DEGRADASI ELEKTROKATALITIK FENOL DALAM AIR LIMBAH

Abstract

The treatment of phenol in wastewater found, from lite¬rature, to be an elaborate effort. Oxidation by either ozone or hydrogen peroxide give conversion percent less than 30 %. If that degradation was catalylized by ferrous sulfate salt, the ferrous ion will take part in water as a new pollutant. There is an effort to oxidise fenol by mean of electrolysis and give good result, that is 90 %. The oxide, Sn02, having catalytic properties piled up to titanium metal bar and than constructed as anode in the electolysis cell with the plati¬num coil covered in ceramic material utilized as a cathode. However, platinum and titanium employed as electrode are fa¬in very expensive if applied on large scale field. That is meaning that the electrode must be replace by more decrease material. Carbon possessing properties as the electrically good conductor probably can be utilized as an electrode. The Al203 oxide, in such a manner, known having properties as a good suport for catalysts action may be used as an electrode material. However, capability of those examples of electrode in oxidation of phenol in the wastewater no known yet. The aim of the experiment is determining the capability of catalytically Sn02/Al203 and Sn02/Karbon electrode in the oxidation of either phenol in prepared model solution and in wastewater. The capability was expressed in measurable term of conversion percent. The experiment carried out in 2 stage, that is cataly¬tical anode preparation continued by electrocatalytic per¬formance testing. The catalysts prepared according to copre¬cipitation of precursor with alumina support and impregnati¬on into either the alumina and carbon. The catalyst packed as an electrode tested as an anode in electolytically oxida¬tion of either phenol in the prepared model solution and in wastewater. The testing worked out in either flow and non flow electrolysis manner. Raney reactor was employed in that electrolysis. Dissapearance of phenol caused bay electolysis was monitored by UV-Vis Spectrophotometer at wavelength 505 nanometer. In advance of absorbance measuring phenol reacted by 4-aminoantipyrine in precence of potassium ferricianide in order to produce complex compound. The absorbance data A transferred to concentration values C based on standard cur¬ve calibration methods, and then compared to initial concen¬trations to get the conversion percent. The conversion per¬cent data then worked out in according to simple statistical methods. The experimental result show the so many variety of the conversion percent value. By varying concentration of prepa¬red model phenol sulutiom to be 2.50, 5.00, 7.50 and 10 ppm, under current of 0.01, 0.05 and 0.10 A, obtained that values distributed from 26.23 % to 30.09 % (pellete, non-flow) and 25.38 - 29.27 % (pellete, flow). Elektrocatalyst powder give 28.23 - 39.52 7. (non-flow) and 30.11 - 38.19 % (flow). Cata¬lysts, if piled up to carbon bar, resulting 31.79 - 51.88 % (non-flow) and 35.15 - 59.15 7. (flow). Of the waste treating pellete packed electrocatalyst give the result 20.78 - 22.40 percent (non-flow) and 23.75 - 26.09 % (flow). Powder packed give 24.63 - 28.17 Y. (non-flow) and 24.05 - 27.17 7. (flow). Conversion percent resulting from the SnO2 piled carbon bar are 28.75 - 32.52 (non-flow), and 31.40 - 34.98 % (flow). Conversion percent from waste treatment, at the same condi¬tions, less than result from prepared model solution. Conclusions have been drawn from the experimental facts that conversion percent of phenol via electrocatalysis de¬pend on the current and initial concentration factors. How¬ever, the dependence pattern no clear yet. The best electro¬des are carbon bar which piled up with catalyst material and that degradation of phenol carried out in flow-electrolysis modes. The research no true-brad yet; each parameters such as electric current, initial concentration, preparation condi¬tion and process, and electrode packing must be handled, one by one. It is so many parameters must be tested. For elect¬rolysis, variation in applied electric potential to find the volt-ampere characteristics, presence of other species than phenol effects to volt-ampere characteristics, flow rate of the electrolysis, initial concentration and surface area of the electrode, for example must be examined in the detailed manner; as well as overpotential, crystallinities, porosity, prorous distribution, acidity, and selectivities of electro¬des. (Chemistry Department, Faculty of Science and Mathematics, Diponegoro University, Semarang; under contract No.: 3157/ PT09.H2/N/1997). Dari penelusuran pustaka, didapatkan bahwa pengolahan limbah fenol sukar dilakukan. Oksidasi memakai ozon maupun hidrogen peroksida hanya memberikan persen konversi kurang dari 30 %. Kalau dikatalisis dengan garam Fero sulfat, ion besinya jus¬tru mencemari air. Telah ada usaha untuk mengoksidasi fenol secara elektrolisis dan menghasilkan persen konversi di atas 90 %. Oksida Sn02 yang mempunyai sifat katalitik dilapiskan ke batang titanium, kemudian dipasang sebagai anoda di dalam sel elektrolisis. Namun, elektroda platina dan titanium yang digunakan sangat mahal kalau diterapkan di lapangan berskala besar. Berarti elektrodanya mesti diganti dengan bahan-bahan yang lebih murah. Karbon yang diketahui punya sifat sebagai penghantar listrik yang baik, agaknya dapat dimanfaatkan se¬bagai elektroda. Demikian juga oksida Al203, yang diketahui punya sifat sebagi suport yang bagus bagi aktivitas katalis, bisa juga dimanfaatkan sebagai bahan elektroda. Akan tetapi, kemampuan kedua contoh elektroda tersebut untuk mengoksidasi fenol dalam air limbah belum diketahui. Penelitian bertujuan menentukan kemampuan elektroda katalis Sn02/Al203 dan Sn02/Karbon untuk mengoksidasi fenol di dalam larutan model dan air limbah. Kemampuan diungkapkan ke dalam parameter persen konversi yang dapat diukur. Penelitian dilaksanakan melalui 2 tahap, yaitu tahap prepa¬rasi anoda katalis, dilanjutkan tahap pengujiannya. Katalis disiapkan lewat metode kopresipitasi dengan suport aluminium oksida dan impregnasi ke dalam suport karbon serta aluminium oksida. Katalis yang dikemas menjadi elektroda diuji dengan cara menerapkannya sebagai anoda untuk oksidasi elektrolitik fenol, baik dalam larutan model maupun air limbah. Pengujian tersebut dilakukan menurut metode elektrolisis fasa alir dan elektrolisis tanpa aliran. Reaktor model Raney dipergunakan untuk melakukan elektrolisis fasa alir maupun tanpa aliran. Berkurangnya konsentrasi fenol setelah elektrolisis, relatif terhadap konsentrasi awal yang divariasi, diikuti via metode sekali parameter yang harus diuji. Untuk sistem elektrolisis antara lain adalah variasi potensial listrik terpasang untuk mendapatkan karakter valt-amper, pengaruh zat-zat selain fe¬nol terhadap karakter volt-amper, laju aliran, konsentrasi awal reaktan dan luas permukaan elektroda. Yang menyangkut elektroda katalis bisa meliputi polaritas yang diukur dengan overpotensial; juga kristalinitas, porositas, distribusi po¬ri, keasaman dan selektivitasnya. (Kimia, Fakultas Matematika dan Ilmu Pengetahuan Alam, Uni¬versitas Diponegoro, Kontrak Nomor: 3157/PT09.H2/N/1997)