Material and Process Selection for Biosorption

Pollution in all the essential elements such as air, water and land is a serious environmental problem for the last few decades. Among various methods for removing pollutants from environment, adsorption is the most economic and eco-friendly method. Nowadays, the use of biosorption process for removal of pollutants has been increased due to its efficiency, reusability of biosorbents and low cost of operation. The rate and efficiency of biosorption depend on the selection of suitable biosorbent and the process. To select an effective biosorbent for any process, the characteristics such as porosity, surface area and other chemical natures need to be studied. This chapter describes the various types of biosorbents, treatments applied to biosorbents, techniques and methods to study the characteristics of biosorbents, mechanisms, modes of operation, recovery and regeneration of biosorbents, kinetics, and modelling studies. Microscopic techniques such as electron microscopy (SEM and TEM) and atomic force microscopy (AFM) can be used to reveal the surface characteristics of the biosorbents. Pore volume and surface area of the biosorbent can be determined by Brunauer–Emmett–Teller (BET) analyser. Other characteristics such as thermal stability and particle size can be measured by instruments such as thermogravimetric analyser (TGA), differential scanning calorimetry (DSC) and particle size analyser. The mechanisms of biosorption at various locations (intracellular, cell surface and extracellular) are also discussed in detail in this chapter. The biosorption process can be performed in a batch and continuous modes depending on the type of pollutant removed. The selection of suitable mode of operation for different pollutants is emphasized. This chapter also covers the different factors influencing the biosorption process.