Adsorption of Methylene Blue on Poly (Methacrylic Acid) Modified Chitosan and Photocatalytic Regeneration of the Adsorbent

The preparation of poly(methacrylic acid) modified chitosan microspheres (PMAA-GLA-CTS) and its application for the removal of cationic dye, methylene blue (MB), in aqueous solution in a batch system were described. The modified chitosan was characterized using FTIR and XPS analysis. The effects of the pH of the solution, contact time, and initial dye concentration were studied. The adsorption capacity of the microspheres for MB increased significantly after the modification as a large number of carboxyl groups were introduced. The equilibrium process was better described by the Langmuir rather than the Freundlich isotherm. According to the Langmuir equation, the maximum adsorption capacity was 1 g · g^?1 for MB. Kinetic studies showed better correlation coefficients for a pseudo-second-order kinetic model, confirming that the sorption rate was controlled by a chemisorption process. Photocatalytic regeneration of spent PMAA-GLA-CTS using UV/TiO₂ is effective. Further, the regenerated PMAA-GLA-CTS exhibits 90% efficiency for a subsequent adsorption cycle with MB aqueous solutions.     

Removal of Methylene Blue from Aqueous Solutions by using Cold Plasma,Microwave Radiation and Formaldehyde Treated Acorn Shell

In this paper, cold plasma (CPTAS), formaldehyde (FTAS), and microwave radiation treated (MTAS) acorn shell obtained from Quercus petraea tree as biosorbent was characterized and its dye removal ability at different dye concentrations was studied. The isoelectric point, functional groups and morphology of acorn shell was investigated as adsorbent surface characteristics. Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and UV–Vis spectrophotometry were used. Methylene blue (MB) was used as model cationic dye. The Langmuir and Freundlich adsorption isotherm models were applied to describe the equilibrium isotherms. The results indicated that the data for adsorption of MB onto treated acorn shell fitted well with the Langmuir isotherm model. Comparison of adsorption capacities of CPTAS with FTAS has shown a significant increase by as much as about 30 mg/g (33.32%) in MB adsorption.The pseudo-first order, pseudo-second order kinetic models were examined to evaluate the kinetic data, and the rate constants were calculated. Adsorption kinetic of dyes followed pseudo-first order kinetics. Thermodynamic parameters such as free energy, enthalpy, and entropy of dye adsorption were obtained. The results indicated that acorn shell could be used as a natural biosorbent for the removal of cationic dyes.     

Kinetic Modeling Study on Methylene Blue Sorption onto Agave americana fibers: Fractal Kinetics and Regeneration Studies

Kinetics sorption study was carried out with varying pH, concentration, and temperature to determine the potential of Agave americana fiber for the removal of methylene blue. The thermodynamic properties (ΔG°, ΔH° and ΔS°) were determined. In order to investigate the sorption mechanisms, kinetic parameters were determined using the Lagergren, the pseudo-second order and the recently established fractal kinetic equations. The experimental kinetics data have been fitted with the non linear form of the new Brouers sotolongo kinetic model. Fractal kinetic equation gives higher correlation coefficients, indicating that this model can be considered accurate for describing the sorption methylene blue kinetics.     

Competitive Adsorption of Basic Dyes onto Calcite in Single and Binary Component Systems

Equilibrium and kinetic behavior of two basic dyes, Methylene Blue (MB) and Safranine T (ST), onto calcite in single and binary component systems have been studied. Experimental equilibrium results have been well predicted by the Freundlich and the Langmuir isotherm models. The model parameters obtained for single solute systems at 298 K have been used for the calculation of adsorption isotherms in binary dye solutions using multi-component isotherm models. Extended Freundlich and extended Langmuir models satisfactorily fit to MB–ST adsorption in binary solutions. A site distribution function which gives information about the affinity of adsorption sites for competing species in a binary system has been mathematically calculated by using Freundlich isotherm parameters. Time-dependent results for single and binary dye solutions have been analyzed according to the Vermeulen and McKay models based on homogeneous and heterogeneous diffusion processes, respectively. Thermodynamic functions for the transition state have been evaluated from the temperature dependence of diffusion coefficients using the Eyring equation.     

Evaluation of Red Marine Alga Kappaphycus alvarezii as Biosorbent for Methylene Blue: Isotherm,Kinetic, and Mechanism Studies

In this work, non-living red seaweed (Kappaphycus alvarezii) biomass was investigated as a new biosorbent of methylene blue from aqueous solution. The effect of operational parameters such as equilibrium pH, agitation time, initial dye concentrations, and biosorbent dosage on the biosorption capacity of Kappaphycus alvarezii was studied. The equilibrium solution pH was found to profoundly affect methylene blue sorption capacity of Kappaphycus alvarezii with pH 8 found to be optimum. Evidence from Fourier-transform infrared spectroscopy and scanning electron microscopy pictures confirmed the dye biosorption mechanism as electrostatic interaction between the negatively charged seaweed surface and positively charged methylene blue. Biosorption isotherms indicated that Kappaphycus alvarezii exhibited methylene blue uptake of 74.4 mg/g, according to the Langmuir model. The equilibrium isotherm data were evaluated using the Freundlich, Langmuir, Redlich-Peterson, and Toth models. Kinetic studies revealed that methylene blue uptake was fast with 97% or more of the uptake occurred within 60 min of contact time. The pseudo first and second order models were applied to describe kinetic data, of which the pseudo-first order described experimental data better with high correlation coefficient and low percentage of error values.     

p-Sulphonatocalix[8]arene functionalized silica resin for the enhanced removal of methylene blue from wastewater: equilibrium and kinetic study

ABSTRACT

The present investigation represents the synthesis of new p-sulphonatocalix[8]arene-based silica resin, p-SC8SR (5) and its application for the enhanced removal of methylene blue (MB) dye from contaminated water. The new p-SC8SR (5) resin was characterized by FT-IR, SEM, and EDX spectroscopy. The adsorption of MB on p-SC8SR (5) was investigated systematically by evaluating the effects of adsorbent dosage, initial pH, contact time, dye concentration, and ionic strength. Excellent adsorption (94%) of MB on p-SC8SR (5) was achieved at pH 9.5, contact time 10 min by using 0.2 mol L^?1 ionic strength and 2 × 10^?5 M initial MB dye concentration. Kinetic behavior of MB dye adsorption process on the newly synthesized p-SC8SR (5) adsorbent follows the pseudo-second-order rate model (R² = 0.998 and 0.999 for 2 × 10^?5 M and 1 × 10^?4 M, respectively). Adsorption isotherms were fitted well by the Freundlich model with excellent value of coefficient of determination (R²) = 0.995 which demonstrated that the adsorption of MB follows multilayer mechanism. Wastewater samples contaminated with MB were used to assess efficiency of the p-SC8SR (5) adsorbent. Results indicated that newly synthesized p-SC8SR (5) was found to be efficient adsorbent. During the removal process, the role of different functional groups’ cyclic structure was scrutinized and found that the ionic property as well as π–π interaction of host molecules played imperative role in the extent of adsorption.     

Anodic oxidation of the dye materials methylene blue,acid blue 25, reactive blue 2 and reactive blue 15 and the characterisation of novel intermediate compounds in the anodic oxidation of methylene blue

Anodic oxidation of the dye molecules, methylene blue, acid blue 25, reactive blue 2 and reactive blue 15 in chloride solution leads to colour destruction but UV and TOC data show that the oxidation reactions do not lead to complete destruction of the organic molecules. Analysis of the anodic oxidation products of [3,7‐bis (dimethylamino) phenothiazinium] chloride (methylene blue) in a chloride solution provides evidence for formation of seven neutral and two charged intermediates. The main intermediate is identified by its X‐ray diffraction crystal structure and accurate mass spectrometry as the novel leuco dye 4,6‐dichloro‐7‐dimethylamino‐3H‐phenothiazin‐3‐one, C₁₄H₁₀Cl₂N₂OS (I) formed by replacement of one of the dimethylamino groups of methylene blue with oxygen accompanied by regiospecific chlorination of the carbocyclic systems. The mass spectra of other intermediates formed are interpreted in terms of the structure of I. © 2002 Society of Chemical Industry     

用于太阳能装置的柔性透明隔热材料

目前所使用的太阳能收集器是由既硬又重的材料制成的,这也就是为什么这样的太阳能收集器不能灵活移动的原因.因此,欧盟资助一项研究项目,用于开发新的太阳能收集系统,首先要柔韧和可移动,这样就可以在任意地方安置这类太阳能收集器.     

Ball milling–based piezocatalysis using .5Ba(Zr0.2Ti0.8)O3–.5(Ba0.7Sr0.3)TiO3 ceramics

One of the newly light on processes utilized in applications for cleaning water is piezocatalysis. Mechanical vibrations generated through ultrasonication are generally used to separate out the charges in ferroelectric ceramics. The current research presents a novel prospective methodology of ball milling, where it is used as a facile and green technique for water remediation. The movement of the planetary ball mill imparts enough force such that reactive species are produced which are responsible for organic dye degradation. One of the results in the parametric analysis showed that by using 0.30 g of the 0.5Ba(Zr_0.2Ti_0.8)O₃–0.5(Ba_0.7Sr_0.3)TiO₃ (BST–BZT) powder, 62% of the methylene blue (MB) dye was degraded in 60 minutes.