Pseudomonas aeruginosa metabolizes pyocyanin, a redox molecule related to diverse biological activities. Culture conditions for the production of pyocyanin in a defined medium were optimized using a statistical design and response surface methodology. The obtained conditions were replicated using as substrate an alkaline residual liquid of cooked maize and its by-products. The untreated effluent (raw nejayote, RN) was processed to obtain a fraction without insoluble solids (clarified fraction, CL), then separated by a 30 kDa membrane where two fractions, namely, retentate (RE) and filtered (FI), were obtained. Optimal conditions in the defined medium were 29.6 °C, 223.7 rpm and pH = 6.92, which produced 2.21 μg mL⁻¹ of pyocyanin, and by using the wastewater, it was possible to obtain 3.25 μg mL⁻¹ of pyocyanin in the retentate fraction at 40 h. The retentate fraction presented the highest concentration of total solids related to the maximum concentration of pyocyanin (PYO) obtained. The pyocyanin redox behavior was analyzed using electrochemical techniques. In this way, valorization of lime-cooked maize wastewater (nejayote) used as a substrate was demonstrated in the production of a value-added compound, such as pyocyanin, a redox metabolite of Pseudomonas aeruginosa NEJ01R.

In the industry, sodium carbonate is used to prepare sodium silicate; however, this process generates great volumes of CO₂. In this work, sodium hydroxide has been proposed to prepare sodium silicate using natural sand. Two experimental variables were considered, sodium hydroxide concentration and temperature to prepare sodium silicate. Results show the formation of sodium silicate with a NaOH:sand ratio = 1.1 at 550 °C. Moreover, an economical revision was achieved to compare costs of sodium silicate with sodium hydroxide and sodium carbonate. The use of sodium hydroxide permits to decrease CO₂ emissions generated in the decomposition of sodium carbonate. Additionally, the sodium silicate prepared herein was used to synthesize a zeolite type material, SBA-15. SBA-15 obtained has similar characteristics than the commercial mesoporous material. The use of sodium silicate prepared with non-pure sand for preparing mesoporous materials is an economical and friendly environmental alternative.