Granular waterworks sludge-biochar composites: Characterization and dye removal application
Chatchaya Nuanhchamnong, Ketwalee Kositkanawuth, Nichakorn Wantaneeyakul
Abstract
Development of composite adsorbents from waste materials has the potential to build circular economies to meet environmental sustainability goals. This study investigates granular waterworks sludge-biochar composites, which combine the high carbon and surface area of biochar with the clay properties of waterworks sludge in a synergy to increase the composite's functions on dye removal. The sorption ability of methylene blue (MB) dye onto two composite adsorbents; (1) rice husk biochar sludge composite (BSC) and (2) raw rice husk sludge composite (RSC) is investigated as compared to a control of unmodified raw materials including rice husk biochar (RHB) and waterworks sludge (sludge). The composite materials exhibit surface properties inherited from both raw materials; however, their chemical compositions are more comparable to sludge. As compared to sludge, higher surface area and MB removal capacity are noticed from both composites. Both BSC and RSC exhibit a similar adsorption isotherm to RHB, which is better described by a Langmuir model, while a Freundlich adsorption isotherm model is better fit for sludge. BSC possesses the highest MB sorption capacity of 16.949 mg/g, followed by RHB, RSC, and sludge with the capacity of 14.493, 13.966, and 8.576 mg/g, respectively.