Adsorption of Cr(VI) ions onto poly(ethylene glycol dimethacrylate‐1‐vinyl‐1,2,4‐triazole)

Abstract

Poly(ethylene glycol dimethacrylate-1-vinyl-1,2,4-triazole) [poly(EGDMA-VTAZ)] beads (average diameter ¼ 150-200 lm) were prepared by copolymerizing ethylene glycol dimethacrylate (EGDMA) with 1-vinyl-1,2,4-triazole (VTAZ). Poly(EGDMA-VTAZ) beads were characterized by swelling studies and scanning electron microscope (SEM). The adsorption of Cr(VI) from solutions was carried at different contact times, Cr(VI) concentrations, pH, and temperatures. High adsorption rates were achieved in about 240 min. The amount of Cr(VI) adsorbed increased with increasing concentration and decreasing pH and temperature. The intraparticle diffusion rate constants at various temperatures were calculated. Adsorption isotherms of Cr(VI) onto poly(EGDMA-VTAZ) have been determined and correlated with common isotherm equations such as Langmuir and Freundlich isotherm models. The Langmuir isotherm model appeared to fit the isotherm data better than the Freundlich isotherm model. The pseudo first-order kinetic model was used to describe the kinetic data. The study of temperature effect was quantified by calculating various thermodynamic parameters such as Gibbs free energy, enthalpy, and entropy changes. The dimensionless separation factor (R L ) showed that the adsorption of metal ions onto poly(EGDMA-VTAZ) was favorable. It was seen that values of distribution coefficient (K D ) decreasing with Cr(VI) concentration in solution at equilibrium (C e ) indicated that the occupation of activate surface sites of adsorbent increased with Cr(VI).

Adsorption of Cr(VI) ions from aqueous systems using thermally sodium organo-bentonite biopolymer composite (TSOBC): response surface methodology, isotherm, kinetic and thermodynamic studies

“…The RSM was employed to evaluate the combined effects of pH (X 1 ), TSOBC dose (X 2 ), initial Cr(VI) concentration (X 3 ) and time (X 4 ) on the adsorption process. In the experimental design model, pH (2)(3)(4)(5)(6)(7)(8), TSOBC dose (0.1-1.5 g), initial Cr(VI) concentration (20-200 mg/L) and time (60-240 min) were taken as input variables. Percentage removal of Cr(VI) was taken as the response of the adsorption system.…”

“…2− [5,6]. The cationic form is relatively immobile and innocuous [7], whereas Cr(VI) is carcinogenic and mutagenic and it is considered as one of the most harmful materials to human health by the EPA [8].…”

Physicochemical studies

“…The value of n ranges between 2.086 and 2.608. If the value of n is in the range 1< n <10, the adsorption is favorable (Kara, 2009). …”

Copper(II) Removal from Aqueous Solutions by Adsorption Method: Isothermal, Thermodynamic and Kinetic Studies

“…Water contamination from industrial waste is an increasing case with each passing day. Since heavy metals can accumulate in human body, heavy metal content of water may have a great potential to be very hazardous to human health and natural life [1][2][3]. Copper(II) is an essential nutritional source such as zinc, manganese, iron, boron, molybdenium, chlorine.…”