Adsorption of four perfluorinated acids on non ion exchange polymer sorbents.

Perfluorinated compounds (PFCs) have attracted global concern due to their ubiquitous distribution and properties of persistence, bio accumulation and toxicity. The process of adsorption has been identified as an effective technique to remove PFCs in water. Different non ion-exchange polymeric adsorbents were tested with regard to their sorption kinetics and isotherms at low PFCs concentrations. Selected PFCs were perfluorobutanoic acid (PFBA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA) and perfluorodecanoic acid (PFDA) and the tested polymers were three types of Dowex optopores (V-493, V503, and L493), Amberlite XAD-4, and Filtrasorb 400 (Granular Activated Carbon-GAC). We observed the selective adsorption of PFCs on synthetic polymers. For PFDA, Amberlite XAD-4 gave the Freundlich adsorption constant of 2,965 (microg PFCs/g sorbent)(microg PFCs/L)(-n), which was higher than that of GAC (121.89 (microg PFCs/g sorbent) (microg PFCS/L)(-n)). In the case of PFBA, GAC showed better performance (13.36) (microg PFCs/g sorbent) microg PFCS/L)(-n) than synthetic polymers (0.62-5.23) (microg PFCs/g sorbent) (microg PFCS/L)(-n). Adsorption kinetics of all adsorbents were well described (R2 = 0.85-1) by pseudo-second order kinetic model. Sorption capacity was influenced by initial PFCs concentration for all adsorbents. GAC reached the equilibrium concentration within 4 hours, Amberlite XAD 4 reached it within 10 hours and other polymers took more than 70 hours.

A comparative study of adsorption of perfluorooctane sulfonate (PFOS) onto granular activated carbon, ion-exchange polymers and non-ion-exchange polymers.

Perfluorooctane sulfonate (PFOS) is the latest chemical categorized as persistent organic pollutants (POPs). PFOS appears in the environmental water and tap water in ng L(-1) level. The process of adsorption has been identified as an effective technique to eliminate PFOS in water. Three non-ion-exchange polymers (DowV493, DowL493 and AmbXAD4), two ion-exchange polymers (DowMarathonA and AmbIRA400) and one granular activated carbon (GAC) (Filtersorb400) were tested with regard to their sorption kinetics and isotherms at low PFOS concentrations (100-1000 ng L(-1) equilibrium concentrations). The sorption capacities at 1 microg L(-1) equilibrium concentration decreased in the following order: ion-exchange polymers>non-ion-exchange polymers > GAC, but at further low equilibrium concentration (100 ng L(-1)) non-ion-exchange polymers showed higher adsorption capacity than other adsorbents. In the case of sorption kinetics, GAC and ion-exchange polymers reached the equilibrium concentration within 4 h and AmbXAD4 within 10 h. DowV493 and DowL493 took more than 80 h to reach equilibrium concentration. AmbIRA400 was identified as the best filter material to eliminate PFOS at equilibrium concentration > 1000 ng L(-1). Considering both adsorption isotherms and adsorption kinetics, AmbXAD4 and DowMarathonA were recommended to eliminate PFOS at ng L(-1) equilibrium concentration.

Analysis of parameter variations in L-Q equations for river runoff processes from the viewpoint of spatial and temporal conditions.

This study aims to find out variation characteristics of the parameters of 'a' and 'b' in L = a x Q(b), an empirical equation for run-off loading (L) and flow rate (Q), by evaluating the effects of flow conditions and regional properties of the watersheds on the values. We selected the Kamo River basin (155 km2) as a study field, and conducted various kinds of investigations, such as 80 day high frequency observations, continuous monitoring for more than 2 years, storm event surveys, and simultaneous surveys of 39 stations. Then, we obtained 7-170 data in each of 39 sampling stations. The main results obtained are as follows: (1) L-Q equation with a range of 'a' can express L-Q relation in most of the WQIs (water quality indices); (2) 'a' receives temporal (flow condition) effects more in SS, VSS and Al, while it receives regional effect more in inorganic carbon, TN, Ca and Fe; (3) both of flow change in storm events, and base flow levels affect the L-Q relation, and their effects can classify the WQIs into several groups; (4) the effects of regional properties were obviously observed in 'a', and quantitatively evaluated, especially for density of population.