CuFe 2 O 4 @graphene nanocomposite was synthesized by chemical co-precipitation method. The nanocomposite was characterized by Fourier infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Adsorption of alizarine yellow (AY) by graphene, CuFe 2 O 4 , and CuFe 2 O 4 @graphene nanocomposite was studied. Effect of different factors including agitation time, pH, and adsorbate concentration on the adsorption capacity of adsorbent for AY dye was investigated. Experimental results demonstrated that AY could be effectively removed from aqueous solution by CuFe 2 O 4 @graphene nanocomposite within 40 min of contact time and pH 3. Two common kinetic models, pseudo-first order and pseudo-second order, were employed to describe the adsorption kinetics. The results indicated that the adsorption kinetics of AY well matched with pseudosecond-order rate expression. The equilibrium adsorption was best described by the Langmuir isotherm model. Various thermodynamic parameters such as the Gibbs free energy (ΔG˚), enthalpy (ΔH˚), and entropy (ΔS˚) change were also evaluated. Thermodynamic results revealed that the adsorption of AY onto CuFe 2 O 4 @graphene is endothermic, spontaneously process and feasible in the range of 303-333 K. The adsorption capacity of CuFe 2 O 4 , graphene, and CuFe 2 O 4 @graphene was found to be 98, 105, and 145 mg g −1 for AY, respectively.

It is well known that SCN -has important effects on the environment and the human body. It has been reported that the presence of SCN -has some relation to local goiter. 1 The concentration of SCN -in saliva can be used as identification of non-smokers and smokers. 2 Saliva thiocyanate may also have an antibacterial role in the mouth, decreasing the corrosion potential of amalgams 3 or carries danger. 4 In addition, the detrimental effect of SCN -on the iodination of proteins has been recognized. 5 The importance of determining thiocyanate levels in effluent streams downstream from a plant outlet can not be underestimated. Though not as toxic as cyanide, thiocyanate is harmful to aquatic life. Thiocyanate is a common constituent of hydrometallurgical solutions. 6 It is formed when pyretic materials are leached with solutions containing cyanide. For efficient plant control, it is important to monitor continuously and to determine the level of thiocyanate and the subsequent consumption of free cyanide in these process solutions. Several methods have been developed for the determination of thiocyanate in metallurgical processes, 6 waste waters, 7-10 biological samples, 10-18 and food. 19,20 A variety of detection systems were applied in these applications for monitoring the level of thiocyanate in samples. The detection systems that were used in these applications include spectrophotometers, [6][7][8]10,13,15,16 ion-selective electrodes, 9,21 chromatography, 11,12,16,20 voltammetry, 19 fluorometry, 11 amperometry 14 and flame atomic absorption spectrometry. 18 The spectrophotometric method is mainly based on the formation of the red iron(III) thiocyanate complex. 22,23 It possesses high sensitivity, but suffers from several interferences.In our investigation of thiocyanate-catalyzed oxidation of MB, a kinetic spectrophotometric method for the determination of trace amounts of thiocyanate is proposed based on the catalytic effect of thiocyanate on the oxidation of MB by bromate in acidic media. The reaction is followed spectrophotometrically by monitoring the decrease in absorbance of MB at 664 nm with a fixed time of 0.5 -4.0 min and was found in acidic bromate solution thiocyanate catalyzed oxidation of MB. Thus, we developed a simple, sensitive and selective method for the kinetic determination of thiocyanate. The resulting method, which has a detection limit (3σ) 3.8 ng/ml, has been successfully applied to the determination of thiocyanate in real samples. Experimental Reagents and standard samplesAll chemicals used were of analytical reagent grade and were used without further purification. Double distilled water was used throughout in the experiment. A 250 ml standard stock thiocyanate solution of 1000 mg/l was prepared by dissolving 0.4189 g of potassium thiocyanate (Merck) in water. Working solutions were obtained by appropriate dilution with water daily.Potassium bromate stock solution of 2.0 × 10 -2 M was prepared by dissolving 0.8350 g of KBrO3 (Merck) in an appropriate amount of water and this mixture was...