Kinetic modeling and energy evaluation of sodium dodecylbenzenesulfonate photocatalytic degradation in a new LED reactor

• Performance of a novel upgraded Light Emitting Diodes (LED) reactor.
• Sodium dodecylbenzenesulfonate (SDBS) oxidation kinetics as function of radiation.
• Energy requirement evaluation using Electrical Energy per Order (EEO) parameter.
• Comparison of light sources: from Hg lamps to novel LED.

Photocatalysis is an effective technology for the removal of organic pollutants from wastewater. Artificial light sources are still required for continuous operation, representing a large fraction of the operating costs. Thus, energy efficiency becomes a key issue that needs optimization. In this work, the performance of a novel upgraded Light Emitting Diodes (LED) reactor was studied varying the radiation applied. The evaluation was based on the degradation yield of the surfactant sodium dodecylbenzenesulfonate (SDBS) and on the energy requirement, determined by the parameter “Electrical Energy per Order” (EEO). The best SDBS removal, 94% after 480 min, was attained using 27.5 mW cm−2. Nevertheless, the best energy consumption was for 3.22 mW cm−2, with an EEO of 47.5 kW h m−3 order−1. Moreover, the hydroxyl radicals (OH) generated were quantified and a three-region kinetic model considering radiation was proposed. 92% of the simulated results fell within [OH]gen,exp ± 15% [OH]gen,exp. Furthermore, a comparison with a 1st generation LED reactor and a Hg lamp reactor was carried out. The last one showed the highest performance, achieving complete SDBS removal after 360 min; however, its energy requirement was one order of magnitude higher than that of the upgraded LED reactor.

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