土壌燐酸の固定とその有効化に関する研究(第3報) : モンモリロナイト系

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The aspects of phosphate fixation in pure chemical solution was covered in the previous paper of this series. The present paper dealt with the interaction between H_3P0_4 and montmollironite clays at various pH values. the minerals studied were TUYAMA-, ARIMA (pink)-, and ARIMA (yellow)-bentonites. The methods used for studying phosphate fixation were similar as those reported in the preceding papers and briefly are as follows : Five grams of mineral was mixed with 90ml of N/120 H_3P0_4 and adequate NaOH or HCl to adjust pH values. The mixture was incubated at 30℃ for 5days with occational shaking. The pH value of the mixture was determined with glass electrode and then the mineral was centrifuged, and the fixed phosphate was obtained from the difference between the amount of added phosphorus and that left in solution. The phosphorus determination was carried out by the Sherman's sulfonic acid method. As preliminary treatments the sample minerals were a) ground to pass a 100mesh sieve by means of a porcelain mortar and pestle ("ground Natural-clay"), b) suspended to pass a 0.25 mm sieve without grinding ("unground Natural-clay"), c) leached with 0.2N HCl("unground Hydrogen clay"), and d) leached with 0.2N HCl after grinding ("ground Hydrogen-clay "). The results obtained were as follows : 1) The interaction between H_3P0_4 and bentonites took place rapidly and reached equilibrium within a few days. 2) The lower the amount of phosphorus added, the higher the phosphorus fixation ratio, whereas, the amount of fixation was lower. 3) The pH range where the peak had appeared tended to shift towards alkaline side with decreasing phosphate concentration. 4) The grinding of bentonite exerted no influence upon the type of phosphate fixation. 5) A comparison between the fixation curves of the natural bentonite and the 0.2N HCl leached bentonite showed the fact that in the natural bentonite only one peak occurred at pH3,while in the leached bentonite besides the high peak at pH 3,and there was another peak at pH 6. It was assumed from the present experiment in some detail that these two peaks appeared at pH values of 3 and 6 were probably due to iron and aluminium, respectively. 6) Moreover, the retention of phosphate increased again at pH above 9,when the natural bentonite was used. On the other hand, in the leached bentonite there was no increase above pH 9. This increase in the alkaline range was possibly regarded as due to the presence of calcium ion. 7) ARIMA (yellow)-bentonite in natural state had shown alreadly two peaks at pH 3 and 6,before the treatment by 0.2N HCl leaching, hence this mineral was much more rich in exchangeable aluminium ion than the other clay minerals employed.
社団法人日本土壌肥料学会の論文
1956-07-05

土壌燐酸の固定とその有効化に関する研究(第3報) : モンモリロナイト系

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