Synthesis of lamellar mesostructure aluminophosphate nanoparticles and their conversion to a highly efficient adsorbent using ultrasound waves for partial template removal

Abstract

The partial removal of the structure-directing templates from mesoporous aluminophosphate (AlPO) was studied for developing simple and effective adsorbents for elimination of anionic dyes from wastewater. The template species were removed from the as-synthesized AlPO samples using progressive sequences of sonication of the as-synthesized AlPO in ethanol. The ultrasound-treated AlPO materials were characterized using standard solid-state techniques. The micellar types are altered in the modified samples following the sonication. The as-synthesized and ultrasound-treated AIPOs were examined for adsorption of congo red (CR) as an anionic probe dye. The presence of feasible admicelles in the treated samples provides suitable conditions for establishment of effective interactions between CR and the adsorbent. The products sonicated for 15 min show the highest adsorption for CR, and longer irradiation of ultrasound does not improve this. The obtained adsorption data fit well with the Langmuir isotherm model based on the calculations performed on the linear form of the equation. A remarkable maximum CR adsorption of 666.3 mg g⁻¹ was observed for our superior sample. The removal of CR by our AlPO materials follows both pseudo-first order and pseudo-second order reaction kinetics, but fits more with the first order based on the calculated correlation coefficients.