Target-oriented element activation and functional group synthesis lead to high quality modified clay for Prorocentrum donghaiense control

Abstract

Single source with series modifications (SSSM) is a new method to modify clay surfaces by activating clay mineral resources for harmful algal blooms control. In this study, the optimal preparation conditions for this method were obtained using response surface methodology. Based on the material analysis, an important way to obtain modified clay (MC) with the excellent Prorocentrum donghaiense removal performance was explored and the optimum preparation conditions were as follows: calcination temperature 750°C, alkali neutralization pH 3.7 and clay supplementation ratio 1.3:1. Under these conditions, the calcination treatment can effectively activate the aluminum element in the clay lattice and obtain the largest amount of highly active Al IV and Al V, which are readily released from the lattice as activated aluminum. When the alkali neutralization pH was adjusted to 3.7, the activated aluminum was hydrolyzed and induced into highly positively charged polyhydroxyaluminum compounds. The supplemented kaolin increased the yield of the MC product by surface convergence of the activated aluminum in the system. As a result, the optimized MC can form large particle size flocs with good regeneration and stability during the algal removal process, which greatly improved its ability to coagulate and sediment algal cells. Overall, the MC prepared by the SSSM method achieved high algal removal efficiency through targeted element activation and functional group shaping.