Correlation between antioxidant activity of synthetic zeolites pillared titanium dioxide and iron (III) oxide with adsorption DPPH
Korelasi antara aktivitas antioksidan zeolit sintesis terpilar titaniium dioksida dan besi (III) oksida dengan adsorpsi DPPH
Rininingsih EM, Uning
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Degenerative diseases caused by the excess of free radicals in the body are the highest causes of death in the world. Free radicals in the body bring about premature aging by damaging the fatty tissue under the skin, decreasing skin firmness and causing wrinkled skin. One way to cope with the excess of free radicals is by adding natural antioxidants to pharmaceutical and food products. Zeolite is one material that has the potential as an antioxidant. Zeolite acts as an antioxidant by means of trapping free radicals in its structure so that free radicals become inactive and are safely removed from the body. Zeolit performance as an antioxidant can be improved by pillaring zeolite with metal oxides, for example TiO2 or Fe2O3. The objective of this study was to synthesize zeolite from the kaolin of Bangka Belitung, which was then pillared with TiO2 and Fe2O3 and to observe the correlation between antioxidant activity and DPPH adsorption. The method in this study began with kaolin calcination at a temperature of 700 °C for 6 hours. Then the result of calcination (metakaolin) was made to react with NaOH 2M and heated at 40 °C for 6 hours. The heating was continued at 100 °C for 24 hours. The synthetic zeolite obtained was washed with deionized aquades until the pH was neutral before being dried at 100 °C for 24 hours. The zeolites obtained were then heated again at 300 °C and there were some pillared by TiO2 and Fe2O3. The pillar making was done in 2 ways: physically and hydrothermally. Synthetic zeolite and its composite were characterized by diffracted X-ray method (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS). The characterization result by XRD showed that the synthetic zeolite which was formed was zeolite of type A. The success of the pillar making was demonstrated by the presence of a new peak of a pillar maker on synthetic zeolit when characterized by XRD. Analysis of the antioxidant activity test using UV spectrophotometer was indicated by a wave length of 517.5nm, while the adsorption capacity was measured at a wavelength of 664.5nm. The antioxidant activity was measured as a decrease in absorbance of DPPH solution and expressed in IC50. The lower the IC50 is, the higher the zeolite antioxidant activity will be. The lowest IC50 value was shown by ZSTi, that is, 19 ppm. This IC50 value is still 4 times greater than vitamin C, but much lower than synthetic zeolite (99973ppm) and synthetic zeolite which were pillared with Fe2O3 (IC50:3542 ppm). Hydrothermal pillar making produces a higher antioxidant activity than physical pillar making because another compound allegedly formed was more reactive than the metal oxide during the process of pillar making going on in disabling free radicals. The work mechanism of the pillared zeolite as an antioxidant was thought not only to involve common adsorption but there was also another mechanism that could not be observed in detail. The characteristic of zeolite adsorption and zeolite composite on blue methylene followed the pattern of the Langmuir adsorption isotherm. This showed the adsorption process was dominated by the adsorption on the adsorbate surface to form a single layer (monolayer). Based on correlation value between the variables (IC50 and the adsorption value on DPPH), the value of Pearson’s correlation obtained was -0.531 with a P value of 0.093. The value of Pearson’s correlation obtained in this research was -0.531 going farther than -1, while P value obtained was 0.093 higher than α = 0.05. Based on the correlation value between the variables (IC50 and the capacity of blue methylene), the value of Pearson’s correlation obtained was 0.239 with a P value of 0.569. Therefore, it can be concluded that there was no correlation between variable IC50 and both adsorption value on DPPH and the capacity of blue methylene.Penyakit degeneraif akibat berlebihnya radikal bebas di dalam tubuh merupakan penyebab kematian tertinggi di dunia. Radikal bebas dalam tubuh mengakibatkan penuaan dini dengan merusak jaringan lemak yangberada di bawah kulit sehingga menghilangkan kekencangan kulit dan kulit menjadi keriput.Salah satu cara untuk menanggulangikelebihan radikal bebas adalah dengan menambahkan antioksidan alami pada produk farmasi dan bahan pangan. Zeolit merupakan salah satu material yang berpotensi sebagai antioksidan. Zeolit bekerja sebagai antioksidan dengan cara memerangkap radikal bebas dalam strukturnya sehingga radika bebas menajdi tidak aktif dan aman dihilangkan dari tubuh. Kinerja zeolit sebagai antioksidan dapat ditingkatkan dengan memilar zeolit dengan oksida logam misalnya TiO₂ atau Fe₂O₃.