JOURNAL OF CHEMISTRY

ROYAL SOC CHEMISTRY

Año: 2017

1144-0546

The aim of this study was to investigate phosphorus removal in water by using a polyampholyte obtained by the reaction of methacrylic acid, ethylene glycol diglycidyl ether and imidazole by a one step synthesis, mixed with diatomaceous earth. The material was characterized before and after phosphorus exposure by FT-IR, Raman and Solid State 31P-NMR and 13C-NMR spectroscopy concluding that the charged imidazole units were involved in the interaction between the phosphorus and the polyampholyte and that only H2PO4- specie was adsorbed. The point of zero charge value was 5.09. Concomitantly, the optimal pH for P adsorption was 5.0. As pH raised, the polymer turned more negative, and the phosphate repulsion diminished the adsorption. In the batch experiments, the adsorption isotherms at pH 5.0 and 7.0 were studied. The effect of different flow rates, P influent concentration and the interference of nitrate and sulfate in the breakthrough curves were performed. The shorter breakthrough time occurred at a higher flow rate. The q0 not only increased from lower to higher influent levels but also showed a decrease with the presence of S and N as interferents demonstrating that there was a competition for the adsorption sites between those anions and the phosphate.