MoS₂@Hydrochar nanocomposites with cost-effective fluid turbulent eddies induced piezoelectric catalytic peroxymonosulfate utilization efficiency for water polluted dye degradation

Piezoelectric materials can induce strain due to the fluid turbulent force produced during fluid shaking, which may be used to activate peroxymonosulfate (PMS). In this study, the effective interfacial interaction of few-odd-numbered layered MoS₂ nanosheets and hydrochar (HC) nanocomposites as the piezoelectric material was used in a hydrodynamics energy-driven piezoelectric catalytic PMS activation process (piezo-PMS activation process) for Eriochrome Black T dye degradation. The results showed that Black T dye was efficiently degraded with an efficiency of 99.23 % within 15 min and a pseudo-first-order rate constant of 3.10 min⁻¹ in the MoS₂@HC-(6.5:3.5)/PMS/Shaking system. To clearly see the influence of hydraulic gradient (G) value, the hydrodynamics energy-driven piezo-PMS activation process for Black T dye degradation was performed at different shaking frequencies. The results indicated an optimal G value of (14.106 s⁻¹) for Black T dye degradation. Notably, the MoS₂@HC-(6.5:3.5)/ PMS/Shaking system produced the lowest EE/O value (34.05 kWhm⁻³ order⁻¹), resulting in energy savings over 127 times of HC and 9 times of MoS₂. Furthermore, piezoelectrochemical measurements of MoS₂@HC-(6.5:3.5) indicated that these superior performances primarily resulted from the synergistic effects of MoS₂ and HC. This led to a stronger piezoelectric response with effective piezo-generated charge separation, which in turn improved the efficiency of producing reactive species. Combining the scavenger test, FT-IR, and zeta potential analysis, we determined that •OH and SO₄^•− played a major role, while O₂•− and ¹O₂ played a secondary role in Black T dye degradation. The steady-state concentrations of [•OH]_ss, and [SO₄^•−]_ss were 14.52 × 10⁻¹⁴ M and 20.00 × 10⁻¹⁴ M, respectively in the fluid turbulent force driven piezo-PMS activation process. Furthermore, a plausible degradation pathway of Black T dye was proposed based on the assessment of carbon number reduction, the mean oxidation number of organic carbon (MOC) and the predicted TOC/color index.