Judul: Adsorpsi dan desorpsi kromium (VI) pada zeolit alam asal Lampung termodifikasi Heksadesiltrimetilamonium bromida
Abstrak: Zeolite is a mineral that is able to adsorp chromium. Chromium has three stable forms in nature,i.e. metal chromium, trivalent chromium, and hexavalent chromium. Among these forms, hexavalent chromium are the most toxic and generally obtained in its anion form as chromat (CrO4 2-) and dichromat (Cr2O7 2-). Therefore, it is very important to decrease content in environment. The function of negative zeolite structure were cation exchange and their somewhat for anion exchange. Therefore, modified zeolite with hexadeciltrimethylammonium bromide (HDTMABr) was attempted to increase anion adsorption capacity of zeolite in solution. Modified zeolite with HDTMABr at 50% dosage of its cation exchange capacity, caused an increase the adsorption capacity of zeolite to chromium(VI) from 0.74 to 1.40 mg/g. Adsorption was carried out by varying adsorption time, solution acidity, and initial concentration of chromium(VI). The optimum adsorption time, solution acidity, and initial concentration of chromium(VI) for unmodified-zeolite were 20 hours, 3.5, and 350 ppm, respectively. On the other hand, the optimum adsorption for modified-zeolite were 23 hours, 5, and 350 ppm, respectively. Isotherm type for both of adsorbent followed Freundlich isotherm. Desorption of chromium(VI) on unmodifiedzeolite and modified-zeolite a lot off obtained using aquadest at level 30.56 and 0.33%, respectively.
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Judul: Elektrode Pasta Karbon Zeolit Alam Termodifikasi Heksadesiltrimetilamonium Bromida untuk Deteksi Kromium(VI)
Abstrak: The extensive use of chromium in metallurgic, leather tanning, electroplating, lumber, electricity generating and other industries have promoted enormous ecological impact in numerous sites that are being contaminated by chromium. Chromium has two dominant species, namely Cr(III) and Cr(VI). Among them, attention concerning the possible hazards arising from the use of Cr(VI) than Cr(III) because hexavalent chromium is around 1000 times more toxic than trivalent one. Therefore, methods for differentiation and quantification of these species are very important in water analysis. Research on chemical modified carbon paste electrode have been carried out starting from 1990 especially in electroanalysis field caused by better improvement than conventional electrode. Continuous research on chemical modified carbon paste electrode has been increasing use of inorganic materials as a modifiers of electrode material. Among inorganic materials, zeolites have been widely used as an ion exchanger due to size, shape, and unique charge selectivity, high capacity ion exchangers, high thermal stability, low cost resistance to extreme conditions. Zeolites have a permanent negative charge on its crystal structure making it suitable as a cation exchanger. This negative charge is also possible to do modifications on the zeolite surface using cationic surfactant of hexadecyltrimethylammonium (HDTMA) ions. Cation exchange capacity value of zeolite origin from Cikembar (23.7 meq/100 g), Cikalong (47.6 meq/100 g), Bayah (39.7 meq/100 g), and Lampung (42.4 meq/100 g). After activation with NaOH, all cation exchange capacity values showed increasing were Cikembar (60.4 meq/100 g), Cikalong (60.4 meq/100 g), Bayah (42.5 meq/100 g), and Lampung (107.5 meq/100 g). Therefore, Lampung zeolite was selected to do modification with surfactant and was obtained highest adsorption amount of 200 mM HDTMABr as 3.9923 mmol/g zeolit. Cr(VI) adsorption test using diphenylcarbazide (DPC) method toward Lampung zeolite, 100 mM and 200 mM HDTMABr modified NaOH activated Lampung zeolite showed increasing adsorption capacity (Q). Cr(VI) adsorption capacity (Q) at steady state were obtained toward Lampung zeolite, 100 mM and 200 mM zeolite-NaOH-HDTMABr as 58.0457, 134.0522, 148.5602 mg Cr(VI)/g zeolite, respectively. This showed an increase of Cr(VI) amount bound on the zeolite surface. XRD characterization showed 3 significant peaks were obtained on Lampung zeolite, Lampung zeolite activated NaOH, and HDTMABr modified zeolite-NaOH. This showed no structural change on natural and modified zeolite. The degree of crystallinity decreased with the order of natural zeolite, zeolite-NaOH, and HDTMABr modified zeolite-NaOH showed partial loss of impurities contained in natural zeolite and adsorption of HDTMABr molecules on zeolite surface. Zeolite-NaOH-HDTMABr showed incorporation of absorption peaks originating from bending δH-O-H (1637.65 cm-1), vibration vT-O (T= Si,Al) symmetric (1055.56 cm-1), vT-O asymmetric (793.17 cm-1), δSi-O-Al (608.86 cm-1 and 525.67 cm-1), and δO-T-O (468.41 cm-1) also peak absorption originating from HDTMABr were stretching vC-H methylene asymmetric (2920.05 cm-1) and bending δC-H methylene (2851.01 cm-1, 1489.21 cm-1). Characterization by thermal analysis (TG-DTA) showed percentage of loss mass was quite large aat 15.1% in temperature range of 200-300 oC. This result indicates surfactant double layer formed by hydrophobic-hydrophobic interaction of nonpolar groups on the surface of HDTMABr modified Lampung zeolite. The existence of electrostatic interactions between HDTMABr molecules on zeolite surface forming s single layer
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Judul: Perencanaan lanskap agrowisata tanaman hias kampung panyairan, Desa Cihideung, Kecamatan Parongpong, Bandung
Abstrak: Perkembangan pada bidang industri pariwisata belakangan ini terus berkembang, termasuk wisata alami pedesaan. Wisata ini makin diminati masyarakat karena lingkungan perkotaan yang sudah tidak asri lagi sehingga kebutuhan rekreasi pun meningkat. Bandung adalah kota yang penuh dengan kebun dan taman, dan Panyairan berada di utara Bandung dimana area ini terkenal dengan iklimnya yang sejuk dan nyaman. Studi ini bertujuan untuk merencanakan sebuah lanskap agrowisata tanaman hias di kampung Panyairan dengan melakukan penataan berbagai elemen lanskap, pengeturan tata ruang, pembuatan sistem sirkulasi, penyusunan paket wisata, dengan tetap memperhatikan dan menjaga kelestarian serta fungsi ekologis lingkungan. Metode studi yang digunakan adalah metode survei dengan mengacu pada proses perencanaan Gold (1980). Pada studi ini dibatasi hanya sampai dengan perencanaan saja. Tahap pertama yang dilakukan adalah pengumpulan data (inventarisasi) dan menghasilkan gambar Tata Guna Lahan. Kemudian data ini dianalisis permasalahannya dan memberikan solusinya sehingga dihasilkan gambar analisis. Setelah itu dilakukan sintesis yang menghasilkan beberapa gambar pengembangan konsep. Dari pengembangan konsep kemudian dilakukan perencanaan lanskap yang menghasilkan sebuah gambar rencana lanskap. Kampung Panyairan terletak 23 km utara kotaBandung, dengan ketinggian berkisar antara 1.192 1.260 m dpl dan luas 107,1 ha. Suhu rata-rata pada tapak adalah 19° sampai 24°C dengan kelembaban antara 70% sampai 78%. Topografi lahan bervariasi, namun perencanaan ini dilakukan pada lahan yang relatif datar. Tapak dilewati oleh anak sungai Cibeureum dengan debit rata-rata 2,26 m³/detik. Jenis tanah Andosol sangat menunjang kegiatan budidaya tanaman hias. Kegiatan ekonomi masyarakat lokal sebagian besar adalah bertani. Hanya satu yang masih beroperasi yaitu KUD Puspa Mekar, namun koperasi ini bergerak dibidang peternakan sapi. Kebudayaan khas Panyairan adalah budaya Sasapian. Perumahan Real Estate menyediakan fasilitas penunjang seperti rumah makan (Sapu Lidi di Triniti dan Kampung Daun di Graha Puspa) dan peternakan kuda di Triniti. ...
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