Judul: Removal of Hexavalent Chromium with Scrap Iron Filling.
Abstrak: Chromium is a transition element commonly found in the environment as trivalent and hexavalent forms. Apparently, the hexavalent form is much more toxic than the trivalent form. Textile wastewater treatment is required in order to prevent hexavalent chromium to contaminate the environment. The methods of this research consisted of effect of pH determination, effect of agitating rate determination, effect of agitating time determination, and effect of iron level determination; and its application in textile wastewater sample. The methods used in textile wastewater application are: determination of textile wastewater hexavalent chromium concentration, determination of textile wastewater hexavalent chromium concentration with standard addition method, and removal of hexavalent chromium in textile wastewater with scrap iron filling. Concentration of hexavalent chromium was determined using visible light spectrophotometry method. Optimum conditions of pH, agitating rate, iron amount, and agitating time obtained were pH 3, 450 rpm, 5 grams, and 10 minutes giving concentrations of hexavalent chromium 16.98 ppm, 15.96 ppm, 0.24 ppm, and 0.14 ppm, respectively. Iron filling could effectively remove hexavalent chromium ions from textile wastewater in a relatively short time. Absorbance of hexavalent chromium in textile coloring process wastewater after the addition of iron filling was 0.002, whereas in textile final wastewater was 0.000.
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Judul: Limbah Arang Sekam Padi Sebagai Adsorben Ion Cr(III) dan Cr(VI)
Abstrak: The major sources of heavy metal contaminations are industrial effluents. Chromium metal and its compound have wide application in industrial sector. Its two most stable states are Cr(III) and Cr(VI). Trivalent chromium toxicity is negligible because it often forms insoluble hydroxide at netral pH. Hexavalent chromium is considered powerful carcinogenic agent Lots of waste treatment efforts are conducted; one of which is to make use of agricultural by products that are potential to be utilized as adsorbent. This paper utilizes carbonized rice husk from rice husk stove as Cr(III) and Cr(VI) adsorbent. Carbonized rice husk was activated potassium hydroxide (KOH). As a comparison, activated carbon that originated from coconut shell, a commercially-used adsorbent, was used. Adsorption was carried out by varying adsorption time, adsorbent weight, and initial concentrations of Cr(III) and Cr(VI). The optimum condition of carbonized rice husk adsorbent for Cr(III) and Cr(VI) were 60 minutes; 0.5 g; and 250 ppm. The optimum conditions for activated carbon, as comparison, for Cr(III) were 90 minutes; 0.5 g; and 250 ppm. And the optimum conditions for activated carbon, as comparison, for Cr(VI) were 90 minutes; 0.5 g; and 250 ppm. In single solution test of Cr(III) and Cr(VI), adsorption capacity for carbonized rice husk were 8.400 mg/g; with adsorption efficiency were 84.00 %.
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Judul: Karakteristik Anatomi Skelet Kepala Buaya senyulong (Tomistoma schlegelii).
Abstrak: Buaya sepit atau senyulong (Tomistoma schlegelii) merupakan jenis buaya asli Indonesia yang berhabitat di sungai-sungai Sumatera, Kalimantan, dan juga pedalaman Sulawesi. Salah satu ciri khas buaya senyulong adalah bentuk moncong yang runcing dan sempit, namun hingga saat ini informasi mengenai struktur skelet kepala buaya senyulong sangat terbatas. Penelitian ini bertujuan untuk mempelajari karakteristik anatomi skelet kepala buaya senyulong yang dikatikan dengan fungsi dan perilakunya. Penelitian dilakukan secara eksploratif dengan melakukan pengamatan, pencatatan, dan pengambilan gambar dari skelet kepala buaya senyulong. Skelet kepala berukuran panjang 70 cm, lebar 29 cm, dan tingggi 17 cm dengan permukaan kasar pada os nasale, os frontale, os maxilla, os mandibula, os lacrimale, os jugale. Jumlah gigi pada buaya ini sebanyak 78 buah, terdiri dari 4 buah gigi premaxila, 16 buah gigi maxila, dan 19 buah gigi mandibula. Pada regio orbitalis ditemukan dua pasang fenestrae temporales yang berkembang baik. Fenestra supratemporale merupakan lubang oval yang membentang di sepanjang os parietale. Fenestra infratemporale berbentuk segitiga dan dibatasi oleh os squamosum, os postorbitale, os jugulare, dan os quadratum. Os mandibula hewan ini mempunyai symphysis mandibularis yang panjang yaitu garis yang melintang di corpus mandibulae. Secara fungsional ukuran symphysis mandibularis berkaitan dengan adaptasi hewan terhadap diet makan.
Keyword: kepala, moncong, Tomistoma schlegelii