In this study, silver nanoparticles (Ag-NPs) as catalysts in the photocatalytic degradation reaction of Sunset yellow FCF (SYF) azo dye in aqueous solution were investigated. Ag-NPs were prepared by using walnut (Juglans regia L.) leaf extract. The synthesis of Ag-NPs has been done using green chemistry, which is an environmentally friendly, low-cost, fast, and safe method. Extraction was done with a facile method, as well as the synthesis of Ag-NPs in a short period and with high efficiency. The Ag-NPs were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDS), X-Ray Diffraction (XRD), and Fourier Transform InfraRed (FT-IR) spectroscopy. Optimum conditions for dye degradation were determined using Taguchi experimental design method with (L9(34)) orthogonal array. Analysis of the response of each experiment was based Signal to Noise (S/NL) ratio calculated. The effects of operational parameters such as catalyst amount, pH, irradiation time, and temperature in three levels for each factor were studied. The Taguchi results showed that catalyst amount= 20 mg/l (level 2), pH= 4 (level 1), irradiation time = 45 min. (level 3) and temperature= 30 °C (level 3) was the optimum conditions for this process. The most influence of each factor on the process was determined using the Analysis of Variance (ANOVA) method. The most significant factor in this process was pH. The interaction between pH×catalyst amount was the most influencing interaction. The analysis of primary ANOVA showed that percent (p(%)) parameters were: catalyst amount (12.002%), pH (46.298%), irradiation time (35.311%), and temperature (6.383%). The contribution of factors in this process was found to be in the following order: catalyst amount (0.142), pH (0.431), irradiation time (0.397), and temperature (0.18). A pseudo-first-order kinetic reaction with rate constant k=0.0721 min−1 was observed for dye photocatalytic degradation.

The highly cross-linked PDMA star polymer (PDMA-b-PEGDMA) was successfully synthesized by group transfer polymerization (GTP) using 2-(N, N-dimethylamino)ethyl methacrylate (DMA) and cross-linking agent ethylene glycol dimethacrylate (EGDMA) monomers. Highly cross-linked polymer as a huge molecule has many functional groups. Thanks to these properties, dye adsorption performance of this kind of polymer was investigated. Sunset yellow FCF (SY) dye was used to determine whether the polymer showed adsorption properties. The effect of solution pH, dye concentration change and adsorbent amount on adsorption were investigated and the most effective adsorption conditions were determined for polymer. According to these parameters, the reaction rate constants in the dye adsorption of highly cross-linked polymer and the thermodynamic parameters (Δ, H°, , Δ, G°,and Δ, S°, ) of the adsorption were calculated. The reaction was spontaneous (Δ, G°,  , < , 0) at all temperatures (20 °, C, 35 °, C, and 50 °, C). Kinetic of adsorption of SY dye onto polymer was studied, as well as its adsorption isotherm. At the last stage of the study, recovery of the polymer was carried out. The polymer was recovered using the dissolution–, precipitation method. adsorption studies were performed using UV–, Vis spectrophotometer. The characterizations of the synthesized highly cross-linked star polymer and the recovered polymer were carried out using proton NMR (1H NMR) spectroscopy and gel permeation chromatography (GPC).

The objective of this study was to assess the potential of cadmium sulfide nanoparticles loaded onto activated carbon (CdSN-AC) for the removal of Sunset yellow (SY) dye from aqueous solution. adsorption studies were conducted in a batch mode varying solution pH, contact time, initial dye concentration, CdSN-AC dose. In order to investigate the efficiency of SY adsorption on CdSN-AC, pseudo-first-order, pseudo-second order kinetic models were studied. It was observed that the pseudo-second-order kinetic model fits better than other kinetic models with good correlation coefficient. Equilibrium data were fitted to the Langmuir model. It was found that the sorption of SY onto CdSN-AC is followed by these results.

In this work, the micellization behavior of tetradecyltrimethylammonium bromide ‎‎(TTAB) surfactant was investigated in aqueous solvent mixtures of methanol, ethanol ‎and propanol on different mass fractions (10-30%) and aqueous solution of Ponceau 4R ‎and Sunset yellow FCF dyes at concentrations (0.001-0.007mM) based on ‎conductometric technique at T=(298-313)K. The critical micelle concentration (CMC) ‎values and dissociation degrees of TTAB surfactant were determined. The obtained ‎results showed that the CMC value increases with rising of methanol and ethanol mas ‎fractions but the CMC value decreases with rising of propanol mas fractions. Also, the ‎obtained results indicated that the CMC value decreases with concentration increasing of ‎Ponceau 4R and Sunset yellow FCF dyes. In addition, thermodynamic properties such as ‎the Gibbs energy, enthalpy and entropy of micellization were calculated as a function of ‎temperature, dye concentration and alcohol mass fractions. ‎

In this research, the ability of magnesium oxide (MgO) nanoparticles to the adsorbent was studied for the removal of Sunset yellow (SY) dye in an aqueous solution. Different techniques, including Fourier Transform InfraRed (FT-IR) spectroscopy and Scanning Electron Microscopy (SEM) were employed to identify the adsorbed dye. adsorption experiments were carried out in a batch mode with varying pHs, MgO concentrations, initial dye concentrations, contact times, and temperatures. To study SY adsorption's efficiency on the surface of MgO nanoparticles, pseudo-first-order, second-order, and intra-particle diffusion kinetic models were investigated. The pseudo-second-order kinetic model demonstrated a better fitting than other kinetic models (correlation coefficient: R2=0. 99). The Freundlich model with an R2=0. 93 value proved to fit with equilibrium data. In addition, thermodynamic parameters consisting of enthalpy, entropy, and activation energy were calculated too. It was noticed that the adsorption of SY on MgO was exothermic and spontaneous at low temperatures. The suggested adsorbent can be utilized for removing SY with an efficiency of more than 85%.

The present research was aimed to analyze the possibility of a novel low-cost biosorbent, Methanol Modified Walnut Shell (MMWS), to improve its biosorption properties with respect to the removal of Sunset yellow (SY) from aqueous solution, The influences of process parameters, such as pH, temperature, and initial concentration of SY on its adsorption capacity were investigated in a batch system. The equilibrium data were evaluated using the Langmuir and the Freundlich models and the latter could provide a better fit. The Langmuir maximum adsorption capacity of SY onto MMWS was 18. 35 mg/g at 298 K, which showed a significant improvement as compared to the raw walnut shell. The obtained thermodynamic parameters demonstrated a spontaneous and endothermic nature of the adsorption process of SY onto walnut shell biomass. The adsorption kinetics fitted well with the pseudo-second-order model. It was concluded that intra-particle diffusion was one of the rate-controlling steps in this process. MMWS was proved to be a promising adsorbent to treat dye wastewater.