In this study, we investigated the essential role of feed solution pH so as to gain insights into the transport mechanisms of succinic acid concentration by osmotically-driven forward osmosis （FO） process. FO perfor...In this study, we investigated the essential role of feed solution pH so as to gain insights into the transport mechanisms of succinic acid concentration by osmotically-driven forward osmosis （FO） process. FO performances including water flux and bidirectional transport of succinate and chloride anions were systematically examined using cellulose triacetate-based FO membrane. Additionally, real seawater was explored as draw solution. Experimental results revealed that the pH-dependent speciation of succinic acid can affect the FO performances. Ionization of succinic acid at higher solution pH enhanced the osmotic pressure of feed solution, thus leading to lower water flux performance. A strong effect was pointed out on the succinate rejection for which nearly 100% rejections were achieved at pH above its pKa2 value. The rejection of succinate increased in the following order of chemical form： C2H4C2O4H2 〈 C2H4C2OH- 〈 C2H4C2O24-. With real seawater as the draw solution, low to moderate water fluxes （〈4 L. m- 2. h- 1 ） were observed. The divalent succinate anion was highly retained in the feed side despite differences in the succinic acid feed concentration at pH of approximately 6.90.展开更多
Densities of aqueous solutions of eight amino acids, glycine, L-alanine, L-valine, L-isoleucine, L-serine, L-threonine, L-arginine and L-phenylalanine, are measured as a function of amino acid concentration from 293.1...Densities of aqueous solutions of eight amino acids, glycine, L-alanine, L-valine, L-isoleucine, L-serine, L-threonine, L-arginine and L-phenylalanine, are measured as a function of amino acid concentration from 293.15K to 333.15K. These data are used to calculate the apparent molar volume Vφ and infinite dilution apparent molar volume Vφo (partial molar volume). Data of five amino acids are used to correlate partial molar volume Vφo usinggroup contribution method to estimate the contributions of the zwitterionic end groups (NH3+,COO-) and CH2 group, OH group, CNHNHNH2 group and C6H5(phenyl) group of amino acids. The results show that Vφo values for all kinds of groups of amino acids studied increase with increase of temperature except those for CH2 group, which are almost constant within the studied temperature range. Data of other amino acids, L-valine, L-isoleucine and L-threonine, are chosen for comparison with the predicted partial molar volume Vφo using the group additivity parameters obtained. The results confirm that this group additivity method has excellent predictive utility.展开更多
基金the financial support for this work provided by the LRGS/2013/UKM-UKM/PT/03 grant from the Ministry of Education Malaysia
文摘In this study, we investigated the essential role of feed solution pH so as to gain insights into the transport mechanisms of succinic acid concentration by osmotically-driven forward osmosis （FO） process. FO performances including water flux and bidirectional transport of succinate and chloride anions were systematically examined using cellulose triacetate-based FO membrane. Additionally, real seawater was explored as draw solution. Experimental results revealed that the pH-dependent speciation of succinic acid can affect the FO performances. Ionization of succinic acid at higher solution pH enhanced the osmotic pressure of feed solution, thus leading to lower water flux performance. A strong effect was pointed out on the succinate rejection for which nearly 100% rejections were achieved at pH above its pKa2 value. The rejection of succinate increased in the following order of chemical form： C2H4C2O4H2 〈 C2H4C2OH- 〈 C2H4C2O24-. With real seawater as the draw solution, low to moderate water fluxes （〈4 L. m- 2. h- 1 ） were observed. The divalent succinate anion was highly retained in the feed side despite differences in the succinic acid feed concentration at pH of approximately 6.90.
基金the Educational Department Doctor Foundation of China (No. 2000005608).
文摘Densities of aqueous solutions of eight amino acids, glycine, L-alanine, L-valine, L-isoleucine, L-serine, L-threonine, L-arginine and L-phenylalanine, are measured as a function of amino acid concentration from 293.15K to 333.15K. These data are used to calculate the apparent molar volume Vφ and infinite dilution apparent molar volume Vφo (partial molar volume). Data of five amino acids are used to correlate partial molar volume Vφo usinggroup contribution method to estimate the contributions of the zwitterionic end groups (NH3+,COO-) and CH2 group, OH group, CNHNHNH2 group and C6H5(phenyl) group of amino acids. The results show that Vφo values for all kinds of groups of amino acids studied increase with increase of temperature except those for CH2 group, which are almost constant within the studied temperature range. Data of other amino acids, L-valine, L-isoleucine and L-threonine, are chosen for comparison with the predicted partial molar volume Vφo using the group additivity parameters obtained. The results confirm that this group additivity method has excellent predictive utility.
