Bismuth oxide (Bi2O3) is a well-studied photocatalyst for degradation of various environmental contaminants. In this research Bi2O3 has been synthesized by precipitation method using two different bases (NH4OH and NaOH). The samples thus obtained were then analyzed using FTIR, XRD, and SEM for surface functionalization, crystal structures and morphological differences, respectively. The Bi2O3 precipitated using NH4OH showed a flower like structure made up of individual plates having α-Bi2O3 crystal structure. The precipitate obtained using NaOH showed a honeycomb like flower structure with a mixture of both α-Bi2O3 and γ-Bi2O3 crystal structure. Degradation of methyl orange (MO) was used as a model system to test the photocatalytic activity of the bismuth oxide. The Bi2O3 synthesized using NH4OH showed superior photocatalytic degradation of methyl orange than the one synthesized using NaOH.
Telah dilakukan penelitian tentang kinetika adsorpsi zeolit alam dengan surfaktan heksadesiltrimetilammonium klorida sebagai adsorben ion nitrat dan fosfat. Penelitian ini bertujuan untuk menentukan konstanta laju adsorpsi (k) optimum pada anion nitrat dan fosfat. Penelitian ini dilakukan dengan proses modifikasi,dan adsorpsi. Proses modifikasi dilakukan dua tahap, yaitu tahap aktivasi zeolit alam yang dilakukan dengan menambahkan larutan HF 1% selama 10 menit dan penambahan larutan NH4Cl 2M selama 4 jam, selanjutnya zeolit aktif dimodifikasi dengan HDTMA-Cl menggunakan kolom. Proses adsorpsi ion nitrat dan fosfat pada ZMS dilakukan pada variasi waktu 5;10;15;20;24 jam dan dengan variasi konsentrasi 350;400;450;500 ppm. . Hasil spektra FTIR untuk nitrat muncul pada bilangan gelombang 1473,62 cm-1 dan untuk fosfat muncul pada bilangan gelombang 462,92 cm-1 yang menunjukkan vibrasi bending (v2) PO43- dengan intensitas lemah, hal ini membuktikan bahwa anion nitrat dan fosfat berhasil teradsopsi oleh ZMS. Konstanta laju adsorpsi optimum untuk ion fosfat adalah 0,1154 g/mg.min besarnya konstanta laju adsorpsi optimum untuk ion nitrat adalah 0,00293 g/mg.min. Hasil adsorpsi pada nitrat dan fosfat menunjukkan kecenderungan bahwa ZMS mengikuti persamaan laju adsorpsi orde 2 semu untuk anion nitrat dan fosfat.
A r t i c l e I n f o A b s t r a c t Keywords:Zeolites, rice husk ashThe synthesis of zeolites from rice husk ash by varying hydrothermal time and temperature has been conducted. Peranan silika pada sintesis zeolit sebagai bahan dasar sangat mutlak disamping alumina. Salah satu sumber di alam yang kaya akan silika adalah sekam padi, dimana sekam padi selama ini kurang dimanfaatkan penggunaanya. Kandungan silika dalam abu sekam padi mencapai 86,9-97,80%. Katsuki dan Komarneni [5] telah mensintesis zeolit Na-A dari bahan dasar sekam padi menunjukkan rasio Si/Al sebesar 2 dengan diameter pori-pori 3,9 nm dan nilai KTK 506 meq/100 gram.Hui dan Chao [6] telah mensintesis zeolit 4A dari fly ash batu bara dengan menggunakan metode hidrotermal menunjukkan bahwa zeolit yang terbentuk adalah zeolit 4A. Sintesis tersebut dapat menghilangkan ion kalsium dalam air sadah, namun dalam bentuk morfologi kristal serta ukuran diameter pori-pori kurang baik yaitu dengan diameter pori-pori sebesar 2-4,5 μm dan nilai KTK sebesar 190 meq/100 gram.Jiang dkk. [7] telah melakukan sintesis zeolit A dari palygorskite dengan variasi waktu hidrotermal menghasilkan zeolit sintesis dengan ukuran diameter pori-pori 2 μm dan nilai KTK 318 meq/100 gram dan rasio Si/Al sebesar 1,53-3,05 pada waktu hidrotermal 5 jam. Waktu hidrotermal dalam sintesis zeolit berpengaruh terhadap ukuran pori, luas permukaan, volume zeolit, dan kristalinitas zeolit.Berdasarkan kajian penelitian diatas, maka pada penelitian ini di lakukan sintesis zeolit dari sekam padi dengan menggunakan metode hidrotermal dengan variasi waktu dan suhu hidrotermal, kemudian dikarakterisasi dengan XRD dan ditetukan nilai KTK.
This study aims to synthesize bismuth oxide/activated carbon composites composed of rice husks for battery anodes and to determine the effect of bismuth nitrate pentahydrate mole variations on the characteristics of the resulting composites. The bismuth oxide/activated carbon composite synthesis was carried out using bismuth nitrate pentahydrate, sodium sulfate, and sodium hydroxide precursors which were mixed with rice husk-based activated carbon. A variation was made for the mole of bismuth nitrate pentahydrate used, while the compositions of activated carbon and other precursors were made fixed. The composites were synthesized using the hydrothermal method at a temperature of 110 0 C for 5 hours. The results showed that bismuth oxide was successfully formed as a composite in the 8 mmol variation with a composite electrical conductivity value of 2.40 x 10 -3 S.m -1 .
Activated carbon is one of the most commonly used adsorbents in a variety of separation processes because it is inexpensive, and also the design and principal of application are quite simple. The ability of activated carbon as an adsorbent is related to its large surface area and pore volume, varying pore structure, and diverse surface reactivity. The use of microwave radiation can further improve the efficiency of activated carbon adsorption. Micro-waves can affect the pore texture and surface of the activated carbon, but rarely do both practitioners and researchers control these variables influencing the relationship between features and performance of biomass-based activated carbon as an adsorbent at the time of manufacture from the initial stage (carbonation) to carbon application active (e.g., adsorption of heavy metals, surfactants, and organic molecules). This study aims to synthesize activated carbon from rice husk, which has the efficiency and capacity of adsorption of heavy metals such as Pb and activator organic molecules used is ZnCl2 30% and microwave radiation. This research has succeeded in making activated carbon using the ZnCl2 activator and microwave radiation. The time and power of microwave radiation that provides the highest efficiency in the carbon activation process for Pb ion adsorbate, were 7 minutes and 800 W. For phenol adsorbate was 5 minutes at 800 W. The highest efficiency time and concentration of adsorption for Pb ion adsorbate were 40 minutes at 60 ppm while for phenol adsorbate were 5 hours at 100 ppm. The adsorption efficiency for Pb cation adsorbate was 99.57%. While for phenol adsorbate is 81.05%. Characterization with FTIR, SEM-EDX, and SAA showed a C-Cl bond, the pores were visible, and an increased surface area of activated carbon was 36.9 times the surface area of carbon and the pores formed were mesoporous.
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