Search

This study aimed to synthesise a novel adsorbent of poly(AMPS/HEMA)/TiO2/ZnO hydrogel nanocomposite by γ-irradiation polymerisation of 2-acrylamido-2-methylpropane sulphonic acid (AMPS) solution and 2-hydroxyethyl methacrylate (HEMA) monomer incorporated with TiO2/ZnO nanoparticles for potential use in the uptake of methylene blue (MB) and crystal violet (CV) dyes from wastewater. The effect of irradiation dose and AMPS/HEMA composition ratio on gel content (%) and swelling (%) were studied. From the results of the gel content (%) and swelling (%), the composition ratio AMPS/HEMA (80/20) and the dose of 15 kGy were selected for the preparation of the hydrogel nanocomposite. The properties of prepared materials were characterised by different analytical techniques. FTIR results proved the successful interaction of TiO2/ZnO nanoparticles within AMPS and HEMA chains. The SEM/EDS results proved the peaks corresponding to C, O, S, Zn, and Ti. XRD of nanocomposite indicated the peaks of TiO2 and ZnO nanoparticles. The factors affecting the uptake of MB and CV dyes were evaluated according to the impact of reaction time, pH, dye concentration, dosage, and temperature. The adsorption amount of MB and CV onto poly(AMPS/HEMA)/TiO2/ZnO hydrogel nanocomposite was fast time and effective for highly concentrated dye-bearing effluents. The uptake characteristics of the two dyes were similar. The ideal adsorption capacity of nanocomposite towards MB and CV dyes were 257.6 and 215.9 (mg/g) with a removal rate of 89.7% and 81.8%, respectively. The optimal conditions were pH 9 and 7, a reaction time of 70 min, dye concentration of 300 mg/L, and 0.3 g nanocomposite dosage. The adsorption process was chemisorption, endothermic and spontaneous. It is fitted with Langmuir isotherm and Pseudo-second-order models. Furthermore, the poly(AMPS/HEMA)/TiO2/ZnO nanocomposite supports the high capability for adsorption of binary MB/CV dyes mixture. The prepared hydrogel nanocomposite is a novel adsorbent for the uptake of dyes from wastewater with good recyclability. [ABSTRACT FROM AUTHOR]

In this study, a facile thermal condensation method was employed to prepare graphitic carbon nitride (g-C3N4) nanoparticles, and characterised by different advanced techniques. The TEM results proved that g-C3N4 had an average size of 49.7–89.3 nm. The EDX analysis of g-C3N4 confirms the existence of only C and N elements. Polyethylene oxide/polyacrylamide (PEO/PAAm) hydrogel and PEO/PAAm/g-C3N4 nanocomposite of different ratios of g-C3N4 (5, 10, and 15%) were synthesised by gamma irradiation-induced crosslinking reaction. In addition, novel magnetic (PEO/PAAm/g-C3N4/Fe3O4) nanocomposite was successfully fabricated by alkaline co-precipitation of swollen PEO/PAAm/g-C3N4 in Fe3+/Fe2+ solutions for use in the removal of Sr2+, Zn2+, and Cd2+ ions from wastewater. The PEO/PAAm/g-C3N4/Fe3O4 nanocomposite was characterised by FTIR, XRD, SEM, EDX, and VSM techniques. The XRD of PEO/PAAm/g-C3N4/Fe3O4 nanocomposite showed the presence of the typical peaks of both g-C3N4 and Fe3O4 nanoparticles. The VSM analysis indicated that the saturation magnetisation value of the nanocomposite was 18.96 emu/g, which is suitable for magnetic separation and adsorption processing. The uptake ability of PEO/PAAm/g-C3N4/Fe3O4 nanocomposite towards the Sr2+, Zn2+, and Cd2+ was examined under the effect of pH, reaction time, pH, and adsorbent dosage as well as different adsorption kinetics and isotherms models were applied. The maximum removal percentage of Cd2+, Zn2+, and Sr2+ ions was 89.8%, 97.3%, and 91.5% and achieved after 25 min at the optimum pH of 6 for Cd2+ and Zn2+, and pH 4.0 for Sr2+ ions. The fast and easy uptake of PEO/PAAm/g-C3N4/Fe3O4 nanocomposite adsorbent for the pollutants owing to the synergistic effect of existing functional groups of PEO/PAAm as well as g-C3N4 and Fe3O4 improved the removal performance of metal ions for great application in environmental remediation of wastewater treatments. [ABSTRACT FROM AUTHOR]

AbstractA novel polyvinylpyrrolidone/copper–silver (PVP/Cu–Ag) nanocomposite was synthesized via aqueous solution reduction and gamma radiation techniques for the treatment of methylene blue dye (MB) polluted water as a common organic dye pollutant in wastewater which is harmful to human health and aquatic life. Different analyses were used for the characterization of the synthesized Cu–Ag nanoparticles (NPs) and PVP/Cu–Ag nanocomposites such as XRD, TEM, DLS, FTIR, EDX, and TGA The XRD results indicated the typical peaks of CuNPs and AgNPs and the formation of pure crystalline nanoparticles in addition to their corresponding peaks were noticed in the PVP/Cu–Ag nanocomposite. Results of FTIR for the PVP/Cu–Ag nanocomposite confirmed the successful interaction between Cu–Ag NPs and PVP chains. The SEM of the PVP/Cu–Ag nanocomposite appeared rough and dense porous surface with white spots of Cu–Ag nanoparticles that dispersed homogeneously all over the surface of the PVP matrix. The effect of the dose of gamma radiation on the gelation and swelling of PVP hydrogel and PVP/Cu–Ag nanocomposite was studied. Using 15 kGy, the gel content of 89% and 97.1% for PVP and PVP/Cu–Ag, respectively. The swelling degree of PVP/Cu–Ag nanocomposite shows pH dependence and the maximum swelling was at pH 6. The point of zero charge (pHpzc) of PVP/Cu–Ag nanocomposite was 5.8. The factors affecting the removal of MB dye were evaluated as the effect of reaction time, dosage, temperature, pH, and dye concentration. The PVP/Cu–Ag nanocomposite shows fast adsorption of MB dye with a removal percentage of 95% after 50 min, at pH 8, 200 mg/L dye concentration, and 0.1 g nanocomposite dosage. Based on the kinetic, isotherm, and thermodynamic studies, it was found that the adsorption of MB dye onto PVP/Cu–Ag nanocomposite fitted to the Pseudo-second-order kinetic model and the Langmuir isotherm model and the reaction was an endothermic, spontaneous, and chemisorption. The fast removal of the dye using the PVP/Cu–Ag nanocomposite confirms its possible use in wastewater treatment applications as an effective adsorbent for dye treatment. [ABSTRACT FROM AUTHOR]

In this work, a hybrid composite of activated carbon (AC) functionalized with terpolymer hydrogel of polyvinyl alcohol/polyacrylamide/polyacrylic acid (PVA/PAAm/PAA) was prepared by γ-irradiation and used efficiently for sorption of Eu(III) and Sm(III) ions from aquatic solutions. Sewage sludge from the wastewater treatment plant was used to prepare AC, then activated by zinc chloride (ZnCl2) and thermal treatment at 550 °C. The modification of AC by functionalized terpolymer has successfully occurred mainly to limit its precipitation and to increase its adsorption capacity which allowed capable interaction with the metal ions. Different advanced techniques were used to investigate the structure and properties of (PVA/PAAm/PAA)/AC composite before and after the sorption process. Using 20 kGy is sufficient to get gel fraction of 87.5% and equilibrium swelling was 39.1 g/g. The (PVA/PAm/PAA)/AC composite hydrogel showed a pHpzc at pH ∼3. FTIR and EDS confirmed the successful integration of the functional groups and constituent elements of AC into terpolymer hydrogel components. XRD results confirmed the typical diffraction peaks of AC in the composite and the calculated average crystallite size was 167.4 nm. The SEM morphology of AC appeared as grains distributed well into the composite. The effect of synthesized AC, PVA/PAAm/PAA and (PVA/PAAm/PAA)/AC sorbents were tested to uptake of Eu(III) and Sm(III) ions. The highest uptake was noticed for (PVA/PAAm/PAA)/AC composite and it was selected for studying the parameters affecting the sorption process such as pH, shaking time, initial concentration, and adsorbent dosage. Results of the experimental data showed that Langmuir isotherm and Pseudo-second-order kinetic models fit well the sorption process of both Eu(III) and Sm(III) ions with maximum sorption capacities of 173.24 and 160.41 mg/g and uptake percentage of 82.3% and 83.4%, respectively at the optimum conditions of pH 4, 180 min, 100 mg/L metal concentration and 0.01 g adsorbent mass. The thermodynamic parameters indicated endothermic and spontaneous nature of the sorption process. Additionally, the as-prepared composite afford high selectivity and uptake capacity for Eu(III) and Sm(III) ions at pH 4 even in the presence of competing cations; Cd(II), Co(II), Sr(II) and Cs(I). The (PVA/PAAm/PAA)/AC composite was used efficiently as a unique and selective adsorbent for the sorption of Eu(III) and Sm(III) ions. [ABSTRACT FROM AUTHOR]