Research On The Removal Of Cr(?),Acid Red And Methyl Orange Dyes From Aqueous By Synthesis Of Nanoscale Iron Particles

Nanoscale iron particle is one of the most intensively studied materials for removing environmental pollutants in recent decades.The green synthesis of n ZVI has been recently proposed as a cost effective,environmental friendly alternative to chemical and p Hysical methods since a variety of materials from biorenewable of natural sources can be employed.In this paper,the green nanoscale iron particles(GS-Fe NPs)were synthesized by using grape seed extracts and the removal of Cr(?),acid red and methyl orange dyes from aqueous by GS-Fe NPs was investigated.The TEM characterization results show that GS-Fe NPs had sizes from 30 to 80 nm.The SEM characterization results show that GS-Fe NPs had sizes from 100 to 300 nm after vacuum drying.The XRD characterization results show that the GS-Fe NPs composition mainly conclude zero-valent iron and iron-based oxides.The effects of three different preparations of single factor(polyp Henols,Fe2+ and GS-Fe NPs),iron salt concentration,temperature,and p H on the removal of Cr(VI)were investigated experimentally.Response surface analysis was performed with the reaction time,temperature,and p H as three influencing factors and the removal rate of Cr(VI)was the response value.The results show that the optimum conditions for removing Cr(VI)by GS-Fe NPs were as follows: Fe2+ concentration was 0.1 mol�L-1,temperature was 30�C,p Hwas 3.The three factors strongly influenced the Cr(?)removal rate and fit well in the whole regression region.It is suitable for the optimization of Cr(?)removal conditions.The effects of the three factors on the Cr(?)removal rate is p H > reaction time > temperature.Pseudo first order kinetic model,pseudo second order kinetic model and intra-particular diffusion model were used to describe the kinetic behavior.The results showed that the pseudo second order kinetic model had the best agreement with the experimental data.Activation energy was about 22.0 KJ/mol-1,suggesting that the process of Cr(?)removal by GS-Fe NPs is a chemically diffusion-controlled reaction.The GS-Fe NPs were used as catalysts.It was combined with H2O2 to degrade acid red(AR)by Fenton-like method from aqueous solution.The effects of H2O2 addition,initial concentration of AR,temperature and p H were investigated.Response surface analysis was performed with the reaction time,temperature,and p H as three influencing factors and the degradation rate of AR was the response value.The results showed that the AR degradation rate increased with the decrease of initial concentration of AR,the rise of temperature and the decrease of p H in the range of the research.The AR got the highest degradation rate with 20 m L H2O2(10%)in the range of 5-30 m L.At the p H value of 3-11,the degradation rate of AR can reach more than 80% after 180 minutes of reaction,indicating that the p H value is relative to AR.Degradation has a wide range of adaptation.The results of response surface methodology showed that the three factors strongly influenced the degradation of AR and the order of influence was p H> reaction time> temperature.Pseudo first order kinetic model,pseudo second order kinetic model and intra-particular diffusion model were used to describe the kinetic behavior.The results showed that the second order kinetic model(R2=0.998)had the best agreement with the experimental data,The activation energy is 23.7KJ�mol-1.It indicated that the degradation of AR with GS-Fe NPs as catalysts is a chemically diffusion-controlled reaction.The GS-Fe NPs were used as a catalyst and combined with H2O2 to degrade the methyl orange(MO)by Fenton-like method from aqueous solution.The effects of H2O2 addition,initial concentration of MO,temperature and p H were investigated.Responsesurface analysis was performed with the reaction time,temperature,and p H as three influencing factors and the degradation rate of MO was the response value.The results showed that the MO degradation rate increased with the decrease of initial concentration of MO,the rise of temperature and the decrease of p H in the range of the research.The MO got the highest degradation rate with 10 m L H2O2(10%)in the range of 5-30 m L.The experiment demonstrates that p H has a greater impact on the degradation of MO with GS-Fe NPs as the catalyst,and acidic and neutral strips are more beneficial to the catalytic degradation of MO.The results of response surface methodology showed that the three factors strongly influenced the degradation of MO and the order of influence was p H> reaction time> temperature.Pseudo first order kinetic model,pseudo second order kinetic model and intra-particular diffusion model were used to describe the kinetic behavior.The results showed that the second order kinetic model(R2=0.991)had the best agreement with the experimental data,The activation energy is 54.9KJ�mol-1.It indicated that the degradation of AR with GS-Fe NPs as catalysts is a chemically diffusion-controlled reaction.In summary,Cr(VI)can be removed from aqueous effectively by GS-Fe NPs,and it also degrade the organic dyes AR and MO catalytically.It is a promising nano material.