Evaluation of Artocarpus heterophyllus seed performance and kinetics in the coagulation–flocculation process for the purification of paint industrial wastewater

The Artocarpus heterophyllus (AH) seed was used as a coagulant in this study to explore the effects of pH, settling time, and coagulant doses on the removal of colour, turbidity, and heavy metals from paint industrial wastewater. The AH coagulant was instrumentally characterized by SEM, FTIR, and XRD. The maximum colour and turbidity removal efficiencies were 94.33% and 99.94% at the dosage of 0.2 g/L, pH 2. The mercury removal efficiency of 99.29% was achieved at the optimal conditions of 0.8 g/L coagulant dosage and pH 8. At a dose of 1.0 g/L and a pH of 10, the highest lead removal efficiency was 99.76%. The best removal efficiency for arsenic was 75.24% at a 0.8 g/L coagulant dosage and pH of 8. All at a time of 50 and 40 min, respectively. XRD diffraction results before treatment depict that the AH coagulant was crystalline and changed to amorphous after treatment. The SEM and FTIR results of the coagulant revealed changes in the surface morphology and functional groups before and after treatment. The reaction kinetics were best modelled in second order.