Judul: Literature Review on Composite Zeolites for the Adsorption of Heavy Metal Ions
Abstrak: Perairan merupakan sumber air yang sangat penting bagi kehidupan sehingga berbagai upaya dilakukan untuk membuat perairan terbebas dari ion-ion logam berat yang berbahaya, salah satunya ialah dengan metode adsorpsi. Zeolit merupakan salah satu adsorben yang umum digunakan pada saat ini untuk menghilangkan ion logam berat. Berkembangnya ilmu teknologi memungkinkan adsorben diperoleh melalui penggabungan dua material atau yang disebut komposit. Komposit dibentuk dengan tujuan meningkatkan kemampuan adsorben dalam menghilangkan ion logam berat. Ulasan ini akan memberikan informasi terkait komposit zeolit dengan kitosan, selulosa asetat dan karbon aktif pada beberapa logam berat. Penelitian dilakukan dengan mencari sumber informasi dalam beberapa pangkalan data ilmiah. Masing-masing komposit menunjukkan hasil adsorpsi yang bagus., Water bodies are crucial course of water for life, thus various efforts have been undertaken to rid these water sources of hazardous heavy metal ions, one of which involves adsorption methods. Zeolite is a commonly used adsorbent today to eliminate heavy metals ions. The advancement of science and technology has enabled the creation of composite materials, known as adsorbent for heavy metals ions, with the aim of enhancing their adsorption capacity. This review provides information on zeolite composites with chitosan, cellulose acetate, and activated carbon for several heavy metals. The research was conducted by sourcing information from various scientific databases. The obtained composites from these three materials indicate successful composite formation, as evidenced by the higher adsorption capacity values of the composites compared to their individual component materials.
Keyword: adsorption, activated carbon, chitosan, composite, zeolite

Judul: Adsorption System of Composite Zeolite@AuNPs@MET were Synthesized by Binahong (Anredera cordifolia)Leaf Extract as Bioreductor
Abstrak: Berbagai penelitian telah dilakukan untuk mengurangi atau bahkan menghilangkan logam berat berbahaya dari limbah industri sebelum dibuang ke perairan. Adsorpsi dengan material berpori merupakan metode yang mudah dan sederhana, juga efektif untuk menghilangkan ion logam berat. Diantara jenis adsorben seperti karbon aktif, silika gel dan zeolit, zeolit merupakan material dengan bentuk kristal sangat teratur dengan rongga yang saling berhubungan ke segala arah.Untuk memperbaiki karakter zeolit alam sehingga dapat digunakan sebagai katalis, absorben, atau aplikasi lainnya, biasanya dilakukan aktivasi dan modifikasi terlebih dahulu (Yuanita 2010)., Various studies have been done to reduceoreven eliminate harmful heavymetals from industrial wastewater before discharge to waters. Adsorptionis a method that is often used because it’seasyandsimple, also effective to remove heavy metal ions. Among the various types of adsorbents such asactivated carbon, silicagel and zeolite, zeoliteis the best material to use because it has in sequence crystal form with cavities interconnected in all directions. To improve the character of natural zeolite that can be use dascatalysts, absorbents, orotherapplications, typically performed prior activation and modification (Yuanita 2010).
Keyword: adsorbent, bioreductor, binahong leaf, zeolite@AuNPs@MET

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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