linear alkylbenzene sulfonate
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Linear alkylbenzene sulfonate and anthracene are chemical compounds which form pollutant mixtures with high toxic potential, causing damage to ecosystems. The process known as biodegradation is an effective, low-cost process carried out by microbial populations that reduces the toxic effect of linear alkylbenzene sulfonate and anthracene. In the present study, biodegradation was determined at different concentrations of linear alkylbenzene sulfonate, anthracene and the mixture of both compounds. The resulting reduction in toxicity produced by the mixture, the compounds separately and their biodegradation intermediaries was assessed using a microbial model. The ISO 9439 system was used to assess the biodegradation effect of a microbial consortium isolated from polluted sediment on 5, 10 and 20 mg/l of linear alkylbenzene sulfonate and the same concentrations of anthracene. Toxicity was determined by measuring inhibition of Bacillus cereus dehydrogenase activity produced by 0.25 ml aliquots of the linear alkylbenzene sulfonate, anthracene and the mixture of both compounds before and after they had been subjected to the biodegradation test. After 11 days, the linear alkylbenzene sulfonate -anthracene mixture was biodegraded to a greater degree than the compounds individually (3057.36 μmol CO2), but at a concentration of 20 mg/l of both compounds, a marked inhibition of biodegradation was observed. A reduction in toxicity produced by the biodegradation of linear alkylbenzene sulfonate and its mixture with anthracene at 5 and 10 mg/l respectively was observed.

Simultaneous electrochemical removal of Zn⁺₂ and Ni⁺₂ ions and photooxidation of linear alkylbenzene sulfonate (LAS) over TiO₂ particles were investigated. To achieve this objective, first, the effect of different variables such as current density, pH and flow rate on sole electrochemical reduction of metal ions was studied. Both controlling pH in the range of 5.5-6 and increasing the liquid volumetric flux effectively improved the rate of Zn⁺₂ ion reduction, but they did not have any significant effect on the rate of Ni⁺₂ ion reduction. Under optimum operating conditions ... and using total electrolyte volume of 6 L, zinc and nickel were reduced by 86% and 53% respectively, over a 7-hour treatment period. Sole photocatalytic treatment of LAS and controlling pH between 5-5.5 resulted in 60% LAS degradation. However, temperature and flow rate did not have any considerable effect on the rate of LAS degradation compared to the photocatalytic system alone. LAS was degraded in the combined system by 76% compared to 60% in the sole photocatalytic system. However, using the combined system, zinc and nickel were reduced by 81% and 47% respectively, which were slightly less than those obtained in the electrochemical system alone.

Simultaneous electrochemical removal of Zn⁺₂ and Ni⁺₂ ions and photooxidation of linear alkylbenzene sulfonate (LAS) over TiO₂ particles were investigated. To achieve this objective, first, the effect of different variables such as current density, pH and flow rate on sole electrochemical reduction of metal ions was studied. Both controlling pH in the range of 5.5-6 and increasing the liquid volumetric flux effectively improved the rate of Zn⁺₂ ion reduction, but they did not have any significant effect on the rate of Ni⁺₂ ion reduction. Under optimum operating conditions ... and using total electrolyte volume of 6 L, zinc and nickel were reduced by 86% and 53% respectively, over a 7-hour treatment period. Sole photocatalytic treatment of LAS and controlling pH between 5-5.5 resulted in 60% LAS degradation. However, temperature and flow rate did not have any considerable effect on the rate of LAS degradation compared to the photocatalytic system alone. LAS was degraded in the combined system by 76% compared to 60% in the sole photocatalytic system. However, using the combined system, zinc and nickel were reduced by 81% and 47% respectively, which were slightly less than those obtained in the electrochemical system alone.