In this study, the ZnFe 2 O 4 @SiO2@Tragacanth gum magnetic nanocomposite as a novel adsorbent was synthesized and was confirmed by FTIR, XRD, TEM, TGA and VSM methods. Then, the prepared nanocomposite has been tested for the removal of methylene blue dye from aqueous solution for adsorption process, and the effect of various parameters including pH (2-12), adsorbent dosage (0.2-2 g/L), temperature (15-45 °C), initial dye concentration (10-60 mg/L) and contact time (5-120 min), also its isotherms and kinetics has been studied. The results showed that the optimum pH, contact time, initial dye concentration, adsorbent dosage and maximum adsorption capacity were 8, 60 min, 60 mg/L, 0.2 g/L and 109.37 mg/g, respectively. Furthermore, the experimental data determined that the adsorption of methylene blue dye interpreted the Freundlich isotherm (R 2 = 0.979) and the pseudosecond-order kinetics model (R 2 = 0.998). Also, the thermodynamic parameters of the absorption system, such as changes in enthalpy (ΔH = + 9.36 kJ/mol), entropy (ΔS = + 40.72 J/mol k) and Gibbs free energy (ΔG = − 3.5 kJ/mol), were measured and showed that adsorption process of ZnFe 2 O 4 @SiO2@Tragacanth gum magnetic nanocomposite was endothermic and spontaneous process. As a result, due to high adsorption capacity, environment friendly, low cost, rapid extraction and non-toxicity, the ZnFe 2 O 4 @SiO2@TG magnetic nanocomposite can be used as an effective adsorbent for methylene blue removal from aqueous solutions.

A new composite of cobalt ferrite and Tragacanth gum (TG) was developed and applied to remove methyl orange (MO) and methyl red (MR) from wastewater samples simultaneously. The results showed that the presence of TG improved the capability of cobalt ferrite in removing the pollutants in considerably. The adsorption properties and surface morphology of the sorbent were compared with those of bare cobalt ferrite, TG, and TG grafted copolymer. The properties of the adsorbents were studied using Fourier transform infrared, scanning electron microscope, transmission electron microscope, X-ray diffraction, and vibrating sample magnetometer, and the effects of different factors such as the amount of the adsorbent, sample pH, contact time, and initial concentration were also evaluated and optimized through response surface methodology using central composite design. The optimal conditions for the adsorption of both dyes (100 mg L −1 as the concentration) were pH of 4.0, adsorbent dose of 0.5 mg mL −1 , and contact time of 110 min. Under these conditions, the MO and MR adsorption processes were found to follow pseudo-second-order kinetic model. The equilibrium adsorption data followed the Langmuir isotherm and the highest adsorption capacity was determined to be 336 and 387 mg g −1 for MO and MR, respectively.

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A hybrid nanocomposite cobalt ferrite and Tragacanth gum, denoted as Co x Fe 3-x O 4 @silica@TG was developed and applied in concurrent removal of chromate and nitrate ions from wastewater. The results showed that the presence of Tragacanth gum considerably improved the capability of cobalt ferrite for removing the pollutants. The adsorption properties and surface morphology of the sorbent were compared with those of bare cobalt ferrite, Tragacanth gum, and Tragacanth gum crosslinked copolymer. The properties of the proposed nanocomposite were studied using FT-IR, transmission electron microscopy (TEM), and vibrating-sample magnetometer (VSM) techniques. The effect of different factors including the amount of the adsorbent, sample pH, contact time and initial concentration was also evaluated and optimized through response surface methodology using central composite design. The optimal conditions for the adsorption of both chromate and nitrate ions (30 mg L À 1 as the concentration of both of them) were pH = 3, an adsorbent dose of 1 mg mL À 1 and 22.4 min contact time. The adsorption process was found to follow the pseudosecond order and intra-particle diffusion kinetic models. The equilibrium adsorption data followed the Langmuir isotherm and the highest adsorption capacity was determined to be 44.1 and 30.7 mg g À 1 for chromate and nitrate, respectively.