Facile synthesis and investigation of NiO–ZnO–Ag nanocomposites as efficient photocatalysts for degradation of methylene blue dye

In the present study, NiO–ZnO–Ag photocatalytic nanocomposites were synthesized using two-stage precipitation method. The synthesized composite powders were investigated and characterized using different techniques including XRD, FESEM, FT-IR, TGA and UV–Vis. XRD results showed that by increasing the Ag content, the crystallite size of ZnO decreased. FESEM micrographs showed that addition of Ag could lead to formation of more uniform particles in the size range of 30–500 nm. Diffuse reflectance spectroscopy results confirmed that addition of Ag nanoparticles led to the increase of light absorption, which was attributed to the plasmon surface resonance of Ag. Band gap energies of NiO–ZnO, NiO–ZnO–5%Ag, NiO–ZnO–3%Ag, NiO–ZnO–1%Ag and ZnO–1%Ag were estimated to be 3.13, 3.14, 3.147, 3.19 and 3.17 eV, respectively. Investigation of degradation process showed that by adding up to 1 wt% Ag to NiO–ZnO composite led to the increase of methylene blue degradation from 67% to 94%, but further addition resulted in decrease of degradation.     

表面活性剂对C.I.活性蓝221的增溶作用

分别以NaCl、AEO9、AEO3、JFC、AES和L-64为添加剂,研究了它们对C.I.活性蓝221在25 ℃水中的溶解度的影响。实验结果表明,NaCl的加入会大幅降低染料的溶解度;而五种表面活性剂对染料都有增溶作用,增溶效果依次为：JFC（L-64）>AEO9>AEO3>AES。当JFC或L-64用量为80 g/L时,可使C.I.活性蓝221的溶解度由空白时的100 g/L提高至190 g/L。以JFC,L-64,AEO9为混合助溶剂时,当溶液中含有15 g/L JFC, 20 g/L L-64和5 g/L AEO9时,C.I.活性蓝221的溶解度可以提升至200 g/L,染料溶液稳定时间达20 h以上。     

川阿格雷钠舒张血管的作用及机制研究

目的 研究川阿格雷钠(MC-002)对大鼠胸主动脉的舒张作用,并探讨其可能的作用机制。方法 测定川阿格雷钠对去甲肾上腺素(NE)和高钾预收缩的大鼠胸主动脉血管环的舒张作用,并观察L-硝基精氨酸甲酯(L-NAME)、亚甲蓝、吲哚美辛、格列本脲、蜂毒明肽、氯化钡和4-氨基吡啶对其作用的影响。结果 川阿格雷钠(3~300 μmol/L)能浓度依赖性地舒张NE预收缩的完整血管环,去内皮、亚甲蓝孵育和吲哚美辛孵育均能显著抑制其舒血管作用(P<0.05,P<0.01),L-NAME孵育无显著影响。川阿格雷钠拮抗高钾诱导完整血管环收缩的作用被格列本脲(ATP敏感型钾通道KATP抑制剂)和蜂毒明肽(小传导性钙激活型钾通道SKCa抑制剂)显著降低(P<0.01),氯化钡和4-氨基吡啶无显著影响。川阿格雷钠使NE预收缩的血管平滑肌的钙浓度-收缩曲线下移、右移,且呈现浓度依赖性。结论 川阿格雷钠可能通过内皮细胞的鸟苷酸环化酶途径和环氧合酶途径、开放KATP和SKCa引起平滑肌细胞膜超极化以及减少钙内流而松弛血管。     

Methylene blue as electron promoters in microbial fuel cell

Microbes and enzymes deliver electrons from carbon sources under anaerobic condition. Electrons are generated as the microorganisms are actively catabolized organic substances. The liberated electrons travel to anode surface. Saccharomyces cerevisiae (PTCC 5269) was implemented as biocatalyst in the anaerobic anode compartment. Glucose was used as carbon source. Also mediator as electron promoter was incorporated in the anode. Among several mediators, methylene blue (MB) as electron promoter with concentration of 50, 100, 200, 300 and 400 μM was selected to shuttle the liberated electron to anode surface. Maximum power and current with MB concentration of 300 μM were obtained. Resistances were applied to control the electron flow from anode to cathode chambers. Data were recorded through an online data-logger. Polarization curves with and without mediator were analyzed in the fabricated cell. MB had good ability to enhance power generation. Maximum open circuit voltage of 250 mV was achieved; the voltage was stabled for the duration of 36 h.     

掺钴二水草酸亚铁晶格畸变及红外谱频移

采用室温固相法制备了不同钴含量掺杂的二水草酸亚铁。XRD和FTIR分析表明,钴离子以掺杂的形式进入FeC2O4·2H2O晶格,并形成了具有原子级掺杂的（CoxFe2-x）1／2C2O4·2H2O前驱体。钴掺杂导致前驱体晶格收缩畸变,晶格中Fe—O键收缩使键能强度增加,振动频率增大,是红外振动峰发生蓝移的原因之一。     

Silica particles settling characteristics and removal performances of oxide chemical mechanical polishing wastewater treated by electrocoagulation technology

This study aimed at investigating the feasibility of using jackfruit peel (JFP), a solid waste, abundantly available in Malaysia, for the adsorption of methylene blue, a cationic dye. Batch adsorption studies were conducted to evaluate the effects of contact time, initial concentration (35-400mg/L), pH (2-11), and adsorbent dose (0.05-1.20g) on the removal of dye at temperature of 30 degrees C. The experimental data were analyzed by the four different types of linearized Langmuir isotherm, the Freundlich isotherm and the Temkin isotherm. The experimental data fitted well with the type 2 Langmuir model with a maximum adsorption capacity of 285.713mg/g. Pseudo-first and pseudo-second-order kinetics models were tested with the experimental data, and pseudo-second-order kinetics was the best for the adsorption of MB by JFP with coefficients of correlation R(2)> or =0.9967 for all initial MB concentrations studied. The results demonstrated that the JFP is very effective for the adsorption of methylene blue (MB) from aqueous solutions.     

A novel agricultural waste adsorbent for the removal of cationic dye from aqueous solutions

In this paper, pineapple stem (PS) waste, an agricultural waste available in large quantity in Malaysia, was utilized as low-cost adsorbent to remove basic dye (methylene blue, MB) from aqueous solution by adsorption. Batch mode experiments were conducted at 30 degrees C to study the effects of initial concentration of methylene blue, contact time and pH on dye adsorption. Equilibrium adsorption isotherms and kinetic were investigated. The experimental data were analyzed by the Langmuir and Freundlich models and the isotherm data fitted well to the Langmuir isotherm with monolayer adsorption capacity of 119.05mg/g. The kinetic data obtained at different concentrations were analyzed using a pseudo-first-order and pseudo-second-order equation and intraparticle diffusion equation. The experimental data fitted very well the pseudo-second-order kinetic model. The PS was found to be very effective adsorbent for MB adsorption.     

Enhancement of titania by doping rare earth for photodegradation of organic dye (Direct Blue)

Lanthanide ions (La³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, and Yb³⁺)/doped TiO₂ nanoparticles were successfully synthesized by sol–gel method. Their photocatalytic activities were evaluated using Direct Blue dye (DB53) as a decomposition objective. The structural features of TiO₂ and lanthanide ions/TiO₂ were investigated by XRD, SEM, UV-diffuse reflectance, and nitrogen adsorption measurements. Our findings indicated that XRD data characteristic anatase phase reflections and also XRD analysis showed that lanthanides phase was not observed on Lanthanide ions/TiO₂. The results indicated that Gd³⁺/TiO₂ has the lowest bandgap and particle size and also the highest surface area and pore volume (V_p) as well. Lanthanide ions can enhance the photocatalytic activity of TiO₂ to some extent as compared with pure TiO₂ and it was found that Gd³⁺/TiO₂ is the most effective photocatalyst. The photocatalytic tests indicate that at the optimum conditions; illumination time 40 min, pH ∼4, 0.3 g/L photocatalyst loading and 100 ppm DB53; the dye removal efficiency was 100%. Details of the synthesis procedure and results of the characterization studies of the produced lanthanide ions/TiO₂ are presented in this paper.     

Adsorptive removal of methylene blue by tea waste

The potentiality of tea waste for the adsorptive removal of methylene blue, a cationic dye, from aqueous solution was studied. Batch kinetics and isotherm studies were carried out under varying experimental conditions of contact time, initial methylene blue concentration, adsorbent dosage and pH. The nature of the possible adsorbent and methylene blue interactions was examined by the FTIR technique. The pH(pzc) of the adsorbent was estimated by titration method and a value of 4.3+/-0.2 was obtained. An adsorption-desorption study was carried out resulting the mechanism of adsorption was reversible and ion-exchange. Adsorption equilibrium of tea waste reached within 5h for methylene blue concentrations of 20-50mg/L. The sorption was analyzed using pseudo-first-order and pseudo-second order kinetic models and the sorption kinetics was found to follow a pseudo-second order kinetic model. The extent of the dye removal increased with increasing initial dye concentration. The equilibrium data in aqueous solutions were well represented by the Langmuir isotherm model. The adsorption capacity of methylene blue onto tea waste was found to be as high as 85.16mg/g, which is several folds higher than the adsorption capacity of a number of recently studied in the literature potential adsorbents. Tea waste appears as a very prospective adsorbent for the removal of methylene blue from aqueous solution.     

Removal of methylene blue from aqueous solution by adsorption onto pineapple leaf powder

The ability of an unconventional bio-adsorbent, pineapple leaf powder (PLP) for the adsorption of methylene blue (MB) from aqueous solution was studied. It was observed that intra-particle diffusion was involved in the adsorption process and that the kinetic data fitted well with a pseudo-second-order equation. Fitting parameters revealed that the rate of adsorption increased with decrease in dye concentration and decrease in ionic strength while the mixing speed did not have a significant effect on adsorption. The adsorption was favorable at higher pH and lower temperature, and the equilibrium data were well fitted by the Langmuir isotherm. The maximum adsorption capacity varied from 4.68 × 10⁻⁴ to 9.28 × 10⁻⁴ mol/g when pH increases from 3.5 to 9.5. Thermodynamic parameters suggest that the adsorption is a typical physical process, spontaneous, and exothermic in nature. The results revealed that this agricultural waste has potential to be used as an economical adsorbent for the removal of methylene blue from aqueous solution.