Removal Of Cadmium From Weak Acidic Irrigation Water By Manganese Ammonium Phosphate Series Materials

The heavy metal cadmium pollution irrigation water is serious in Hunan,and because of the source of pollution,acid pollution of irrigation water should not be overlooked.In this paper,manganese ammonium phosphate series materials was used to remove cadmium in water.The effects of different materials on the preparation of three kinds of materials(manganese ethylenediamine phosphate,manganese hydrazine phosphate,manganese methyl-ammonium phosphate)prepared under different preparation conditions were studied.Class,different cationic concentrations,different adsorption times and the initial concentrations of different adsorbents on the adsorption of cadmium.The manganese ethylenediamine phosphate is a lamellar crystal with a thickness of 40 nm and length and width of about 4 ?m,The internal pore size is 2 nm and the microporous mesoporous material with a small proportion of 10-20 nm mesopores is 262.621 m2 / g.The manganese hydrazine phosphate is length of 2 ?m,width 1.8 ?m,a thickness of 200 nm laminated sheet material,the internal pore size was about 2 nm and the specific surface area was 224.127 m2 / g.The manganese methyl-ammonium phosphate is a columnar crystal with a length of about 15 ?m and a width of about 10 ?m.Its internal pore size is about 2 nm and the specific surface area is 82.410 m2 / g.Under the condition of cadmium concentration of 100 mg / L and manganese sulfate ethylenediamine(NMP(C2H8N2))0.2 g / L,the removal rate of cadmium could reach more than 94%.When the cadmium concentration was less than 50 mg / L Case,the removal rate can reach more than 99%.With the increase of cadmium concentration,the adsorption capacity of NMP(C2H8N2)increased gradually.When the concentration of cadmium reached 1000 mg / L,the adsorption capacity was 2601 mg / g.0.2 g / L manganese phosphate(NMP(N2H4))in the cadmium concentration at 100 mg / L removal rate of about 80%,with the cadmium concentration increased to 750 mg / L when the adsorption capacity increased to 2413 mg / g,while The adsorption capacity increased to 2635 mg / g at 1000 mg / L,and the curve trend was close to steady.(NMP(C4H13NO))content of 0.2 g / L,the removal rate of cadmium at 100 mg / L was only 42% and that of cadmium was 1000 mg / L,the maximum adsorption capacity was 1876 mg / G.The first two reach the adsorption equilibrium time is longer,close to 10 h,and NMP(C4H13NO)only need about 2h.In addition to the small effect of sodium ions on NMP(C2H8N2),the effects of the two cations on the adsorption of the three materials were significant,and the removal rate was higher,especially the effect of calcium ions.The reason is that the three materials Most of the adsorption is mainly ion exchange and complex adsorption,adsorption is calcium contention.PH as the most important part of the adsorption study,the three materials showed better acid resistance,and the removal effect at pH 4 was still not affected,and the optimum pH of NMP(C2H8N2)was 5,To adapt to the adsorption of cadmium in weak acid water.NMP(C2H8N2)accounts for 21.67% of cadmium,60.88% of complex adsorption and 17.45% of coordination and adsorption.NMP(N2H4)ion exchange accounts for 45% of cadmium,and 42.5 %,coordination adsorption accounted for 12.5%;NMP(C4H13NO)on the adsorption of cadmium more than 90% for the ion exchange effect,less than 10% for the coordination of adsorption.The difference in the adsorption properties of the three materials from the crystal form,specific surface area,pore size and cadmium is large.It is presumed that the chain type of the material is affected by the chain.The longer the chain is,the more obvious the sheet is,The larger the pore size,the shorter the chain type,the closer the interlayer spacing,the easy formation of columnar crystal form.The main elements of the three materials are nitrogen,phosphorus and manganese,and the decomposition of the unstable part will not cause secondary pollution to the environment.Phosphorus and nitrogen are all beneficial elements to the crops and have good biocompatibility.The pH of the contaminated irrigation water is almost 4.5-5.5,and the removal efficiency of cadmium in the three pH range is very small.Due to the difference of the adsorption capacity of the three materials,It was suggested that the removal efficiency of NMP(C2H8N2)was better,and it was suggested that the most important manganese phosphate diamine was the best.