Super Effective Removal of Toxic Metals Water Pollutants Using Multi Functionalized Polyacrylonitrile and Arabic Gum Grafts

Abstract

Super adsorbent polymers can be considered to be a very efficient solution for wastewater treatment. In general, their adsorption capacities depend on the type and amount of the functional groups present on the surface of the polymers, while their economic value is affected by their cost. Therefore, this study aims to understand the effect of multi-functionalization of cheap Arabic gum on the adsorption capability toward heavy metals. Graft copolymers of polyacrylonitrile (PAN) onto Arabic gum (AG) were prepared in aqueous solution using (KMnO4/HNO3) as a redox initiator. Chemical modification of the graft copolymer was carried out by reaction with hydrazine hydrochloride followed by hydrolysis in the basic medium. The modified graft product was characterized by various techniques, such as Fourier transform infrared spectroscopy (FTIR), elemental analysis, scanning electron microscope (SEM), and X-ray powder diffraction (XRD). The modified graft copolymer was used to adsorb Pb2+, Cd2+ and Cu2+ from their aqueous solutions using batch extraction. Different parameters influence the uptake behavior, including contact time, pH, and the initial concentration of the metal ions; all of these were investigated. The kinetics were investigated using the pseudo first order and pseudo second order, and the equilibrium data were analyzed using the Langmuir and Freundlich model. The modified graft product showed the superadsorbent capacity to obtain maximum values (Qmax) 1017, 413 and 396 mg/g for Pb2+, Cd2+ and Cu2+, respectively. Acid treatment with 0.2 M HNO3 resulted in 96%, 99% and 99% metal recovery for the Pb2+, Cd2+ and Cu2+, respectively. This indicates the recyclability of product for further usage upon drying between treatments.

Novel Superadsorbent Highly Porous Hydrogel Based on Arabic Gum and Acrylamide Grafts for Fast and Efficient Methylene Blue Removal

“…where C 0 refers to the largest initial MB dye concentration. R L is an important value to examine the type and the nature of the sorption process as the adsorption is unfavorable when R L > 1, favorable when its value is between 0 to 1, linear if R L = 1 and irreversible when R L is zero [31]. In our work, the R L value was 0.0095 which explain the sorbents favorability of MB adsorption on the superadsorbent hydrogel.…”

“…Furthermore, a small peak at 1018 cm −1 and a broad peak at 1072 cm −1 are due to stretching vibrations of a C-O-C bond that link between different sugar units of AG [28]. On the other hand, the IR spectrum of PAM-g-AG copolymer ( Figure 1b) showed a new shoulder peak at 3201 cm −1 and a sharp one at 1663 cm −1 , respectively, corresponding to -NH and C=O stretching vibrations [31,33], thus confirming the grafting of acrylamide units onto AG. Crosslinked AG-g-PAM/PAA ( Figure 1c) showed a new band at 1563 cm −1 due to carboxylate group stretching vibration results from the hydrolyzation of amide groups [32].…”

“…Grafting reaction was carried out under mild conditions as reported previously [31]. Arabic gum (0.5 g) was dissolved in 5 mL of distilled water under stirring.…”

“…Systems with a good adsorption design are essential for a clear understanding of the adsorption isotherms. The Langmuir (Equation (7)) and Langmuir isotherm (Equation (8)) mathematical equations were applied to explain the adsorption coverage of different ions on the solid interface to the concentration of these ions in the solution at a definite temperature [31,45].…”

“…Results show that the Langmuir adsorption isotherm for the porous hydrogel granted the best fit (R 2 = 0.995) compared to the Freundlich isotherm (R 2 = 0.785). Additionally, 1/n value equal to 0.263 which indicates growing of the sorption capacity and formation of new adsorption sites [31].…”