Study on the Pore and Fibre metric Characteristics of Natural Organic Polymer for Colour Degradation in Wastewater: Face-Centred Central Composite Design

The use of natural organic polymer (NOP) coagulants in the removal of pollutants from industrial wastewater has been the subject of continuous research. The importance of applying Vigna subterranean coagulant (VSC) for colour removal from crystal Ponceau 6R dye was investigated in this study. The precursor's proximate analysis, structure, surface morphology, fibre metric, and pore size distribution were examined. The pH, coagulant dosage, dye concentration, and time were optimized using response surface methodology (RSM) and face-centred central composite design (FCCD). For the coagulant precursor, the proximate analysis gave high protein content of 18.15 %, the Fourier Infra-Red (FTIR) analysis confirmed the existence of O-H, N-H, and C=H, the SEM image revealed polymer rough surfaces, the most occurring pore size of 0.41 μm2, different fibre length between 2.11 μm -17.94 μm, and a compact net structure. As can be seen in the main effects plots, pH has the greatest impact on colour removal, followed by time. Coagulant dosages and dye concentration have less influence on the process. The colour removal efficiency obtained from the optimization analysis was 99.60% at process conditions of pH 2.11, coagulant dosage 293.32 mg/L, dye concentration 13.75 mg/L and time 533.3 min. The projected values were confirmed in the verification experiments, with a standard error of 2.10 %. Overlay contour plot established optimum areas where the predicted response variable is in an acceptable range (≥ 80%) with respect to optimum conditions. When compared to the main effect plots, the FCCD approach proves more appropriate for improving the process and yielding higher removal efficiency. As a result, protein extract from Vigna subterranean seed has the potential to be used as an effective coagulant for colour removals from industrial wastewaters