海泡石对有机染料的吸附行为研究

以热酸活化过的海泡石为吸附剂,研究其对亚甲基蓝、结晶紫和甲基绿3种染料的吸附动力学过程,并分析了浓度、温度等因素对海泡石吸附效果的影响。结果表明,温度的变化对吸附的影响较小,而染料溶液浓度的改变则会对吸附产生很大的影响,由此确定出较适合的反应条件。采用傅立叶红外光谱技术对吸附前后海泡石的结构进行了分析,发现亚甲基蓝由于分子体积较小可以进入海泡石内部通道,而大体积的结晶紫和甲基绿的吸附主要发生在海泡石外表面,且一价有机阳离子会在中性位置发生吸附,形成带电或中性复合物。     

微生物电化学体系中金红石可见光还原降解偶氮染料的实验研究

利用双室微生物电化学装置对微生物和半导体矿物协同作用下偶氮类染料废水的还原脱色降解进行了系统的实验研究.不同光照条件及不同阴极电极材料的对比实验结果显示,偶氮染料甲基橙(MO)可作为终端电子受体直接从固体电极上获得电子被还原脱色;各对比实验中,在微生物催化与半导体矿物光催化协同作用条件下,MO还原脱色效率最高.电化学交流阻抗谱(EIS)的拟合结果显示金红石涂布阴极电极光照下极化内阻(Rp)为443.4 Ω,较无光条件下的1378 Ω显著降低,证明光照下金红石阴极的电子转移过程受其光催化作用的驱动.不同初始浓度下MO的生物-半导体催化还原反应符合准一级动力学模型,其反应速率随MO初始浓度降低而增加.通过对脱色产物的进一步分析,推测该实验中MO的还原脱色反应机制为: 阳极初始电子供体在微生物的催化作用下将电子通过阳极电极和外电路传递给阴极半导体矿物电极,进而在半导体矿物的光催化作用下通过光生电子还原终端电子受体MO,使MO中的偶氮键断裂,生成无色的联氨类衍生物.     

Adsorption Performance and Mechanism in Binding of Azo Dye by Raw Bentonite

The adsorption behavior of methyl orange (MO) from aqueous solution onto raw bentonite (RB) sample was investigated as a function of parameters such as pH, inorganic anion, contact time, and temperature. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. Langmuir adsorption capacity was found to be 34.34 mg/g at pH 4.0. The pseudo‐first‐order, pseudo‐second‐order kinetic, and the intra‐particle diffusion models were used to describe the kinetic data. The values of the energy (E_a), enthalpy (ΔH^≠), and entropy of activation (ΔS^≠) were calculated as 38.62 kJ/mol, 36.04 kJ/mol, and ?150.05 J/mol K, respectively, at pH 4.0.     

Decolorization of Textile Azo‐metal Complex Dyes by a Halophilic Bacterium Isolated from Çamaltı Saltern in Turkey

The decolorization of some of azo‐metal complex dyes used in textile industry was investigated in this study. The halophilic prokaryotes isolated from a solar sea‐saltern (Çamalt?) in Turkey were screened for resistance to five commercial azo and mixture of azo‐metal complex dyes. Only one bacterium was found to be resistant against two of dyes, namely Lanaset Navy R and Lanaset Brown B. The bacterium was identified as Halobacillus sp. C‐22 according to 16S rRNA gene sequence analyses. Decolorization experiments were carried out at 120 mg/L concentration of both dyes, at room temperature, and with an acidic pH of 4.5. Lanaset Brown B was decolorized at a high adsorbance ratio (96.12%) at the 78th hour. However, Lanaset Navy R was rapidly decolorized in 10 min (46.67%) and showed the highest adsorbance ratio (60.66%) at the third hour. Freundlich and Langmuir equilibrium isotherm models were used to evaluate the adsorption of dyes and Freundlich isoterm was more suitable for biosorpsiyon of both azo dyes. The functional groups on Halobacillus sp. C‐22 for decolorization were characterized by FT‐IR. This is the first study to reveal potential of Halobacillus sp. for decolorization of textile azo‐metal complex dyes.     

Statistical Optimization of Anaerobic Biological Processes for Dye Treatment

In the present study both the synthetic media composition as well as some process parameters in the anaerobic decolorization of Reactive Black 5 (RB5) by activated sludge were studied and optimized using statistical design of experiments (DOEs). Statistical analysis of the results of Plackett–Burman DOE showed that the addition of Mn or Fe, or increase in concentration of Mg, had a positive effect on the anaerobic decolorization efficiency whereas the effect of increase in concentration of glucose, ammonium chloride, and calcium chloride was negative. The effect of change in the concentration of glucose, mixed liquor suspended solid (MLSS), and RB5 on the anaerobic decolorization efficiency and rate and chemical oxygen demand (COD) removal was studied using central composite design methodology. Statistical analysis of the data showed that all the factors had significant effect on both the dye decolorization efficiency and rate. The interaction of glucose with MLSS and with dye and the interaction of MLSS with glucose and with dye were significant when the response was decolorization efficiency and rate, respectively. When COD removal was the response, the effect of change in glucose and MLSS concentration and the interaction between these two factors had statistically significant effect on the response.     

Dye Removal from Colored Textile Wastewater by Poly(propylene imine) Dendrimer: Operational Parameters and Isotherm Studies

This paper deals with the removal of textile dyes from aqueous solutions by poly(propylene imine) dendrimer (PPI). Direct red 80 (DR80), Acid Green 25 (AG25), Acid Blue 7 (AB7), and Direct Red 23 (DR23) were used as model dyes. The effects of operational parameters on dye removal such as dendrimer concentration, dye concentration, salt (inorganic anions), and pH have been studied at 25°C. The Langmuir and Freundlich isotherm models were investigated. In addition, dye desorption of dendrimer was studied. The results indicated that acidic pH supported the adsorption of dyes by dendrimer. Furthermore studies of dye concentration and salt effects exhibited that dye removal percentage by dendrimer was decreased. It was found that the isotherm data of DR80, AG25, and DR23 followed Langmuir isotherm and isotherm data of AB7 followed Freundlich isotherm models. Desorption tests showed that maximum dye releasing of 76.5% for DR80, 84.5% for AG25, 87% for AB7, and 93% for DR23 were achieved in aqueous solution at pH 12. Based on the data of present study, one could conclude that the dendrimer being an environmentally friendly adsorbent with relatively large adsorption capacity might be a suitable alternative for elimination of dyes from colored textile wastewater.