Performance of surfactant modified zeolite/hydrous zirconium oxide as a multi-functional adsorbent

Abstract

Surfactant modified zeolite from coal fly ash (SMZFA) was previously developed as a multi-functional adsorbent. But its ability to capture anionic pollutants depends on the type and composition of coal fly ash and the synthesis process of zeolite (ZFA), the precursor of SMZFA, produces waste alkaline solution. To tackle these problems, the composite of zeolite and hydrous zirconia (ZFA/HZ) was synthesized by neutralizing waste alkaline solution with zirconium salt and was then modified with the surfactant of hexadecyltrimethylammonium to develop a new type of multi-functional adsorbent, SMZFA/HZ. The obtained materials were evaluated for their performances to sequester multiple classes of pollutants from water. The target pollutants include cationic pollutant (ammonium), anionic pollutant (phosphate) and organic pollutants (humic acid and bisphenol A). Results showed that, when compared with ZFA, ZFA/HZ had 3 times higher adsorption capacity for phosphate, and more negative charges on both external (by 16.9%) and internal surfaces (by 12.3%). For both ZFA and ZFA/HZ, modification with surfactant reduced the capacity for uptake of ammonium by less than 10% and the reduction was trivial for phosphate. However, surfactant modification greatly augmented the adsorption performances for humic acid and bisphenol A. Compared with SMZFA, SMZFA/HZ was found to have higher potential for the retention of each pollutant and is thus a more excellent versatile adsorbent.