Abstract
Over the last few years, there is a significant growth in research exploring natural based coagulant due to its various benefits to decrease or even substitute the usage of inorganic chemical coagulants. Polysaccharide based coagulant and coagulant aid is a promising source for this purpose, due to its abundance. In this study, we reported utilization of galactomannan extracted from spent coffee grounds as natural coagulant aid in coagulation of Congo red synthetic wastewater. The coagulation was done at fixed dosage of FeCl3 (160 mg/L) and pH of 6. The effect of galactomannan as coagulant aid was observed by varying galactomannan dosage (0-140 mg/L) and Congo red concentration (20–70 mg/L). It was found that galactomannan as coagulant aid could increase the removal of Congo red, around 30–90% removal, depends on Congo red concentration, compared FeCl3 only (0–65%). The coagulation adsorption study was also investigated using Langmuir, Freundlich, and Brunauer – Emmet – Teller (BET) isotherm models. It was found that Congo red coagulation using FeCl3 only was following Langmuir isotherm, indicating monolayer – homogenous formation during the coagulation. On the other hand, with the presence of galactomannan the coagulation was best described by BET isotherm, indicating multilayer – heterogeneous adsorption, possibly due to interparticle bridging of galactomannan during colloid aggregation. The findings in this study suggest synergistic effect of galactomannan and FeCl3 in the coagulation process and proved potential of galactomannan from spent coffee grounds as natural coagulant aid.
Selectivity of the Lindlar catalyst in alkyne semi-hydrogenation: a direct liquid-phase adsorption study
