Enhanced Performance of Natural Polymer Coagulants For Dye Removal From Wastewater: Coagulation Kinetics, And Mathematical Modelling Approach

Abstract This study explores the potentials of Brachystegia eurycoma coagulant (BEC) and Vigna subterranean coagulant (VSC) as natural organic polymers (NOPs) for the decolourisation of Crystal Ponceau 6R (AR 44) in wastewater. Materials characterisation studies were done on the precursors. Detailed kinetics study was employed. The decolourisation procedures were evalu­ated through time-dependent reduction in the concentration of particles, with the variation of the independent parameters. The proximate analysis showed protein contents of 19.77% and 18.15% for BEC and VSC, respectively. The functional test shows the presence of –OH, N–H, and C=H. Surface morphological study reveals that some rough surfaces, different pores sizes, and compact-net structures were evidenced. The order of removal efficiency was VSC > BEC with an optimum of 88.8% and 73.3%, respectively. The values of K and α obtained for BEC and VSC were 6.38 x 10-4 Lmg-1min-1, 1.8 and 4.03 x 10-3 L/mg-1min-1, 1.9, respectively. The coagulation time, Tag of 31.35 and 26.96 min for BEC and VSC respectively disclosed a quick coagulation. The coagulation-flocculation kinetics demonstrated that the process conforms to the pseudo-second-order model with R2 >0.997, suggesting that the rate-controlling mechanism is governed by chemisorption. The experimental data were well predicted by the cross-validation test, with percentage mean relative deviation modulus (M%) of 3.26 and 2.54 for BEC and VSC, respectively. These coagulants have added meaningful progress in wastewater treatment by coagulation-flocculation while displaying significant adsorption features. Likewise, the usage of kinetics studies and particle behaviour modelling should be a prerequisite in water treatment processes.