Owing to their high surface to volume ratio and fast electron transfer, zinc oxide (ZnO) nanorods have been well-known as potential nanostructured material for various applications including sensors, dye sensitized solar cells, optoelectronic, transparent heater and biomedical devices. Among other synthesizing techniques for obtaining ZnO nanorods, chemical bath deposition (CBD) has been thought as a simple and low-cost method. However, there are several processing parameters that need to be investigated for the above-mentioned applications where the highly optical transparency of thin film ZnO nanorods grown on glass substrates is one of important targets to be achieved. In this work, ZnO nanorods were synthesized through CBD process at low temperature (0°C) by using seed solution prepared by dissolving 1: 1 equimolar zinc nitrate tetrahydrate and hexamethylene tetraamine. For investigation purposes, three different concentration of seed solutions i.e. 0.005, 0.025 and 0.05 M were used. Thin films containing ZnO nanoseeds were formed by spin coating the precursors on the glass substrates, followed with annealing at 2000C for 5 minutes. Finally, the ZnO nanorods were further grown at 90ºC for 3 hours in the beaker glass using the same solution. Xray diffraction (XRD) analysis showed that all ZnO nanorods demonstrated a strong (002) peak belong to wurtzite phase. It was found that the estimated crystallite size and band gap energy (Eg ) for ZnO nanorods derived from the seed solutions of 0.005, 0.025 and 0.05 M were 21.42, 137.11, 171.39 nm, and 3.60, 3.20, 3.18 eV, respectively. However, the optical transparency was adversely lowered from about 75 to 40 % as a result of increased coverage of ZnO nanorods on the glass substrate. For transparent heater application where, a desired combination of high optical transparency and suitable electronic properties is needed, the current results were considered to be promising.
Sumbawa has the potential to transition into a smart city, utilizing solar energy as their main source of its alternative energy. Located in the tropical country of Indonesia, Sumbawa’s dry season lasts eight months, during which it sees a solar intensity of 4.51 watt/m2/h, making solar energy a promising resource for the area. Its level of abundance and no pollution attribute are the main factors that make solar energy an attractive renewable resource. Raw calculation showed that solar energy is able to provide massive amount of energy, while solar panel and photovoltaic can produce zero greenhouse gases when converting solar energy into electricity. However, the high initial cost of installing solar cells hinder popularization of it as an alternative energy source, meanwhile some of the substance materials that compose solar panel may have a negative impact on the environment. This study intends to review the potential for inexpensive semiconductor-based solar panels to be applied as independent source of lighting by analysing the cost and environmental impact. Discussion on simple chemical method without high cost equipment instalment is also highlighted in this work, which offers recommendation of methods that can contribute on lowering the production cost of solar panel.
One dimensional Zinc Oxide (ZnO) nanostructures in the forms of nanowire, nanorod, nanotube have been attracting scientific and technology interests in the last few years. This current study investigated the effects of chemical bath deposition (CBD) synthesis parameters i.e. seeding solution concentration and growing time on the nanostructural characteristics of ZnO nanorods and considering their potential application for transparent heater. Seed solutions were prepared by dissolving 1:1 equimolar zinc nitrate tetrahydrate and hexamethylenetetraamine in water at 0°C for 1 hour. Upon the synthesis, the seeding solution concentration was varied from 0.005, 0.025, 0.05 M. The formation of thin films containing ZnO nanoseeds was carried out by spin coating the precursors on the conducting indium tin oxide (ITO) glass substrates, followed with annealing at 200 o C for 5 minutes then further growing the ZnO nanorods at 90 o C for 3 hours. Another variation in this work was also carried out by selecting a different route upon CBD process, i.e. with a fixed 0.05 M seeding solution prepared from the same equimolar zinc nitrate tetrahydrate and hexamethylenetetraamine in water at 25 o C for 1 hour, followed with the same annealing stage but continued by variation in the growing stage at 90 o C for different times (3, 4 and 5 hours). ZnO nanorods were characterized using x-ray diffraction, field emission scanning electron microscopy and ultraviolet-visual spectroscopy. The results of these investigations demonstrated that with the increase in reaction time from 3 to 5 hours, the band gap energy, Eg of the nanorods decreased from 3.63 to 3.13 eV, a consequence of the increase in their diameter and crystallite size from 325 to 583 nm and 22.68 to 34.28 nm, respectively. The desired coverage of ZnO nanorods for transparent heater applications was obtained with a 0.05 M seeding solution and 5-hour reaction time.
Recovery of manganese from manganese ores was investigated by reductive leaching method using reeds as a reductant in the sulfuric acid medium. Cellulose, hemicellulose, and lignin are natural reducing agents which are widely used as reducing agents to recover manganese. Effects of calcination temperature and the holding time calcination on the leaching efficiency of manganese and impurities were examined. The calcination temperature and the holding time calcination have a significant effect on the extraction of manganese. The experimental results demonstrated that the higher the calcination temperature used, the higher the percentage of manganese obtained, namely 79.58% and 87.38%, respectively. The XRD (x-ray diffraction) pattern shows that the manganese phases formed at 700 and 800 °C are Mn3O4 (hausmannite) and Mn2O3 (bixbite), respectively. The morphology in the sample with calcination temperature at 700 °C showed agglomerate- shaped particles and unevenly dispersed. Meanwhile, the sample with calcination temperature at 800 °C exhibited agglomerated particles of inhomogeneous size and were more evenly distributed. Variation of holding time in the manganese ores recovery process also affects the results of manganese recovery. The composition of the manganese recovery in the samples using holding time calcination variations of 3 and 4 hours was 83.88% and 89.24%, respectively. The results of the XRD analysis showed that the manganese phase formed using 3 hours of calcination holding time was dominated by Mn3O4 (hausmannite). Meanwhile, the manganese phase formed using 4 hours of holding time of calcination was dominated by Mn2O3 (bixbite).
Sampah plastik merupakan sampah yang paling sering dijumpai, salah satunya di lingkungan sekolah, bahkan terkadang keberadaannnya tidak dihiraukan. Sehingga, menyebabkan jumlah sampah plastik meningkat setiap harinya. Peningkatan jumlah sampah plastik disebabkan proses pengelolaan sampah yang rumit dan biaya investasi yang mahal. Permasalahan sampah merupakan tanggung jawab bersama, termasuk generasi muda. Sehingga, pengenalaan pengelolaan sampah pada siswa-siswa sangat penting, karena akan menumbuhkan karakter yang peduli akan linkungannya. Salah satu metode dalam pengelolaan sampah yang ramah lingkungan yaitu dengan pembuatan batu bata ramah lingkungan (ecobrick). Program Studi Teknik metalurgi dan mahasiswa Program MBKM UTS Mengajar bekerjasama dengan SMKN 2 Sumbawa Besar untuk mengolah limbah sampah plastik. SMKN 2 Sumbawa Besar memiliki tempat pembuangan sampah induk yang didominasi oleh sampah anorganik dari botol plastik dan bungkusan makanan ringan. Dalam kegiatan pengabdian ini, metode yang digunakan yaitu diawali dengan observasi lapangan metode diskusi, pelatihan dan praktek langsung pembuatan ecobrick. Kegiatan ini bertujuan untuk memberikan pemahaman tentang bahaya sampah anorganik bagi Kesehatan dan lingkungan, serta dengan adanya pelatihan ini diharapkan dapat meningkatkan kreatifitas para siswa SMKN 2 Sumbawa Besar untuk mengelola sampah anorganik. Berdasarkan hasil kegiatan pengabdian yang telah dilaksanakan, menunjukkan para siswa-siswi memiliki keinginan dan kemauan yang tinggi dalam mempelajari proses pengelolaan sampah dari limbah sampah plastik, yang ditandai dengan partisipasi aktif para siswa mengikuti setiap proses-proses dalam pembuatan bata ramah lingkungan (ecobrick).
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