Synthesis, characterization, and process optimization of natural coagulants from jackfruit and durian seeds for turbidity removal

Abstract

Starch was extracted from jackfruit and durian seeds using distilled water and alkaline methods, with higher yields obtained via distilled water (27.7% and 18.4%, respectively). The extracted starches were cationized using 3-chloro-2-hydroxypropyltrimethylammonium chloride (CTA) to enhance coagulation performance. Characterization confirmed successful functionalization, with particle size increases of 32% (jackfruit) and 45% (durian). Coagulation performance was optimized using Box–Behnken design and response surface methodology. Optimal conditions were pH 5, 40.7 mg/L dosage, and 240 rpm for jackfruit seed starch (JSS), and pH 5, 190 mg/L, and 210 rpm for durian seed starch (DSS). Maximum turbidity removal reached 88 ± 2% in synthetic kaolin water. Application to river water (initial turbidity: 172 NTU) demonstrated superior performance of JSS and DSS compared to alum, achieving over 81% turbidity removal. These results highlight the potential of cationized seed starches as sustainable alternatives to conventional coagulants.

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