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The feasibility of methyldiethanolamine (MDEA) degradation in thermally activated PS system was evaluated. Effects of the PS concentration, pH, activation temperature and reaction time on MDEA degradation were investigated. Simultaneity, the thermodynamic analysis and degradation process were also performed. Several findings were made in this study including the following: the degradation rates of MDEA in thermally activated PS systems were higher than other systems. MDEA could be readily degraded at 40°C with a PS concentration of 25.2 mM, the process of MDEA degradation was accelerated by higher PS dose and reaction temperature, and MDEA degradation and PS consumption followed the pseudo-first-order kinetic model. The thermodynamic analysis showed that the activation process followed an endothermic path of the positive value of [Formula: see text] and spontaneous with the negative value of [Formula: see text], high temperature was favorable to the degradation of MDEA with the apparent activation energy of 87.11 KJ/mol. Combined FT-IR with GC-MS analysis techniques, MDEA could be oxidative degraded after the C-N bond broken to small molecules of organic acids, alcohols or nitro compounds until oxidized to CO

The petroleum refinery industry generates a significant amount of wastewater that contains a high level of organic matter, which calls for effective and costly treatments. In this research, the effectiveness of the petroleum refinery effluent (PRE) treatment with physicochemical process of combined adsorption and coagulation was evaluated. The effects of initial pH, hydraulic condition , and combined sequence of treatment process, different treating reagent types and dosages on the chemical oxygen demand (COD) removal were investigated. Additionally, the elimination efficiency of pollutant wastewater was monitored by gas chromatography-mass spectrometry (GC-MS), and Fourier transformed infrared (FT-IR) spectrophotometer was adopted to describe the structure of the wastewater. Wooden activated carbon was chosen as adsorbent at the dosage of 10 g/L as a primary treatment, and 1500 mg/L polymeric magnesium ferric sulfate was used in coagulation. Results showed that adsorption and subsequent coagulation displayed the best performance when initial pH was 9 at shear rates (G) of G1 = 65 s

Semi-rational directed evolution was applied to the D5 variant of monoamine oxidase from Aspergillus niger (MAO-N-D5) with the aim of deriving the more desirable (R)-mexiletine through the kinetic resolution of mexiletine enantiomers. Although MAO-N-D5 shows no activity towards rac-mexiletine, theoretical molecular docking studies revealed the potential binding conformations of both mexiletine enantiomers and MAO-N-D5. The key factors affecting the catalytic activity and specificity were identified. Based on the docking results, six residues in the binding pocket and along the binding pathway were selected as key sites for saturation mutagenesis of MAO-N-D5. Through several rounds of screening and combinatorial experiments, two active MAO variants with high enantioselectivities towards (S)-mexiletine evolved, namely A-1 (F210V/L213C, E = 101) and AC-1 (F210V/I367T, E = 69). Molecular simulation experiments indicated that the introduced activity of these variants may be due to the reduced steric hindrance in the binding pocket of the relatively small-sized amino acid residues, a synergetic effect of the entrance residue mutation, and the formation of a new disulfide bond.

Thermally activated delayed fluorescence (TADF) materials are promising for the next generation of organic light-emitting diodes. To realize reverse intersystem crossing (RISC) effectively for TADF molecules requires basically small energy gap (ΔEST) between the lowest singlet (S1) and triplet (T1) excited states. In this work, 1,8-naphthalimide was selected as a fixed acceptor (A) because of its large rigid conjugate structure with a high radiative decay rate. Twelve naph- thalimide-based intramolecular charge transfer (ICT) compounds were constructed by the conjunction of naphthalimide moi- ety with each of donors (D) including 9,9-dimethyl-9,10-dihydroacridine, phenoxazine, etc. Their energy gaps were calculat- ed with the Gaussian 09 package at TD-DFT level using the optimal Hartree-Fock exchange method reported by Huang Shuping recently. The results show that D-A structure of naphthalimide-based ICT compounds has smaller ΔEST and longer starting fluorescence emission wavelengths (λ) than those for corresponding D-phenyl-A type. However, strong electron do- nor like 9-(9H-carbazol-3-yl)-9H-carbazole (DCZ) seems to have no significant effect on ΔEST and λ at high CT amount. To achieve small ΔEST of these naphthalimide-based ICT compounds, increasing the twisting angle between D and A, together with enhancing electron donating ability of D is found to be a practical strategy to stabilize the energy of the lowest local- ly-excited triplet state ( 3 LE) and substantially lower the energy of its lowest CT triplet excited state ( 3 CT). As a result, 4-(9,9-dimethyl-9,10-dihydroacridine)-N-phenyl-1,8-naphthalimide (4b) and 4-(phenoxazine)-N-phenyl-1,8-naphthalimide (5b) show small ΔEST of 0.01 eV and 0.02 eV, respectively. Their λ and oscillator strengths of vertical absorption from ground state (S0) to S1 are 575 nm and 0.0002 for 4b, while 621 nm and 0.0025 for 5b, respectively. In addition, the λ of compound 5b obtained from its photoluminescence curve is 600 nm, which consists with the computed one with an error of 0.07 eV. Therefore, compounds 4b and 5b can be expected to be potential reddish-orange and red TADF emitters. Keywords naphthalimide; thermally activated delayed fluorescence; energy gaps; quantum chemical calculation