Influence of Acid Activation on Natural Calcium Montmorillonite Clay

Abstract

Natural clay drags attention because of their wide application, ample availability, lower cost and ease of modification. Acid treatment of raw clay is easiest way to activate clay. Acid activation improves their bleaching action and also enhances their efficiency as adsorbent. In this paper, study is focused on different aspects of acid activation. Changes in structure, chemical and mineralogical composition and surface morphology have been studied using advanced techniques like FTIR, EDAX, XRD and SEM, respectively. Textural characteristics like surface area, pore volume and average pore diameter were also determined using BET method. The results indicate that surface area is increased four times after acid activation and mesoporosity of the sample also increased. It is observed that octahedral cations were more prone to acid attack rather than tetrahedral one. Due to leaching of octahedral cations and interlayer exchangeable cations, changes in chemical composition and modification in structure has occurred as identified by EDX and FTIR. XRD studies of untreated clay confirmed montmorillonite nature of sample. Results further showed the presence of mineral phase other than montmorillonite. For activated clay, XRD results indicate partial degradation of clay structure as a consequence of acid treatment. Surface morphology reveals that surface of clay is getting improved and grains of quartz can be observed after acid activation.