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Polysaccharide is a renewable, biocompatible and biodegradable material that has received considerable attention. In this work, a series of polysaccharide gels were synthesized from the chemical cross-linking of pullulan with diglycerols. The effects of the diglycerol chain length on the performance of the gels were evaluated by XRD, TGA, SEM, rheological testings and swelling measurements. Overall, increasing the chain length resulted in a smaller pore size and stronger mechanical strength. Tetramethylene glycol diglycidyl ether (longest chain length)-derived Gel-T, which had the best performance (acceptable porous structure, good swelling ability and strong rigidity), was used to produce a nanocomposite hydrogel with montmorillonite (MMT). The incorporation of MMT led to a decrease in gel swelling and an increase in gel strength. The obtained nanocomposite system exhibited excellent adsorption properties (80 mg/g) towards crystal violet, and the adsorption behaviours were well represented by the pseudo-second-order kinetic and Langmuir isotherm models. Altogether, this study provides a better understanding of the structure-function relationships of pullulan-constructed hydrogel materials and will help to design more practical adsorbents for dye removal., (Copyright © 2019. Published by Elsevier Inc.)

Herein, we reported the photo-catalytic degradation/anti-bacterial property of Ag-doped ZnO nanoparticles (SDZO Nps) prepared by a facile gel-combustion technique and its self-cleaning/self-refreshing/self-disinfectant behaviour while on impregnating as pigment into the alkyd resin based coating. The influence of doping Ag (1% & 2%) with ZnO has been evaluated in terms of crystal structure, morphology, optical properties, etc. using X-ray diffraction analysis, Field Emission Scanning Electron Microscope, UV-Vis analysis, and Photoluminescence spectra. The photo-catalytic degradation of crystal violet solution by SDZO Nps is spectroscopically followed employing UV-Vis spectroscopy. From the obtained results, the rate of degradation of 1% SDZO Nps is found higher than that of other samples under sunlight illumination; degrading 1 mg of crystal violet in 30 min. Thus, implementing the synergic effect of nano ZnO and the doped Ag provides a suitable pathway for the development of high efficient photo-catalyst. Further, alkyd resin based self-cleaning coating is formulated using 1% SDZO Nps as pigment along with other additives; the contents are milled to form a homogeneous mixture by high energy ball milling technique. Crystal violet solution coated over dried alkyd coating gets decolorized on exposure to sunlight indicating the mineralization of pollutants and proves the fact that the as obtained coating possess self-cleaning nature. Besides the self-cleaning property, the coating exhibits self-refreshing property which is essential for the long lasting self-cleaning activity. Further, the disinfectant properties of 1% SDZO Nps and 1% SDZO Nps impregnated coating have been evaluated against gram negative Escherichia coli bacterial strain. The acquired experimental outcomes suggest the potential use of self-cleaning coating to keep the environment clean and hygienic economically., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Cellulose (Cel) and sugarcane bagasse (SB) were oxidized with an H 3 PO 4 -NaNO 2 mixture to obtain adsorbent materials with high contents of carboxylic groups. The oxidation reactions of Cel and SB were optimized using design of experiments (DOE) and response surface methodology (RSM). The optimized synthesis conditions yielded Cox and SBox with 4.8mmol/g and 4.5mmol/g of carboxylic acid groups, respectively. Cox and SBox were characterized by FTIR, TGA, PZC and solid-state 13 C NMR. The adsorption of the model cationic dyes crystal violet (CV) and auramine-O (AO) on Cox and SBox in aqueous solution was investigated as a function of the solution pH, the contact time and the initial dye concentration. The adsorption of CV and AO on Cox was described by the Elovich equation and the pseudo-first-order kinetic model respectively, while the adsorption of CV and AO on SBox was described by the pseudo-second-order kinetic model. Adsorption isotherms were well fitted by the Langmuir and Konda models, with maximum adsorption capacities (Q max ) of 1117.8mg/g of CV and 1223.3mg/g of AO on Cox and 1018.2mg/g of CV and 682.8mg/g of AO on SBox. Desorption efficiencies were in the range of 50-52% and re-adsorption capacities varied from 65 to 81%, showing the possibility of reuse of both adsorbent materials., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Uniform submicron-scale Au spheres with an average dimension of 574 nm were facilely prepared from the redox reaction between HAuCl4 and 3,4-ethylenedioxythiophene (EDOT) in aqueous solution under ambient conditions. HAuCl4 precursor readily polymerized to poly(3,4-ethylenedioxythiophene) (PEDOT) and metallic Au spheres simultaneously formed within a short period of time. The Au spheres are consisted of two slightly different types of spherical particles based on their surface textures. Major raspberry-like Au spheres are formed through the assembly of very tiny Au nanoparticles, while minor rosette-like Au spheres are formed through the dense packing of Au nanoplates. Both Au spheres are pure metallic face-centered cubic Au based on X-ray photoelectron spectroscopy and powder X-ray diffraction. The resultant Au spheres are adequate for application to surface-enhanced Raman scattering (SERS) due to their rough surfaces and nanogaps on the surfaces. Both methylene blue and crystal violet molecules were detectable at concentrations as low as 10(-7) M., (Copyright © 2013 Elsevier Inc. All rights reserved.)

A systematic study was carried out to characterize the adsorption of organic cations as monomers, micelles, or polymers on montmorillonite by monitoring zeta potential (ξ) as a function of cation loading on the clay. In general, the clay's ξ became less negative as cation loading increased. A fairly good linear correlation between adsorption of organic cations on the clay, up to the cation exchange capacity (CEC) of the clay, and ξ potential of the composites was fitted. However, when the adsorption of the larger cation exceeded the CEC, a nonlinear increase in ξ was measured. The degree of this increase corresponds to the cation size and affinity to the clay (in the order surfactant

Adsolubilisation has been defined as the incorporation to solid-water interfaces of molecules that do not adsorb spontaneously to such interfaces, but can be incorporated through an interaction with an adsorbing surfactant molecule. The aim of this work was to study the adsolubilisation of organic molecules with different hydrophobicity on collagen fibres. Hide powder collagen was treated under mild acidic aqueous conditions with an anionic surfactant, sodium dodecylbenzene sulphonate. Thereafter, five different organic molecules, i.e., benzyl alcohol, 2-naphtol, pararosaniline, hexamethylpararosaniline and nonylphenol with 10 mol ethylene oxide were separately applied to the treated collagen in order to study adsolubilisation as a function of their hydrophobicity. It was found that under acidic conditions all molecules were scarcely adsorbed or not adsorbed by the native hide powder collagen. However, all organic molecules, except benzyl alcohol, were adsolubilised if the hide powder collagen was previously treated with the anionic surfactant. The hydrophobicity of the molecules plays an important role in the adsolubilisation phenomenon with the result that the higher the hydrophobicity (nonylphenol with 10 mol ethylene oxide), the higher the adsolubilisation., (Copyright © 2010 Elsevier Inc. All rights reserved.)

The adsorption performance of the materials bottom ash (BA), a power plant waste, and de-oiled soya (DOS), a soya bean industry waste for removal of crystal violet dye, has been investigated through batch and column experiments. Batch studies have been performed to describe the impact of parameters such as pH, amount of adsorbent, dye concentration, temperature, and contact time on the removal of the dye. Experimental data have been modeled by using Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich (D-R) isotherms. Thermodynamic parameters (DeltaG(o), DeltaH(o), and DeltaS(o)) were evaluated for the dye-adsorbent systems, which revealed that the adsorption process is endothermic in nature. Pseudo-first- and second-order kinetic models have been applied to the experimental data and pseudo-second-order kinetics was found to describe the adsorption of the dye (crystal violet) on the adsorbents. In order to achieve bulk removal of the dye, column operations were made. Recovery of the dye was made by eluting HCl solution through the exhausted columns and almost 95% and 78% of the dye was recovered from BA and DOS columns, respectively., (2009 Elsevier Inc. All rights reserved.)

Adsorption of 2,4,5-trichlorophenol (TCP) and picric acid (PA) by montmorillonite preloaded with crystal violet (CV) up to 80, 100, and 125% of the cation exchange capacity was studied. The adsorption isotherms indicated a strong interaction of TCP and PA with the organoclay. While the adsorption isotherms of both pollutants can be described by the Langmuir model with relatively good fit, the adsorption of TCP is more adequately described by the dual-mode model (DMM), which combines the Langmuir equation with a partition mechanism. Competitive adsorption experiments and adsorption experiments in water:ethanol mixed medium as a solvent confirmed the assumption that the removal of TCP from water by the organoclay follows two different mechanisms: site-specific adsorption occurs in the low concentration range, whereas a partition mechanism dominates the high concentration range. This double mechanism in organoclays exhibits both complete removal at low pollutant concentrations and high sorption capacity in the high concentration range, and therefore may be effective in water treatment for a wide range of pollution levels.