Judul: Kajian Pustaka Silika Gel Asal Sekam Padi sebagai Adsorben Logam Berat
Abstrak: Meningkatnya kemajuan industri, pencemaran akibat limbah yang mengandung logam berat juga meningkat. Penanggulangan logam berat dengan proses adsorpsi yang memanfaatkan sekam padi sebagai adsorben. Sekam padi memiliki kandungan silika yang cukup tinggi. Kajian literatur ini bertujuan mengetahui potensi silika asal sekam padi sebagai adsorben logam berat melalui perlakukan yang berbeda. Sintesis silika menggunakan metode sol gel. Untuk meningkatkan kapasitas adsorpsi dilakukan penambahan aktivator asam bertujuan menghilangkan pengotor pada permukaan Selain itu, dilakukan modifikasi pada permukaan silika yang berhasil meningkatkan keasaman permukaan dan penambahan gugus fungsi baru yang dapat meningkatkan keaktifan pembentukan ikatan dengan logam berat. Hasil aktivasi dan modifikasi didukung dengan analisis gugus fungsi, permukaan, dan komposisi adsorben. Selain itu, dilakukan optimasi beberapa parameter adsorpsi berupa pH yang akan menghasilkan kapasitas adsorpsi maksimum., As the industrial sector grows, contamination from industrial waste that contains heavy metals is also increasing. One of the methods to remove heavy metals from industrial waste is the adsorption process by utilizing agricultural waste in the form of rice husks as adsorbent. Rice husk has high silica components. This literature review aims to determine the potential of silica from rice husks as an adsorbent of heavy metals through several different treatments. Silica synthesis using the sol-gel method. To improve the adsorption capacity, acid activation was carried out to remove impurities on the surface and modification of the silica surface. The modifications made were successful in increasing surface acidity and the addition of new functional groups which could increase the activity of bond formation with heavy metals. The results of activation and modification are supported by analysis of functional groups, surface, and composition of the adsorbent. In addition, the optimization of several.
Keyword: adsorbent, adsorption, heavy metals, rice husk, silica gel

Judul: Adsorpsi Timbal dengan Hibrida Merkapto-Silika dari Abu Jerami Padi
Abstrak: Silica gel is an adsorbent mostly used to adsorb heavy metals. Raw material for preparing silica gel is silicate (SiO2). Rice straw ash contains 94.5% Si, so that it is potential to be synthesized to silica gel. The weakness of silica gel as adsorbent is its low effectiveness toward metals adsorption, therefore active groups are needed to enhance its effectiveness. Silica gel mercapto-silica hybrid was made by adding HCl 3M to the mixture of 3-(trimethoxylil)-1-propanethiol (TMSP) and Na2SiO3 solution obtained from rice straw ash fused using NaOH until pH 7. The results were characterized using fourier transform infrared spectroscopy (FTIR), X-ray diffraction, energy dispersive x-ray (EDX), and scanning electron microscope. FTIR analysis showed that there were functional group of –CH2 on the silica gel TMSP but the expected –SH group was not detected. However, EDX result showed there was a composition of sulfur compound on silica gel TMSP. The modified silica gel with TMSP enhanced the capacity of Pb(II) adsorption. Commercial silica gel, the synthesized silica gel, and silica gel TMSP were all following Langmuir isotherm.
Keyword: rice straw ash, Pb adsorption, mercapto-silica hybrid

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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