Removal of cadmium from waste water using Saudi activated bentonite

Abstract

Application of Saudi activated clay (bentonite) to remove cadmium from wastewater was investigated. Natural local clay which was obtained from Khulays bentonite deposit was selected and activated using sulfuric acid to increase its adsorptive capacity. The removal characteristics of cadmium ions from wastewater were investigated under various operating variables such as contact time, initial metal concentration, clay dosage and solution pH. Batch scale equilibrium adsorption was carried out for a wide range of initial metals concentration. The results showed that the sorption of cadmium ions on Saudi activated clay was relatively fast and the equilibrium was achieved after only 20 min. The sorption data suggests that solution pH was the most important parameter in controlling cadmium sorption onto bentonite. They also showed that increasing the initial cadmium concentration decreased cadmium removal percentage due to the saturation of clay with cadmium ions. Furthermore, the adsorption of cadmium increased with increase in solution pH. The adsorption isotherm data were well fitted with both the linearized Langmuir and Freundlich models.

Potential of Saudi natural clay as an effective adsorbent in heavy metals removal from wastewater

“…As the pH of the solution increases, the % removal efficiency also increases. This observation is in a good agreement with the behavior observed by Al-Shihrani [31][32][33]. This behavior was anticipated because adsorption of heavy metal ions onto clay is significantly affected by the pH of the solution.…”

“…Therefore, the need for wastewater treatment is crucial to meet the water supply in the agriculture and industrial sectors. The use of indigenous natural clay as adsorbent materials has been examined earlier for treating wastewater and removing heavy metals [4,[30][31][32][33]. Clay minerals from different parts of the world have been studied for their potential role as absorbent materials to remove heavy metals from wastewater shown in Table 1.…”

Removal of Cadmium Ions from Aqueous Solutions Using Flax Seeds as an Adsorbent

“…Figure 3 shows that the rate of cadmium adsorption decreases with the increases of the flax seeds particle size, hence, the percentage removal of Cd(II) decreased from 75, 70, 55, 50, and 45% with increasing of the particle size to 75, 150, 300, 425, and 600 μm respectively. This can be related to the fact that the particle size when decrease this will increase the surface area [11,16] Figure3: Particle size effect on the percentage removal rate of Cd(II)…”

“…At low pH, protons compete with metal ion for sorption sites on the adsorbent surface [24]. On the other hand, the greatest cadmium removal was at pH 5 and at higher pH, the lower number of H + with higher surface negative charge results in more cadmium adsorption (16) . When the aqueous medium became alkalinity medium, the adsorption decreased, because of some functional groups are deprotonated to release H + ions competing with Cd (II) ions to reduce the uptake process.…”

“…Sugar cane bagasse are an agricultural waste produced, has given good adsorption capacity for cadmium from which the adsorption rate depended on agitation rate, pH and contact time [14]. Minerals, like clay, also, could be used as a natural resource and low cost adsorbent, the experiments of cadmium adsorption onto clay succeeded with low concentration ranges for cadmium [15,16]. Defatted flax seeds was recycled to remove organochlorine compounds and the results were effective [17].…”