Search

Due to the amphiphilic structure of surfactants, aqueous surfactant solutions can behave like very good solvents and dissolve both polar and non-polar solutes. This study reports on the solubilisation of a direct dye (Direct Blue 86) in a micellar medium using the cationic surfactant cetyltrimethylammonium bromide (CTAB). Solubilisation of dyes is important for their subsequent removal from aqueous media. UV spectroscopy and conductometry, among others, were used to quantitatively evaluate this process. The extent of solubilisation, the interaction between the molecules and the stability of the processes were checked using the partition coefficient (K x), the binding constant (K b) and the corresponding thermodynamic parameters. From the results, it could be concluded that the solubilisation of Direct Blue 86 is a spontaneous process supported by an increase in entropy. It was also found that the micellar medium CTAB is efficient for solubilisation and binding of the dye and can be used economically.

This study reports the fabrication of Fe2O3, Bi2O3, and BiFeO3, characterization and evaluation of the photocatalytic performances for methylene blue dye degradation. The materials were synthesized by precipitation method and characterized by scanning electron microscopy, X-ray diffraction, energy dispersive X-rays analyses, and Fourier transform infrared analyses. The photocatalytic activities of Fe2O3, Bi2O3, and BiFeO3 were compared by performing degradation experiments with 50 mL of 100 mg/L methylene blue solution. The as-prepared BiFeO3 was found as 2.4 times and 1.7 times more effective than Fe2O3 and Bi2O3, with a 79, 47, and 57% catalytic activity, respectively. The degradation of methylene blue over the BiFeO3 catalyst was optimized in terms of pH, catalyst dosage, temperature, and methylene blue concentration. The Eley–Rideal mechanism was proposed to describe the reaction kinetics in terms of the first order and second order kinetics model. Activation energy E (kJ/mol), enthalpy ΔH (kJ/mol), entropy ΔS (J/mol) and free energy ΔG (kJ/mol) were calculated as 20.8, 18.2, 197.5 and −45.3 respectively. The negative value of free energy shows that photodegradation is favored in present conditions.

The gamma ray induced degradation of moxifloxacin in aqueous media has been evaluated. The drug solutions (50 & 100 mg/L) were irradiated to absorbed doses of 0.3, 0.6, 0.9, 1.2, 1.5, 2, 3 and 4 kGy using Cs-137 gamma radiation source. The parameters such as drug initial concentration, oxidant (H2O2) concentration and gamma ray absorbed doses were optimized. The efficiency of Advanced oxidation processes (AOP) was evaluated on the basis of degradation, reduction in chemical oxygen demand (COD) and toxicity reduction of the drug. The maximum degradation of 94.01 and 88.30% was achieved when drug solutions were exposed to gamma irradiation absorbed dose of 4 kGy which enhanced to 100 and 99.06% in the presence of H2O2 (0.5 mL/L) for 50 and 100 mg/L respectively. A significant reduction in COD 72 and 75% for 50 mg/L while 65 and 69% in case of 100 mg/L was noted using gamma and gamma/H2O2 respectively at absorbed dose of 4 kGy. The parameters such as dose constant (k), removal efficiency (G-value), gamma ray absorbed doses required for 50, 90 and 99% degradation (D 0.50, D 0.90 and D 0.99) have been calculated. The radiolytic degradation was monitored by UV–Vis spectrophotometer and HPLC, FT-IR studies were performed to investigate the change in functional groups before and after treatment, while GC-MS analysis was carried out to monitor intermediates/degraded end-products. The FT-IR spectra has shown complete destruction of aromatic rings after radiation treatment but a minor peak appeared at 1216 cm−1 corresponding to CO stretching. The GC-MS study for the drug samples treated with gamma/H2O2 has shown no any significant peak which confirms the complete degradation. The cytotoxicity of treated samples was carried out by hemolytic assay and mutagenicity using Ames test before and after each treatment. The hemolytic test showed 73.92% hemolysis, while gamma/H2O2 treatment reduced the mutagenicity to 74.08 and 65.66% against TA98 and TA100 bacterial strains respectively. The response surface methodology (RSM) was employed to optimize the data. The obtained data elaborate that gamma/H2O2process is promising approach for the remediation of pharmaceutical waste effluent.

In this study, Co3O4and Ag-Co3O4were synthesized by a novel and green method using leaves extract ofHelianthus annuusfrom cobalt nitrate and silver nitrate. The synthesized particles were characterized using X-ray powder diffraction, thermal gravimetric analyses, scanning electron microscopy, particle size analyses and UV-Visible spectroscopy. The photo catalytic activities of synthesized Co3O4and Ag-Co3O4were appraised by degrading methyl orange dye and after 120 minutes of reaction a degradation of 53 and 87% was achieved using 100 mg/L (50 mL) solution of methyl orange and 0.1 g Co3O4and Ag-Co3O4as catalyst respectively. This green synthesis of Ag-Co3O4proves to be an eco-benign, environmental benign, simple and effective approach for degradation of dyes in aqueous medium.

Photo catalytic degradation of pollutants is one of the techniques used for treatment of dye contaminated wastewater. TiO2 has attracted much attention as photo catalyst for treatment of contaminated water. In this study, the photo catalytic performance of TiO2 has been enhanced by formation of p–n Co3O4-TiO2 hetero-junction. The p–n Co3O4-TiO2 hetero-junction was prepared by wet incipient impregnation method and characterized by various techniques. The photo catalytic activity of prepared composite was evaluated by photo degradation of methyl orange. The as prepared Co3O4-TiO2 composite was found as effective catalyst than Co3O4 and TiO2. The higher photo catalytic activity was attributed to p–n junction formed between Co3O4 and TiO2. The degradation data was analyzed according to Eley–Rideal mechanism in terms of 1st and 2nd order kinetics.

The presence of heavy metals in water causes serious problems and their treatment before incorporating into the water body is a challenge for researchers. The present study was conducted to compare the sorption study of Ni (II) using silica gel, amberlite IR-120 and sawdust of mulberry wood in batch system under the influence of pH, initial Ni (II) concentration and contact time. It was observed that sorption process was depending upon pH and maximum sorption was achieved at pH 7.0. Kinetic data were well fitted into pseudo-second order kinetic model due to high R2 values and closeness of experimental sorption capacity and calculated sorption capacity of pseudo-second order. Isotherms study showed that Langmuir is one of the most suitable choices to explain sorption data due to high R2 values. The monolayer sorption capacities of silica gel, amberlite IR-120 and sawdust were found to be 33.33, 25.19, and 33.67 mg g−1, respectively. Desorption study revealed that NaCl is one of the most appropriate desorbent. It may be concluded from this study that sawdust is a suitable sorbent due to low cost, abundant availability and recycling of the materials for further study.

The plants assisted green synthesis of nanoparticles have drawn a momentous importance worldwide. NiO is one the metal oxides researched comprehensively for decades and still has dominance in the field of photo-catalysis. In present study NiO and Ag–NiO were successfully prepared by a simple and environmentally friendly method using nickel nitrate, silver nitrate and leaves extract of Azadirachta indica L. plant as precursor materials. The prepared materials were characterized by XRD, SEM and TGA. Then the photo-catalytic efficiency of NiO and Ag–NiO were evaluated by aqueous phase photo-degradation of rhodamine B as a model pollutant under ultraviolet irradiations. About 40% and 96% of 200 mg/L (50 mL) degraded in 120 min at 40 °C over NiO and Ag–NiO as photo-catalyst respectively. The apparent rate constants were determined as 0.0109, 0.0165, 0.0175 and 0.0190 per min at 30, 40, 50 and 60 °C respectively. 14.6 kJ/mol was calculated as activation energy of reaction.

This manuscript reports the solubilization of two reactive dyes viz. reactive black-5 (RB-5) and reactive black-8 (RB-8) in the micellar media of cationic surfactant, cetyl trimethylammonium bromide (CTAB) by differential UV/visible spectroscopy. Absorption spectra of said dyes in the presence of CTAB provide strong evidence about dye–surfactant interaction. In premicellar region ion association pair is formed between dye and surfactant while in post micellar region dye molecules get accommodated within the micelles. The values of critical micelle concentration (CMC) of CTAB in the presence of dyes, partition coefficient; Kx , free energy of partition, ∆Gp , binding constant, Kb and free energy of binding, ∆Gb were determined and compared for both dyes. It is, thus, concluded that RB-5 is solubilized to greater extent than RB-8 because of its incorporation in palisade layer of micelle close to micelle-water interface.

We herein report the synthesis of zinc oxide and evaluation of its catalytic performance for degradation of Rhodamine B dye in aqueous medium. Sodium hydroxide and zinc acetate dihydrate were used as precursor materials for synthesis of zinc oxide catalyst. X-ray difractometry, Fourier transform infer red spectroscopy, scanning electron microscopy, thermogravimetric and surface area analyses were used as characterization techniques. Catalytic performance of prepared zinc oxide was evaluated for degradation of Rhodamine B dye in aqueous medium. Catalytic degradation of dye was taking place according to Eley-Rideal mechanism which states that oxygen adsorbed at the surface of ZnO reacts with dye in fluid phase. During the reaction, reactive radicals are formed as a result of electron-hole pair formation between conduction and valence band of zinc oxide catalyst which degrade the dye into water and carbon dioxide.

This study explores the lab prepared nickel hydroxide catalyzed oxidative degradation of Methylene Blue (MB) in aqueous medium using batch reactor. Nickel hydroxide was prepared by reaction of sodium hypochlorite, sodium hydroxide and nickel sulphate hexahydrate in distilled water. The catalytic oxidative degradation of Methylene Blue was explored in terms of various parameters like effect of time, hydrogen peroxide, temperature, initial concentration of dye, catalyst dosage and effect of speed of agitation on degradation of Methylene Blue. Experimental data was subjected to kinetics analysis using Curve Expert software. Degradation reaction was taking place according to Langmuir-Hinshelwood mechanism. According to this mechanism the reactants adsorb at the surface of catalyst in first step followed by chemical reaction between adsorbed reactants in second step. Catalyst was heterogeneous in nature which was separated by simple filtration easily.

A low cost and environment-friendly agriculture waste material, orange peel, was investigated for the removal and accumulation of Pb(II) from water and wastewater. Orange peel treated with acid (AOP) as well as converted into carbon (COP) and the effect of various parameters on biosorption of Pb(II) on AOP and COP was studied. The biosorption of Pb(II) was found to be pH dependant in both cases and maximum biosorption of Pb(II) (100 %) on AOP was achieved at pH 6 and 60 min shaking time while using COP the maximum biosorption (100 %) was obtained at pH 5.5 and 80 min contact time. The monolayer biosorption capacities of AOP and COP were found to be 1 040 mg g−1 and 993 mg g−1 using Langmuir isotherm at room temperature respectively. Similarly Freundlich empirical constants, KF and n obtained for Pb(II) on AOP and on COP were 0.453 L g−1, 1.90 and 0.334 L g−1, 2.51 respectively. For the kinetic study of biosorption of Pb(II) on AOP and COP pseudo-first-order and pseudo-second-order intraparticle d...