Ultrasound-assisted synthesis of polyacrylamide-grafted sodium alginate and its application in dye removal

Abstract

A polymeric adsorbent based on sodium alginate (SAG) grafted with polyacrylamide (PAM) (SAG-g-PAM) was synthesized using an ultrasound-assisted method. The addition polymerization was carried out with ammonium persulfate as the initiator, at different acrylamide (AM) concentrations. The SAG-g-PAM copolymers were evaluated by FTIR and 13 C NMR spectroscopies, thermogravimetric analysis, grafting efficiency (%GE) and intrinsic viscosity in NaCl solution at 25 °C. Graft copolymers could be obtained in reaction lasting until 10 min by using ultrasound energy with grafting efficiency above 75%. The decolorization efficiency and adsorption capacity of the SAG-g-PAM copolymers were investigated in the adsorption of methylene blue (MB). The dye adsorption was pH dependent, and adsorption capacity (69.13 mg/g) maxima was at pH 10. All the graft copolymers have shown the same decolorization efficiency (99%), and the best one for MB removing is the SAG-g-PAM 6 (%GE = 75%), since lower acrylamide content is required in the synthesis.

New Type of Sodium Alginate-g-acrylamide Polyelectrolyte Obtained by Electron Beam Irradiation: Characterization and Study of Flocculation Efficacy and Heavy Metal Removal Capacity

“…Moreover, the band located at 3192–3190 cm −1 that is due to the OH stretching vibration [25] shows variations in intensity depending on the irradiation dose, which indicates the participation of hydroxyl groups in the chemical reaction, as shown in Figure 8. More than that, some additional bands in the copolymer spectrum are at 1651–1648, 1614–1605, and 1415–1414 cm −1 which correspond to the carbonyl amide, N–H, and C–N stretching vibrations [25,47]. All these bands have confirmed the grafting of polyacrylamide on the sodium alginate backbone, as in Figure 8.…”

“…The band near 3400 cm −1 that corresponds to the stretching vibration of –OH groups of sodium alginate [25,46,47,48,49] can be seen in both AMD/ALg I (Figure 3a,c) and AMD/ALg II (Figure 3b,d) spectra. On this band, modifications are observed in absorbance for samples obtained at the same irradiation dose as a function of sodium alginate concentration.…”

“…In order to correlate the results obtained by the FTIR technique with those obtained after the evaluation of the flocculation performance, based on other results presented in the literature [25,47,56], a possible reaction mechanism is proposed (Figure 8) to highlight how the PAM is bound to the sodium alginate structure, and that the sodium alginate is responsible for the performances of SALg- g -PAM type as flocculant.…”

“…The sodium alginate spectrum exhibits mainly bands due to: The Na−O stretching at 815–800 cm −1 , the stretching frequency of the –OH group at 3400–3000 cm −1 , the COO– group at 1610–1605 cm −1 and 1417–1415 cm −1 , and the C−O group [25,47].…”

Adsorption of Methylene Blue from Aqueous Solution Using Locust Bean Gum graft Copolymer-bentonite Composite

“…The adsorption of MB on sodium alginate-graftpolyacrylamide was reported [28]. The adsorption was observed to be pH dependent with maximum adsorption capacity of 69.13 mg/g recorded at pH 10.…”