This paper discusses an optimisation of methyl orange photodegradation using TiO2-zeolite photocatalyst and H2O2 (with condition of pH 2, 10 ppm, UV light). A 15 mmol TiO2 in 1 gram activated zeolite was used. The influence of H2O2 concentration (4, 8, 12, 16%) and irradiation time (20, 30 40, 50, 60 minutes) was also investigated, as well as initial methyl orange concentration (10, 20, 30 ppm) toward reaction rate constant. As the H2O2 concentration increase, the photodegradation percentage is also increased until it reaches optimum condition (H2O212% for 10 ppm MO solution). Identical effect also showed by the irradiation time in which an optimum point reached at 60 minutes (for 10 ppm MO solution) and 50 minutes (for 20 and 30 ppm MO solutions). Moreover, the higher initial MO concentration used, the lower reaction rate constant obtained. The highest rate constant was shown by MO solution of 10 ppm. The reuse of TiO2-Zeolite photocatalyst remains effective and efficient in photodegradation of methyl orange in solution for up to 4 times.
TiO 2 -zeolite photocatalyst has been prepared by impregnation of TiO 2 onto acid-activated natural zeolite. The XRD data confirmed that natural zeolite used in this work is predominated with mordenite and clinoptilolite types, whereas anatase type can be attributed to TiO 2 . The highest performance of TiO 2 -zeolite, which is indicated by the surface area of 13.304 m 2 /g and band gap energy of 3.15 eV, is obtained when 10 mmol of TiO 2 is impregnated onto the zeolite. The ability of this photocatalyst is evaluated by examining degradation of methylene blue (MB) in the presence of UV source. The effects of MB concentration, pH and UV irradiation time on the degradation are studied in a batch reactor. It is interesting since the addition of H 2 O 2 can improve the degradation efficiency of MB. The optimum result is achieved at pH 11, duration of UV irradiation of 50 min, showing degradation amount of 98.25%. Surprisingly, the chemical oxygen demand (COD) in the degraded MB aqueous solution can be reduced about 77.9%, exhibiting the improvement of water quality. No loss of the activity of the degradation efficiency after reusability of this TiO 2 -zeolite photocatalyst for at least 4 times.
Phonological errors in communicating will let the listener gain a different meaning and communication becomes impeded. The students' errors are due to their lack of understanding of the sound system of language, as their second-language acquisition. The problem in this research is what type of phonological errors are made by students when they are listening to the short story and will impact on their speaking. The data is conducted in the language laboratory of The National University in Jakarta by secondsemester students in the subject of Spoken English. in the Faculty of Letters, English Department. The purpose of this research study is to learnthe difficulties of students when learning Basic Spoken English. The method used is descriptive with content analysis techniques. The result showed the most the biggest of surface structure taxonomy of phonological errors created by the students when they are listening to the short story and has impacted on speaking is global errors in diphthong (61,29%). This is because in Indonesian there is no sound of a diphthong. These global errors will have an effect on good communication. The students should study the phonological system in the target language, especially diphthong sound, in addition to vowels and consonants. It is expected that the lecturer often guides students' pronunciation based on the point and the manner of articulation and improve if they are not able to.
The cooperative learning model is part of a learning structure that has a broad scope. Inside there are approaches, strategies, methods and techniques. One important aspect of a learning model is syntax, which is the standard steps that must be taken in implementing the model. The purpose of this study is to develop management learning system on teaching materials based on active learning in cooperative learning. The collected-data can be in the forms of poll result, stuffing and field notes on the instrument activity sheet on the state of implementation of lectures and learning. Data were analyzed using statistical methods. Hypotheses were tested using t-tests to see the impact of cooperative learning models. The results of this research are: (1) teaching materials based on active learning and (2) article related to active-cooperative learning. The results of the expert validation of learning, teaching materials to be eligible, for subsequent use in learning. In relation to the advantages of using the cooperative learning model which is proved can make a positive interdependence; recognition in responding to individual differences; students are involved in class planning and management; a relaxed and pleasant class atmosphere; establishing a warm and friendly relationship between students and teachers; and having many opportunities to express pleasant emotional experiences.
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