Dual application of natural clay material for decolorization and adsorption of methylene blue dye

Abstract

In this study, a clay sample recovered from an archaeological excavation from the Krobo Mountains in Ghana was examined for its potential to decolorize and adsorb cationic methylene blue. The raw and calcined clay samples were characterized with XRD, SEM, FTIR and EDX. The supernatant obtained by washing the raw clay with 70% ethanol solution decolorized methylene blue. The decolorization of methylene blue was independent of calcination temperature up to 300°C. The clay material subjected to calcination temperature at 600°C showed strong adsorption towards cationic methylene blue. The equilibrium adsorption data fitted well with the Freundlich isotherm indicating adsorption unto heterogeneous surface with the interaction between the adsorbed molecules which is not restricted to the formation of a monolayer. The data also fitted well with the Weber and Morris model which described the rate-controlling steps. The intra-particle diffusion was controlled by pore and surface diffusion. In addition, the adsorption data followed a pseudo-second-order kinetic model, indicating a chemisorption process. The results highlight a unique property of the clay material as an effective decolorizing and adsorption agent for the removal of water-soluble dyes from contaminated water bodies.

The Politics of Knowledge Production: Training and Practice of Archaeological Science in Africa

“…Questions of power and participation in African archaeology drum home issues of inequality in how research is carried out. First, a lack of specialist training and equipment leads many African archaeologists to partner with non-archaeologists in the fields of material science, engineering, earth science, and nuclear science at well-endowed foreign and African universities, such as the University of Ghana and the University of Cape Town, to process and conduct analyses on some of their finds (see Asare et al, 2020 ; Nyankson et al, 2020 ).…”

Effect of Tetrabutylammonium on Methylene Blue Adsorption

“…The clay used in adsorption is not only charged, such as montmorillonite. Neutral clays such as pyrophyllite are also quite commonly used as adsorbents for fluorides, heavy metal, polyaromatics, humic acids and dyes [13][14][15][16][17]. Pyrophyllite as methylene blue adsorbent is considered quite effective, especially if the pyrophyllite is modified with EDTA [15].…”