Simultaneous removing algal and its extracellular organic matters by Mg/Al-layered double hydroxide /La-montmorillonite

Abstract

ABSTRACT Rapid and effective simultaneous removal of algal and extracellular organic matter (EOM) is essential for algal blooms water emergency treatment. In this study, a composite material was prepared by physical and chemical interaction between La-montmorillonite (La-MMT) and Mg/Al-layered double hydroxide (LDHs), and its removal effect of algal and extracellular organic matters (EOM) was investigated. The results showed that the removal rate of chlorophyll a (chl-a) was 96.8% within 2 h when the LDHs/La-MMT2:1 dosage was 1.0 g/L. Three-dimensional fluorescence characteristic spectra and parallel factor analysis showed that the removal of EOM by composite material mainly reflected in the removal of humus-like substances. The reaction heat of composite material for the algal solution was −32.7 J/g. Zeta potential changed from −25.7 mV to −16.9 mV, the main treatment mechanisms of composite material were surface adsorption, complexation precipitation, charge neutralisation, and ion exchange. These findings herein proposed that composite material was a potential and proper treating agent for removing algal cells and EOM from algal blooms water.