Rapid and Efficient Adsorption Removal of Reactive Blue 4 from Aqueous Solution by Cross-Linked Microcrystalline Cellulose–Epichlorohydrin Polymers: Isothermal, Kinetic, and Thermodynamic Study

In this study, we modified microcrystalline cellulose by cross-linking it with epichlorohydrin to obtain a rapid and efficient adsorbent for the removal of Reactive Blue 4 dye from aqueous solution. Evidences of the cross-linking of the microcrystalline cellulose were obtained by Fourier transform infrared spectroscopy, X-ray diff raction, Brunauer–Emmett–Teller analysis, thermogravimetric analysis, and scanning electron microscopy. We investigated the eff ects of adsorbent dosage, p H, initial dye concentration, temperature, and contact time on the dye adsorption capacity. The results showed that the adsorption equilibrium time was just 20 min and the maximum adsorption capacity was 69.79 mg/g. The adsorption isotherm data fitted the Langmuir isotherm model well, and the adsorption kinetics data followed the pseudo-second-order kinetic model. The results of the thermodynamic analysis suggest that the adsorption process was spontaneous and exothermic. Recyclability experiments demonstrated the good reusability of this adsorbent. Electrostatic interaction was found to dominate the adsorption process.

Preparation and Spectra Properties of Reactive Blue Rare Earth Dyestuffs

Reactive blue rare earth dyestuffs were prepared by using reactive blue and lanthanum oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, erbium oxide, lutetium oxide and yttrium oxide respectively for dyeing silk cloth. The degrees of dyeing of reactive blue gadolinium and fixation of reactive blue neodymium were the biggest respectively, were 84.83% and 97.96 respectively, were 24.13% and 8.36% were increased with that of reactive blue respectively. The spectra of reactive blue rare earths and reactive blue were studied by UV-VIS. In 200.00～800.00 nm, the λmax of reactive blue, reactive blue lanthanum, reactive blue praseodymium, reactive blue neodymium, reactive blue samarium, reactive blue europium, reactive blue gadolinium, reactive blue terbium, reactive blue dysprosium, reactive blue erbium, reactive blue lutetium and reactive blue yttrium are 599.00, 600.00, 602.00, 601.00, 600.00, 600.50, 600.50, 601.00, 600.00, 600.50, 599.50 and 600.50 nm respectively. Reactive blue lanthanum, reactive blue praseodymium, reactive blue neodymium, reactive blue samarium, reactive blue europium, reactive blue gadolinium, reactive blue terbium, reactive blue dysprosium, reactive blue erbium, reactive blue lutetium, reactive blue yttrium and reactive blue had almost same color.

Rational design of Aspergillus flavus A5p1-immobilized cell system to enhance the decolorization of reactive blue 4(RB4)

Anthraquinone dyes are a class of typical carcinogenic and hard-biodegradable organic pollutants.This study aimed to enhance the decolorization of anthraquinone dye by rationally designing an expected immobilized system.Reactive blue 4(RB4) was used as a substrate model and a previous isolated dyedegrading strain Aspergillus flavus A5pl was purposefully immobilized.Considering the effects of cell attachment and mass transfer,the polyurethane foam(PUF) with open pore structure was selected as the immobilization carrier.Results showed that the RB4 decolorization efficiency was significant enhanced after immobilization.Compared to the free mycelium system,the decolorization time of200 mg·L^(-1)RB4 was shortened from 48 h to 28 h by the PUF-immobilized cell system.Moreover,the PUF-immobilized system could tolerate RB4 up to 2000 mg-L^(-1).In the packed bed bioreactor(PBBR),an average decolorization efficiency of 93.3% could be maintained by the PUF-immobilized system for26 days.The decolorization process of RB4 was well described by the logistic equation and the degradation pathway was discussed.It was found that the higher specific growth rate of the PUF-immobilized cells was one of reasons for the enhanced decolorization.The good performance of the PUFimmobilized cell system would make it have potential application value for RB4 bioremediation.

Photodegradation of reactive blue 19 dye using magnetic nanophotocatalyst α-Fe_(2)O_(3)/WO_(3):A comparison study of α-Fe_(2)O_(3)/WO_(3)and WO_(3)/NaOH

The photocatalytic degradation of reactive blue 19(RB19)dye was investigated in a slurry system using ultraviolet(UV)and light-emitting diode(LED)lamps as light sources and using magnetic tungsten trioxide nanophotocatalysts(α-Fe_(2)O_(3)/WO_(3)and WO_(3)/NaOH)as photocatalysts.The effects of different parameters including irradiation time,initial concentration of RB19,nanophotocatalyst dosage,and pH were examined.The magnetic nanophotocatalysts were also characterized with different methods including scanning electron microscopy(SEM),energy-dispersive X-ray spectroscopy(EDS),transmission electron microscopy(TEM),X-ray diffraction(XRD),photoluminescence(PL),differen-tial reflectance spectroscopy(DRS),Fourier transform infrared spectroscopy(FTIR),and vibrating sample magnetometry(VSM).The XRD and FTIR analyses confirmed the presence of tungsten trioxide on the iron oxide nanoparticles.The VSM analysis confirmed the magnetic ability of the new synthesized nanophotocatalyst α-Fe_(2)O_(3)/WO_(3)with 39.6 emu/g of saturation magnetization.The reactor performance showed consid-erable improvement in the α-Fe_(2)O_(3)-modified nanophotocatalyst.The impact of visible light was specifically investigated,and it was compared with UV-C light under the same experimental conditions.The reusability of the magnetic nanophotocatalyst α-Fe_(2)O_(3)/WO_(3)was tested during six cycles,and the magnetic materials showed an excellent removal efficiency after six cycles,with just a 7%decline.

Synthesis and Characterization of Naphthalenesulfonic Formaldehyde Condensates for Improving the Solubility of C.I. Reactive Blue 19 in Alkali Liquor

The solubility of C.I. reactive blue 19 in aqueous alkali is poor, so it isn't used to dye cellulosic fiber in cold pad-batch dyeing. In order to improve the solubility of this dyestuff in alkali liquor, the right dispersants will be needed. A series of condensates are synthesized by changing the synthesis conditions such as the ratio of naphthalenesulfonic (N) to formaldehyde (F), acidity, and their compositions are confirmed by MS spectrum. It is found that in acidity scope of 20%-24% and the ratio of N to F 1∶0.33, the synthesized condensates can efficiently improve the solubility of C.I. reactive blue 19 in alkali liquor. In addition, the influences of the condensates on the exhaust dyeing and the cold pad-batch dyeing are tested.

Application of Fe^0/C/Clay ceramics for decoloration of synthetic Acid Red 73 and Reactive Blue 4 wastewater by micro-electrolysis

Dyes are common pollutants in textile wastewaters, and the treatment of the wastewater has now attracted much attention due to its wide application and low biodegradability. In this study, Fe^0/C/Clay ceramics, a kind of novel micro-electrolysis filler, were sintered and employed in a dynamic micro-electrolysis reactor for synthetic Acid Red 73 （AR73） and Reactive Blue 4 （RB4） wastewater treatment. The effects ofinfluent pH, hydraulic retention time （HRT）, and aeration on the decoloration efficiencies of AR73 and RB4 were studied. The optimum conditions for wastewater treatment were： AR73, influent pH of 4, HRT of 2 h and aeration; RB4, influent pH of 5, HRT of 6 h and aeration. Under the optimum conditions, decoloration efficiency of AR73 and RB4 wastewater was 96% and 83%, respectively. Results of UV-vis spectrum scanning demonstrated that the chromophores were broken. Continuous running tests showed that improvement of micro-electrolysis system with Fe^0/C/Clay ceramics for AR73 and RB4 synthetic wastewater treatment could avoid failure of micro-electrolysis reactor, which indicated great potential for the practical application of the ceramics in the field of actual industrial wastewater treatment.

Preparation of magnetic anion exchange resin and their adsorption kinetic behavior of reactive blue

Magnetic anion exchange resin （MD-1） was prepared from quaternization of magnetic copolymeric resin （glycidyl methacry- late-co-divinylbenzene）. For comparison, magnetic resin MD-0 without quaternization and non-magnetic resin （D-l） were also synthesized for the adsorption process. It was found that the adsorption was mainly contributed to the chemical interaction between quaternary ammonium groups and reactive blue RXHC. Due to the smaller size, MD- 1 had faster adsorption and desorption kinetics than D-1. Coupled with the advantage of easy separation, the magnetic anion exchange resin was considered to be superior to common anion exchange resin in removal of reactive dye.

Decolourization of Reactive Brilliant Blue KN-R by immobilized cells of Aspergillus ficuum

Aspergillus ficuum was immobilized with sodium alginate, and decolourization of Reactive Brilliant Blue KN-R was studied on immobilized and free Aspergillus ficuum. The optimal preparation condition of the strain immobilization was obtained by the orthogonal test, it is sodium alginate 3%, CaCl_2 5%, wet mycelia 30 g/L, calcific time 8 h. It was found that the immobilized cells could effectively decolourize Reactive Brilliant Blue KN-R, the optimum temperature and pH were 33℃ and 5.0, respectively. The kinetics study of decolourization of immobilized cells showed that the decolourization of Aspergillus ficuum immobilized conformed to zero-order reaction model. The decolourization efficiency of immobilized cell compared with that of free cell in different physical conditions. Results showed that the decolourization of immobilized cells with mycelia had the best efficiency. The immobilized cells could be reused after the first decolourization.

Photocatalytic Activity of Lanthanum and Sulfur Co-doped TiO_2 Photocatalyst under Visible Light

A novel lanthanum and sulfur co-doped TiO2 photocatalyst was synthesized by precipitation- dipping method, and characterized by X-ray diffraction（XRD）, transmission electron microscopy（TEM） and UV-Vis diffuse reflectance spectroscopy. Compared with the S-doped TiO, La-doped TiO2 and the standard Degussa P25 photocatalysts, the lanthanum and sulfur co-doped TiO2 photocatalyst （the molar percentage of La is 3.0%） calcined at 450 ℃ for 2 h showed the strongest absorption for visible light and highest activities for degradation of reactive blue 19 dye in aqueous solution under visible light（λ〉400 nm） irradiation. It was also discovered that the co-doping of lanthanum and sulfur hindered the aggregation and growth of TiO2 particles, and the doping of lanthanum reduced slightly the phase transition temperature ofTiO2 from anatase to rutile.

Fe-Mn-sepiolite as an effective heterogeneous Fenton-like catalyst for the decolorization of reactive brilliant blue

A study of the decolorization of reactive brilliant blue in an aqueous solution using Fe-Mn-sepiolite as a heterogeneous Fenton-like catalyst has been performed. The Fourier transform infrared （FTIR） spectra of the catalyst showed bending vibrations of the Fe-O. The Xray diffraction （XRD） patterns of the catalyst showed characteristic diffraction peaks of α-Fe203, γ-Fe203 and MnO. A four factor central composite design （CCD） coupled with response surface methodology （RSM） was applied to evaluate and optimize the important variables （catalyst addition, hydrogen peroxide dosage, initial pH value and initial dye concentration）. When the reaction conditions were catalyst dosage = 0.4 g, [H202]= 0.3 mL, pH= 2.5, [reactive brilliant blue]o = 50mg·L-1, and volume of solution = 500 mL at room temperature, the decolorization efficiency of reactive brilliant blue was 91.98% within 60min. Moreover, the Fe-Mn-sepiolite catalyst had good stability for the degradation of reactive brilliant blue even after six cycles. Leaching of iron ions （ 〈 0.4 mg·L-l） was observed. The decoloring process was reactive brilliant blue specific via a redox reaction. The benzene ring and naphthalene ring were first oxidized to open ring; these were then oxidized to the alcohol and carboxylic acid. The reactive brilliant blue was decom- posed mainly by the attack of .OH radicals including surface-bound .OH radicals generated on the catalyst surface.

From pollutant to solution of wastewater pollution: Synthesis of activated carbon from textile sludge for dye adsorption

Adsorption is an important process in wastewater treatment,and conversion of waste materials to adsorbent offers a solution to high material cost related to the use of commercial activated carbon.This study investigated the adsorption behaviour of Reactive Black 5（RB5）and methylene blue（MB）onto activated carbon produced from textile sludge（TSAC）.The activated carbon was synthesized through chemical activation of precursor followed with carbonization at 650℃ under nitrogen flow.Effects of time（0–200 min）,pH（2–10）,temperature（25–60℃）,initial dye concentration（0–200 mg·L^-1）,and adsorbent dosage（0.01–0.15 g）on dye removal efficiency were investigated.Preliminary screening revealed that TSAC synthesized via H2SO4activation showed higher adsorption behaviour than TSAC activated by KCl and ZnCl2.The adsorption capacity of TSAC was found to be 11.98 mg·g^-1（RB5）and 13.27 mg·g^-1（MB）,and is dependent on adsorption time and initial dye concentration.The adsorption data for both dyes were well fitted to Freundlich isotherm model which explains the heterogeneous nature of TSAC surface.The dye adsorption obeyed pseudo-second order kinetic model,thus chemisorption was the controlling step.This study reveals potential of textile sludge in removal of dyes from aqueous solution,and further studies are required to establish the applicability of the synthesized adsorbent for the treatment of waste water containing toxic dyes from textile industry.