Contact-electro-catalysis for the degradation of organic pollutants using pristine dielectric powders

Mechanochemistry has been studied for some time, but research on the reactivity of charges exchanged by contact-electrification (CE) during mechanical stimulation remains scarce. Here, we demonstrate that electrons transferred during the CE between pristine dielectric powders and water can be utilized to directly catalyze reactions without the use of conventional catalysts. Specifically, frequent CE at Fluorinated Ethylene Propylene (FEP) - water interface induces electron-exchanges, thus forming reactive oxygen species for the degradation of an aqueous methyl orange solution. Contact-electro-catalysis, by conjunction of CE, mechanochemistry and catalysis, has been proposed as a general mechanism, which has been demonstrated to be effective for various dielectric materials, such as Teflon, Nylon-6,6 and rubber. This original catalytic principle not only expands the range of catalytic materials, but also enables us to envisage catalytic processes through mechano-induced contact-electrification.

The Adsorption Performance of Polyaniline/ZnO Synthesized through a Two-Step Method

Polyaniline/Zinc oxide (PANI/ZnO) were prepared using a two-step method, and the morphology and the structure of PANI/ZnO composites were characterized through a scanning electron microscope (SEM) and X-ray diffraction (XRD). Factors such as the content of ZnO, the adsorption time and the mass of the adsorbent, and the kinetic equation of PANI/ZnO as adsorbents for the adsorption of methyl orange solution were studied. The results showed that the adsorption efficiency of methyl orange by polyaniline with the increase of adsorbent mass firstly increased and then decreased. Among the composites with the same quality, PANI composites with 8% ZnO have a better adsorption effect for methyl orange, and the maximum adsorption ratio can reach 69% with the increase of adsorption time at 0.033 g; With the increase of adsorbent mass, the adsorption efficiency of PANI composites with 8% ZnO increased continuously. When the mass increased from 0.033 g to 0.132 g, the adsorption rate increased from 69% to 93%, and the adsorption of the methyl orange solution by PANI/ZnO composites was more in line with the quasi-second-order kinetic equation.

The ferrocenium/ferrocene couple: a versatile redox switch

Woodward and co-workers in 1952 characterised the unique structural features of ferrocene (the first sandwich compound), demonstrated its aromatic nature and observed that on treatment with mild oxidising agents (aqueous Ag2SO4, p-benzoquinone in organic solvents) the orange solution of ferrocene (Fc) turned blue due to the formation of ferrocenium (Fc+). A few months later, the one-electron Fc/Fc+ redox change was characterised polarographically by Page and Wilkinson with E1/2 = 0.31 V vs SCE (0.56 V vs NHE) in ethanol/water 9:1. Since then ferrocene has become an icon of organometallic electrochemistry. Owing to the stability of its molecular framework, to the ease of functionalisation at the cyclopentadienyl rings and to the fast, reversible and kinetically uncomplicated Fc/Fc+ redox change, ferrocene has been used as a building block for the design of switchable functional systems. In this review, we will consider (1) electrochemical sensors for metal ions, anions and metal–anion pairs operating through the Fc/Fc+ redox change, (2) ferrocene-based redox switches of fluorescence and (3) cross-transport of electrons and anions through a liquid membrane mediated by lipophilic ferrocene derivatives. Graphic abstract

Photocatalytic Activity of Nonprecious Metal WSe2/g-C3N4 Composite Under Visible Light Irradiation

The WSe2/g-C3N4 (graphite carbon nitride) composite with photocatalytic properties was synthesized using a hydrothermal method. This synthesis pathway can be characterized by being simple, inexpensive and nonpolluting, integrating the concept of green chemistry. The WSe2/g-C3N4 composite could effectively degrade methyl orange solution under visible light irradiation. The decolorization experiment of methyl orange solution shows that the degradation rate of the 30[Formula: see text]wt.% WSe2/g-C3N4 composite can reach 98.7% after 100[Formula: see text]min of illumination, while the degradation rate of pure g-C3N4 was only 87.6% under the same conditions. This can be attributed to the fact that the combination of WSe2 and g-C3N4 nanosheets can increase the number of active binding sites, increasing the rate of charge separation and transport ability, decreasing the recombination rate of the photogenerated electron–hole pairs. Therefore, the WSe2/g-C3N4 composite will have potential development as a new material with low cost, easy synthesis and excellent performance in photocatalytic degradation of water pollution.

Uncertainty Estimation of the Fe Content Measurement in the Clean Water Using UV- Vis Spectrophotometer

Good laboratories should be able to apply procedures uncertainty for measuring of both conventional and instrument equipment. As well as the testing for Fe content using UV-Vis Spectrophotometer. As for the purpose for calculating the uncertainty estimated to determine the range of values within which estimated the true value of the testing standard solution Fe using UV-Vis Spectrophotometer. The uncertainty estimation are influenced by several factors such as sample used, reading of spectrophotometer, repeatability, sample volume. The uncertainty of the calculation obtained a value of ± 0,02 mg/L. Further testing of Fe content in the clean water using UV-Vis Spectrophotometer at the 500 nm wavelength which forms an orange solution as indication of Fe content in the water. The result of Fe content has quality standards according to the spesifications issued by ministry of health Republic of Indonesia in 2010 for drinking water.

Degradation of Methyl Orange by Photoassisted Fenton Reaction Using Indonesian Bauxite as Catalyst

A Novel catalyst prepared from Indonesia bauxite was used as a catalyst for photo fenton degradation of methyl orange solution. This catalyst is more cheaper than Nafion-based catalyst and more greener than other synthesized catalysts. It is easily prepared from Indonesian natural resources. X-ray diffraction measurements provide structure and mineral compostion of bauxite, while XRF provides information on the composition of Fe by 18% by weight of bauxite mass. The presence of large amounts of Fe in bauxite acts as a catalyst in the decomposition of metyl orange. Testing of photo fenton activity to decompose metyl orange showed that indonesian bauxite had high catalytic activity, was able to decompose 99.4% metyl orange within 40 minutes on irradiation using an 8Watt UVC radiation source

Preparation of Nitrogen-Doped Mesoporous TiO2/RGO Composites and Its Application to Visible Light-Assisted Photocatalytic Degradation

A series of nitrogen-doped mesoporous TiO2 nanomaterials and nitrogen-doped mesoporous TiO2/reduced graphene oxide (RGO) composites were successfully prepared by hydrothermal method using triammonium citrate as the nitrogen source. The effects of nitrogen and graphene oxide (GO) dopping on the photocatalytic properties of the TiO2 were investigated to optimize preparation conditions. The results showed that all prepared samples were mainly composed of the anatase phase and possessed a mesoporous structure. The use of the triammonium citrate not only significantly increased the specific surface area of the synthesized samples but also caused the partial reduction of GO to RGO, leading to further increase of the specific surface area and the improvement of quantum efficiency of the photogenerated electrons. All synthesized samples showed superior photocatalytic performance for methyl orange solution. Among them, the NMT/RGO-1.8-10 was found to be the best; the degradation rate of methyl orange solution on the sample reached 100% in 30 minutes under visible light irradiation.