Mechanism and Kinetic Studies of the Adsorption of Congo Red on Three Adsorbent Materials

Abstract

The enormous loss of agroforestry resources should attract the attention of the scientific community. A cultivated plant has more unused organs than those harvested by the grower. For an agroforestry resource to be put to good use, its parts, previously considered waste, must be exploited for profit. This is why this study examined the potential of the hulls of Lophira lanceolata, an agricultural waste product, as a precursor for adsorbent materials such as activated carbon and composite materials. The two adsorbent materials are obtained by impregnation with orthophosphoric acid in a 2:1 ratio, followed by activation and pyrolysis at 500°C. The use of these adsorbent materials and clay for the removal of Congo red has proved effective, with removal rates more than 90%. Adsorption on these materials is chemical in nature and occurs on energetically heterogeneous surfaces, which fits well with the pseudo-second-order kinetic model and Freundlich isotherms. The estimated qmax values for the Langmuir model are 145.0, 362.0, and 452.0 mg.g-1 for clay, composite material and activated carbon respectively. The hulls of Lophira lanceolata could be used to obtain various adsorbent materials for eliminating anionic dyes from industrial wastewater to comply with discharge standards.