The Preparation And Application Of Ferrite-halloysite Composite Material

With the development of science and technology,human beings have a strong desire to explore the secret of sea.However the exploitation of marine resources has caused a chain reaction of marine environment.Today marine pollution has become a serious problem.Dye wastewater is a kind of industrial wastewater with dark color,high toxicity,high salinity and pore degradability.Discharge of raw dye wastewater into the sea will make our environment deteriorate ever further.The aim of this work is to find a kind of low-cost but efficient adsorbent to treat dye wastewater.In this work,three different magnetic adsorbents were prepared through high temperature sintering method.NHNTs was short for NiFe2O4/HNTs composite.WMH and MH were short for MnFe2O4/HNTs composite.The TEM and XRD analysis indicated that during calcination hydrated HNTs lost the crystalliferous water and then transmuted into dehydrated HNTs.From a microscope viewpoint,the structure of NHNTs was similar to HNTs and many NiFe2O4 particles adhered to the lumen of HNTs.The difference between WMH and MH was that the ferrite nanoparticles of WMH were mainly adhered to the outer surface of HNTs while that of MH were in the inner wall.In methylene blue(MB)adsorption,the adsorption equilibrium was established after 55 min and the removal rates generally increased with pH values.The kinetics suggested that the pseudo-second-order kinetic model was suitable for the MB adsorption processes which meant that chemisorption was the rate controlling step.Isotherm study suggested that the MB adsorption fit the Langmuir isotherm well which indicated that the MB adsorption by these three adsorbents was monolayer adsorption.The calculated maximum adsorption capacities of NHNTs,MH and WMH were 20.11 mg-g-1,18.52 mg-g-1 and 19.19 mg-g-1,respectively.With the assistance of microwave radiation,the adsorption rate was much faster.Compared with MH,WMH exhibited higher equilibrium removal rate.In this study,the magnetic adsorbents were separated by giving an external magnetic field.The recovery rate of MH and WMH were higher than 86%after each cycle,suggesting that magnetic separation was a useful method to recover the as-prepared nanocomposites.The MB removal rates by WMH and MH maintained at higher than 97%even after 5 regeneration times.Compared to other adsorbents,the as-prepared materials have good absorbability and stability.When given an external magnetic field,these nanocomposites can be easily separated from the aqueous solution after adsorption.With the advantages of low cost,good absorbability,efficient separation and high recyclability,these as-prepared nanocomposites are potential "green" adsorbents which can be used in polluted seawater treatment.