Biodecolorization and partial mineralization of Reactive Black 5 by a strain of Rhodopseudomonas palustris

A strain of photosynthetic bacterium, Rhodopseudomonas palustris W1, isolated from a lab-scale anaerobic moving bed biofilm reactor (MBBR) treating textile e?uent was demonstrated to decolorize Reactive Black 5 (RB5) effciently under anaerobic condition. By a series of batch tests, the suitable conditions for RB5 decolorization were obtained, namely, pH < 10, light presence, glutamine or lactate as carbon source with concentration more than 500 mg/L when lactate is selected, NH4Cl as a nitrogen source wi...

Effects of glucose on the decolorization of Reactive Black 5 by yeast isolates

The cometabolic roles of glucose were investigated in decolorization of an azo dye, Reactive Black 5, by yeast isolates, Debaryomyces polymorphus and Candida tropicalis. The results indicated that the dye degradation by the two yeasts was highly associated with the yeast growth process and glucose presence in the medium. Color removal of 200 mg dye/L was increased from 76.4% to 92.7% within 60 h to 100% within 18-24 h with the increase of glucose from 5 to 10 g/L, although the activity of manganese dependent peroxidase （MnP） decreased by 2-8 times in this case. Hydrogen peroxide of 233.3 μg/L was detected in 6 h in D. polymorphus culture. The cometabolic functions of glucose and hydrogen peroxide could be also confirmed by the further color removals of 95.8% or 78,9% in the second cycle of decolorization tests in which 7 g glucose/L or 250 μg H202/L was superadded respectively together with 200 mg dye/L.

Development of the N-Doped Cu-Carbon Composite as a Novel Catalyst for the Removal Reactive Black 5

In this study, two Cu-based catalysts with and without N doped carbon matrix, named N-Cu/CuO/C and Cu/CuO were synthesized via calcination of melamine-cupper acetate complex and cupper acetate at 500°C under an inert atmosphere. The catalysts were characterized by X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), and CHNS elemental analyzer. The catalytic activity of both catalysts was evaluated through the NaBH4 associated reduction of commercial textile dye named reactive black 5 (RB5). The kinetics of the reduction of reactive black 5 was also described by the pseudo-first-order kinetic equation. For the studied reduction, N-Cu/CuO/C exhibited enhanced catalytic activity both in conversion and kinetics (97% conv. in 315 sec) compared to that of by Cu/CuO/C (25% conv. in 1500 sec). Besides, N-Cu/CuO/C also demonstrated good reusability up to four consecutive cycles.

The application of iron mesh double layer as anode for the electrochemical treatment of Reactive Black 5 dye

In this work a novel anode configuration consisting of an iron mesh double layer is proposed for the electrochemical treatment of wastewater. The removal of Reactive Black 5 dye（RB5） from synthetic contaminated water was used as a model system. At a constant anode surface area, identical process operating parameters and batch process mode, the iron mesh double layer electrode showed better performance compared to the conventional single layer iron mesh. The double layer electrode was characterized by RB5 and chemical oxygen demand（COD） removal efficiency of 98.2% and 97.7%, respectively, kinetic rate constant of 0.0385/min, diffusion coefficient of 4.9 × 10^（-5）cm^2/sec and electrical energy consumption of 20.53 kWh/kgdye removed. In the continuous flow system, the optimum conditions suggested by Response Surface Methodology（RSM） are： initial solution p H of 6.29,current density of 1.6 m A/cm^2, electrolyte dose of 0.15 g/L and flow rate of 11.47 m L/min which resulted in an RB5 removal efficiency of 81.62%.

Preparation of nZVI embedded modified mesoporous carbon for catalytic persulfate to degradation of reactive black 5

High-efficiency and cost-effective catalysts with available strategies for persulfate(PS)activation are critical for the complete mineralization of organic contaminants in the environmental remediation and protection fields.A nanoscale zero-valent iron-embedded modified mesoporous carbon(MCNZVI)with a core-shell structure is synthesized using the hydrothermal synthesis method and high-temperature pyrolysis.The results showed that nZVI could be impregnated within mesoporous carbon frameworks with a comparatively high graphitization degree,rich nitrogen doping content,and a large surface area and pore volume.This material was used as a persulfate activator for the oxidation removal of Reactive Black 5(RB5).The effects of the material dosage,PS concentration,pH,and some inorganic anions(i.e.,Cl^(−),SO_(4)^(2−))on RB5 degradation were then investigated.The highest degradation efficiency(97.3%)of RB5 was achieved via PS(20 mmol/L)activation by the MCNZVI(0.5 g/L).The pseudo-first-order kinetics(k=2.11×10^(−2)min^(−1))in the MCNZVI/PS(0.5 g/L,20 mmol/L)was greater than 100 times than that in the MCNZVI and PS.The reactive oxygen species(ROS),including^(1)O_(2),SO_(4)^(·−),HO^(.),and·O_(2)^(−),were generated by PS activation with the MCNZVI.Singlet oxygen was demonstrated to be the primary ROS responsible for the RB5 degradation.The MCNZVI could be reused and regenerated for recycling.This work provides new insights into PS activation to remove organic contamination.

Ilmenite:Properties and photodegradation kinetic on Reactive Black 5 dye

Ilmenite is natural mineral ore made up with titanium and iron mineral; including small portion of magnesium and manganese. To the best of our knowledge, photo-degradation of Reactive Black 5 dye（RB5） using ilmenite under solar irradiation is still lacking. In the present study, the physicochemical properties of ilmenite were characterized by using X-ray diffraction（XRD）, Scanning electron microscope（SEM）, BET and Raman Spectroscopy. Based on our results obtained, 73% solar-driven photo-degradation of RB 5 was successfully obtained when the catalyst loading increased up to 2.0 g/L for 20 min. In general,the photo-degradation of RB 5 by ilmenite followed first-order kinetics. The p H had a significant effect,with the most rapid degradation occurring at p H less than 7.

LaNiO_(3)/g-C_(3)N_(4) nanocomposite:An efficient Z-scheme photocatalyst for wastewater treatment using direct sunlight

The major findings in this report are(ⅰ)development of nanocomposite photocatalyst working through Z-scheme charge transfer pathway across the heterojunction,(ⅱ)utilization of direct sunlight as the photo-source,and(ⅲ)prospect of ligand-hole in photocatalysis through enhanced sub-band gap absorption,The photocatalysts,namely LaNiO_(3),g-C_(3)N_(4) and LaNiO_(3)/g-C_(3)N_(4) nanocomposites were synthesized via facile route and were characterized for their structure,morphology,microstructure,texture,elemental mapping and surface oxidation states by using several physicochemical techniques.The photocatalytic performance of the nanocomposite was tested through the degradation of hazardous azo dye pollutants,namely reactive black 5 and methylene blue as well as the colorless antibiotic-pollutant tetracycline hydrochloride in aqueous solution in presence of natural sunlight with excellent recycling activity.The 10%LaNiO_(3)/g-C_(3)N_(4) nanocomposite sample shows the best catalytic activity,degrading respectively 94%,98.6%and 88.1%of reactive black 5,methylene blue and tetracycline hydrochloride in60,180 and 120 min.The photocatalytic activity of the nanocomposite phase is several times superior to that of the pure phases.The improvements of photocatalytic activity of g-C_(3)N_(4) in the nanocomposite have been rationalized through the construction of direct Z-scheme heterojunction and suppression of electron-hole pair recombination efficiency.The enhanced photo-absorption of the nanocomposite can possibly be related to sub-bandgap absorption,which is associated to the midgap state originating from ligand-hole formation or defects in the structure.The photodegradation process is mediated through the formation of super oxide radical(O_(2))and hole(h^(+))as the main responsible species.