Development of activated carbon pellets using a facile low-cost binder for effective malachite green dye removal

Abstract

Activated carbon pellet (ACP) is advantageous to the industrial-based adsorption process owing to its easy handling, large volumetric adsorption capacity and good mechanical properties. This study introduces a straightforward phosphoric acid-impregnated sawdust as economical binder to convert textile sludge activated carbon powder into water resistant pellets. The effects of activation time and drying technique on the physicochemical and mechanical properties of ACPs were investigated. The materials were characterized using N2 gas adsorption-desorption, scanning electron microscope, Boehm titration, pHpzc and compressive strength test. It was discovered that the physiochemical properties of ACPs were close to that of base activated carbon. Moreover, a longer activation time promotes the development of micropore on ACPs and enhances the compressive strength. The microporosity, surface area and compressive strength of ACPs are in the range of 16–23%, 668–979 m2/g and 0.4–1.5 MPa, respectively. The ACP prepared at 560 °C for 3 h showed a 395 mg/g of malachite green removal, whilst retaining its cylindrical shape. The Langmuir model gave the best conformity to the equilibrium data, suggesting a possible monolayer adsorption onto ACPs. This study demonstrated the potential of sawdust as low-cost binder and the applicability of ACPs in dye adsorption.