A sustainable solar-driven electrochemical process for reforming lignocellulosic biomass effluent into high value-added products: green hydrogen, carboxylic and vanillic acids.

There is a growing concern with waste minimization and the promotion of the circular economy. Within this framework, using membrane-equipped electrochemical systems, the electrochemical oxidation (EO) of organic compounds and simultaneous hydrogen (H2) production can considerably improve the sustainability and economic viability of this process. Here, we propose an innovative-integrate electrochemical treatment strategy to maximize the economic benefits and sustainability of selectively producing organic acids and energy-saving H2 production from biomass platform compounds. The results clearly demonstrated that, on the one hand, more than 80 mg L-1 of oxalic acid was obtained in the anodic reservoir (using a boron-doped diamond electrode) with an alkaline medium (0.5 mol L-1 NaOH) by applying 100 mA cm-2 as well as vanillic acid production of 0.6795 mg L-1 under the same conditions. On the other hand, simultaneously green H2 production greater than 2.6 L was produced, in the cathodic compartment with a Ni-Fe-based mesh as cathode, with a 90% faradaic efficiency during the process. Thus, the electrochemical conversion of lignocellulosic biomass effluent into high-value-added products and an energy vector was sustainably accomplished, suggesting that it is a promising energy-saving and cost-effective integrated approach for biomass valorization using solar energy.

Electrochemical Production of Hydrogen Peroxide in Perchloric Acid Supporting Electrolytes for the Synthesis of Chlorine Dioxide.

This work focuses on the electrochemical production of hydrogen peroxide in supporting electrolytes containing perchlorate ions for being used as a reagent in the reduction of chlorates to produce chlorine dioxide, as a first step in the manufacture of portable ClO2 production devices. This study evaluates the effect of the current density, pressure, and temperature on the production of hydrogen peroxide, and concentrations over 400 mg L-1 are reached. The average rate for the formation of hydrogen peroxide is 9.85 mg h-1, and the effect of increasing electrolyte concentration (3.0 and 30.0 g L-1 perchloric acid), intensity, and pressure results in values of, respectively, -2.99, -4.49, and +7.73 mg h-1. During the manufacturing process, hydrogen peroxide is decomposed through two mechanisms. The average destruction rate is 1.93 mg h-1, and the effects of the three factors results in values of, respectively, +0.07, +0.11, and -0.12 mg h-1. Solutions of this hydrogen peroxide produced electrochemically in a perchloric acid aqueous electrolyte were used to reduce chlorates in strongly acidic media and produce chlorine dioxide. Conversions of around 100% were obtained, demonstrating that this electrochemical product can be used efficiently to reduce chlorates to chlorine dioxide.