Hematite (α-Fe2O3) with uniform hexagonal flake morphology has been successfully synthesized using a combination of gelatin as natural template with F127 via hydrothermal method. The resulting hematite was investigated as adsorbent and photocatalyst for removal of ibuprofen as pharmaceutical waste. Hexagonal flake-like hematite was obtained following calcination at 500 °C with the average size was measured at 1–3 µm. Increasing the calcination temperature to 700 °C transformed the uniform hexagonal structure into cubic shape morphology. Hematite also showed high thermal stability with increasing the calcination temperatures; however, the surface area was reduced from 47 m2/g to 9 m2/g. FTIR analysis further confirmed the formation Fe-O-Fe bonds, and the main constituent elements of Fe and O were observed in EDX analysis for all samples. α-Fe2O3 samples have an average adsorption capacity of 55–25.5 mg/g at 12–22% of removal efficiency when used as adsorbent for ibuprofen. The adsorption capacity was reduced as the calcination temperatures increased due to the reduction of available surface area of the hexagonal flakes after transforming into cubes. Photocatalytic degradation of ibuprofen using hematite flakes achieved 50% removal efficiency; meanwhile, combination of adsorption and photocatalytic degradation further removed 80% of ibuprofen in water/hexane mixtures.
This research aims to analyze TPACK items using the Rasch model in terms of validity, reliability, item difficulty and bias items. The method used is descriptive quantitative with 34 pre-service chemistry teachers in semester VI consisting of 26 female students and 8 students from Sebelas Maret University (UNS). The instrument used in this study was the matter of Teachnological Pedagogical Content Knowledge (TPACK) which was adapted from the PPG Teachnological Pedagogical Content Knowledge (TPACK), which consisted of 30 multiple choice questions. The results showed that: 1) the validity of the suitability level of items was 27 questions that were fit and 3 questions that were not fit. 2) the results of raw variance data of 33.5% indicate that the requirements for Raw variance explained by measures of at least 20% can be met and the variance that cannot be explained by the instrument of 8.2% also meet the criteria ie, not to exceed 15%. 3) Reliability of pre-service chemistry teachers is 0.52 in the weak category, item reliability is 0.90 in the good category and reliability between pre-service chemistry teachers and items 0.64 in the sufficient category. 4) The level of difficulty of the questions is very difficult, difficult, easy, very easy and is dominated by questions that are categorized as difficult. 5) there are no questions that have a probability of less than 5% so there are no biased items. In conclusion, TPACK item analysis using the Rasch model is valid, reliable, item difficulty is very good and there are no biased items. So the questions that have been analyzed can be used to measure TPACK on pre-service chemistry teachers.
TiO2/SBA-15 photocatalysts were successfully prepared by impregnating low loading titania to SBA-15 via slow calcination. The photocatalyst is efficient for fast methylene blue removal via adsorption and photodegradation methods. The impregnation of low TiO2 loading via slow calcination enhanced TiO2 dispersion that preserved the SBA-15 porosity and uniform morphology. High interfacial interaction of TiO2/SBA-15 improves TiO2 photoresponse by narrowing the bandgap, resulting in a stronger redox ability. The methylene blue removal on 10%TiO2/SBA-15 followed the pseudo-second-order kinetic model that reached 67% removal efficiency in 90 min. The synergy between adsorption and photodegradation is responsible for the fast methylene blue removal. These results indicate the importance of maintaining the adsorption capacity in SBA-15 after impregnation with TiO2 for efficient adsorption-photodegradation processes, which can be achieved by controlling the deposition of TiO2 on SBA-15. A low titania loading further reduced the cost of photocatalysts, thus becoming a potential material for environmental pollution treatment.
In this paper, a carbon foam of gelatin (CFG) with large pore size was synthesized for the first time using gelatin as a carbon precursor and sulfuric acid as the catalyst which is pyrolyzed at 900 C for 3 h under argon atmosphere flow. The structural and textural properties of the CFG samples were characterized by scanning electron microscopy (SEM), energy dispersive X-Ray (EDX), thermal gravimetry analysis (TGA), Fourier transforms infrared (FTIR) spectroscopy and nitrogen adsorption-desorption techniques. The surface area of CFG sample is about 62.5 m 2 /g and pore size with average size range at 20-30 nm and broken hole size up to 10 mm according to the N 2 isotherm curve and SEM. The high pore size of CFG and dominated by carbon and oxygen with the unique structure composed of disordered arrays of carbon nanopipes in a macropore system. TGA curve showed degradation of gelatin due to water weight loss and decomposition reaction of gelatin. The TGA results indicated that there was big CFG degradation at 1000 ºC that showed the high thermal stability of CFG. The study on thermal behavior and character of CFG structural would create a new generation of the hard template.
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