Wyniki wyszukiwania - BazTech

1

Retention efficiency of vegetative filter strips for nitrogen in Danjiangkou Reservoir area, Central China

Lei Junshan, Chen Jiazhou, Yin Wei

Ecological Chemistry and Engineering. S

|

2019

|

Vol. 26, nr 2

279--297

EN

To investigate the retention efficiency and mechanism of nitrogen of Vegetative filter strips (VFSs) in the Danjiangkou Reservoir area, simulated runoff discharging experiments were carried out in a new-established Bermuda VFS. The results showed that the Bermuda VFS reduced 73.1-86.1 % of surface runoff through infiltration. The outflow rate of runoff increased first and then became stable with time. The concentration reduction rates (CRRs) and load reduction rates (LRRs) of NH3-N increased initially and then decreased with the increase of inflow concentration. The average CRRs and LRRs of NH3-N in three treatments ranged 66.1-90.3 % and 90.0-96.7 %, respectively. The concentration reduction of NH3-N was primarily achieved by soil adsorption. The optimal inflow concentration of NH3-N for the optimum CRR was between 0.65 and 3.52 mg/dm3. The CRRs and LRRs of NO3-N fluctuated between 6.8-14.0 % and 72.0-77.9 % in three treatments. The concentration reduction of NO3-N was primarily achieved by plant uptake and soil microbe assimilation. The optimal inflow concentration of NO3-N for optimum CRR exceeded 6.78 mg/dm3. The CRRs and LRRs of TN increased with the increase of inflow concentrations. The average CRRs in the low, moderate and high treatments reached 9.7, 14.8 and 27.4 %, respectively, and the average LRRs reached 72.1, 74.3 and 81.2 %, respectively. The optimal inflow concentration of TN for optimum CRR exceeded 10.21 mg/dm3. The study showed that Bermuda grass can retain nitrogen in runoff efficiently and should be promoted around the Danjiangkou reservoir.

2

Relationship between micellar liquid chromatography retention of sulfonamides and the pH and concentration of surfactants and organic modifiers in the mobile phase

Szymański A.

Ars Separatoria Acta

|

2011

|

No. 8

51-67

EN

The paper presents an attempt to adapt a retention model suggested and verified by classic RP LC in micellar liquid chromatography, MLC. Instead of hydrophobic interactions with ODS groups and electrostatic interactions with silanol residues in C-18 packing, hydrophobic interactions with alkyl groups and ionic interactions with anionic moieties of the SDS-modified stationary phase were considered. Due to the different characteristics of the stationary phase in the MLC depending on the pH of the mobile phase, the equation used to determine the contribution of electrostatic interactions to retention was modified. Theoretical curves for the relationship between retention and SDS micelle concentration in the mobile phase, organic modifier concentration and eluent pH were determined. For comparison, curves based on data obtained in basic sulfonamide studies were plotted in the same coordinate systems and units. A complete qualitative similarity was noted between the theoretical curves predicting retention changes with changing micellar mobile phase parameters and the curves determined based on experimental results for the sulfonamides. The qualitative similarity involves a similar shape of the respective curves and identical tendencies. In general, a larger reduction of sulfonamide retention with respect to the predicted value is noted. The deviation results from changes in the sulfonamide property with changing pH of the mobile phase.

3

Unexpected aliphatic acid peak profiles — Preliminary investigations

Zapała W., Kostka J, Kaczmarski K.

Acta Chromatographica

|

2011

|

Vol. 23, no. 4

673--679

EN

A hypothetical retention mechanism is proposed for the modeling of the strongly distorted peak profiles of four aliphatic acids on the Acclaim RS PA2 column. The obtained experimental band profiles are mathematically described with the modified POR model of the chromatographic column.

4

Salting-out chromatography : a practical review

Komsta Ł., Skibiński R., Bojarczuk A, Radoń M.

Acta Chromatographica

|

2011

|

Vol. 23, no. 2

191--203

EN

This review focuses on the salting-out effect and its use in chromatographic analysis, mainly thin-layer chromatography. First, a theoretical background is given, focusing on the general salting-out theory and a comparison with chaotropic salt addition, practised recently in reversed-phase chromatography. All the salting-out chromatographic applications in literature (from the 1960s to the present moment) are then reviewed.