Hierarchical Bi2S3 nanoflowers: A novel photocatalyst for enhanced photocatalytic degradation of binary mixture of Rhodamine B and Methylene blue dyes and degradation of mixture of p-nitrophenol and p-chlorophenol

Hierarchical nanostructures of bismuth sulfide (Bi₂S₃) have been synthesized by a facile hydrothermal method. The potentiality of Bi₂S₃ hierarchical nanostructures for the photocatalytic degradation of Rhodamine B (RhB), Methylene blue (MB) and the mixture of RhB-MB organic dyes have been demonstrated and compared with commercial TiO₂ (Degussa P25) sample under visible light illumination. The degradation efficiency of Bi₂S₃ and Degussa P25 is found to be higher in the single as well as in the binary dye solution for MB degradation as compared to RhB degradation. Furthermore, the degradation rate of RhB and MB is enhanced by ～8 times and ～3 times in their binary solution as compared to that in single dye solution. Whereas, Bi₂S₃ has demonstrated ～14 times higher degradation rate of both RhB and MB in their binary solution than that of Degussa P25 for RhB and MB degradation in the binary solution under visible light exposure, respectively. Interestingly, Bi₂S₃ nanostructures has exhibited larger improvement in the degradation efficiency for RhB in its binary solution which is attributed to the faster separation of photogenerated charge carriers due to the proper alignments between the molecular orbits of dyes and band level positions of Bi₂S₃ in RhB-MB-Bi₂S₃ heterogenous system. The photocatalytic degradation study of colourless contaminants, p-chlorophenol (CP), p-nitrophenol (NP) and their mixture (CP-NP) is also investigated in the presence of Bi₂S₃ nanoflowers. Among the phenolic compounds, the degradation rate of NP is observed to be highest in the single solution. However, the degradation rate of both CP and NP is found to decrease in binary mixture solution in comparison to their individual solution. A possible mechanism for the enhanced photodegradation of RhB-MB dye mixture based on the active species trapping experiment has been proposed.     

Separation of aniline from aqueous solutions using emulsion liquid membranes

An emulsion liquid membrane process is developed to separate aniline from dilute aqueous solution. Aniline (amino-benzene) is a carcinogenic chemical common in industry and industrial wastewater. Due to aniline's high boiling point (183°C) and low concentration in wastewater, more traditional methods of separation such as distillation are very energy intensive. This emulsion process is offered as a low energy alternative. All separations occur in a Rushton stirred tank. The membrane phase consists of kerosene and the surfactant sorbitan monooleate (span 80). Hydrogen chloride solution is the internal phase. This study also examines the effects of HCl concentration, aniline concentration, and the amount of emulsion on separation. Up to 99.5% of the aniline is removed from solutions containing 5000 ppm in as little as 4 min depending on process conditions. Leakage is minimal and swelling is only about 3% after 5 min of processing. Approximately 98% of the membrane phase (both kerosene and span 80) is successfully recovered and recycled by using heat and/or adding 2-propanol for demulsification.     

Adsorption of Direct Red 80 dye from aqueous solution onto almond shells: effect of pH, initial concentration and shell type

The adsorption of Direct Red 80 (DR 80) dye from aqueous solution on almond shells as an eco-friendly and low-cost adsorbent was studied. The effect of shell type (internal, external and mixture shells), pH and initial dye concentration were considered to evaluate the sorption capacity of almond shell adsorbent. The mixture type of almond shell showed to be more effective. The adsorption studies revealed that the mixture type of almond shells remove about 97% of the DR 80 dye from aqueous phase after 1h of the adsorption process in a batch system. Although, pH changes did not appreciably affect the adsorption process but the maximum adsorption capacity of different types of almond shells (20.5, 16.96 and 16.4 mg/g for mixture, external and internal shells) were obtained at pH 2. However, in order to have a better control on the experimental conditions, pH 6 was selected for conducting all adsorption experiments. Initial dye concentration was varied from 50 to 150 mg/L. Higher concentrations of dye in aqueous solution reduced DR 80 dye adsorption efficiency of almond shells. Equilibrium data were attempted by various adsorption isotherms including Langmuir, Freundlich and Brunauer-Emmett-Teller (BET) models. It was found that the adsorption process by mixture type of almond shells follows the Langmuir non-linear isotherm. Furthermore, the experimental data by internal and external almond shells could be well described by the BET and Freundlich isotherm models, respectively. The pseudo-second-order kinetics provides the best correlation of the experimental data.     

Adsorption of basic dyes from single and binary component systems onto bentonite: simultaneous analysis of Basic Red 46 and Basic Yellow 28 by first order derivative spectrophotometric analysis method

The present study deals with the simultaneous analysis and adsorption of Basic Yellow 28 and Basic Red 46 dyes in binary mixture onto bentonite. First order derivative spectrophotometric method was used for simultaneous analysis of BY28 and BR46 in binary mixtures. The adsorption experiments were carried out in a batch system. The mono- and multi-component Langmuir and Freundlich isotherm models were applied to experimental data and the isotherm constants were calculated for BY28 and BR46 dyes. The monolayer coverage capacities of bentonite for BY28 and BR46 dyes in single solution system were found as 256.4 mg/g and 333.3mg/g, respectively. It was observed that the equilibrium uptake amounts of BY28 and BR46 dyes in binary mixture onto bentonite decreased considerably with increasing concentrations of the other dye resulting in their antagonistic effect. The adsorption equilibrium data fitted more adequately to mono-component Langmuir isotherm model than mono-component Freundlich isotherm model, while the extended Freundlich isotherm model adequately predicted the multi-component adsorption equilibrium data at moderate ranges of concentration. Thermodynamic parameters showed that adsorption of BR46 and BY28 was endothermic and spontaneous in nature.     

Extraction of Co(II) from aqueous solution using emulsion liquid membrane

The extraction equilibrium of Co(II) from thiocyanate medium by CYANEX 923 (mixture of straight chain alkylated phosphine oxides) in cyclohexane was studied. The stoichiometry of the extraction reaction was postulated based on slope analysis method and the extraction constant Kex was calculated. The stripping percentage of Co(II) with sulphuric acid from the loaded CYANEX 923 was found to increase with the increase in acid concentration. The extraction of Co(II) from aqueous thiocyanate medium into emulsion liquid membrane using CYANEX 923 extractant was also studied. The influence of different parameters such as stirring speed, surfactant concentration, pH of the extractant phase, carrier concentration, internal phase stripping acid concentration, initial Co(II) concentration as well as temperature on the emulsion stability were investigated. The applicability of the emulsion liquid membrane (ELM) process using CYANEX 923 as extractant and SPAN 80 as surfactant for the removal and the concentration of Co(II) from thiocyanate solution was investigated. The results show that it is possible to recover 95% of cobalt in the inner phase after 10 min of contacting time with a concentration factor of 5.     

Kinetics of the decoloration of reactive dyes over visible light-irradiated TiO(2) semiconductor photocatalyst

Photocatalytic decoloration kinetics of triazine (Reactive Red 11, Reactive Red 2, and Reactive Orange 84) and vinylsulfone type (Reactive Orange 16 and Reactive Black 5) of reactive dyes have been studied spectrophotometrically by following the decrease in dye concentration with time. At ambient conditions, over 90-95% decoloration of above dyes have been observed upon prolonged illumination (15 h) of the reacting system with a 150 W xenon lamp. It was found that the decoloration reaction followed first-order kinetics. The values of observed rate constants were found to be dependent of the structure of dyes at low dye concentration, but independent at higher concentration. It also reports for the first time the decoloration of two different dyes together in a binary dye mixture using visible light-irradiated TiO(2) photocatalyst. Rate of decoloration of two different dyes together in a binary dye mixture using visible light-irradiated TiO(2) photocatalyst is governed by the adsorptivity of the particular dye onto the surface of the TiO(2) photocatalyst.     

Synthesis of biosurfactant‐coated magnesium oxide nanoparticles for methylene blue removal and selective Pb2+ sensing

Dyes and lead (Pb²⁺) are toxic compounds that can contaminant water. In this study, magnesium oxide (MgO) nanoparticles (NPs) prepared using clove, i.e. Syzygium aromaticum extract [clove extract (CE)] were used for methylene blue (MB) removal and Pb²⁺ ion sensing in aqueous solution. Maximum 90% MB removal was achieved using MgO NPs. The MB adsorption on MgO NPs surface followed second‐order kinetics and Langmuir isotherm. MB dye was adsorbed as a monolayer on the surface of MgO NPs with maximum adsorption capacity, 5555 mg g⁻¹. MgO NPs were also able to selectively detect lead (Pb²⁺) in 1 nM–200 µM range with 24 µM (3σ) limit of detection. So, CE prepared MgO NPs are useful for MB dye adsorption and metal ion sensing applications.Inspec keywords: magnesium compounds, nanoparticles, dyes, lead, chemical sensors, adsorptionOther keywords: biosurfactant‐coated magnesium oxide nanoparticles, methylene blue removal, selective lead sensing, dyes, toxic compounds, Syzygium aromaticum extract, clove extract, MB adsorption, second‐order kinetics, Langmuir isotherm, maximum adsorption capacity, MgO, Pb²⁺      

Kinetics of adsorption of dyes from aqueous solution using activated carbon prepared from waste apricot

Adsorbent (WA11Zn5) has been prepared from waste apricot by chemical activation with ZnCl(2). Pore properties of the activated carbon such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by N(2) adsorption and DFT plus software. Adsorption of three dyes, namely, Methylene Blue (MB), Malachite Green (MG), Crystal Violet (CV), onto activated carbon in aqueous solution was studied in a batch system with respect to contact time, temperature. The kinetics of adsorption of MB, MG and CV have been discussed using six kinetic models, i.e., the pseudo-first-order model, the pseudo-second-order model, the Elovich equation, the intraparticle diffusion model, the Bangham equation, the modified Freundlich equation. Kinetic parameters and correlation coefficients were determined. It was shown that the second-order kinetic equation could describe the adsorption kinetics for three dyes. The dyes uptake process was found to be controlled by external mass transfer at earlier stages (before 5 min) and by intraparticle diffusion at later stages (after 5 min). Thermodynamic parameters, such as DeltaG, DeltaH and DeltaS, have been calculated by using the thermodynamic equilibrium coefficient obtained at different temperatures and concentrations. The thermodynamics of dyes-WA11Zn5 system indicates endothermic process.     

Adsorption kinetics and isotherm of anionic dyes onto organo-bentonite from single and multisolute systems

The performances of polydiallydimethylammonium modified bentonite (PDADMA–bentonite) as an adsorbent to remove anionic dyes, namely Acid Scarlet GR (AS-GR), Acid Turquoise Blue 2G (ATB-2G) and Indigo Carmine (IC), were investigated in single, binary and ternary dye systems. In adsorption from single dye solutions with initial concentration of 100 μmol/L, the dosage of PDADMA–bentonite needed to remove 95% dye was 0.42, 0.68 and 0.75 g/L for AS-GR, ATB-2G and IC, respectively. The adsorption isotherms of the three dyes obeyed the Langmuir isotherm model with the equilibrium constants of 0.372, 0.629 and 4.31 L/μmol, the saturation adsorption amount of 176.3, 149.2 and 228.7 μmol/g for ATB-2G, IC and AS-GR, respectively. In adsorption from mixed dye solutions, the isotherm of each individual dye followed an expanded Langmuir isotherm model and the relationship between the total amount of dyes adsorbed and the total equilibrium dye concentration was interpreted well by Langmuir isotherm model. In the region of insufficient dosage of PDADMA–bentonite, the dye with a larger affinity was preferentially removed by adsorption. Desorption was observed in the kinetic curve of the dye with lower affinity on PDADMA–bentonite surface by the competitive adsorption. The kinetics in single dye solution and the total adsorption of dyes in binary and ternary dye systems nicely followed pseudo-second-order kinetic model.     

液膜法萃取青霉素的研究

介绍了乳状液膜法萃取模拟发酵液中青素的研究工作，考究了混合槽中液膜组成、试剂比、油内比、乳水比及外水相ＰＨ变化对传质过程的影响，找出了一个较为适宜的液膜组成及室浊下适宜操作的萃取工艺条件。     

Decolorization of adsorbed textile dyes by developed consortium of Pseudomonas sp. SUK1 and Aspergillus ochraceus NCIM-1146 under solid state fermentation

The objective of this study was to develop consortium using Pseudomonas sp. SUK1 and Aspergillus ochraceus NCIM-1146 to decolorize adsorbed dyes from textile effluent wastewater under solid state fermentation. Among various agricultural wastes rice bran showed dye adsorption up to 90, 62 and 80% from textile dye reactive navy blue HE2R (RNB HE2R) solution, mixture of textile dyes and textile industry wastewater, respectively. Pseudomonas sp. SUK1 and A. ochraceus NCIM-1146 showed 62 and 38% decolorization of RNB HE2R adsorbed on rice bran in 24h under solid state fermentation. However, the consortium of Pseudomonas sp. SUK1 and A. ochraceus NCIM-1146 (consortium-PA) showed 80% decolorization in 24h. The consortium-PA showed effective ADMI removal ratio of adsorbed dyes from textile industry wastewater (77%), mixture of textile dyes (82%) and chemical precipitate of textile dye effluent (CPTDE) (86%). Secretion of extracellular enzymes such as laccase, azoreductase, tyrosinase and NADH-DCIP reductase and their significant induction in the presence of adsorbed dye suggests their role in the decolorization of RNB HE2R. GCMS and HPLC analysis of product suggests the different fates of biodegradation of RNB HE2R when used Pseudomonas sp. SUK1, A. ochraceus NCIM-1146 and consortium PA.     

乳状液膜法提取赖氨酸

研究了用乳状液膜法提取赖氨酸的液膜配方及一些重要操作参数 ,初步得出了既能相对减少溶胀 ,又能保持较高分离效率的膜组成及最佳工艺条件 .赖氨酸提取的液膜组成为 :载体二 - (2 -乙基己基 )磷酸脂 7% (质量分数 ) ,表面活性剂 (Span - 80 ) 5 % (质量分数 ) ,膜溶剂 5 0 % (体积分数 )液体石蜡和 5 0 %煤油 .内相选用 0 .5mol/L的HCl溶液 ,处理比为 3.75 ,提取率可达 72 .6 %     

Absorbents based on maleic anhydride-modified cellulose fibers/diatomite for dye removal

In this work, an absorbent consisting of the maleic anhydride-modified cellulose beads combined with alkali-treated diatomite (MCDBs) was prepared in an attempt to remove basic dyes. An appropriate amount of calcium carbonate was added during the formation of MCDBs to increase the pore structure under an acidic condition. The synthesized MCDBs were characterized with FT-IR, TGA, and BET. The degree of carboxylation of MCDBs was quantified using a polyelectrolyte titration method. The removal of basic dyes such as methylene blue (MB) and methyl violet (MV) from aqueous solution was systematically investigated. The influence of pH, shaking time, and temperature on the removal process was identified. The results indicated that the MCDBs had a strong adsorption capacity toward basic dyes. The adsorption capacity increased from 51.6 to 116.6 mg/g for MB, depending on the initial concentration of the dye. A similar trend was also found for MV, i.e., adsorption increased from 30.5 to 61.1 mg/g. The experimental data fitted two kinetic models; the results demonstrated that the adsorption of MB and MV onto the MCDBs fits the pseudo-second-order model very well. The removal efficiencies of the basic dyes under the optimal conditions were up to 97.5 %. The adsorption data were also fitted using Langmuir, Freundlich, and Temkin isotherms, separately. It was found that the adsorption process for the basic dyes was better described by the Langmuir isotherm model.     

浓乳液快速聚合方法制备丙烯腈/丙烯酸丁酯共聚物

研究了丙烯腈／丙烯酸丁酯的浓乳液快速聚合，在绝热环境下反应30min后的单体转化率可达80％。通过研究乳液浓度、共单体的组成与引发剂的组成对反应转化率与共聚物的组成等的影响，确定出一种极性烯烃单体的节能、快速的新型聚合方法。     

Extraction and recovery of methylene blue from industrial wastewater using benzoic acid as an extractant

Liquid-liquid extraction (LLE) of methylene blue (MB) from industrial wastewater using benzoic acid (extractant) in xylene has been studied at 27 degrees C. The extraction of the dye increased with increasing extractant concentration. The extraction abilities have been studied on benzoic acid concentration in the range of 0.36-5.8x10(-2) M. The distribution ratio of the dye is reasonably high (D=49.5) even in the presence of inorganic salts. Irrespective of the concentration of dye, extraction under optimal conditions was 90-99% after 15 min of phase separation. The extracted dye in the organic phase can be back extracted into sulphuric acid solution. The resultant recovered organic phase can be reused in succeeding extraction of dye with the yield ranging from 99 to 87% after 15 times reused, depending on the concentration of the initial feed solution. Experimental parameters examined were benzoic acid concentration, effect of diluent, effect of pH, effect of initial dye concentration, effect of equilibration time, various stripping agents, aqueous to organic phase ratio in extraction, organic to aqueous phase ratio in stripping and reusability of solvent.     

TiO2共混丝朊接枝聚丙烯腈过滤膜制备及性能研究

针对传统高分子过滤膜使用有机溶剂易造成环境污染的问题,以氯化锌水溶液为溶剂,丝朊均相接枝聚丙烯腈,加入纳米TiO2得到铸模液,以水为凝固浴,制备TiO2共混的丝朊接枝聚丙烯腈(SF-g-PAN/TiO2)过滤膜。通过扫描电子显微镜,红外光谱等方法对膜进行表征,研究不同TiO2含量的SF-g-PAN过滤膜的亲水性、抗污染性能、力学性能以及SF-g-PAN/TiO2膜对不同分子量染料的截留。结果表明:随着TiO2含量的增加,膜的力学强度先增大后减小。TiO2含量为1%(质量分数)时,膜的力学和抗污染性能最好;在0.10 MPa下,SF-g-PAN/TiO2膜对于分子量大于660的染料截留率为96%以上,通量达到80 L/(m^2·h)。     

Adsorption of dyes on Sahara desert sand

Sahara desert sand (SaDeS) was employed as a mineral sorbent for retaining organic dyes from aqueous solutions. Natural sand has demonstrated a strong affinity for organic dyes but significantly lost its adsorption capacity when it was washed with water. Therefore, characterization of both natural and water washed sand was performed by XRD, BET, SEM and FTIR techniques. It was found that water-soluble kyanite, which is detected in natural sand, is the dominant factor affecting adsorbance of cationic dyes. The sand adsorbs over 75% of cationic dyes but less than 21% for anionic ones. Among the dyes studied, Methylene Blue (MB) demonstrated the strongest affinity for Sahara desert sand (Q_e = 11.98 mg/g, for initial dye solution concentration 3.5 × 10⁻⁵ mol/L). The effects of initial dye concentration, the amount of the adsorbent, the temperature and the pH of the solution on adsorption capacity were tested by using Methylene Blue as model dye. Pseudo-first-order, pseudo-second-order and intraparticle diffusion models were applied. It was concluded that adsorption of Methylene Blue on Sahara desert sand followed pseudo-second order kinetics. Gibbs free energy, enthalpy change and entropy change were calculated and found −6411 J/mol, −30360 J/mol and −76.58 J/mol K, respectively. These values indicate that the adsorption is an exothermic process and has a spontaneous nature at low temperatures.     

Removal of phenols from aqueous solutions by emulsion liquid membranes

The present study deals with the extraction of phenols from aqueous solutions by using the emulsion liquid membranes technique. Besides phenol, two derivatives of phenol, i.e., tyrosol (2-(4-hydroxyphenyl)ethanol) and p-coumaric acid (4-hydroxycinnamic acid), which are typical components of the effluents produced in olive oil plants, were selected as the target solutes. The effect of the composition of the organic phase on the removal of solutes was examined. The influence of pH of feed phase on the extraction of tyrosol and p-coumaric was tested for the membrane with Cyanex 923 as an extractant. The use of 2% Cyanex 923 allowed obtaining a very high extraction of phenols (97-99%) in 5-6 min of contact time for either single solute solutions or for their mixtures. The removal efficiency of phenol and p-coumaric acid attained equivalent values by using the system with 2% isodecanol, but the removal rate of tyrosol was found greatly reduced. The extraction of tyrosol and p-coumaric acid from their binary mixture was also analysed for different operating conditions like the volume ratio of feed phase to stripping phase (sodium hydroxide), the temperature and the initial concentration of solute in the feed phase.     

Preparation of hemicellulose-containing latex and its application as absorbent toward dyes

The removal of hazardous dyes from process water has become one of the most important tasks for water clarification. In this work, a novel type of latex, prepared by the emulsion polymerization of butyl acrylate (BA) and acrylamide (AM) in the presence of hemicellulose, was developed. Under the optimal polymerization conditions, the conversion of monomers reached as high as 97.6 %. The resulting hemicellulose-containing latex (HCL) was assessed as an absorbent toward dyes, methylene blue (MB) in particular. Much effort was made to revealing the impact of adsorption conditions of the dye removal induced by HCL. The maximum removal of the dye by HCL was about 93.8 %, much higher than that of the control sample. The dye adsorption isotherm was determined to further understand the adsorption mechanism. The adsorption data were found to fit Langmuir model well (R ²=0.99904). The maximum adsorption capacity obtained at 25 °C was 42.7 mg g^?1, suggesting that the HCL is promising as an excellent absorbent for the removal of dyes from effluents.     

Tailoring of 2D MoS2 microspheres on 3D low-cost DE for the efficient removal of hazardous cationic dyes

The primary challenge involved in the water treatment field is to treat/clean the contaminated waste dye solutions before it releases into the environment. Industrial contaminant such as dyes are released into water streams, rendering the water unfit for further use. Treatment of such dye contaminants is still a challenging tasks that has evolved as one of the leading issues in environmental remediation. Some of the significant limitations in dye adsorption include time-consuming, synthetic routes, expensive adsorbents, more contact time, less adsorption performances and use of more adsorbents. To address such problems, herein in this work, 2D MoS₂ molybdenum disulfide)-3D DE (diatomaceous earth) hybrid materials were synthesized by a facile and efficient hydrothermal route. The prepared innovative combination of 2D & 3D porous hybrid materials demonstrated to be efficient adsorbents for the efficient removal of malachite green (MG) dye from aqueous solution with superior 97 % removal efficiency within 5 mins and with an extended 60 mins of contact time possible to achieve 99.9 % of removal efficiency. Furthermore, the maximum adsorption capacity for DE was only 0.78 mg/g and developed 2D MoS₂-3D DE exhibited an outstanding 110 mg/g for MB dye which is a significant improvement when compared to pristine DE. On the other hand, the 2D MoS₂-3D DE was explored as a membrane-based filter for the removal of other important cationic pollutant methylene blue (MB) dye which showed 100 % rejection for varied MB volumes from 50 to 200 mL with average flux rate of 2200 L.m^?2.h^?1. Additionally, the 2D-3D hybrid adsorbents substantiated with better recyclability with up to 5 cycle performances which could be an excellent candidate for the removal of industrially important cationic dyes in the future.