Abstract
Environmental pollution with dyes released from industrial effluent is one of the major and most critical problems in the world. To alleviate this issue, advanced and safe materials with fast and highly efficient dye removal should be designed. Great attention has been paid recently to hydrogels based on polysaccharides such as Arabic Gum (AG) grafted with polyacrylamide (PAM) and polyacrylic acid (PAA). These materials combine the merits of natural polymers such as biodegradability and non-toxicity with the high adsorption ability of PAM and PAA towards cationic dyes such as methylene blue (MB). Many previous works have been done to enhance three-dimensional (3D) structure and swelling ability of the graft copolymers by using a crosslinking agent or even adding nanomaterials as a filler inside the hydrogel matrix. However, these additives may negatively affect the adsorption ability, and few previous studies could reach 2000 mg/g of maximum MB capacity removal within a good period of time. In our work, we synthesized partially hydrolyzed polyacrylamide grafted Arabic gum (AG-g-PAM/PAA) to have both amide and carboxylate groups. The modified water dissolved graft product undergoes water in oil (W/O) emulsion using paraffin oil as the continuous phase and Triton X-100 as a stabilizing agent; then, the system was inversed to oil in water (O/W) emulsion by increasing the shear mixing rate and cross-linked using Epichlorohydrin (ECH). The precipitated graft product showed hierarchically interconnected micro and macropores’ sponge like shape with fast water swelling and high MB adsorption capacity (2300 mg g−1) after 45 min at near neutral pH conditions.
Highlights
Great interest has been paid recently to environmental issues such as wastewater containing dye pollutants
The results revealed an ability of the novel porous hydrogel to adsorb 99% of methylene blue (MB) dye in only 10 min the conventional crosslinked graft copolymer didn’t show significant MB dye adsorption after 10 min
The influence of contact time was studied by changing the equilibrium time from 2 min to Figure S2 clearly demonstrated that after only 10 min for initial dye concentration 1600 mg/L the one hour near-neutral pH and at room temperature for MB adsorption onto the porous amount of MB adsorbed onto the porous hydrogel was nearly 1800 mg/g
Summary
Great interest has been paid recently to environmental issues such as wastewater containing dye pollutants. Adding nonmetals as a filler for better 3D structure and swelling ability [21,22] These additives may affect the performance of the prepared graft copolymer; for example, Dai et al [23]. Emulsification inversion occurs when the dispersed phase inversed to the continuous phase or the revere [26], and this could be driven by controlling many factors such as shear rate, viscosity, and temperature This method is highly recommended for preparing hierarchically porous materials having different pores size [30]. The results revealed an ability of the novel porous hydrogel to adsorb 99% of MB dye in only 10 min the conventional crosslinked graft copolymer didn’t show significant MB dye adsorption after 10 min
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