Composition, Application And Recycling Of RHA To Value-Added Products: A Review

Abstract

Leveraging waste products and by-products is essential for addressing current fiscal woes. The primary agricultural by-product from rice production is rice husk that results from rice milling. A total of 741 million tons of rice were produced globally each year, and 148 million tons of husks are also produced that corresponds to 20% of the grain weight. Rice husk ash (RHA), which is dispersed widely throughout the rice milling process, is the main waste product that results from burning rice husks. Burnt rice husk poses a challenging disposal issue and adds to further environmental deterioration; as a result, recycling of rice husk to value added products hold importance.  RHA is a thin, fragile, and incredibly permeable substance. RHA typically contains 90% amorphous silica. The study discusses the chemical composition as well as characterization of RHA, its use as an adsorption material the making of silica and biochar, and also provides an insight into the purification of wastewater produced by various sources, including iron and steel plants, dye factories, and rice mills, by RHA and RHA as a catalyst and biomedical applications of rice husks and ash from rice Husks across multiple industries and products with value.