EGG SHELL AND SPENT TEA: AN ECO-FRIENDLY COST EFFECTIVE ADSORBENT
As the current global trend towards more stringent environmental standards, technical applicability and costeffectiveness became key factors in the selection of adsorbents for water and wastewater treatment. Recently, various low-cost adsorbents derived from agricultural waste, industrial by-products or natural materials, have been intensively investigated. In this respect, the eggshells from egg-breaking operations constitute significant waste disposal problems for the food industry, so the development of value-added by-products from this waste is to be welcomed. The egg processing industry is very competitive, with low profit margins due to global competition and cheap imports. Additionally, the costs associated with the eggshell disposal (mainly on landfill sites) are significant, and expected to continue increasing as landfill taxes increase. The aim of the present review is to provide an overview on the development of low-cost adsorbents derived from eggshell byproducts and spent tea waste. Activated carbon is the most widely used adsorbent for this purpose because it has a high capacity for adsorption of organic matter, but its use is limited because of its high cost. In order to decrease the cost of treatment, attempts have been made to find low cost alternative adsorbents. Numerous approaches have been made by various researchers to develop cheaper and effective adsorbents to remove dyes and chemical contaminants from a variety of starting materials from waste.