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Herein, a novel hydrogel (HG-cl-poly(AA)) was synthesized by grafting acrylic acid (AA) onto Hing gum (HG) using methylene-bis-acrylamide (MBA) as a cross-linker and ammonium persulfate (APS) as an initiator in a hot air oven. The percentage swelling of the hydrogel was examined by optimizing various reaction parameters to ensure its maximum swelling percentage. The formation of crosslinked networks was confirmed using Fourier-Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA) techniques. The surface area and hydrophilicity of the prepared hydrogel were determined using Brunauer–Emmett–Teller analyzer and wettability studies, demonstrating a clear correlation with adsorption. The adsorption of crystal violet (CV) dye on the prepared hydrogel was studied via a batch adsorption system based on the amount of adsorbent, immersion time, pH level, and initial dye concentration. The prepared hydrogel showed a 99% removal rate and an excellent adsorption capacity of 492.61mg/g due to the electrostatic, H-bonding, and dipole–dipole interactions between the adsorbent surface and dye molecules. The results were further analyzed using the Langmuir, Freundlich, and Tempkin isotherm models. The study suggests consistency with the pseudo-second-order kinetic model ($R^2=0.998$), further supported by the best data fit with the Langmuir isotherm model ($R^2=0.991$). The thermodynamic study results indicated that the adsorption process is endothermic and spontaneous. Regeneration (desorption) studies showed that the prepared hydrogel could remove CV dye from an aqueous solution and maintain the highest adsorption capacity even after multiple adsorption and desorption cycles. Therefore, the prepared HG-cl-poly(AA) hydrogel could be a potential adsorbent for dye removal and have an admirable capacity for cleaning the aquatic environment.

Serendipity has been a major player in most dye discoveries, and phthalocyanines are no exception. The true account of their discovery in 1928 is given using information provided by one of the individuals involved (Ron Greig). One of the inventors, Drescher, after making a key observation as to the nature of the insoluble blue impurity formed in the routine manufacture of phthalimide from phthalic anhydride, was killed weeks later when, on his beloved Sunbeam motorcycle, he had a head-on collision with a steamroller on his way to work. The unique properties of phthalocyanine dyes and pigments make them the colorant of choice for most blue and green colours. Thus most blue and green cars, including sports cars, are coloured by phthalocyanine pigments. In addition to these traditional uses, phthalocyanines are also finding extensive use in modern hi-tech areas. They are used for their colour as, for example, cyan dyes in ink jet printing, and in colourless applications such as infrared absorbers in security. The discovery, traditional and hitech applications of phthalocyanines are described in detail in this paper.

We present our results on nonlinear optical (NLO) of chicago sky blue 6B doped polyvinyl alcohol (PVA) film. This film was studied at 633 nm and 532 nm using a continuous wave laser. We have evaluated the sign and magnitude of the third-order nonlinearity from the closed aperture Z-scan data while the nonlinear absorption properties were assessed using the open aperture data. The chicago sky blue 6B doped PVA film exhibited nonlinear saturated absorption and strong self-defocusing effect. The limiting effect of the sample was studied and the results indicate that the film possesses good characteristic of optical limiting.

We report results from investigations of the nonlinear refractive index and nonlinear absorption coefficient of (2E)-3-[4-(Dimethylamino)phenyl]-1-(2,5-dimethylthiophen-3-yl)prop-2-en-1-one and (2E)-3-(3,4-Dimethoxyphenyl)-1-(2,5-dimethylthiophen-3-yl) prop-2-en-1-one using Z-scan technique with a continuous wave (cw) laser at wavelengths 488 nm and 514 nm. The nonlinear refractive index and nonlinear absorption coefficient of both samples were evaluated. The origin of the nonlinear effects was discussed. Optical limiting based on light induced nonlinear refractive index variation is demonstrated. The limiting thresholds were estimated for both samples. The results suggested that these materials offer promise as candidates for optical limiting and optical devices in the low power regime.

A new dyad 9(ZnP-P) has been synthesized linking 5,15-bis(4-carboxyphenyl)-10,20-bis(4-nitrophenyl) porphyrin 4(P) and Zn(II) 5-(4-aminophenyl)-10,15,20-tris(4-methoxylphenyl) porphyrin 8(ZnP) by an amide bond. The structural moieties of dyad 9(ZnP-P) present both different singlet state energy and redox properties. Dyad 9 was designed to improve the intramolecular electron transfer capacity. The ZnP moiety bears electron-donating methoxy groups and a zinc ion, while the other porphyrin structure, P, is substituted by electron-withdrawing nitro groups. On the other hand, structure P bears a carboxylic acid group, which is able to benefit from the orientation of dyad 9 adsorbed on the SnO₂ electrode. Absorption spectroscopic studies indicated only a very weak interaction between the chromophores in the ground state. The fluorescence analysis shows that both porphyrin moieties in dyad 9 are strongly quenched and that the quenching increases in a polar solvent. The ZnP moiety acts like an antenna for porphyrin P, but, singlet-singlet energy transfer is not complete. Thermodynamically, dyad 9 presents a high capacity to form the photoinduced charge-separated state, ZnP^·+-P^·-. Dyad 9 sensitizes the SnO₂ electrode and the photocurrent action spectrum closely matches the absorption spectrum, which confirms that light absorption by dyad is the initial step in the charge transfer mechanism. The photocurrent efficiency of dyad 9 is considerably higher than those of porphyrin monomers used as models of ZnP and P structures. Two processes may be contributing to enhance the charge injection efficiency in dyad 9; one involves an antenna effect that produces energy transfer from ZnP to P and the other includes electron transfer from the ZnP moiety to the photooxidizable free-base P. This dyad design, with P in direct contact with the substrate through the free carboxylic acid group, is a promising architecture of organic material for spectral sensitization of semiconductor solar cells.

Novel complexes of cobalt(II) with sulfonated derivatives of phthalocyanines are synthesized. The influence of the sulfonated group's number in peripheral substituent on solubility of macrocycle and ability to form ordered structures in solution is showed. Transition from H-aggregates to monomeric phthalocyanine structures and sandwich-type dimers was found during formation of metallophthalocyanine complexes with 1,4-diazabicyclo[2.2.2]octane. The catalytic activity of metallophthalocyanines was studied on the model of Merox process.

The use of adsorption capacity of porous and large-surface-area materials is an important approach to treat dye-containing effluents. In this study, the porous carbon nanocages (CNCs) were synthesized from the precursor of phenol in home-made chemical vapor deposition (CVD) setup at 600–1000^°C, and were convincingly characterized. The as-prepared CNCs are amorphous, porous and hollow, and have the size of 50–100nm in width, 100–200nm in length and several nm in thickness, causing to the large surface area of 800m²/g and pore volume of 1.63cm³/g. The growth of amorphous-like CNCs was related to the thermolysis species of phenol. Interestingly, each CNC has large volume hollow coelom and small opening (a typical ink bottle pore), being in favor of adsorption but in disfavor of desorption, thus it is very fit for acting as the adsorbent of dye. As expected, the products showed excellent adsorbility of rhodamine B when compared with the most used activated carbon having straight and slit pore structures, displaying broad application prospects in removing dye from wastewater.

It is interesting to obtain catalysts to degrade organic dye pollutants at room temperature for simultaneous purposes of environment-treating and energy-saving. In this work, a novel ZrHIO${}_6\cdot 4$H₂O catalyst was synthesized by reacting ZrO(NO${}_3{)}_2$ with H₅IO₆ in aqueous nitric acid. The catalyst was found effective in degradation of rhodamine B (RhB) or methylene blue (MB) dyes at room temperature without light illumination. We used the ultraviolet–visible (UV–Vis) absorption spectra of dye solution as well as X-ray photoelectron spectroscopy (XPS) of ZrHIO${}_6\cdot 4$H₂O to confirm that the dye degradation was due to its catalytic role. Importantly, the ZrHIO${}_6\cdot 4$H₂O catalyst can be recycled five times without obvious activity loss and it achieved higher mineralization efficiency than the previously reported analogue in the degradation experiments.

A new type of Cy5-encapsulated photostable fluorescent silica nanoparticles (FSNPs) bearing positive charges have been successfully fabricated by a reverse microemulsion synthesis in one-pot. The Cy5 dye containing four primary amines are embedded into silica via covalent bonds through a silane coupling agent (GPTMS), followed by co-condensation with tetraethylorthosilicate. The uniform-sized, spherical and monodispersed FSNPs have high fluorescence intensity and photostability. The FSNPs exhibit high stability, good biocompatibility as well as low cytotoxicity. These FSNPs can be internalized into live cells and thus fluorescently label the cells. This study provides a simple synthesis approach that can be applied to other water-soluble and amino-modified organic dye molecules for biological targeting and fluorescent cell imaging.

The ZnO film prepared by doctor blade method are highly porous in presence of structure directing agent PEG and then can be easily sensitized by various molecules. In the present work, the nanostructured ZnO/dye hybrid film prepared by doctor blade method has been investigated in conductivity and photoconductivity measurements in view of applications in dye-sensitized solar cells (DSSC) and in optoelectronics, since electron transport in these devices plays a decisive role for the electron collection efficiency and therefore for the overall efficiency. The absorption of ZnO film sensitized by Rose Bengal dye (RB) has been studied by UV spectroscopy which indicates that after the dye is adsorbed on the ZnO electrode, its absorption spectra showed red-shift in the peak position compared to the absorbance spectra of dye in ethanol. Highly porous ZnO films are found to have high dark conductivity, probably because of a higher n-doping, which is due to higher concentration of Zn atoms in the film. On the other hand, ZnO/RB hybrid film is found to show a much higher sensitivity to illumination with visible light in photoconductivity measurements due to a higher absolute photoconductivity and lower conductivity in the dark.

In this work, we used the modified Hummers method to synthesize graphene oxide, and the redox reaction of FeCl${}_3\cdot 6$H₂O with the carboxyl group on the surface of acidified graphene was carried out to prepare magnetic nanoparticles modified on the surface of graphene (magnetic graphene nanocomposite). X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Vibrating Sample Magnetometer (VSM) and Brunauer–Emmett–Teller measurement (BET) analyses were used to characterize the nanocomposite properties. SEM and TEM images of the nanocomposite show that the magnetic nanoparticles are distributed on both sides of the graphene, and the magnetic nanoparticles diameter is between 100 and 150nm. The XRD pattern indicates that the magnetic nanoparticles are Fe₃O₄ nanoparticles. Based on the VSM, the nanocomposite exhibits a saturation magnetization value of 14.94$\mathrm{\text{emu}}\cdot {\mathrm{\text{g}}}^{-1}$. By BET measurement, the specific surface area of the nanocomposite is 26.54m${}^2\cdot {\mathrm{\text{g}}}^{-1}$, and the surface of the nanocomposite is highly porous. In the experiment of dyes adsorption, the adsorption efficiency in the solution was close to 100%. It can be applied in biomedical and environmental fields such as water purification owing to its high surface, magnetic attraction properties and good adsorption efficiency.

Effluents from dyeing companies are a major polluter of the environment and water bodies. An estimated 70 tons of dye are generated globally each year, with more than one-third of this amount lost to the environment. To combat this issue, novel chemical compounds that are more efficient than existing ones are proposed. The soft synthetic approach was used to create [Ni(II)(Tpy)₂] MOF by reacting nickel nitrate with terpyridine (Tpy). The melting point of the MOF was determined, as well as the EA, HSM, TGA, PXRD, and X-ray crystallographic studies. The MOF results support the synthesis and coordination of the nickel (II) ion with the two Tpy molecules. In application, [Ni(II)(Tpy)₂] MOF was utilized to study the adsorption of Congo red. After 30 min of adsorption time, 1 g of [Ni(II)(Tpy)₂] MOF adsorbed a high amount of Congo red (138.26 mg) at $25^{\circ }$C and a pH of 2. When compared to other isotherms, the Langmuir isotherm provided the best fit. Adsorption kinetics demonstrating electrostatic interaction between MOF and Congo red might be interpreted using the pseudo-second-order model.

Density functional theory, Monte Carlo, and molecular dynamics simulations of the [Ni(II)(Tpy)₂] MOF over Congo red dye were computed. Density functional theory calculations provide insights into the reactivity of the novel [Ni(II)(Tpy)₂] MOF by furnishing chemical reactivity parameters that explain the interactions and adsorption processes between the [Ni(II)(Tpy)₂] MOF and Congo red. The quantum mechanical calculations provide data for an insightful understanding of the reactivity of the MOF and its high adsorption on the Congo red surface. Low band gaps (1.40 and 1.43 eV in the gas phase and water, respectively) obtained for the [Ni(II)(Tpy)₂] MOF suggest that this will make an extrinsic semiconductor with high electrical conductivity. Thus, it would readily interact with and be adsorbed on the Congo red.

The aggregates of carbon nanotubes in aqueous solution limit their potential application as effective adsorbents for organic contaminants. In the present study, Manganese dioxide coated on multi-walled carbon nanotubes (MnO²/MWNT) was prepared by redox reaction. Adsorption properties of two dyes (malachite green and rhodamine B) on MnO²/MWNT were examined to explore the potential of MnO²/MWNT for the removal of dyes from aqueous solutions. Compared with MWNT, MnO²/MWNT showed extraordinarily high adsorption affinity for both tested dyes, adsorption of the test dyes was enhanced 3-10 times. It was proposed that the strong adsorption mechanisms were π−π electron donor-acceptor interaction and Lewis acid-base interaction. The effecst of pH and dissolved humic acids on adsorption were also assessed. For two dyes, similar patterns of pH-dependent adsorption were observed, implying the predominance of graphene structures for the adsorption to MnO²/MWNT. The presence of humic acids suppressed the adsorption of two dyes on MnO²/MWNT.

The optimum condition and the specific energy consumption of ozone generation in a coaxial cylindrical ozonizer under dielectric barrier discharge were studied. In addition, we investigated the efficiency and the specific energy consumption of organic compound degradation in ZnO photocatalytic ozonation system. We have found that the optimum conditions in pilot ozone generator for the synthesis of ozone correspond to voltage of 6.2 kV and pressure of 0.5 psi. The specific energy consumptions of ozone generation and dye degradation are decreases to less than 100 kWh/kg and 0.1 kWh/ppm for high dye concentrations, respectively.