Organic Dyes

Gum polysaccharides are one of the most abundant bio-based polymers. This study demonstrates the synthesis of locust bean gum-cl-poly (acrylonitrile) based hydrogel were obtained using acrylonitrile monomer, MBA as crosslinker and APS as initiator by involving free radical co-polymerization and crosslinking reaction technique. The factors influencing the adsorption capacities, including the initial concentrations of dye solutions, contact time, initial pH values and dosage of the adsorbent as well as ionic strength of the solution are discussed. The locust bean gum-cl-poly(acrylonitrile) based hydrogel was found to be pH sensitive. The kinetics studies show that the adsorption of the dye fitted a pseudo-second-order equation.

It is necessary to choose the sorbent, which would provide a selective extraction and quantification of polar compounds from aqueous solutions, for the effective implementation of the method of sorption concentration. In recent years as potential adsorbents are increasingly attracting attention carbon sorbents based on detonation nanodiamond that possess a number of unique physical and chemical properties. Detonation nanodiamonds used directly in liquid chromatography impossible. Porous microdispersed detonation nanodiamonds
(PMDN) are suitable for these purposes. The presence on the surface of various polar functional groups indicating that this sorbent is polar, which could promote increase the selectivity of the sorption of
polar compounds. The purpose of this work was to study the physicochemical patterns of adsorption of polar sorbates having the properties of acids, bases and amphoteric compounds on porous microdispersed detonation nanodiamonds. It has been shown that treatment of PMDN with acid or base does not affect the surface
area of the sorbent. Average values of specific surface area and pore diameter equal to 256 m2/g and 3.8 nm, respectively. The amount of acidic and basic groups on the sorbent surface were determined by method of acid-base titration and Boehm titration. It is shown that the treatment of PMDN with acid or base leads to a reproducible amounts of basic and acidic groups. This may indicate that the obtained results are reliable. The data on adsorption of acidic and basic dyes on the surface of PMDN have shown that the surface of the sorbent contains both basic and acidic groups. Treatment of the initial sample with acid or base leads to a decrease of adsorption of acidic and basic dyes, which may be due to the removal of impurities from the PMDN surface.

The present work highlights the synthesis of xanthan gum-cl-Dimethyl acrylamide hydrogel containing silica via microwave assisted method,in which N, N'-methylene bis-acrylamide (MBA) and ammonium persulfate (APS) were used as crosslinker and initiator, respectively. Silica was incorporated into the hydrogel matrix during the grafting reaction. The formation of XG-cl-DMAA/SiO 2 hydrogel nanocomposite under optimized reaction conditions was verified by the infrared spectra (FTIR) and Scanning electron microscopy (SEM). XG-cl-DMAA/SiO 2 hydrogel nanocomposite was used for adsorption of Cd 2+ ions from aqueous solution. The Cd 2+ ions adsorption was measured by inductively coupled plasma mass spectrometry. The factors influencing adsorption capacity of the absorbents such contact time, and initial dye concentration were investigated via a batch adsorption system. The maximum adsorption capacity, q max , of 150.7 mg/gat 30°C was calculated based on the Langmuir isotherm. Heavy metal adsorption data fitted well to the pseudo-second-order model and equilibrium data were best described by Langmuir model.

Changes in the formulation of pigments and paint binders and the presence of additives used in the history of painting can complicate the interpretation of analytical data and may influence the characterization of the materials used in artworks. The limitations of the common analytical tools used to identify potential paint components including metallic driers, pigments, and the inorganic substrates of lake colors may also make analysis more difficult. X-Ray Fluorescence (XRF) spectroscopy is a common non-destructive technique used to collect inorganic elemental information from artworks. Advancements in XRF technology now permit the gathering of data from multi-layered paint systems and scanning technology can help characterize pigments across the entire surface of an artwork. These tools require an even greater understanding of the potential materials in an artwork to avoid misinterpretation of the data. The authors tested XRF's ability to characterize lead, manganese, and cob...

In the present work, the synthesis of k-carrageenan-crosslinked poly(acrylonitrile co-acrylamide) hydrogel through copolymerization of acrylonitrile and acrylamide. The optimum conditions for the synthesis of k-carrageenan-crosslinked poly(acrylonitrile co-acrylamide) hydrogel were determined by varying several parameters such as monomers, cross linker, initiator and reaction time. The structure and morphology of the synthesized hydrogel and the exposed hydrogel (containing Brilliant Green) were characterized by FT-IR and adsorption experiments were carried out using various adsorbent dosages. The adsorption kinetics results showed that the adsorption followed pseudo-second order, this implies that the adsorption of the dye took plase through chemisorption mechanism.

The colour manufacturing industry represents a relatively small part of the overall chemical industry. Dyes and pigments are highly visible material. A major source of colour release into the environment is associated with the incomplete exhaustion of dyes onto textile fibre from an aqueous dyeing process and the need to reduce the amount of residual dye in textile effluent has become a major concern in recent years. The aim of this work is to evaluate the efficiency of ozone and UV on the removal of five different dyes from fresh and sea water, followed by determination of the final compounds after ozone and ozone-UV treatment using GC-Ms analysis. Finally, assess the effect of the treated water which contains the final decomposed compounds on the selected marine organisms for water reuse.

The utilization of an optical fiber reflectometer on the evaluation of filtration capability by SiO2 membranes is reported. Quartz powder obtained by milling of natural quartz was pressed under 30 MPa and sintered under ~1000°C for producing 4.35 mm thickness ceramic membranes. The SEM analysis revealed a high porosity material and the XRD measurement indicated an α-quartz structure. Next, the membranes were tested on the retention of commercial food coloring (Dr. Oetker, Color Index 16185). The dye was diluted in DI water, and solutions were prepared with concentrations varying from 0 to 100% (v/v). Since the refractive index of solutions varies with the dye concentration, the samples could be analyzed by a fiber sensor, in which the reflected light at the fiber-liquid interface is related to the sample refractive index, according to the Fresnel equation. The sensor was calibrated for the dye diluted solutions, and then tested for the filtered samples. It was observed that the volumetric concentration varied from 60% to 50.3% after passing the solution through the porous material. It is a very significant result, since it is commonly necessary to use high-tech processes in order to produce materials capable of retaining such small structures, and shows that the use of quartz is effective in reducing the concentration of a dye commonly used in food industry, being an economical and eco-friendly alternative for the treatment of industrial and domestic effluents. Moreover, the methodology of using an optical fiber sensor is also attractive for the analysis and control of chemical processes, being minimally invasive, chemically inert, and presenting practically realtime results.

Surface-modified hydroxyapatite (HA) nanocomposites have been synthesized from Dfructose-1,6-phosphate trisodium salt octahydrate (DFP) via a simple and green hydrothermal process. Comprehensive X-ray powder diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Thermal gravimetrical analysis (TGA), Fourier transform infrared (FT-IR) and solid state nuclear magnetic resonance (SSNMR) characterizations revealed that the HA nanocomposite adopt a rod-like core/shell morphology in which the inorganic HA core is covered with an organic shell of polyalcohol species.

The HA nanocomposite exhibits a large surface area of 203.18 m2/g, and enhanced adsorption capacities of organic dyes such as Methyl orange (MO) and Congo red (CR) . Remarkably, the adsorption processes were particularly fast in which the equilibriums are reached within minutes. The adsorption kinetics can be well described by a pseudo-second-order kinetic model.

These experimental results demonstrated that such HA nanocomposites are promising adsorbents for the efficient removal of organic dyes from water.