Clay Research

Determination of CEC (Cation Exchange Capacity) of a clay mineral is an important part of its characterization. Ammonium acetate method is quite widely accepted but it is tedious to follow. Estimation of exchangeable cations in solution after replacing with quarternary ammonium ions like Benzyl trimethyl ammonium (BTA) by flame photometer/AAS/ICPS is also another method frequently adopted. In the current work, we have used one simple, fast, novel and efficient method for finding the total CEC of clay. It involves exchange of the available cations with copper bis-ethylenediamino (Cu-en) complex cations and estimation of the absorbance by UV-VIS spectrophotometer. The CEC values for eight different Indian bentonite clays in raw state are measured. Effects of buffers on CEC values are discussed. CEC determined by other standard methods are also compared. Though BTA procedure is one of the standard procedures, the current procedure is very useful when there is no AAS or ICPS and total CEC is required. This method is less cumbersome than ammonium acetate method.