We present a novel and highly efficient method for exfoliating of graphite to produce graphene via the synergistic effects of in-situ plasma induced electrochemical exfoliation with ultrasonic energy, called ultrasonic-assisted cathodic electrochemical discharge. This method can work at moderate temperatures without the need of acidic media or expensive ionic electrolyte. The produced graphene exhibited a large lateral dimension of approximately 6μm and a thickness of 2.5nm, corresponding to approximately seven layers of graphene. An exfoliating mechanism of graphite to produce graphene sheets is also proposed in this study.

YFe 1−x CoxO 3 (0.1 ≤ x ≤ 0.5) perovskite-type nanomaterials were successfully synthesized by the chemical co-precipitation method via the hydrolysis of Y(III), Fe(III) and Co(II) cations in boiling water using 5 % aqueous KOH solution as a precipitating agent. Along with the increase of cobalt ion concentration (x values, from 0.1 to 0,5), there was an decrease in the crystallite size nanomaterials (from 25.68 to 22.89 nm), as well as in the lattice constants (a = 5.5781-5.5217Å; b = 5.2732-5.2177Å, c = 7.5902-7.5009Å; V = 223.26-216.11Å), but there was an increase in the magnetic parameters including coercive force (Hc = 88.86 Oe), remnant magnetization (Mr = 0.031-0.268 emu/g), saturation magnetization (Ms = 0.413-1.006 emu/g) and maximum energy product ((BH)max = 0.413-1.006 emu/g).

The coal gasification wastewater figures prominently among types of industrial effluents due to its complex and phenolic composition, posing great difficulty for conventional water treatment processes. Since the coking wastewater is toxic and mutagenic to humans and animals, treatment of coal gasification wastewater is genuinely necessary. In this study, we established a lab-scale A2O (Anaerobic-Anoxic—Oxic) with moving bed biological reactor (MBBR) system and evaluated some water indicators of wastewater pretreated with internal electrolysis, of wastewater output of the established A2O-MBBR system, and of the wastewater treated by the combination thereof. The wastewater was taken from a coking plant at Thai Nguyen Iron and Steel Joint Stock Company in Vietnam. COD, BOD5, NH4+-N, phenol, and pH of the input coal gasification wastewater were 2359, 1105, 319, 172 mg/L, and 8 ± 0.1, respectively. The conditions of internal electrolysis were as follows: 720 min of reaction time, pH = 4, 25 g/L Fe-C dosage, and 100 mg/L PAM dosage. After internal electrolysis process, the removal of COD, BOD5, NH4+-N, and phenol were 53.7%, 56.7% 60.5%, and 73.3%, respectively. After 24 h of treatment, the treatment efficiencies of the combined treatment process are as follows: 100% phenol removal, 71.3% of TSS removal; 97.7% reduction of BOD5, and 97.1% reduction of COD; total N content reduced by 97.6%; total P content decreased by 81.6%; and NH4+-N content decreased by 97.5%. All above indicators after treatment have met QCVN 52: 2017/BTNMT (column A) Vietnamese standard for steel industry wastewater.

Fe-Cu materials were synthesized using the chemical plating method from Fe powder and CuSO4 5% solution and then characterized for surface morphology, composition and structure by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The as-synthesized Fe-Cu material was used for removal of phenol from aqueous solution by internal microelectrolysis. The internal electrolysis-induced phenol decomposition was then studied with respect to various parameters such as pH, time, Fe-Cu material weight, phenol concentration and shaking speed. The optimal phenol decomposition (92.7%) was achieved under the conditions of (1) a pH value of phenol solution of 3, (2) 12 h of shaking at the speed of 200 rpm, (3) Fe-Cu material weight of 10 g/L, (4) initial phenol concentration of 100.98 mg/L and (5) at room temperature (25 ± 0.5 °C). The degradation of phenol using Fe-Cu materials obeyed the second-order apparent kinetics equation with a reaction rate constant of k of 0.009 h−1L mg−1. The optimal process was then tested against real coking wastewater samples, resulting in treated wastewater with favorable water indicators. Current findings justify the use of Fe-Cu materials in practical internal electrolysis processes.

In this work, the mixture of red mud slurry and inorganic salt ((NH4)2SO4) has been used as an electrolyte for electrochemical activation of graphite. The red mud-activated graphite composite was then used as an adsorbent for removing methylene blue from aqueous solution by the batch method. The effect of pH, contact time, adsorbent dosage, and the initial concentration of methylene blue was investigated. The optimal condition was found at pH 6, contact time 120 min, and amount of adsorbent 1 mg/L. The maximum adsorption capacity was found to be 89.28 mg/g based on the Langmuir isotherm equation, suggesting that the red mud-activated graphite composite is a very potential adsorbent for removing methylene blue and is also used in other coloured wastewater treatments.

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Studies showed that competency-based assessment improvement had generated a much greater impact on students’ achievements on standardized tests than other forms of educational activities. However, studies also indicated a number of challenges for teachers when designing competence assessment tools (CAT), especially in building assessment tasks that replicate real-life practice. There have been many different models for teachers’ assessment competencies, but the competency of designing competence assessment tools (CDCAT) was not paid much attention. In hope to develop a competency model that would serve as a supporting role in developing the CDCAT for pre-service teachers and teachers, this study used a multi-step development process to construct a teachable model that reflectived the complexity of designing assessment tools. The model consisted of 12 behavioural indicators spreading across four dimensions informed by the existing literature and empirical findings in particular contexts. To guarantee the content value of the proposed model, the research twice used the expert method by two panels. The reliability of the model was tested by analyzing the data collected from the survey with students. Interesting findings were met, and the outlined CDCAT model assisted pre-service teachers in solving issues related to their assessment competence. The model was intended for educational researchers, educators, teachers, and policy makers to support teachers’ assessment competence concerning the current accountability model across educational systems. Specific implications for developing pre-service teachers' CDCAT were discussed, followed by suggestions for future studies.

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