Preparation of novel adsorptive membrane using spent spices waste-derived biochar to treat synthetic wastewater

Abstract

This research work focuses on the development of biochar-infused polymeric mixed matrix membranes, where the biochar is derived from spent spice wastes. While essential oils and fatty acids extracted from spices are used as main ingredients in food items, cosmetics, and pharmaceuticals, the leftover spent spice waste is discarded in landfills. Potentially, the biochar derived by utilizing this spice waste can be used to remove pollutants from industrial wastewater. Although there is literature that uses this biochar to adsorb pollutants, very few investigate adsorption by trapping biochar in a polymer matrix. Here, we test the waste-derived biochar-polymer mixed matrix membranes (MMM) to remove dyes from wastewater to develop a circular economy. Biochar is prepared by pyrolyzing the mixture of spent spices at 350 °C, and then activating it thermally and chemically to increase the surface area available for adsorption, as seen in the FESEM images. It is then mixed with PMMA solution and spin-coated on an inert substrate. The deposited mixed matric membrane is peeled off the substrate and exposed to synthetic wastewater in a vacuum filtration setup. We conclude that not only is the adsorption efficiency of the MMM method comparable within 10% of dye removal efficiency to the batch method, it is also significantly faster and has the potential to continuously treat large volumes of wastewater.