Micellar Aggregation Behavior of Alkylaryl Sulfonate Surfactants for Enhanced Oil Recovery

Alkylaryl sulfonate is a typical family of surfactants used for chemically enhanced oil recovery (EOR). While it has been widely used in surfactant–polymer flooding at Karamay Oilfield (40 °C, salinity 14,000 mg/L), its aggregation behavior in aqueous solutions and the contribution of aggregation to EOR have not been investigated so far. In this study, raw naphthenic arylsulfonate (NAS) and its purified derivatives, alkylaryl monosulfonate (AMS) and alkylaryl disulfonate (ADS), were examined under simulated temperature and salinity environment of Karamay reservoirs for their micellar aggregation behavior through measuring surface tension, micellar size, and micellar aggregation number. It was found that all three alkylaryl sulfonate surfactants could significantly lower the surface tension of their aqueous solutions. Also, it has been noted that an elevation both in temperature and salinity reduced the surface tension and critical micellar concentration. The results promote understanding of the performance of NAS and screening surfactants in EOR.

Selective Preliminary Incubation for Gram-Negative Psychrotrophic Bacteria in Milk

Milk samples containing crystal violet, benzalkonium chloride, crystal violet: benzalkonium chloride, or alkylaryl sulfonate were inoculated with each of Pseudomonas fluorescens, Pseudomonas fragi, Pseudomonas putida, Pseudomonas aeruginosa, Escherichia coli, Bacillus cereus, Staphylococcus aureus, and Streptococcus sp. Samples were incubated at 21°C for 18 h, and growth of the bacteria monitored to evaluate the inhibitory effects of the added reagents. Benzalkonium chloride proved to be the preferred inhibitor for selective incubation. It inhibited growth of Bacillus cereus, Staphylococcus aureus, and Streptococcus sp. at initial cell concentrations of 101, 102, and 104 per ml, while allowing uninhibited growth of all Pseudomonas species tested with an average increase of 3 logs. This finding is most important for the selective preliminary incubation necessary prior to milk quality assessment by plating and rapid instrumentation methods.

Propanil and Adjuvants for Barnyardgrass Control in Rice

A nonphytotoxic paraffinic oil at 2.5, 5, and 10% (v/v) or a blended alkylaryl sulfonate surfactant at 0.5, 1, and 2% (v/v) did not enhance the activity of propanil (3′,4′-dichloropropionanilide) at 1.7, 3.4, and 6.7 kg/ha applied as a foliage spray in aqueous systems on barnyardgrass [Echinochloa crus-galli(L.) Beauv.] or rice (Oryza sativaL. ‘Starbonnet’). Time and rate of applying propanil affected control of barnyardgrass. Barnyardgrass control and rice yield were best with treatments of 3.4 or 6.7 kg/ha of propanil to four-leaf grass plants. Propanil at 6.7 kg/ha controlled tillering and jointing barnyardgrass well enough to increase grain yields over those of untreated rice.