Pengaruh Ph Dan Waktu Kontak Pada Adsorpsi Pb(ii) Menggunakan Adsorben Kitin Terfosforilasi Dari Limbah Cangkang Bekicot (Achatina Fulica)

Limbah cangkang bekicot mengandung kitin yang dapat dimanfaatkan sebagai adsorben ion logam berat. Tujuan dari penelitian ini adalah untuk meningkatkan kapasitas adsorpsi kitin terhadap ion Pb(II) dengan cara fosforilasi dan juga mempelajari pengaruh pH dan waktu kontak larutan terhadap adsorpsi Pb(II) pada kitin terfosforilasi. Kitin diisolasi dari cangkang bekicot melalui proses deproteinasi dan demineralisasi. Kitin difosforilasi dengan asam fosfat dan dinatrium hidrogen fosfat. Penelitian dilakukan dengan variasi pH 2, 3, 4 dan 5 serta variasi waktu kontak 20, 40, 60, 80, 100 dan 120 menit. Hasil yang diperoleh yaitu adsorpsi ion Pb(II) secara maksimum diperoleh pada pH 4 sebesar 86,45% dan waktu kontak selama 60 menit

Studi Awal Tentang Penumbuhan Kristal Tunggal Kromium(iii)-disianamida Dalam Gel Metasilikat

Pengaruh rasio mol dan pH dalam reaksi senyawa kompleks seringkali mempengaruhi komposisi dan sifat dari senyawa yang dihasilkan. Penelitian ini bertujuan untuk mempelajari pengaruh rasio mol dan pH pada sintesis Cr(III)-disianamida (dca) dalam gel metasilikat dengan metoda tabung gelas tunggal dan karakterisasi senyawa hasil sintesis. Natrium metasilikat digunakan sebagai bahan gel metasilikat dan sintesis dilakukan pada variasi pH 5, 6, dan 7, sedangkan rasio mol Cr(III):dca yang digunakan yaitu 1:3 dan 1:4. Sintesis dilakukan pada suhu kamar selama 5 minggu. Hasil penelitian menunjukkan bahwa variasi mol Cr(III):dca dan pH gel berpengaruh pada massa padatan Cr(III)-dca. Massa padatan Cr(III)-dca terbesar dihasilkan pada pH 6 pada setiap rasio. Pada rasio 1:4 diperoleh massa 0,0118 g > pH 7 dengan massa 0,0099 g > pH 5 dengan massa 0,013 g, sedangkan pada rasio 1: 3 diperoleh massa 0,0118 g > pH 7 dengan massa 0,0040 g > pH 5 dengan massa 0,0060 g. ukuran kristal yang diperoleh relatif kecil. Hasil analisa IR menunjukkan dca terikat pada sistem kristal, yaitu pada atom N di ujung dca (N≡C–N-–C≡N) dengan ditunjukan adanya pergeseran pada bilangan gelombang di sekitar 2200 – 2300 cm-1

Upaya Penumbuhan Kristal Tunggal Kromium(iii) Asetilaseton Dengan Metode Gel Metasilikat

Metoda gel merupakan salah satu metoda penumbuhan kristal tunggal garam sederhana maupun garam kompleks yang telah banyak dikembangkan. Upaya penumbuhan kristal tunggal kromium(III)-asetilaseton dalam gel metasilikat telah dilakukan dengan metoda tabung gelas tunggal dengan variasi pH gel metasilikat 5,0; 5,5 dan 6,0 dan rasio mol kromium(III):asetiaseton adalah 1:3. Sintesis dilakukan dengan menambahkan larutan supernatan CrCl3 dengan variasi konsentrasi 0,5 dan 0,75M ke atas gel metasilikat yang sebelumnya telah ditambahkan dengan asetilaseton. Reaksi dilakukan pada suhu kamar selama 28 hari. Karakterisasi tahap awal dilakukan dengan metoda spektrofotometri inframerah. Hasil penelitian menunjukkan bahwa setelah 28 haritidak terdapat kristal tunggal yang tumbuh dalam gel metasilikat pada setiap variasi pH dan konsentrasi supernatan. Diperkirakan dengan penambahan waktu tumbuh yang lebih lama, kristal yang diinginkan akan tumbuh di dalam gel

Utilization of Snail (Achatina Fulica) Shell Waste for Synthesis of Calcium Tartrate Tetrahydrate (CaC4H4O6.4H2O) Single Crystals in Silica Gel

Snail (Achatina fulica) shell waste is massively produced by many home industries in Indonesia, especially in East Java. The snail shell is known for high calcium; therefore it is potential to be used as calcium source of supernatant in the synthesis of piezoeletric material, such as single crystal of calcium tartrate tetrahydrate (CaTT). The aim of this research is to study the synthesis and characterization of CaTT or CaC4H4O6.4H2O from snail shell waste in silica gel. Supernatant solution of CaCl2 was prepared from CaO, which previously made by calcinating the shell at 1000C, and then reacted with HCl 1.5M. Synthesis of CaTT was conducted in a single-tube reaction at room temperature in which silica gel was used as growth medium with gelling time of 10 days and growth time of 2 weeks. The pH of gel and CaCl2 concentration were varied, 3.00; 3.50; 4.00; 4.50; 5.00; and 0.27; 0.36; 0.45; 0.54 M respectively, in order to obtain optimum condition of the synthesis, which is indicated from crystal yields. The synthesized crystals were characterized by atomic adsorption spectrophotometry (AAS), infrared spectroscopy (IR) and powder X-ray diffraction (XRD). Experimental data shows that optimum condition was obtained at pH of 3.50 and [CaCl2] of 0.45M with yield of 69.37%. The obtained single crystal has clear color and octahedral-like shape with size ranged between 4 - 9 mm. Analysis data by FTIR and powder XRD confirmed that the obtained crystal was CaTT single crystals with crystal system of orthorhombic

Utilization of Snail (Achatina fulica) Shell Waste for Synthesis of Calcium Tartrate Tetrahydrate (CaC4H4O6.4H2O) Single Crystals in Silica Gel

Snail (Achatina fulica) shell waste is massively produced by many home industries in Indonesia, especially in East Java. The snail shell is known for high calcium; therefore it is potential to be used as calcium source of supernatant in the synthesis of piezoeletric material, such as single crystal of calcium tartrate tetrahydrate (CaTT). The aim of this research is to study the synthesis and characterization of CaTT or CaC4H4O6.4H2O from snail shell waste in silica gel. Supernatant solution of CaCl2 was prepared from CaO, which previously made by calcinating the shell at 1000°C, and then reacted with HCl 1,5M. Synthesis of CaTT was conducted in a single-tube reaction at room temperature in which silica gel was used as growth medium with gelling time of 10 days and growth time of 2 weeks. The pH of gel and CaCl2 concentration were varied, 3.00; 3.50; 4.00; 4.50; 5.00; and 0.27; 0.36; 0.45; 0.54 M respectively, in order to obtain optimum condition of the synthesis, which is indicated from crystal yields. The synthesized crystals were characterized by atomic adsorption spectrophotometry (AAS), infrared spectroscopy (IR) and powder X-ray diffraction (XRD). Experimental data shows that optimum condition was obtained at pH of 3.50 and [CaCl2] of 0.45M with yield of 69.37%. The obtained single crystal has clear color and octahedral-like shape with size ranged between 4 – 9 mm. Analysis data by FTIR and powder XRD confirmed that the obtained crystal was CaTT single crystals with crystal system of orthorhombic

Sensory and Physicochemical Characteristics of Two Common Roast Defects in Robusta Coffee

Roasting is an important coffee processing step to generate coffee aroma and flavor. Because roasting is time-temperature dependent, the variation of time and temperature applied may influence the structural properties, visual appearance, and chemistry of coffee. Improper roasting creates roast defects that reduce coffee quality and acceptance. Despite this importance, studies on coffee roast defects, particularly in Robusta coffee is limited. This study aims to characterize two common roast defects, i.e., underdeveloped and overdeveloped, compared with medium roast in Robusta coffee. Sensory evaluation by trained panelists and physicochemical evaluation reveal that the two common roast defect in Robusta coffee can be distinguished clearly through differences in sensory (aroma defect) characteristics as well as physicochemical properties. The overdeveloped roast defect produced darker coffee with the highest pH and total dissolve solids (TDS), and can be characterized by pyridine, furan, phenol and pyrrole derivatives. The carbony and ashy notes of the overdeveloped coffee were potentially contributed by phenol and polyphenol derivatives. In contrast to the overdeveloped coffee, the underdeveloped coffee is markedly characterized by higher concentration of aliphatic acids and higher concentration of pyrazines that contributes to raw nut-like notes. The combination of time and temperature during roasting influences the breakdown of chemical compounds through complex mechanisms involving proteins, carbohydrates and polyphenols degradation. Thus, roasting process variations that determine coffee cup quality and in turn drive consumer acceptance should be controlled