UV-Initiated Graft Copolymerization of Cationic Chitosan-Based Flocculants for Treatment of Zinc Phosphate-Contaminated Wastewater

Abstract

In this study, acrylamide and [2-(acryloyloxy)­ethyl] trimethylammonium chloride were grafted onto CS by UV initiation to obtain an environmentally friendly graft copolymer, CS-g-poly­(acrylamide-acryloyloxyethyl) trimethylammonium chloride (CS-g-PAD). Poly­(acrylamide-acryloyloxyethyl) trimethylammonium chloride was named as PAD. Nuclear magnetic resonance hydrogen spectroscopy (1H NMR), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and thermal gravimetric analysis (TG-DSC) were used to characterize CS-g-PAD. Results confirmed the synthesis of CS-g-PAD. SEM results showed that CS-g-PAD exhibited a porous structure with numerous 2–6 μm micropores. The enhanced CaCl2-aided flocculation tests of wastewater contaminated by zinc phosphate coating indicated that CS-g-PAD had better flocculation performance than PAD and the commercially available cationic polyacrylamide (CPAM). The removal rates of zinc concentration, total phosphorus concentration, and chemical oxygen demand were 99.3, 98.8, and 72.5%, respectively, at 6 mg·L–1 CS-g-PAD and pH 10. The precipitated flocs were mainly in crystalline form.

Synthesis and evaluation of a novel inorganic–organic composite flocculant, consisting of chitosan and poly‐ferric cerium silicate

“…This can be attributed to the loss of the structural water from internal OH groups in the flocculant. The characteristics exothermic peak at 302.2°C of CTS is not found in the DSC curve of CTS‐PFCS. This evidence of TG‐DSC further confirmed that the copolymer of CTS‐PFCS was synthesized successfully.…”

Synthesis of a Cationic Polyacrylamide under UV Initiation and Its Flocculation in Estrone Removal

“…The originally ordered structure of PAD was destroyed by the grafting of hydrophobic AODBAC, thus leading to a porous structure with a prodigious surface area which was favorable for the improving of flocculation and water solubility ability of PADA. Besides, Figure 5(b) also showed a linear correlation of the natural logarithms of the perimeter ( ) and the area ( ), indicating that the fractal dimension of the polymer surface could be calculated using Image-Pro Plus 6.0 software [22,23]. The results showed that the fractal dimensions of PAD and PADA were 1.236 and 1.403, respectively.…”

“…There were three obvious weight loss stages in the thermal weight curve of PADA in Figure 6. The first stage ∘ C, weight loss of 15.4 wt%) was ascribed to the moisture evaporation of adsorbed and bound water [23]. The second stage (200-350 ∘ C, weight loss of 20.1 wt%) was attributed to the imine reaction of the amide group as well as the thermal decomposition of methyl in the quaternary ammonium groups [24].…”

Effect of the Cationic Block Structure on the Characteristics of Sludge Flocs Formed by Charge Neutralization and Patching

“…In the first stage, the mass loss was about 10.7 wt % for CPAA in the range of 30–220 °C and 7.7 wt % for TPAA in the range of 30–195 °C, which was assigned to the evaporation of intramolecular and intermolecular moisture in the polymers [28]. In the second stage, mass loss was about 27.5 wt % for CPAA in the range of 220–350 °C and 21.1 wt % for TPAA in the range of 195–350 °C, which was due to the imine reaction of the amide group and the thermal decomposition of methyl in the quaternary ammonium groups [29]. The final stage occurred above 350 °C, and the mass loss was about 44.8 wt % for CPAA while it was about 47.8 wt % for TPAA, which was ascribed to the carbonization of the copolymer.…”