The products of monoammonium phosphate containing Cr^3+resulted in disqualification,and further posed a serious threat to ecological environment and human beings.Herein,the porous adsorbent of fluor(calcium silicate)c...The products of monoammonium phosphate containing Cr^3+resulted in disqualification,and further posed a serious threat to ecological environment and human beings.Herein,the porous adsorbent of fluor(calcium silicate)composites(FCSc)was prepared by hydrothermal method using diatomaceous earth,hydrated lime and additive(NaF)as raw materials,which was characterized and used for the removal of Cr^3+from monoammonium phosphate solutions.The effects of different parameters,such as solution pH,initial Cr^3+concentration,temperature and contact time on the adsorption of Cr^3+onto FCSc were investigated in details.The results indicated that the adsorption process was in agreement with the pseudo-second-order kinetic model and Freundlich isotherm.The spontaneous and endothermic nature of the adsorption process was obtained by analyzing various thermodynamic parameters(△G0,△H0,and△S0).In addition,computational monte carlo simulations between Cr3+ions and FCSc were conducted to elucidate the adsorption mechanism.Such kind of porous adsorbent provided a potential application in the removal of impurities from monoammonium phosphate industry.展开更多
Monoammonium phosphate （MAP） is produced from crude phosphoric acid which contains Fe （III）, AI （III） and Mg （II） ions. In general, the fertilizers MAP was obtained by including various heavy metal micronutrie...Monoammonium phosphate （MAP） is produced from crude phosphoric acid which contains Fe （III）, AI （III） and Mg （II） ions. In general, the fertilizers MAP was obtained by including various heavy metal micronutrients （Co, Cu, Fe, Mn, Mo, Ni and Zn）, fluorine and heavy metals considered toxic （Al and Cd） in. The long-continued application of phosphate fertilizers （MAP） and their by products can redistribute and elevate heavy metal and fluorine concentrations in soil profiles. However, they are subsequently transferred into the human food chain because of their availability to plants, mainly in acid soils. Thus, it is important to eliminate the impurities in MAP. Purified MAP is three times more expensive than the same product before purification and is commonly used in a number of applications such as flame proofing （building materials, pulp and paper） and agriculture. Purified MAP is a key ingredient in specialty all-soluble dry fertilizers, waste water-nutrient for biological purification, fermentation and biotechnology-nutrient. The procedure for purification of industrial MAP is a recrystallization, by using several mixtures of solvents. The physicochemical characterization of this fertilizer upstream and downstream from the purification, through spectroscopic analyses and chemical analyses, shows that recrystallization can eliminate impurities. The physicochemical properties of the purified MAP obtained by recrystallization are comparable to those of the MAP obtained with a pure phosphoric acid.展开更多
基金the National Natural Science Foundation of China(U1633203)the Major Project of the Civil Aviation Administration of China(J2020-108)。
文摘The products of monoammonium phosphate containing Cr^3+resulted in disqualification,and further posed a serious threat to ecological environment and human beings.Herein,the porous adsorbent of fluor(calcium silicate)composites(FCSc)was prepared by hydrothermal method using diatomaceous earth,hydrated lime and additive(NaF)as raw materials,which was characterized and used for the removal of Cr^3+from monoammonium phosphate solutions.The effects of different parameters,such as solution pH,initial Cr^3+concentration,temperature and contact time on the adsorption of Cr^3+onto FCSc were investigated in details.The results indicated that the adsorption process was in agreement with the pseudo-second-order kinetic model and Freundlich isotherm.The spontaneous and endothermic nature of the adsorption process was obtained by analyzing various thermodynamic parameters(△G0,△H0,and△S0).In addition,computational monte carlo simulations between Cr3+ions and FCSc were conducted to elucidate the adsorption mechanism.Such kind of porous adsorbent provided a potential application in the removal of impurities from monoammonium phosphate industry.
文摘Monoammonium phosphate （MAP） is produced from crude phosphoric acid which contains Fe （III）, AI （III） and Mg （II） ions. In general, the fertilizers MAP was obtained by including various heavy metal micronutrients （Co, Cu, Fe, Mn, Mo, Ni and Zn）, fluorine and heavy metals considered toxic （Al and Cd） in. The long-continued application of phosphate fertilizers （MAP） and their by products can redistribute and elevate heavy metal and fluorine concentrations in soil profiles. However, they are subsequently transferred into the human food chain because of their availability to plants, mainly in acid soils. Thus, it is important to eliminate the impurities in MAP. Purified MAP is three times more expensive than the same product before purification and is commonly used in a number of applications such as flame proofing （building materials, pulp and paper） and agriculture. Purified MAP is a key ingredient in specialty all-soluble dry fertilizers, waste water-nutrient for biological purification, fermentation and biotechnology-nutrient. The procedure for purification of industrial MAP is a recrystallization, by using several mixtures of solvents. The physicochemical characterization of this fertilizer upstream and downstream from the purification, through spectroscopic analyses and chemical analyses, shows that recrystallization can eliminate impurities. The physicochemical properties of the purified MAP obtained by recrystallization are comparable to those of the MAP obtained with a pure phosphoric acid.
