Organic compounds in sludges 239
hydroxide, reprecipitated with 0.5 m hydrochloric acid, washed thoroughly in distilled
water and dried in a vacuum desiccator. Each of the isolated fractions (including fulvic
acid) was weighed and an aliquot was dissolved in ethylene diamine for carboxyl and
phenolic hydroxyl determination. Another aliquot dissolved in 0.25 M sodium hydroxide was used for molecular sieving. The acidic functional groups were determined by
potentiometric titration in non-aqueous medium, using a platinum-saturated calomel
electrode combination [199]. 0.1 M solution of sodium aminoethoxide in ethylene
diamine, calibrated against benzoic acid, was used as titrant. To avoid interferences of
carbon dioxide from the air, the titrations were carried out in a current of nitrogen.
The molecular weight distribution was examined by fractionation on Sephadex
gels G-25, G-50 and G-75 having exclusion limits of 100–1000, 500–10 000 and 1000–
50 000 (by dextrans), respectively. For evaluating the molecular weight distribution,
the elution patterns from the three gels were considered. These areas corresponding to
the respective ranges of molecular weight were measured and expressed as a percentage
of the total area included under the elution pattern from G-25.
The infrared spectra of humic and fulvic acids isolated from secondary effluents
are fairly similar. The adsorption bands (cm
−1 ) are in the regions of: 3400, hydrogenbonded OH; 2980, 2940, 2860, 1460, methylene and methyl stretching; 1730, C=O
of carboxyl and ketonic carbonyl; 1630, amine carbonyl or aromatic C=C; 1270,
1130, 1080, carbon-oxygen bond stretching; which is in agreement with the results of
other investigations [201].
Sposito et al [201] used
13 C and proton NMR spectroscopy to investigate fulvic
acid extracted from sewage sludge. Carbon-13 NMR spectroscopy was found to be
useful for studying the organic structure found in fulvic acids.
10.8.5 Sucralose
Minten et al [202] have described a method for the determination of sucralose using
in sewage effluents electrospray liquid chromatography/mass spectrometry in sewage
effluent which had been subjected to tertiary treatment technologies.
10.8.6 Organic carbon
Coulomb et al [203] have described an ultraviolet spectroscopic procedure for the
determination of total organic carbon in marine carbon sewage.
10.8.7 Miscellaneous
Other miscellaneous substances that have been determined in sewage include phenylsulphonyl sarcosine [204], ditallow dimethyl ammonium [205], α-hydroxy butyrate
[206] and α-hydroxy valerate.
10.9 MIXTURES OF ORGANIC COMPOUNDS
10.9.1 Gas chromatography
This is the technique used in the earlier work on the elucidation of the composition
of mixtures of organic substances in sewage. Early on, the necessity was recognised
hydroxide, reprecipitated with 0.5 m hydrochloric acid, washed thoroughly in distilled
water and dried in a vacuum desiccator. Each of the isolated fractions (including fulvic
acid) was weighed and an aliquot was dissolved in ethylene diamine for carboxyl and
phenolic hydroxyl determination. Another aliquot dissolved in 0.25 M sodium hydroxide was used for molecular sieving. The acidic functional groups were determined by
potentiometric titration in non-aqueous medium, using a platinum-saturated calomel
electrode combination [199]. 0.1 M solution of sodium aminoethoxide in ethylene
diamine, calibrated against benzoic acid, was used as titrant. To avoid interferences of
carbon dioxide from the air, the titrations were carried out in a current of nitrogen.
The molecular weight distribution was examined by fractionation on Sephadex
gels G-25, G-50 and G-75 having exclusion limits of 100–1000, 500–10 000 and 1000–
50 000 (by dextrans), respectively. For evaluating the molecular weight distribution,
the elution patterns from the three gels were considered. These areas corresponding to
the respective ranges of molecular weight were measured and expressed as a percentage
of the total area included under the elution pattern from G-25.
The infrared spectra of humic and fulvic acids isolated from secondary effluents
are fairly similar. The adsorption bands (cm
−1 ) are in the regions of: 3400, hydrogenbonded OH; 2980, 2940, 2860, 1460, methylene and methyl stretching; 1730, C=O
of carboxyl and ketonic carbonyl; 1630, amine carbonyl or aromatic C=C; 1270,
1130, 1080, carbon-oxygen bond stretching; which is in agreement with the results of
other investigations [201].
Sposito et al [201] used
13 C and proton NMR spectroscopy to investigate fulvic
acid extracted from sewage sludge. Carbon-13 NMR spectroscopy was found to be
useful for studying the organic structure found in fulvic acids.
10.8.5 Sucralose
Minten et al [202] have described a method for the determination of sucralose using
in sewage effluents electrospray liquid chromatography/mass spectrometry in sewage
effluent which had been subjected to tertiary treatment technologies.
10.8.6 Organic carbon
Coulomb et al [203] have described an ultraviolet spectroscopic procedure for the
determination of total organic carbon in marine carbon sewage.
10.8.7 Miscellaneous
Other miscellaneous substances that have been determined in sewage include phenylsulphonyl sarcosine [204], ditallow dimethyl ammonium [205], α-hydroxy butyrate
[206] and α-hydroxy valerate.
10.9 MIXTURES OF ORGANIC COMPOUNDS
10.9.1 Gas chromatography
This is the technique used in the earlier work on the elucidation of the composition
of mixtures of organic substances in sewage. Early on, the necessity was recognised