Modified Raw Materials: Synthesis, Characterization and Application for Cd²⁺ Ions Removal

Abstract

ABSTRACT. The adsorption behavior of some lowcost adsorbents such as bentonite, meal thistle and carbonized walnut husk with respect to Cd 2+ ions in aqueous solutions has been studied. The several process parameters (contact time, initial metal concentration, sorption capacity, extraction degree, rate constants, sorption rates and sorption energy) were found. For the Cd 2+ ions adsorption the equilibrium time onto bentonite, meal thistle and carbonized walnut husk were found to be 2 h, 25 and 10 min, respectively. Adsorption parameters were determined using both Langmuir and Freundlich isotherms. Sorption isotherms of cadmium ions onto MBT (modified bentonite) and MTM (modified thistle meal) were the best of all described by the equation of Freundlich sorption (correlation coefficients are closest to unit). In contrast the sorption of Cd 2+ ions onto MCWH (modified carbonized walnut husk) was described by the Langmuir isothermic model where the adsorption occurs on homogeneous surface by monolayer sorption without interaction between sorbed ions. The obtained results demonstrate that bentonite, meal thistle and carbonized walnut husk can remove Cd 2+ ions from aqueous solutions. It means that cheap and available raw materials can be efficient adsorbents and capable to remove cationic heavy metal species from waste water. The ion-exchange mechanism of adsorption of cadmium ions by the MBT, MTM, MCWH was proposed.

Preliminary assessment of modified Kazakh natural zeolites as possible sorbents for MnO4- removal from aqueous solutions.

“…Other performance indicators are also mentioned in the literature, for example the adsorption capacity, expressed as the adsorbed species / adsorbent mass ratio (usually in mg/g) [6]. However, all derive from the value of C in equation (1). Table 1, at three different total contact times between solid and liquid phases.…”

“…Wastewater pollution by heavy metal ions is an important issue for many industrial enterprises. Improperly treated wastewater can reach natural reservoirs, where heavy metals may accumulate as bottom sediments, precipitate as carbonates or sulfates and become hence a secondary pollution source [1,2]. Removal of such pollutants is therefore a necessity.…”

“…At higher concentrations, the second layer of surfactant may attach to the first one, due to hydrophobic interactions between the alkyl chains. The positively charged groups of the second layer will be oriented towards the bulk of the aqueous solution due to electrostatic repulsive forces of head groups between internal and external layers [1]. The formation of the second layer causes an excessive positive charge (close to the surface of the adsorbent), that further enables the adsorption of anions.…”

Characterization of Soils in the Almasu Mare Area through the Determination of Lead Concentrations

“…In the very beginning the curiosity and interest of researchers was probably devoted to herbs which were able to grow on heavy metals contaminated soils, restricting metals uptake or accumulating them in their tissues [1][2][3][4][5][6][7]. Sterile dumps are detrimental to natural plant growth due to their physicochemical characteristics, such as low pH, high heavy metal concentrations, deficiencies in soil organic matter and low fertility.…”