An Insight Into the Production, Characterization, and Mechanisms of Action of Low-Cost Adsorbents for Removal of Organics From Aqueous Solution

Abstract

A number of industries currently produce varying organic pollutant-laden waste streams, which is a serious environmental prblem owing to their potential human toxicity. Amongst all the treatments proposed, adsorption is one of the more popular methods for the removal of pollutants from wastewater. In particular, considerable work has been carried out on the use of natural materials, nonconventional adsorbents, and their modifications. These natural materials and nonconventional materials in many instances are relatively cheap, abundant in supply, or thrown away as waste and have significant potential for modification that ultimately leads to enhancement of their adsorption capabilities. The authors review and evaluate literature dedicated to the preparation of adsorbents such as activated carbon and clays and their modifications/activation by recycling different types of waste materials and also to their application in organic pollutant containing aqueous-phase treatments. It should be noted that the reported adsorption capacities of the adsorbents vary, depending on the characteristics of the individual adsorbent, the extent of chemical modifications, the concentration of solutes, and the ionic strength and pH of the medium. Thus characterization of the adsorbents for their functional groups and their nature using IR, XRD, and pH_Zpc has been discussed. The authors further discuss how several key factors such as pH, competitive adsorption, and temperature influence the adsorption taking instances from literature. The authors also provide a summary of recent information obtained using batch studies and deals with the various adsorption mechanisms involved.

KEY WORDS:

• agrowaste
• organics
• pretreatment
• adsorption mechanism