PEMBUATAN KATALIS OKSIDA BESI DENGAN PENGEMBAN KARBON AKTIF DAN UJI AKTIVITAS KATALITIKNYA UNTUK REAKSI DEKOLORISASI METHYLENE BLUE

SHINTA AMELIA, Prof. Ir. Wahyudi Budi Sediawan, S.U., Ph.D;Dr.-Ing. Teguh Ariyanto, S.T.,M.Eng.

2017 | Tesis | S2 Teknik Kimia

Methylene blue merupakan salah satu zat warna thiazine yang sering digunakan dalam industri tekstil. Senyawa ini sangat stabil sehingga sulit terdegradasi di alam dan berbahaya bagi lingkungan apabila dalam konsentrasi yang sangat besar karena dapat meningkatkan nilai Chemical Oxygen Demand (COD) yang dapat merusak keseimbangan ekosistem lingkungan. Pada penelitian ini dilakukan proses penjerapan dan reaksi dekolorisasi methylene blue secara simultan dengan menggunakan katalis oksida besi dengan pengemban karbon aktif. Karbon aktif digunakan sebagai bahan pengemban katalis karena luas permukaan tinggi dan stabilitas kimia yang sangat baik. Sedangkan oksida besi digunakan sebagai bahan aktif katalis karena kombinasi antara hidrogen peroksida dengan besi (Fe) merupakan reagen Fenton yang memiliki kemampuan oksidasi tinggi dalam mengurai limbah zat warna seperti, methylene blue. Jenis karbon aktif berpori yang digunakan yaitu karbon dari biomassa tempurung kelapa dengan karakter mikropori dan karbon polimer sintetis dengan karakter mesopori. Tahapan dalam pembuatan katalis Fe2O3/karbon aktif diawali dengan impregnasi precursor katalis dalam permukaan pori karbon. Setelah katalis selesai dibuat, katalis kemudian digunakan untuk uji dekolorisasi methylene blue dengan reaksi Fenton. Karakterisasi katalis Fe2O3/karbon aktif yang dihasilkan dengan menggunakan SEM-EDX menunjukkan bahwa proses impregnasi dan kalsinasi dapat mendispersikan Fe2O3 dengan baik. Luas permukaan spesifik dari katalis (Fe2O3/karbon aktif) lebih kecil dibandingkan dengan pristine karbon. Katalis Fe2O3 2%/karbon aktif tempurung kelapa dan Fe2O3 2%/karbon aktif polimer sintetis memiliki luas permukaan spesifik berturut-turut 1165 m2/gram dan 1195 m2/gram. Meskipun luas permukaan kedua katalis tersebut hampir sama, namun katalis Fe2O3 2%/karbon aktif polimer sintetis memiliki diameter pori lebih besar dibandingkan dengan katalis Fe2O3 2%/karbon aktif tempurung kelapa. Sehingga % penurunan dye pada katalis Fe2O3 2%/karbon aktif polimer sintetis lebih besar dibandingkan dengan katalis Fe2O3 2%/karbon aktif tempurung kelapa. Penurunan dye untuk t = 1 hari pada katalis Fe2O3 2%/karbon aktif polimer sintetis sebesar 98,6 % sedangkan penurunan dye katalis Fe2O3 2%/karbon aktif tempurung kelapa sebesar 89,7%. Selain itu % penurunan dye pun semakin meningkat seiring dengan bertambahnya % loading oksida besi yang ditambahkan pada permukaan support karbon aktif. Hasil tertinggi didapatkan pada penambahan 2% loading oksida besi baik pada katalis Fe2O3 2%/karbon aktif tempurung kelapa maupun pada katalis Fe2O3 2%/karbon aktif polimer sintetis. Kemudian berdasarkan data penelitian pada penggunaan berulang (recycle) katalis menunjukkan bahwa pada cycle ke empat persentase dye removal katalis masih cukup tinggi yaitu sebesar 98,69%. Berdasarkan data tersebut diharapkan penggunaan katalis secara berulang-ulang tidak menurunkan performa katalis. Nilai kc berkisar antara (0,0032-0,0038 m/s), nilai H berkisar antara (14,06-14,81), nilai De berkisar antara (4,065-5,990) x 10-10 m2/s . Sedangkan nilai kr semakin besar dengan semakin meningkatnya variabel loading Fe. Hasil tertinggi pada katalis polimer konsentrasi loading Fe 2% dengan nilai kr sebesar 0,2352 m3/s.

Methylene blue is one of thiazine dyes that often used in textile industries. This compound is very stable, so it is difficult to degrade naturally. Methylene blue can be harmful to the environment if it is in a very large concentration, because it can increase the value of Chemical Oxygen Demand (COD) which can damage the balance of environment ecosystem. In this research, the process of absorption and reaction of methylene blue decolorization were done simultaneously by using activated carbon impregnated with iron oxide catalyst. Activated carbon was used as a catalyst carrier because of its high surface area and excellent chemical stability. Iron oxide was used as the active ingredient of the catalyst because the combination between hydrogen peroxide with iron (Fe) makes a Fenton reagent which has a high oxidation ability in degrading waste dyes such as methylene blue. The type of porous active carbon used were carbon from coconut shell biomass with micropore character and from synthetic polymeric carbon with mesoporous character.The first step in the preparation of Fe2O3/Activated carbon catalysts was impregnation of the catalyst precursor within the pore surface of the carbon. After the catalyst was ready, the catalyst was then used for the methylene blue decolorization test by Fenton reaction The characterization of the Fe2O3/activated carbon catalyst produced using SEM-EDX shows that Fe2O3 was well dispersed through the impregnation and calcination process. The specific surface area of the catalyst (Fe2O3/activated carbon) is smaller than that of carbon pristine. The catalyst made from 2% Fe2O3/coconut shell activated carbon and 2% Fe2O3/synthetic polymer activated carbon have specific surface area of 1165 m2/gram and 1195 m2/gram respectively. Although the surface area of both catalysts is similar, the 2% Fe2O3/synthetic polymer activated carbon catalyst has a larger pore diameter than the 2% Fe2O3/coconut shell activated carbon catalyst. Thus, the percentage of dye degradation in 2% Fe2O3/synthetic polymer activated carbon is greater than 2% Fe2O3/coconut shell activated carbon catalyst. The degradation of dye after relatively long time (24 hours= 1440 minutes),in which equilibrium reaction is assumed to be achieved, on 2% Fe2O3/synthetic polymer activated carbon catalyst was 98,6% while on 2% Fe2O3/coconut shell activated carbon catalyst was 89,7%. In addition, the percentage of dye degradation also increases with increasing loading of iron oxide added to the surface of activated carbon support. The highest result was obtained with addition of 2% loading of iron oxide either on 2% Fe2O3/coconut shell activated carbon catalyst or on 2% Fe2O3/ synthetic polymer activated carbon catalyst. Multiple applications of the catalyst produced were also investigated. Based on research data on the use of recycle (recycle) catalyst, it showed that at the fourth cycle, the percentage of dye removal of the catalyst is still high enough that is equal to 98,69%. The value of parameters involved in kinetics equation for the decolorization were also extracted from the experimental data. Based on the data, it is expected that repeated use of catalysts untill fourth cycle does not decrease catalyst performance. The value of kc ranges from (0.0032-0.0038 m/s), H values ranged between (14.06-14,81), De values ranged between (4,065-5,990) x 10-10 m2/s. While the value of kr is greater with the increasing of loading variable of Fe. Optimization studies showed that the highest yield were achieved by the polymer catalyst loaded with Fe 2% which had kr value 0.2352 m3/s.

Kata Kunci : Kata kunci : dye removal, karbon aktif, oksida besi, oksidasi katalitik