1,720,967 research outputs found
PENGARUH VARIASI TEMPERATUR KALSINASI ZEOLIT ALAM TERHADAP KEMAMPUAN ADSORPSI LIMBAH FENOL
No full textAbstrak. Aktivasi zeolite alam dengan kalsinasi berbagai temperature telah dilakukan. Zeolite alam dimanfaatkan sebagai absorben penurunan limbah fenol. Tujuan dari penelitian ini untuk mengetahui karakteristik zeolit alam variasi temperatur kalsinasi, temperatur kalsinasi zeolit alam terhadap kemampuan optimum adsorpsi limbah fenol, model isoterm adsorpsi dan kinetika adsorpsi limbah fenol pada zeolit alam terkalsinasi, dan karakteristik zeolit alam setelah proses adsorpsi limbah fenol Zeolit alam dipreparsi, diaktivasi dengan kalsinasi variasi temperatur, dan diaplikasi sebagai adsorben limbah fenol. Variasi temperatur kalsinasi digunakan adalah 400oC, 450oC, dan 500oC. Karakterisasi menggunakan FTIR dan XRD pada zeolit alam sebelum kalsinasi, zeolit alam kalsinasi, dan zeolit alam setelah adsoprsi. Model isoterm adsorpsi ditentukan dengan menggunakan metode regresi linear terhadap persamaan isoterm Langmuir dan Freundlich dan kinetika adsorpsi didasrkan pada kinetika orde nol, orde satu, orde dua, dan orde tiga. Berdasarkan hasil karakterisasi XRD zeolite alam sebelum kalsinasi, 2θ merefleksikan intensitas tajam pada daerah 2θ = 9,82°; 13,46°; 19,69°; 22,35°; 23,15°; 25,68°; 36,34°; dan 27,74° menunjukkan karakteristik zeolit alam modernit. Spektra FTIR zeolit alam sebelum kalsinasi diamati pada bilangan gelombang 300 sapai 4000 cm-1 menunjukkan rentangan simetri O-Al-O atau O-Si-O pada internal tetrahedral yang ditandai munculnya puncak pada bilangan gelombang 650-720 cm-1. Hasil karakterisasi XRD zeolit alam terkalsinasi tidak mengalami perubahan dengan puncak refleksi sebelum kalsinasi. Spectra IR zeolite alam terkalsinasi menunjukkan pergeseran ke bilangan gelombang karena proses dealuminasi. Peningkatan temperatur kalsinasi zeolit alam meningkatkan kemampuan adsorpsi zeolit alam dengan kemampuan adsorpsi tertinggi zeolit alam terjadi pada temperatur kalsinasi 450 ˚C dan konsentrasi awal fenol 6 ppm. Adsorpsi zeolit alam terhadap fenol mengikuti model isoterm Langmuir dan mengikuti kinetika reaksi orde satu, serta tidak merubah struktur zeolit alam. Proses adsorpsi yang terjadi secara fisik antara zeolit alam dan limbah fenol
Krokot Extract (Portulaca Oleracea. L) as Natural Light-harvesting pigments for Dye-Sensitized Solar Cells (DSSCs) : Influence of Dye Acidity
Get PDFDye-sensitized solar cells (DSSCs) was fabricated using natural dyes extracted from krokot (Portulaca Oleracea. L). The effect of dye acidity was investigated on natural pH extract, 5.00, 4.00 and 3.00 of pH. The efficiency and stability DSSCs as a function of the dye acidity was studied. The result of the UV-Vis shows that the absorption of wave-length from dye extract of krokot is located in the visible region with the absorbance peak in 410.5 nm and 664.5 nm which are the peak of chlorophyll. The efficiency of extract krokot dye sensitized solar cells was decreasing 6.88 x 10-3 % to 0.42 x 10-3 % when pH of the dye was adjusted from 6.27 to 3.00. DSSCs stability was also decreased look for efficiency loss from 5.27% to 97.49% in the same conditions
Adsorption and Desorption Metal Cu (II) using Zeolite Synthetic by Bottom Ash Coal Modified Dithizone
No full textZeolite synthetic and zeolite modified dithizone has been succesfully created by hydrotermal method. The aim of this research is to know the characteristics of zeolite synthetic and zeolite modified dithizone and to know capacity of adsorption and desorption. The effect of various variables, such as pH, concentration of Cu (II), contact time and temperature was investigated using batch process, characterization zeolite modified dithizone and zeolite synthetic using XRD, XRF, FTIR and GSA. The result of characterization bottom ash coal by hydrotermal reaction using XRF, be discovered composition Si as many 82,01% and Al 8,54%. product of melting hydrothermally indicate a specific zeolite IR absorption at a wavelength of 300-1250 cm-1. The result XRD showed that be found zeolite-X, zeolite-A, zeolite sodalite and difatogram of dithizone. Zeolite modified dithizone has been succesfully synthesized with a marked presence group of –NH and –SH by using FTIR. Zeolite modified dithizone surface area change from 160,262 m2/g to 69,609 m2/g. The best adsorption metal Cu(II) by zeolite synthetic is pH 7. Kinetics adsorption zeolite synthetic and zeolite modified dithizone follow kinetics of pseudo second orde, with R2 respectively 0,7378 and 0,8689, rate constant of pseudo second orde adsorption at zeolite synthetic is -0,017 g/mg.min-1 and zeolite modified dithizone -0,013 g/mg.min-1. Isotherm type for both of adsorbent follow Langmuir isotherm. Desorption of metal Cu(II) on zeolite modified dithizone and zeolite synthetic a lot off obtained using HCl at level 47,08% and 41,49% respectively
Pengembangan Media Virtual Lab sebagai Alternatif Praktikum Kimia dalam Pembelajaran Daring di Masa Pandemi COVID-19
Get PDFPandemi Covid 19 menuntut pendidik Kimia untuk membuat alternatif dan inovasi pembelajaran dalam praktikum kimia yang dapat diakses melalui pembelajaran daring dan jarak jauh. Salah satunya dengan Media Virtual Lab. Media ini dikembangkan dan diteliti kualitasnya melalui penelitian pengembangan (Research and Development) mengacu pada model pengembangan Borg dan Gall secara terbatas. Adobe animate CC dipilih sebagai program untuk merancang Media Virtual Lab agar media yang dihasilkan lebih menarik dan dapat diakses menggunakan komputer ataupun telepon pintar. Media Virtual Lab hasil pengembangan ditinjau oleh dosen pembimbing, diberi masukan dan saran oleh tiga peer reviewer kemudian divalidasi oleh satu ahli materi dan satu ahli media untuk kemudian dinilai oleh tiga pendidik Kimia SMA/MA. Produk ini juga direspon oleh sepuluh peserta didik kelas XII MIPA. Data diambil dengan lembar angket skala Likert untuk menilai kualitas produk dan lembar angket skala Guttman untuk mengumpulkan respon peserta didik. Hasil penelitian menunjukkan Media Virtual Lab memiliki kategori sangat baik dengan persertase penilaian sebesar 90,62%; 95,83%; dan 92,92% oleh ahli materi, ahli media, dan reviewer secara berturut-turut. Peserta didik sebagai pengguna media merespon positif dengan adanya Media Virtual Lab berbasis Adobe Animate CC ini
Synthesis of ZnO Nanoparticles Doped Zirconium Oxychloride by PSTA BATAN Yogyakarta Production as Photoanode Semiconduktors for Dye Sensitized Solar Cell
No full textDye Sensitized Solar Cell (DSSC) is a device for light conversion to be electrical energy based on the concept of semiconducting sensitivity of the wide gap. This study aims to synthesis nanoparticles of ZnO: Zr semiconductors and tested the performance of ZnO: Zr nanoparticles on the DSSC system. ZnO Doped Zr Nanoparticles from precursor by Science and Technology Acceleration Center of National Nuclear Energy Agency (PSTA BATAN) Yogyakarta production was synthesized by gel-combustion method, and tested its performance on DSSC system. Effect of doping concentration variation Zr (0, 1, 3 and 5%) on the structure crystals and optical properties of ZnO studied by X-ray diffraction, infra-red spectra, and UV-Visible absorbance spectra. In this study also studied about the effect of Zr doping on changes in the parameters of crystal structures such as distances between fields of crystals , crystals lattice (a and c), unit cell volume, crystallite size, microstrain (ε), dislocation density (δ), and the textural coefficient . The synthesized nanoparticles meet the criteria 3-dimensional nanostructure of hexagonal wurtzite crystals. Uptake ZnO infrared radiation shows an increase in intensity as well shift in wave number 610 - 400 due to doping Zr. Doping Zr also influences the electronic structure of semiconductors characterized by the change of bandgap energy from 3,10-3,05 eV. Semiconductor performance test nanoparticles on the DSSC system showed a 1% Zr doping concentration increasing the voltage by 174 mV and the stability of the solar cell than the cell ZnO solar without doping that produces a voltage of 128 mV
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
ADSORPSI ZAT WARNA METHYL ORANGE MENGGUNAKAN ZEOLIT DARI ABU DASAR BATUBARA
No full textTelah dilakukan penelitian adsorpsi zat warna methyl orange menggunakan zeolit abu dasar batubara. Penelitian ini bertujuan untuk mengetahui karakteristik zeolit hasil sintesis dan kesetimbangan adsorpsi, kinetika adsorpsi dan termodinamika adsorpsi zeolit terhadap pewarna methyl orange. Karakterisasi gugus fungsional zeolit menggunakan Spektrofotometer FT-IR dan kristalinitas menggunakan Difraktometer Sinar-X. Kajian adsorpsi zeolit terhadap methyl orange dilakukan pada variasi pH methyl orange range 1, 2, 3, 4, 5, 6, 7 dan 8, variasi waktu kontak adsorpsi yaitu 1, 2, 3, 4, 5, 10, 15, 20, 25, 35, 45, 55, 65, 75, 85, 95, 105, 115, 125, dan 135 menit, variasi konsentrasi yaitu 10, 20, 50, dan 100 mg/L dan variasi temperatur yaitu 28, 35, 45, dan 55 0C. Hasil karakterisasi sintesis zeolit dari abu dasar batubara menggunakan karaterisasi X-Ray Diffraction dan Fourier Transform Infra Red menunjukkan bahwa zeolit hasil sintesis mempunyai struktur material zeolit faujasit yang ditunjukkan dengan puncak utama yaitu 6,2940; 26,8950; dan 31,1900. Adsorpsi zeolit terhadap methyl orange terjadi pada pH 2, kesetimbangan adsorpsi cenderung mengikuti pola isoterm Freundlich dengan kapasitas adsorpsi (n) yaitu 2,392x10-3 mol/L dan konstanta Freundlich (K) yaitu 1,803x10-4 mol/g. Kinetika adsorpsi cenderung mengikuti pseudo orde dua dengan nilai konstanta laju reaksi (k) yaitu 1,866 (g/mg min) dan kapasitas adsorpsi (qe) yaitu 10,341. Termodinamika adsorpsi membuktikan bahwa pembentukan sistem adsorpsi adsorben dengan adsorbat bersifat spontan ditunjukkan dengan nilai ∆G0 (8.825,652 Kj/mol), ∆H0 (-0,2485 Kj/mol), dan ∆S0 (+29,058 Kj/mol)
- …
