Removal of Azo and Anthraquinone Dye by Plant Biomass as Adsorbent – A Review

Acting as a key element for the survival of human and nature, clean water also contributes tremendously to the ever-growing industries in a country. However, the supply of clean water had led to a decrease as pollutants such as dyes had caused a major negative impact on pure and clean main water bodies. In recent years, textile industries have developed and contributed to more than 50% of dye wastewaters in the world. The improper method of discharging dye effluent to the aquatic environment caused the destruction of habitat and degradation of water quality. Advanced treatments such as photocatalysis, electrooxidation, the Fenton process, and biological treatment via bacterium are often used for dye wastewaters. However, these treatment processes are often expensive in operation and maintenance. In conjunction, adsorption is one of the efficient, cost-effective, and environmentally friendly treatment methods. The adsorbent most widely used is the activated carbon adsorbent. Activated carbon comes in two forms, granular activated carbon (GAC) and powdered activated carbon (PAC). There are two methods to activation of carbon that are physical activation and chemical activation. The factors affecting the efficiency of adsorption are the adsorbent dosage, dye concentration, pH value, and temperature. In this article, the efficiency of dye wastewater treatment via adsorption is discussed. Several waste materials are being studied especially agricultural biomass as it has little or no economic value and often poses disposal issues. Some low-cost agricultural biomass-based adsorbents such as tea waste, hazelnut husk, bacteria aggregate, rice ash, pineapple leaf, and fruit waste have been tested to be effective in the dye removal process. There are mainly four categories of agricultural biomass-derived adsorbent, such as leaf-based, peel-based, stem-based, and seed-based adsorbents.