Boric acid and kieserite were prepared from low-grade ascharite by sulfuric acid method.This method results in the recovery of 71.06%and 45.03%for boric acid and kieserite,respectively.Meanwhile,the boric acid was pre...Boric acid and kieserite were prepared from low-grade ascharite by sulfuric acid method.This method results in the recovery of 71.06%and 45.03%for boric acid and kieserite,respectively.Meanwhile,the boric acid was precipitated from the filtrate at low temperature and the solution was recycled without discharging waste liquid in the whole process.The influence of amount of sulfuric acid,mass fraction of sulfuric acid,reaction temperature and reaction time on the leaching rate of boric acid were studied. The results show that the leaching rate of boric acid reaches 93.80%under the following conditions:the amount of sulfuric acid is 85%of theoretical dosage;the mass fraction of sulfuric acid is 25%;reaction temperature is 95℃;and the reaction time is 100 min. Meanwhile,the effects of mass fraction of magnesium sulfate,crystallization temperature and crystallization time on the crystallization of kieserite were investigated and the optimal crystallization conditions are obtained:the mass fraction of magnesium sulfate is 28%;the crystallization temperature is 180℃and the crystallization time is 4h.展开更多
The reduction of Cr（Ⅵ） in aqueous solution by using bauxite ore was investigated.Experimental results for Cr（Ⅵ）reduction in aqueous solution depending on some factors such as time,sulfuric acid amount,bauxite do...The reduction of Cr（Ⅵ） in aqueous solution by using bauxite ore was investigated.Experimental results for Cr（Ⅵ）reduction in aqueous solution depending on some factors such as time,sulfuric acid amount,bauxite dosage,initial Cr（Ⅵ）concentration,formic acid concentration,daylight and temperature were presented.The obtained results show that sulfuric acid amount,bauxite dosage and initial Cr（Ⅵ） concentration of solution are most effective parameters on the reduction process.Also,it has been found that the 60 g/L of bauxite dosage is sufficient to reduce up to 100% of Cr（Ⅵ） from acidic solution under the condition of low initial Cr（Ⅵ） mass concentrations such as 10 mg/L.The reduction reaction is completed within 30 min at 25 ℃ under the experimental conditions：bauxite dosage of 60 g/L,amount of sulfuric acid 40-60 stoichiometric and initial mass concentration of Cr（Ⅵ）,10 mg/L.It was determined that reduction percentage is decreasing with increasing initial Cr（Ⅵ） concentration.The chemical oxygen demand of bauxite ore was found to be 26 mg COD/g.展开更多
SO2 is very rapidly hydrated to sulfurous acid in water solution at pH value above 6.0, whereby sulfite is yielded from the disassociation of protons. We aimed to improve the sulfite transformation efficiency and prov...SO2 is very rapidly hydrated to sulfurous acid in water solution at pH value above 6.0, whereby sulfite is yielded from the disassociation of protons. We aimed to improve the sulfite transformation efficiency and provide a basis for the direct utilization of SO2 from flue gas by a microalgal suspension. Chlorella sp. XQ-20044 was cultured in a medium with 20 mmol/L sodium sulfite under different physicochemical conditions. Under light conditions, sulfite concentration in the algal suspension reduced linearly over time, and was completely converted into sulfate within 8 h. The highest sulfite transformation rate （3.25 mmol/ （L.h）） was obtained under the following conditions： 35℃, light intensity of 300 μmol/（m^2·s）, NaHCO3 concentration of 6 g/L, initial cell density （OD540） of 0.8 and pH of 9-10. There was a positive correlation between sulfite transformation rate and the growth of Chlorella, with the conditions favorable to algal growth giving better sulfite transformation. Although oxygen in the air plays a role in the transformation of SO3^2- to SO^2-, the transformation is mainly dependent on the metabolic activity of algal cells. Chlorella sp. XQ-20044 is capable of tolerating high sulfite concentration, and can utilize sulfite as the sole sulfur source for maintaining healthy growth. We found that sulfite 〈20 mmol/L had no obvious effect on the total lipid content and fatty acid profiles of the algae, Thus, the results suggest it is feasible to use flue gas for the mass production of feedstock for biodiesel using Chlorella sp. XQ-20044, without preliminary removal of SO2, assuming there is adequate control of the pH.展开更多
Lipids were extracted from organs of the starfish Asterias amurens＆ associated with different treatments （raw-control, boiling and heating）, and then analyzed for lipid content, lipid oxidation index, lipid classes...Lipids were extracted from organs of the starfish Asterias amurens＆ associated with different treatments （raw-control, boiling and heating）, and then analyzed for lipid content, lipid oxidation index, lipid classes and fatty acid composition. Results showed that boiling softened the hard starfish shells, thus facilitating the collection of starfish organs. As compared with raw organs, the boiled organs had lower water content and higher lipid content, possibly due to the loss of water-holding capacity caused by pro- tein denaturation. Both boiling and heating increased the peroxide value （PV）, thiobarbituric acid （TBA） value and carbon value （CV） of lipids. Despite slight increases in the content of complex lipids, associated lipid composition had no substantial variations upon boiling and heating. For simple lipids, the content of 1, 2-diglyceride decreased in boiled and heated organs, with free fatty acids observed on thin layer chromatography （TLC）. However, neither boiling nor heating significantly changed the fatty acid composi- tions of simple or complex lipids in starfish organs, suggesting that these two treatments had no significant effects on complex lipids in starfish organs. Together, our results indicated that boiling of starfish soon after capture facilitated the handling and extraction of useful complex lipids consisting of abundant glucosylceramide and eicosapentaenoic acid （EPA）-bounded phospholipids.展开更多
Metam sodium （MS; sodium N-methyl dithiocarbamate） has emerged as a promising soil fumigant in the US to replace methyl bromide （MeBr）. Metam potassium （MK; potassium N-methyl dithiocarbamate） and MS break down ...Metam sodium （MS; sodium N-methyl dithiocarbamate） has emerged as a promising soil fumigant in the US to replace methyl bromide （MeBr）. Metam potassium （MK; potassium N-methyl dithiocarbamate） and MS break down into the volatile gas methyl isothiocyanate （MITC） to control soil borne pests. Many studies have focused on MS, but MK has not been studied as thoroughly. The objective of this research was to determine the effect of increasing organic matter （OM） treatments and soil texture to minimize the off-gassing of MS and MK. Bench-scale soil column studies were performed to simulate organic matter treatments that may decrease the volatilization loss of MITC. Incorporation depth of OM simulated surface tillage （0-15 cm） practices. Soil was packed in steel columns and MS or MK was applied at a depth of 15 cm and MITC volatilization was measured using gas chromatography/mass spectroscopy. Volatilization of MITC behaved similarly for MS and MK with MITC movement impacted by soil texture. MITC volatilization was lower from a sandy clay loam than a sandy soil. Surface incorporation of OM did not significantly decrease MITC volatilization. These results suggest that soil texture is the dominant factor reducing MITC off-gassing and prolonging the time needed to control soil borne pests.展开更多
基金Project(2006AA06Z368) supported by the National High-tech Research and Development Program of China
文摘Boric acid and kieserite were prepared from low-grade ascharite by sulfuric acid method.This method results in the recovery of 71.06%and 45.03%for boric acid and kieserite,respectively.Meanwhile,the boric acid was precipitated from the filtrate at low temperature and the solution was recycled without discharging waste liquid in the whole process.The influence of amount of sulfuric acid,mass fraction of sulfuric acid,reaction temperature and reaction time on the leaching rate of boric acid were studied. The results show that the leaching rate of boric acid reaches 93.80%under the following conditions:the amount of sulfuric acid is 85%of theoretical dosage;the mass fraction of sulfuric acid is 25%;reaction temperature is 95℃;and the reaction time is 100 min. Meanwhile,the effects of mass fraction of magnesium sulfate,crystallization temperature and crystallization time on the crystallization of kieserite were investigated and the optimal crystallization conditions are obtained:the mass fraction of magnesium sulfate is 28%;the crystallization temperature is 180℃and the crystallization time is 4h.
文摘The reduction of Cr（Ⅵ） in aqueous solution by using bauxite ore was investigated.Experimental results for Cr（Ⅵ）reduction in aqueous solution depending on some factors such as time,sulfuric acid amount,bauxite dosage,initial Cr（Ⅵ）concentration,formic acid concentration,daylight and temperature were presented.The obtained results show that sulfuric acid amount,bauxite dosage and initial Cr（Ⅵ） concentration of solution are most effective parameters on the reduction process.Also,it has been found that the 60 g/L of bauxite dosage is sufficient to reduce up to 100% of Cr（Ⅵ） from acidic solution under the condition of low initial Cr（Ⅵ） mass concentrations such as 10 mg/L.The reduction reaction is completed within 30 min at 25 ℃ under the experimental conditions：bauxite dosage of 60 g/L,amount of sulfuric acid 40-60 stoichiometric and initial mass concentration of Cr（Ⅵ）,10 mg/L.It was determined that reduction percentage is decreasing with increasing initial Cr（Ⅵ） concentration.The chemical oxygen demand of bauxite ore was found to be 26 mg COD/g.
基金Supported by the National Natural Science Foundation of China(No.CNSF31272680)the National High Technology Research and Development Program of China(No.2013AA065805)
文摘SO2 is very rapidly hydrated to sulfurous acid in water solution at pH value above 6.0, whereby sulfite is yielded from the disassociation of protons. We aimed to improve the sulfite transformation efficiency and provide a basis for the direct utilization of SO2 from flue gas by a microalgal suspension. Chlorella sp. XQ-20044 was cultured in a medium with 20 mmol/L sodium sulfite under different physicochemical conditions. Under light conditions, sulfite concentration in the algal suspension reduced linearly over time, and was completely converted into sulfate within 8 h. The highest sulfite transformation rate （3.25 mmol/ （L.h）） was obtained under the following conditions： 35℃, light intensity of 300 μmol/（m^2·s）, NaHCO3 concentration of 6 g/L, initial cell density （OD540） of 0.8 and pH of 9-10. There was a positive correlation between sulfite transformation rate and the growth of Chlorella, with the conditions favorable to algal growth giving better sulfite transformation. Although oxygen in the air plays a role in the transformation of SO3^2- to SO^2-, the transformation is mainly dependent on the metabolic activity of algal cells. Chlorella sp. XQ-20044 is capable of tolerating high sulfite concentration, and can utilize sulfite as the sole sulfur source for maintaining healthy growth. We found that sulfite 〈20 mmol/L had no obvious effect on the total lipid content and fatty acid profiles of the algae, Thus, the results suggest it is feasible to use flue gas for the mass production of feedstock for biodiesel using Chlorella sp. XQ-20044, without preliminary removal of SO2, assuming there is adequate control of the pH.
基金supported by the International Science and Technology Cooperation Program of China(GrantNo.2010DFA31330)partically by the Sakura Program of Japan Society for Promotion of Science
文摘Lipids were extracted from organs of the starfish Asterias amurens＆ associated with different treatments （raw-control, boiling and heating）, and then analyzed for lipid content, lipid oxidation index, lipid classes and fatty acid composition. Results showed that boiling softened the hard starfish shells, thus facilitating the collection of starfish organs. As compared with raw organs, the boiled organs had lower water content and higher lipid content, possibly due to the loss of water-holding capacity caused by pro- tein denaturation. Both boiling and heating increased the peroxide value （PV）, thiobarbituric acid （TBA） value and carbon value （CV） of lipids. Despite slight increases in the content of complex lipids, associated lipid composition had no substantial variations upon boiling and heating. For simple lipids, the content of 1, 2-diglyceride decreased in boiled and heated organs, with free fatty acids observed on thin layer chromatography （TLC）. However, neither boiling nor heating significantly changed the fatty acid composi- tions of simple or complex lipids in starfish organs, suggesting that these two treatments had no significant effects on complex lipids in starfish organs. Together, our results indicated that boiling of starfish soon after capture facilitated the handling and extraction of useful complex lipids consisting of abundant glucosylceramide and eicosapentaenoic acid （EPA）-bounded phospholipids.
文摘Metam sodium （MS; sodium N-methyl dithiocarbamate） has emerged as a promising soil fumigant in the US to replace methyl bromide （MeBr）. Metam potassium （MK; potassium N-methyl dithiocarbamate） and MS break down into the volatile gas methyl isothiocyanate （MITC） to control soil borne pests. Many studies have focused on MS, but MK has not been studied as thoroughly. The objective of this research was to determine the effect of increasing organic matter （OM） treatments and soil texture to minimize the off-gassing of MS and MK. Bench-scale soil column studies were performed to simulate organic matter treatments that may decrease the volatilization loss of MITC. Incorporation depth of OM simulated surface tillage （0-15 cm） practices. Soil was packed in steel columns and MS or MK was applied at a depth of 15 cm and MITC volatilization was measured using gas chromatography/mass spectroscopy. Volatilization of MITC behaved similarly for MS and MK with MITC movement impacted by soil texture. MITC volatilization was lower from a sandy clay loam than a sandy soil. Surface incorporation of OM did not significantly decrease MITC volatilization. These results suggest that soil texture is the dominant factor reducing MITC off-gassing and prolonging the time needed to control soil borne pests.
