Perilaku Pemindahan Zat Warna Golongan Thiazine, Azo, dan Triarylmethane dari Tanah Kaolinite yang Terpolusi Bahan Organik dengan Menggunakan Teknologi Remediasi Elektrokinetik (EKR)

Telah dilakukan penelitian tentang potensi teknik remediasi elektro-kinetik (EKR) untuk menghilangkan polutan zat warna dari tanah kaolinite yang terpolusi bahan bahan organik. Methylene blue (MB), methyl orange (MO), dan phenol red (PR) mewakili pewarna golongan thiazine, azo, dan tryarilmethane masing-masing, yang ditambahkan pada kaolinite dipilih sebagai model untuk uji polutan pewarna. Alat EKR (panjang 15 cm) dilengkapi dengan arus listrik DC dengan nilai maksimum 30 V. Elektroda grafit digunakan untuk kedua anoda dan katoda dipasang untuk empat belas hari operasional. Hasilnya, hanya 40-55% pewarna yang berhasil dikeluarkan dari bagian tanah dengan menggunakan air suling. Namun, dengan penambahan beberapa elektrolit; persentase pewarna yang dikeluarkan dari tanah meningkat dari 73- 76% dan 85 - 89% untuk elektrolit natrium sulfat dan monosodium dihidrogen fosfat secara berturut-turut. Dalam konteks pengontrolan pH, ditemukan bahwa hanya 55-64% pewarna yang dikeluarkan tanpa kontrol pH. Peningkatan yang signifikan dicapai dengan mengendalikan pH sistem. Dengan mengendalikan pH di ruang katoda, didapati 23% MB, 25% MO dan 18% PR masih ada dalam sistem. Sementara dengan mengendalikan pH di ruang anoda, hampir 90% pewarna yang diuji dapat dikeluarkan dari ruang kaolinite secara efektif. Pergerakan pewarna thiazine, dari anoda ke ruang katoda dikendalikan oleh fenomena elektro-migrasi dan elektro-osmosis. Sebaliknya, pewarna azo diangkut dari katoda ke ruang anoda dengan cara yang sama. Namun, pewarna triarylmethane dikeluarkan dari bagian tanah dengan hanya melalui fenomena elektro-osmosis dari anoda ke ruang katoda. Untuk tiga jenis pewarna yang diuji, ditemukan bahwa aliran elektro-osmotik bergerak dari arah anoda ke arah katoda. In this study, the investigation about the potency of electro-kinetic remediation technology (EKR) for the removal of organic dyes from the polluted kaolinitic soil has been conducted. Methylene blue (MB), methyl orange (MO), and phenol red (PR) are representing a thiazine, an azo, and a triarylmethane dye respectively, which was introduced to kaolinitic soil were selected as the model for pollutant dyes tests.An EKR tool (15 cm length) equipped with a DC electric current with the maximum values of 30 V. Graphite electrodes were used for both anode and cathode were set up for 14 days operation.As a result, only 40-55 % of dye was removed from the soil sections by using distilled water.However, by the addition of some electrolytes; the percentage of dyes removed from the soil increased from 73-76 % and 85-89 % for sodium sulphate, and monosodium dihydrogen phosphate, respectively. In the context of pH controlling,it was found that 55-64 % of dyes were removed without controlling the pH.The significant improvement was achieved by controlling the pH of the system. By controlling the pH in the cathode chamber, only 23 % of MB, 25 % of MO, and 18 % of PR dyes remain in the soil sections, respectively. While by controlling the pH in the anode chamber, almost 90 % of tested dyes could be removed from the kaolinitic soil chamber effectively.The movement of a thiazine dye, from the anode to the cathode chamber was controlled by electro-migration and electro-osmosis phenomena. An azo dye transported from the cathode to the anode chamber by a similar process. However, a triarylmethane dye was removed from the soil sections by only electro-osmosis process. For three kinds of tested dyes, it was found that electro-osmotic flow moving from the anode to the cathode directions.

Heat-Activated Persulfate by Fe-Based Metallic Glass: A Comparative Study of Two Dyes

In this work, the heat-activated persulfate (PS) in the presence of Fe78Si9B13 metallic glasses (MGs) shows an extremely difference in degradation of azo dye and triarylmethane dye, where Fe78Si9B13 MGs exhibits a superior activation ability for PS with assistance of heat leading to the fast removal of two dyes. The structural features of Fe78Si9B13 MGs are firstly characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC), following analysis of surface topography by scanning electron microscope (SEM). The results show that with the addition of Fe78Si9B13 MGs, the recalcitrant azo dye is completely removed within 5 min while only 6% of removal rate can be achieved without adding MGs, indicating that the refractory azo dye can be easily degraded by sulfate radical (SO4•–) from heat/MGs/PS. On the other hand, no big variation occurs between PS and MGs/PS under heat activation in degrading triarylmethane dye. Sole PS activated by heat results in a fast removal rate, indicating that triarylmethane dye can be easily degraded by PS itself compared to azo dye. The findings in this work present an in-depth understanding of heat/MGs/PS system in dyes degradation.