Micro-area investigation on electrochemical performance improvement with Co and Mn doping in PbO2 electrode materials

Rapid and sensitive in situ detection of heavy metals in fish using enhanced Raman spectroscopy

Heavy metals have been widely applied in industry, agriculture, and other fields because of their outstanding physics and chemistry properties. They are non-degradable even at low concentrations, causing irreversible harm to the human and other organisms. Therefore, it is of great significance to develop high accuracy and sensitivity as well as stable techniques for their detection. Raman scattering spectroscopy and atomic absorption spectrophotometer (AAS) were used parallelly to detect heavy metal ions such as Hg, Cd, and Pb of different concentrations in fish samples. The concentration of the heavy metals is varied from 5 ppb to 5 ppm. Despite the satisfactory recoveries of AAS, their drawbacks are imperative for an alternative technique. In Raman scattering spectroscopy, the intensities and areas of the characteristic peaks are increased with increasing the concentration of the heavy metals. For Hg concentration ≥ 1 ppm, a slight shift is observed in the peak position. The obtained values of peak intensity and peak area are modeled according to Elvoich, Pseudo-first order, Pseudo-second order, and asymptotic1 exponential model. The best modeling was obtained using the Elovich model followed by the asymptotic1 exponential model. The introduced Raman spectroscopy-based approach for on-site detection of trace heavy metal pollution in fish samples is rapid, low-cost, and simple to implement, increasing its visibility in food safety and industrial applications.

PbO2 modified BDD electrode by dicationic ionic liquids assisted electrodeposition for efficient electrocatalytic degradation of pesticide wastewater

Pesticide wastewater is difficult to treat, and it is necessary to develop a new anode material electrochemical oxidation to efficiently degrade pesticide wastewater. DIL-PbO₂-Ti/BDD electrodes with better electrocatalytic oxidation performance were obtained by using dicationic ionic liquid (DIL) for assisted electrodeposition of PbO₂ modified boron-doped diamond (BDD) electrodes. At a current density of 100 mA cm^-2 and a temperature of 25 °C, the DIL-PbO₂-Ti/BDD electrode was used as anode and titanium plate as cathode. The electrochemical window and oxygen evolution potential (OEP) of the DIL-PbO₂-Ti/BDD electrode obtained by CV testing at a scan rate of 50 mV s^-1 in 1 M H₂SO₄ were 4.12 and 3.29 V, respectively. Under the conditions of current density of 100 mA cm^-2, 25 °C, pH 12, salt content of 8%, chemical oxygen demand (COD) of 24,280.98 mg L^-1, and total nitrogen (TN) content of 5268 mg L^-1, after electrification for 12 h, the removal efficiency of COD and TN reached 64.88 and 67.77%, respectively, indicating that the DIL-PbO₂-Ti/BDD electrode has excellent electrocatalytic performance. In order to further understand the mechanism of electrochemical degradation of pesticide wastewater, HPLC-MS was used to detect the intermediates in the degradation process, and the possible degradation pathways were proposed in turn.