Studies On The Capability Of Dye Congo Red/Methyl Blue Adsorption Onto Magnetic Ferrite MnFe₂O₄

Printing and dyeing wastewater with three-induced(carcinogenic,teratogenic,mutagenic)role,has become an important source of pollution,adverse to aquatic organisms,microbial growth,both directly and indirectly harm to human health.In this paper,we use magnetic ferrite MnFe2O4 as adsorbent to remove dye Congo red(CR)and Methyl blue(MB)to determine the optimum conditions for the adsorption.We also study the adsorption behavior in single and binary system,as well as the interaction between CR and MB.MnFe2O4 was prepared by co-precipitation method.The image of MnFe2O4 was determined by atomic force microscope.Measurement of BET surface area and pore distribution were performed using N2 adsorption/desorption isotherms.The X-ray diffraction(XRD)patterns of MnFe2O4 powders were recorded and vibrating sample magnetometer was used to measure the magnetic prosperities of MnFe2O4.A detailed study of the adsorption process was performed by the calcined temperature,sorbent amount,varying pH,ionic strength and interfering ions.The results show that at the optimum conditions,the adsorption efficiency could reach 95%.In single system,the sorption data could be well interpreted by the Langmuir model of CR on MnFe2O4,the maximum adsorption capacity were 25.78 mg/g(298 K),the mean energy of adsorption was calculated to be 0.116 kJ·mol-1 from the D-R adsorption isotherm suggest that the adsorption is a physical process.For 30mg/L and 150mg/L CR solutione,quilibrium were reached within 20 min and 40min,adsorption kinetic results showed that pseudo-second-order model can be used to describe the experimental data with k2 of 0.188 and 0.019 g·mg-1·min-1.Intraparticle diffusion was the limiting step for adsorption of CR.The sorption data could be well interpreted by the Freundlich model of MB on MnFe2O4,KF were 18.77mg/g(298 K),the mean energy of adsorption was calculated to be 0.191 kJ·mol-1 from the D-R adsorption isotherm suggest that the adsorption is a physical process.For 30mg/L and 400mg/L MB solutione,quilibrium were reached within 7 min and 20min,adsorption kinetic results showed that pseudo-second-order model can be used to describe the experimental data with k2 of 1.418 and 0.056 g·mg-1·min-1.Intraparticle diffusion and external mass transfer were both the limiting step for adsorption of MB.In binary system,the sorption data could be well interpreted by the Langmuir model of CR on MnFe2O4,the maximum adsorption capacity were 32.21 mg/g(298 K),the mean energy of adsorption was calculated to be 0.112 kJ·mol-1 from the D-R adsorption isotherm suggest that the adsorption is a physical process.For 30mg/L and 150mg/L CR solutione,quilibrium were reached within 20 min and 40min,adsorption kinetic results showed that pseudo-second-order model can be used to describe the experimental data with k2 of 0.184 and 0.011 g·mg-1·min-1.Intraparticle diffusion was the limiting step for adsorption of CR.The sorption data could be well interpreted by the Freundlich model of MB on MnFe2O4,KF were 11.73mg/g(298 K),the mean energy of adsorption was calculated to be 0.191 kJ·mol-1 from the D—R adsorption isotherm suggest that the adsorption is a physical process.For 30mg/L and 400mg/L MB solutione,quilibrium were reached within 7 min and 20min,adsorption kinetic results showed that pseudo-second-order model can be used to describe the experimental data with k2 of 1.929 and 0.325 g·mg-1·min-1.Intraparticle diffusion and external mass transfer were both the limiting step for adsorption of MB.The interaction between MB and CR was studied by fluorescence spectroscopy.The results showed that the quenching of MB was a static quenching process,One CR molecule bound to one MB molecule,the binding for the MB-CR occurs spontaneously and the main binding forces between CR and MB were hydrogen bond and van der Waals interactions.The adsorbent regeneration experiments show that the thermal decomposition process can be used to treat the MnFe2O4 adsorped CR and MB.The adsorption rate can reach 95%after eight times,so MnFe2O4 having a good re-use performance.