Green coagulant from Dillenia indica for removal of bis(2-ethylhexyl) phthalate and phenol, 4,4’-(1-methylethylidene)bis- from landfill leachate

Abstract

This study was aimed to develop a green, effective, non-toxic, and eco-friendly natural coagulant. Novel extract from Dillenia indica seed powder were used as a primary coagulant for the removal of selected persistent organic pollutants (POPs) from landfill leachate using the coagulation–flocculation process. The influence of operating variables (dosage of extracts from D. indica, pH, and mixing speed) on the coagulation–flocculation process was analysed to optimize the POPs removal. Response surface methodology coupled with Box–Behnken design was employed to determine the optimum conditions. The seed extracts of D. indica contain carbohydrate 19.47%, proteins 12.78%, phytic acid 6.98%, and total phenolics 8.23%. At the optimal conditions, 60% phenol, 4,4’- (1-methylethylidene)bis- (Bisphenol A), and 55% bis(2-ethylhexyl) phthalate (DEHP), removal of POPs were achieved at pH 8.5 and dosages of 1066 mgL −1 and 958 mgL −1 , respectively. Results obtained showed that pH and dosage have a substantial impact on the removal of pollutants. The model indicates high R 2 values of 0.948 and 0.982 for Bisphenol A and DEHP, respectively. The specific surface area of the D. indica seed was found to be 1.6734 m2 /g The FESEM micrograph indicated fibrous netlike structures, which is an indication of aggregation of the pollutant particles during coagulation–flocculation process suggesting adsorption and interparticle bridging. FTIR studies showed that D. indica seed contains hydroxyl, carboxyl, and amino groups, which are the preferred functional groups for the flocculation process. It was concluded that the extract from D. indica is a promising natural coagulant for POPs removal from landfill leachate