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In this paper, the preparation and optical properties of sphere-like ZnS nanocrystals are reported. Pure and uniform cubic-phase sphere-like ZnS nanocrystals with grain sizes of 30–40 nm were synthesized by thermolysis of a new precursor complex (enH₂)_0.5[Zn(en)₃](SCN)₃ (en = ethylenediamine) in nitrogen stream at 800°C. The as-synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), respectively. The XRD analysis reveals the phase of ZnS with cubic zinc blende. UV-Vis and photoluminescence spectra (PL) were utilized to investigate the optical properties of sphere-like ZnS nanocrystals. By testing on UV-Vis spectra, it is concluded that the limiting wavelength of the ZnS nanocrystals is 320 nm and the band gap is 3.88 eV. In room temperature PL spectra, one strong emission peak centered at 322 nm is discovered, which could be attributed to the band to band transitions. The above-mentioned results showed that the thermolysis method is preferable for synthesizing high-quality sphere-like ZnS nanocrystals. The synthesized precursor could be used as morphological templates to prepare nanostructure inorganic compounds.

This paper focuses on the thermal elimination of alkenes from methyl alkyl thionacetates and thiolacetates. Three alkyl groups are calculated: ethyl, isopropyl and tert-butyl. Possible elimination mechanisms are considered, including six- and four-membered ring transition states for alkene elimination, four-membered ring isomerization and a possible five-membered ring decomposition. Theoretical calculations are performed with the MP2 method and the 6-31G* basis set. Wiberg bond indices are also summarized to monitor the reaction progress.

We saw (Section 4.4) that CO₂ (carbon dioxide) reacts with quicklime (calcium oxide) in water at 25°C, under 1 atm generating calcium carbonate or limestone (CaCO₃). The process is a sequence of two reactions (4.14) and (6.1):

A combined process of thermolysis and coagulation-flocculation was carried out to treat textile industry wastewater. For the coagulation-flocculation process, the use of magnesium chloride (MgCl₂) and magnesium chloride-polyethylene oxide (MgCl₂-PEO) hybrid polymer as coagulants were compared. The effects of pH and coagulant dosage were varied to obtain optimum colour removal and COD reduction. By using thermolysis alone, 63.1% colour removal and 52.15% COD reduction was achieved. After thermolysis, the wastewater was subjected to coagulation-flocculation using two different coagulants. For both MgCl₂ and MgCl₂-PEO hybrid polymer, the optimum pH for the process was pH 7. When the MgCl₂ coagulant was used, the optimum colour removal and COD reduction obtained were 98.59% and 90.32%, respectively. At pH 7, 99.15% colour removal and 91.94% COD reduction were achieved with the use of the hybrid polymer. The use of the MgCl₂-PEO hybrid polymer does not only show better efficiency in colour removal and COD reduction but also requires a lower coagulant dosage. The optimum efficiency of MgCl₂-PEO hybrid polymer was obtained at 1000 mg/L while for MgCl₂; the optimum coagulant dosage was 1500 mg/L.