Solar Photocatalytic Degradation of Tartrazine Using Titanium Dioxide
Authors: Abdullah Hashim Hasril Azuan , Mohamed Abdul Rahman , Lee Keat Teong 
Published: January 2013

Perawatan air sisa semakin mendapat perhatian kebelakangan ini, sehingga menjurus kepada penemuan fotopemangkinan, satu kaedah alternatif perawatan air sisa yang berpotensi. Sehingga kini, banyak penyelidikan yang berkaitan dengan pemusnahan bahan pencemar organik tunggal telah dijalankan. Walau bagaimanapun, aplikasinya terhadap pendetoksifikasi sampel campuran bahan pencemar dengan tahap Jumlah Karbon Organik yang tinggi tidak dikaji secara menyeluruh. Walaupun terdapat banyak kaedah perawatan pada masa kini, kebanyakannya tidak memusnahkan bahan pencemar secara lengkap, tetapi hanya menyebabkan perubahan fasa atau pemusnahan bahan pencemar secara separa sahaja. Berbeza daripada kaedah perawatan yang lain, proses fotopemangkinan ialah teknologi bersih yang hanya menggunakan tenaga suria, air dan mangkin yang boleh digunakan semula bagi memusnahkan toksin atau bahan pencemar dalam air. Dalam proses fotopemangkinan, fotomangkin semikonduktor boleh diaktifkan hanya dengan menggunakan sinaran ultra lembayung (UV) daripada radiasi cahaya matahari. Fotomangkin yang telah diaktifkan akan menghasilkan radikal hidroksil yang berkebolehan untuk mendegradasikan bahan cemar. Dalam kajian ini, fotomangkin yang digunakan ialah titanium dioksida (TiO2) dan tartrazin dipilih sebagai bahan cemar. Tartrazin ialah sejenis pewarna yang banyak digunakan dalam industri makanan dan mudah larut dalam air. Pewarna sintetik ini boleh mengakibatkan kanser pada kepekatan yang tinggi. Uji kaji fotopemangkinan dijalankan dengan mengubah jumlah mangkin yang digunakan (0–1.5 g/L), kepekatan awal larutan pewarna (5–35 ppm), dan kadar aliran larutan pewarna (1.0–1.5 L/min). Larutan pewarna didedahkan kepada sinaran matahari selama dua jam. Keputusan uji kaji menunjukkan bahawa peratus degradasi pewarna yang tinggi boleh dicapai dengan menggunakan kombinasi sinaran cahaya dan TiO2. Jumlah mangkin optimum yang digunakan untuk proses degradasi pewarna ini ialah 1.0 g/L. Kepekatan asal pewarna tartrazin dan kadar aliran larutan tartrazin didapati mempengaruhi peratus degradasi pewarna. Kepekatan asal tartrazin yang lebih tinggi mengakibatkan kecekapan proses degradasi menurun, manakala kadar aliran larutan tartrazin yang lebih tinggi mengakibatkan kecekapan proses degradasi meningkat.

Kata kunci: Foto-pemangkinan; mangkin TiO; tartrazin; pendetoksifikasi suria

As wastewater treatments become more important nowadays, photocatalysis, an alternative wastewater treatment method, shows a promising potential. By now, many studies on the photocatalytic destruction of single organic contaminants have been carried out However, its application to the detoxification of samples of contaminants mixtures with high Total Organic Carbon levels has not been thoroughly investigated. Although presently many treatment methods are being used, most of them do not completely destroy the pollutants but only offer phase transfer or partial degradation of the pollutants. On the other hand, solar photocatalytic process is an exciting clean technology that uses only sunlight, water, and a reusable catalyst to remove toxins or pollutants from water. In a photocatalytic process, a semiconductor photocatalyst is activated with ultraviolet (UV) irradiation from the sun. The activated photocatalyst promotes the formation of hydroxyl radicals, which in turn completely degrade the pollutants. In this study, the photocatalyst used was titanium dioxide (TiO2) and tartrazine was chosen as the pollutant. Tartrazine is one of the popular water soluble dyes used in food coloring industries but it is carcinogenic at high concentration. The photocatalytic experiments were conducted with varying catalyst loading (0-1.5 g/L), initial concentration (5-35 ppm), and flowrate of tartrazine solution (1.0-1.5 L/min). The dye solution was exposed to sunlight for about two hours. The experimental results showed that a considerable increase in the degradation efficiency of the tartrazine-compound could be obtained by a combination of TiO2 and solar light. The optimum catalyst weight loading for the degradation of tartrazine dye was found to be 1.0 g/L. The initial concentration of the tartrazine dye and flowrate of tartrazine solution were found to effect the degradation efficiency of the dye. Higher initial concentration resulted in lower degradation efficiencies, while higher tartrazine solution flowrate resulted in higher degradation efficiency.

Key words: Photocatalytic; solar detoxification; tartrazine; TiO2 catalyst