The solubilities of myofibrillar proteins (MPs) increased monotonically with increasing NaCl concentration at pH = pI (isoelectric point), but decreased monotonically with increasing NaCl concentration at pH < pI. At pH > pI, the solubilities decreased initially, but increased with increasing NaCl concentrations from 0.2 to 0.8 M. For chloride salts, the “salt in” effect of cations decreased in the order: Li + > Na + > K + > Rb + . For sodium salts, the “salt in” effect of anions decreased in the sequence: Cl¯ > Br¯ > I¯ > SCN¯. The “salt in” effect of cations were stronger than that of anions. No evidence of increased electrostatic interaction was found during “salt in”. Presence of CH 3 COO¯ decreased the solubilization effect of Na + . These results indicate the “salt in” of MPs is more affected by the cations with higher degree of hydration, which may be interfered by the presence of highly hydrated anions.
Peng Feng,Donghai Xu,Kunkun Song,Gang Yin,Guanyu Jiang,Yang Yang,Yaling He
Supercritical water oxidation efficiently degrades organic waste but faces challenges from salt deposition due to the low solubilities of salts in supercritical water (SCW). This study investigated the characteristics and mechanisms of dissolution and deposition of mixed sulfate and chloride salts in SCW. At low water densities the common ion effect was observed in Na 2 SO 4 /K 2 SO 4 mixtures. Na + tended to occupy the junctions between SO 4 2- , while K + tended to occupy the cluster endings. Due to the weaker electrostatic interaction between K + (with larger ionic radius) and SO 4 2- , large and medium-sized clusters were more prone to decomposition in K + -rich solutions. K 2 SO 4 induced a “salting-in” effect on Na 2 SO 4 , whereas Na 2 SO 4 exerted a “salting-out” effect on K 2 SO 4 at high water densities. Both sulfates exhibited heterogeneous nucleation, depositing on heated sidewalls as nucleation sites, with Na 2 SO 4 proving more difficult to remove than K 2 SO 4 . In KCl/Na 2 SO 4 mixtures, homogeneously nucleated chloride salts created many preferential nucleation sites for Na 2 SO 4 deposition.
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