2-methylpyridine

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption

Remarks:

adsorption

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Published in peer reviewed literature, limitations in design and/or reporting but otherwise adequate for assessment

Data source

Reference

Reference Type:

publication

Title:

Adsorption studies using gas-liquid chromatography-III. experimental factors influencing adsorption

Author:

Martin and Al-Bahrani

Year:

1978

Bibliographic source:

Water Rechearch Vol. 12. pp. 879 to 888 (1978)

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Article abstract by Martin and Al-Bahrani, 1978:
"Gas-liquid chromatography with a flame ionization detector system using the direct injection of aqueous solutions was used to monitor the adsorption of selected organic compounds in water onto activated carbon. The effects of changes in experimental factors influencing adsorption were investigated using both batch (agitated flask) and column (flow through packed bed) systems; solution pH and concentration, carbon particle size, carbon bed depth and flow rate were all studied. The direct injection of aqueous solutions was observed to facilitate the direct analysis of pollutants in water obviating the need for preliminary concentration or extraction steps."

GLP compliance:

no

Type of method:

other: both batch (agitated flask) and column (flow through packed bed) systems

Media:

other: In water onto activated carbon

Test material

Test material information

Constituent 1

Reference substance name:

2-methylpyridine

EC Number:

203-643-7

EC Name:

2-methylpyridine

Cas Number:

109-06-8

Molecular formula:

C6H7N

IUPAC Name:

2-methylpyridine

Details on test material:

- Name of test material (as cited in study report): 2-methylpyridine

Radiolabelling:

no

Study design

HPLC method

Details on study design: HPLC method:

EQUIPMENT
Gas-liquid chromatography with a flame ionization detector system using the direct injection of the aqueous solution. A 1.5 m long. 3.175 mm diameter Teflon column packed with 15% Carbowax 20 M on 85 x 100 mesh Universal B was used for all the analyses (Universal B support. supplied by Phase Separations Ltd.).

MOBILE PHASES
Oxygen-free nitrogen was used as a carrier gas.

Batch equilibrium or other method

Analytical monitoring:

yes

Details on matrix:

Adsorption to Type CAL 12 x 40 (U.S. sieve series) granular activated carbon supplied by Chemviron Ltd. (formerly Pittsburgh Activated Carbon Ltd.) was measured.

Details on test conditions:

The adsorption capacity and adsorption rate were determined

Results and discussion

Any other information on results incl. tables

The authors conclusive summary is:

"The results of the studies may be summarised as follows:

- In a rapidly mixed batch system, the rate of adsorption was controlled by intraparticle diffusion. In column systems, for the most part, film diffusion appeared to be the rate-limiting step for the transfer or solute to the carbon.

- Both the ionised and neutral species of pyridine, 2-methylpyridine and o-cresol were adsorbed on activated carbon; the adsorption of ionised species was more affected by variation in solution pH. The pH effect on adsorption appeared to be mainly due to the competitive effect of hydrogen ions and acid adsorption and the effect of pH variation on the nature of the activated carbon surface.

- Decrease in particle size had no noticeable effect on the total carbon capacity for adsorption. In column systems, the realised carbon capacity for adsorption at breakpoint increased linearly with decrease in particle size.

- The rate of adsorption on carbon increased with decrease in carbon particle size. However, for a particle size below 0.4 mm, the rate or increase in uptake rate was considerably decreased which indicated that little would be gained by using carbon particles smaller than 0.4 mm. In the column system, the time required to reach the breakpoint increased linearly with decrease in particle size. After the breakpoint however, the approach to the exhaustion capacity of the carbon column speeded up with decreasing particle size.

- The rate of adsorption on carbon increased with increase in initial solution concentration. In the column system, the realised carbon capacity for 2-methylpyridine adsorption at breakpoint increased sharply with increase in initial concentration from 1.04 mg/L to 23.6 mg/L but was only slightly increased by a further increase in initial concentration.

- The breakpoint time of a carbon column varied with the carbon bed depth. Although the realised carbon capacity for adsorption at breakpoint increased at a decreasing rate with increase in carbon bed depth, the exhaustion capacity of the carbon column was not affected by the increase in bed depth.

- An increase in the flow rate through the carbon bed from 5.2 to 11.0 m³m^-2h^-1 had little effect on the rate of uptake of 2-methylpyridine on the carbon column.

- For single solute solutions, it was possible to predict the carbon column behaviour from results obtained in batch type experiments. (For solutions containing a complex mixture of organic material however, data obtained from batch type experiments could underestimate the capacity of the activated carbon for adsorption when used in column systems; Martin & Al-Bahrani, 1977.)

- Gas-liquid chromatography with a flame ionization detector system using the direct injection of aqueous solutions was found to be an excellent technique for monitoring the adsorption process for both mono and multi-solute solutions. The injection of aqueous solutions facilitates direct analysis of potential pollutants without the errors which inevitably accompany preliminary concentration or extraction steps. Rapidity, precision, convenience and a reasonable degree of sensitivity were all repeatedly observed; the monitoring of concentrations below 0.1 mg/L would necessitate a more sophisticated detection system such as mass spectrometry."