Synthesis and Application of Zn‑BTC/GO Nanocomposites as Highly Efficient Photocatalysts in the Dye Degradation

Nanocomposite Zn-BTC/GO (BTC: benzene-1,3,5-tricarboxylic, GO: graphene oxide) was successfully synthesized by hydrothermal treatment with a microwave method. Samples were characterized by XRD, FTIR, EDS-mapping, BET, SEM, UV-vis DRS and XPS. SEM-image result showed nano Zn-BTC/GO particles size of 50-80 nm. Nanocomposite Zn-BTC/GO showed the a high surface area (1303 m2/g) and pore volume (1.08 cm3/g). The Zn-BTC/GO nanocomposite were tested for the photocatalytic degradation of reactive dye (Reactive Red 195) in an aqueous solution. The Zn-BTC/GO composites exhibited high photocatalytic activity. Thus, at the pH of 6.5 and the high initial concentration of 30 mg RR-195/L, removal efficiency reached the value of 96.16% after 60 min reaction. Moreover, nano Zn-BTC also showed high RR-195 removal efficiency after 3 catalytic regeneration. This contributes to sustainable development and green chemistry.

Surface Functionalization of Cotton Fabric with Ag3PO4 via Citric Acid Cross-linking Using An Industrialized Padding Process and Its Self-Cleaning Performance

Cotton fabric was first modified with citric acid to introduce surface carboxyl groups, which then coordinated with Ag+ ions to prepare the Ag3PO4 finished cotton fabric through further reacting with PO43- ions using an industrialized pad-dry-cure process. Increasing surface carboxyl groups could significantly enhanced the loaded content of Ag3PO4. The padding process could more strongly fix Ag3PO4 on fabric than the conventional dipping method. The Ag3PO4 finished cotton fabric showed higher photocatalytic capacity than pure Ag3PO4 particles owing to the synergetic effect of the Ag complex with the carboxyl groups on the fabric. Moreover, the treatment of KBr and fixing agent further improved the the stability and anti-photocorrosion performance of the samples. Importantly, the finished fabric also exhibited better self-cleaning performance for Reactive Red 195 as a model stain under varied irradiation. The dye was found to be decomposed and mineralized on the finished fabric under artificial or solar irradiation.

Preparation of EDTA modified cotton fiber iron complex and catalytic properties for aqueous Cr(VI) reduction and dye degradation

Cotton fabric was modified with Na2EDTA using a hydrothermal method to introduce surface hydroxyl groups, and subsequent coordination of Fe(III) ions to produce an Na2EDTA modified cotton-fiber-Fe complex (Fe-EDTA-Cotton). After characterization by SEM and FTIR, Fe-EDTA-Cotton was used as a heterogeneous photocatalyst to reduce Cr(VI) and degrade Reactive Red 195 oxidatively, to evaluate its catalytic activity. The results indicated that high Na2EDTA and/or NaH2PO4 concentrations, and/or high hydrothermal temperature increased the carboxyl group content (QCOOH) of the cotton fiber, high Fe content and elevated temperature could enhance coordination. Fe-EDTA-Cotton had a significant photocatalytic function in reducing Cr(VI). Increasing the QFe value of the complex or stronger irradiation favored photocatalytic reduction of Cr(VI) species. Increasing the system's pH did not help the reduction reaction. Fe-EDTA-Cotton could also remove Cr(VI) and Reactive Red 195 simultaneously from aqueous solution, and showed strong photocatalytic capacity. The reduction or oxidation reaction could be regulated by changing Na2S2O8 concentration in the reaction system, which might provide a new way to treat wastewater containing organic pigments and Cr(VI) species. Highlight Hydrothermal process enhanced EDTA modification of cotton fabric > EDTA modified cotton fiber Fe complex was prepared > Cr(VI) removal was improved by its synergistic effect > Fe complexes can remove Cr (VI) and organic dyes from aqueous solution in one bath > The work might provide a new way to purify the wastewater containing organic pigments and Cr (VI) species.

Auto-combustion Fabrication and Optical Properties of Zinc Oxide Nanoparticles for Degradation of Reactive Red 195 and Methyl Orange Dyes

A new preparation method has been successfully utilized for the fabrication of zinc oxide nanoparticles using the auto-combustion method and fuels (tartaric acid: TA and citric acid: CA) with molar ratio (Zn:TA:CA=1:1:0, 1:0:0.55 and 1:0.5:0.275). The as-fabricated ZTA, ZCA and ZCTA samples annealed at 500 oC for two hours. The calcined zinc oxide nanoparticles were investigated by various tools such as XRD, DRS, FT-IR, and HR-TEM. The average crystallite size of the fabricated zinc oxide was determined to be 24-39 nm. The direct band gap, lattice parameters, unit cell volume (V), the dislocation density (D) and the Zn-O bond length (L) of the synthesized ZTA, ZCA and ZCTA samples were determined. The synthesized zinc oxide nanoparticles are used as nanocatalyst for photodegradation of reactive red 195 and methyl orange dyes under UV light irradiation. The degradation of reactive red 195 dye was 91-94 % after 70 min over the synthesized zinc oxide and the values of degradation increased to be 99-99.8 % in 50 min with H2O2 under UV light irradiation. Also, the degradation of methyl orange dye was 57.55-70.57 % after 300 min over the synthesized zinc oxide (ZTA, ZCA and ZCTA samples) and the values of degradation increased to be 81-95 % in 70 min with H2O2 under UV light irradiation. Finally, the appeared rate constant (Kapp) is determined and the mechanism of the photocatalysis process is suggested for the degradation of the dyes over the synthesized zinc oxide nanoparticles.