The Efficiency of Polyaluminum Silicate Chloride Coagulants in Nickel Removal from Aqueous Solutions

Abstract

Background & Aims: Nickel is one of the toxic heavy metals naturally released into the environment through industrial activities. Coagulation and flocculation are one of the available heavy metal removal methods, but experience has shown that high pH and the addition of coagulant aid are usually required to remove nickel by coagulation and flocculation process. This study aimed to examine the efficiency of polyaluminum silicate chloride (PASiC) coagulant in nickel removal from aqueous solutions. Materials and Methods: This study was conducted experimentally on a laboratory scale using the standard jar testing method. We investigated the effect of pH parameters (4-11), amount of coagulant (7.5-75 mg/L based on aluminum), initial metal concentration (10-400 mg/L), and settling time (15-90 minutes). Nickel concentration was measured by flame atomic absorption spectroscopy. In this study, t test, between-groups ANOVA, and regression were used for analysis. Results: Results showed that the removal efficiency decreased at higher concentrations of nickel metal. Furthermore, increasing the settling time beyond 30 minutes did not significantly change the removal efficiency. PASiC had a removal efficiency of over 99% at an optimum pH of 8, an optimum PASiC concentration of 15 mg/L, an optimum time of 30 minutes, and a nickel concentration of 10-100 mg/L. Conclusion: According to the results, the use of PASiC as a coagulant is a suitable option for removing nickel from polluted wastewater.