| Because of the extremely toxicity of arsenic,arsenic contamination has received extensive attention by many countries.China also has implemented the new standard,to decrease the maximum limited value of arsenic in portable water down to 10?g/L.The new standard is put forward to further promote the research of the technology of the drinking water arsenic removal.Adsorption method has been extensively studied because of its high efficiency and economical property.Because adsorbent is the core of the adsorption method,to develop a kind of the adsorbent which can efficiently remove arsenic is research hotspot recently.The purpose of this research is to synthesize novel Fe-Cu-La composite oxide which combines the advantages of the magnetic separation properties of magnetic iron oxides,the wide application range of copper oxide and the strong adsorption ability to arsenic of lanthanum oxide,and investigating the its properties of arsenic adsorption.Using chemical coprecipitation method to prepare a series of Fe-Cu-La composite oxides.By comparing the various adsorbents adsorption capacity of As(V)and As(III),the Fe: Cu: La ratio of 2:1:4,aging temperature of 50? and drying temperature of 80? was proved to possess the highest adsorption capacity.We found Fe-Cu-La composite oxide was united by nanoscale spherical,lamellar and rod-shaped particles,the surface of the adsorbent is inhomogeneous and porous.The main structure of the material may be inverse cubic spinel,and the material may contains Fe3O4,Fe Cu2O4,La(OH)3 and Cu O.The BET surface area of the material was 27.89 m2/g,the average pore diameter is 32.295 nm(4V/S).The isoelectric point of the material was 7.2,which makes the surface of oxide positively charged at p H<7.9.Through hysteresis loop,we found the coercive force of the material was 50.109emu/g,and the material could be separated rapidly from the water by the permanent magnet.Langmuir model has the best fitting effect on the adsorption process of As(V)and As(III),and the correlation coefficients R2 are above 0.97.The saturated adsorption capacity for As(V)reached 116.59,138.26,155.58 mg/g and for As(III)reached 88.35,93.18,103.83 mg/g at 15,25,35?.By calculating the thermodynamic parameters of the adsorption reaction at different temperatures,the thermodynamic parameters ?H,?S are greater than zero and ?G is less than zero.It means that the adsorption of As(V)and As(III)are spontaneous endothermic process.The adsorption rate is rapid before 480 min,and become stabilized after 720 min.The adsorption kinetic data can be well described by both pseudo-first order model and pseudo-second order model(R2>0.98).Changing ionic strength and p H to study their effects on arsenic adsorption.The results showed that acid or alkali will affect the adsorption and adsorption capacity will reached the maximum under p H 6~8.Ionic strength make little effect on As(V)and As(III)adsorption,probably because arsenic can formed an inner complex with the material.The common ions in water,Ca2+ and Mg2+ have little influence on adsorption,but high concentration of HCO32-,F-,Si O32-and PO43-will have great influences on As(V)and As(III),and the effect on As(III)is greater than As(V).Using Fe-Cu-La composite oxide to adsorb arsenic in the river water of Jilin province and determine the effect of material on arsenic adsorption.If the amount of material is increased,the lower the arsenic concentration in the water is.When the dosage is more than 30 mg/L,the arsenic concentration can satisfy drinking water arsenic concentration standard after adsorption.The dynamic adsorption experiment of water indicate that Fe-Cu-La composite oxide adsorption kinetic data is well described by pseudo-second order model(R2=0.922).Over 80% of the equilibrium adsorption capacity was achieved within 60 min,the arsenic concentration will below 10 ?g/L(international drinking water arsenic limitation)after 120 min.The cost of handling one ton of actual water is 1.74 yuan. |
PDF Full Text Request