Speciation of organic matter in natural waters—interaction of polyacrylates and polymethacrylates with major cation components of seawater

✍ Scribed by Concetta De Stefano; Antonio Gianguzza; Daniela Piazzese; Silvio Sammartano

• Publisher: Elsevier Science
• Year: 2004
• Tongue: English
• Weight: 200 KB
• Volume: 86
• Category: Article
• ISSN: 0304-4203
• DOI: 10.1016/j.marchem.2003.12.001

✦ Synopsis

The speciation of some high molecular weight polycarboxylates was studied in different ionic media. Polyacrylates here investigated (W=2.0, 5.1 and 20.0 kDa) form weak species with alkali metal cations (K=10 2 mol l À1 , t=25 jC, I=0 mol l À1 ) and quite stable complexes with alkaline earth metal cations (K >10 6 mol l À1 , t=25 jC, I=0 mol l À1 ). Results are reported from experiments performed in a multicomponent electrolyte solution simulating the major composition of seawater (artificial seawater). Protonation constants in this medium are expressed as a polynomial function of S 1/2 (S=salinity) and the sharp lowering with respect to values obtained in non-interacting aqueous tetraalkylammonium salts can be ascribed to the formation of alkali and alkaline earth cation complexes. A simplified approach, according to which the seawater salt is considered as a single 1:1 salt, was used to describe the total interacting ability of the major components of seawater towards polyacrylates. Protonation and complex formation data are reported as a function of the degree of proton dissociation and of the molecular weight: empirical equations to take into account these functions are also given.