Kinetic Behavior of Fabricated CuO/ZrO2 Oxygen Carriers for Chemical Looping Oxygen Uncoupling

Chemical looping with oxygen uncoupling (CLOU) is an innovative alternative to conventional combustion. CuO/ZrO2 oxygen carriers were tested in this system for their effectiveness and resilience. Cupric oxide (CuO) was demonstrated to be a reliable oxygen carrier for oxygen-uncoupling with consistent recyclability even after 50 redox cycles in a thermogravimetric analyzer (TGA). The reduction of CuO to generate Cu2O and oxygen was observed to be improved markedly for experiments operated at higher temperatures; however, the oxidation of Cu2O by air to generate CuO was hindered for experiments carried out at elevated temperatures. The reduction rate of fabricated CuO/ZrO2 particles containing 40% CuO was enhanced with increasing temperature and decreased with increasing particle size for experiments operated in a fixed bed reactor. The geometrical contraction and Avrami-Erofe’ev models were demonstrated to be appropriate for describing the reduction and oxidation of CuO/ZrO2, respectively. The activation energies for the reduction and oxidation were determined to be 250.6 kJ/mol and 57.6 kJ/mol, respectively, based on experimental results in the temperature range between 850 and 1000 °C.

Pengembangan E-Magazine Reaksi Reduksi dan Oksidasi Sebagai Media Pembelajaran Kimia Kelas X SMA/MA

This development research refers to several analyzes carried out, namely performance analysis in learning, student analysis, which is a study of student characteristics based on knowledge, skills, and development. Analysis of facts, concepts, principles and needs based on current problems, namely learning from home caused by the covid-19 pandemic which requires learning media. Learning media that can meet today's learning needs are chemistry E-magazines that can be accessed anytime and anywhere with valid, practical, and effective criteria. The e-magazine is then validated first by the supervisor and three material validators and media validators. After the e-magazine is said to be valid, it is tested in learning. The development model used in this study is the ADDIE model (Analysis, Design, Development, Implementation, and Evaluation). After going through the stages of analysis, design, and development of a valid E-Magazine, it was first tested on a small group (initial field trial) and revised. After the initial revision, it was re-tested to a large group (main field trial) to see the effectiveness and practicality of the E-Magazine. The sample in this study were students of class X MIA 2 The initial field trial class amounted to 9 students and Class X MIA 3 as the main field trial class amounted to 30 students at the implementation stage of ADDIE with the object of research namely E-Magazine Reaction Reduction and Oxidation that has been developed. Collecting data using instruments in the form of observation sheets, questionnaires for assessment of material experts, media experts, teachers and students. Qualitative data analysis using a Likert scale and quantitatively based on the Post Test scores of students' learning outcomes. The results of the development obtained that the E-Magazine profile of Reduction and Oxidation Reactions met the validity criteria, showing 1.00 (very high criteria) in terms of questionnaire responses from media experts and material experts. The results of the practicality analysis in terms of the teacher and student response questionnaires obtained each percentage of 90.90% (very practical criteria) for the teacher's response to the initial field trial and 95.45% (very practical criteria) for the main field trial. In the questionnaire responses, students each obtained a percentage of 79.75% (practical criteria) for the initial field trial and 85.50% (very practical criteria) for the main field trial and the results of the effectiveness analysis based on the students' completeness in the post test. obtained a percentage of 79.75% for the initial field trial and the main field trial obtained a percentage of 86.67%. Thus, it can be concluded that the Reduction and Oxidation Reaction E-Magazine that has been developed meets the criteria of being valid, practical, and effective.

TiO2@MOF Photocatalyst for the Synergetic Oxidation of Microcystin-LR and Reduction of Cr(VI) in Aqueous Media

The coexistence of pollutants presents a great challenge to the implementation of photocatalysts. In this work, a novel MIL-101(Fe)/TiO2 composite prepared by in situ growth of MIL-101(Fe) on TiO2 was developed for the synergetic oxidation of MC-LR and Cr(VI) reduction. The heterojunction material shows elevated photocatalytic behavior under ultraviolet compared with the unary pollutant system. Furthermore, quenching experiments and electron spin resonance confirm that the enhanced photodegradation behavior is related to the synergistic effect between the photocatalytic reduction and oxidation process, in which MC-LR consumes the holes and Cr(VI) captures electrons, followed by efficient charge separation through the conventional double-transfer mechanism between MIL-101(Fe) and TiO2. This investigation provides a deeper understanding of the construction of MOFs/semiconductor heterojunctions for the pollutants removal in multi-component contaminants system.