Abstract
<title>Abstract</title> <p>Pyrogallol (1,2,3-trihydroxybenzene) is a widely used phenolic compound in pharmaceutical synthesis, cosmetics, photographic developers, textile dyeing, and leather processing. However, its extensive industrial use has increased its release into aquatic environments, where it may induce oxidative stress through the generation of reactive oxygen species, posing potential risks to aquatic ecosystems. Therefore, the development of efficient and sustainable technologies for pyrogallol removal has become increasingly important. In this study, the degradation of pyrogallol in aqueous solution was investigated using a diode laser-assisted persulfate activation process. Potassium persulfate (K₂S₂O₈) was employed as an oxidant and activated by irradiation from a 380 nm semiconductor diode laser, generating sulfate radicals and secondary reactive oxygen species for pollutant oxidation. The effects of persulfate dosage, reaction temperature, and reaction time on degradation efficiency were optimized using response surface methodology (RSM). Pyrogallol degradation and mineralization were evaluated by high-performance liquid chromatography (HPLC) and total organic carbon (TOC) analyses, respectively. The optimum operating conditions (with RSM) were determined to be a reaction time of 5.86 h, a reaction temperature of 62.58°C, and a persulfate dosage of 5.96 mL of a 3.70 × 10⁻³ M K₂S₂O₈ solution under which 99.97% pyrogallol degradation as determined by HPLC was achieved. In addition, a maximum TOC removal of 89% confirmed substantial mineralization of the organic pollutant. To the best of our knowledge, this study is the first systematic investigation of pyrogallol degradation using diode laser-assisted persulfate activation. The results demonstrate that the proposed process is an efficient, environmentally friendly, and energy-efficient advanced oxidation technology with considerable potential for the treatment of phenolic wastewater.</p>