Degradasi Tirosina Menggunakan Mangkinfoto Berasaskan TiO2

Abstract

Asid amino merupakan bahan asas dalam tisu tumbuhan dan haiwan. Tirosina (Tr) salah satu jenis asid amino yang mengandungi gelang aromatik, telah dipilih sebagai sampel untuk proses degradasi dalam medium akueus. Ini bertujuan melihat kesan penggunaan mangkinfoto dalam sinaran ultralembayung (λ < 400 nm) atau cahaya matahari ke atas molekul tirosina. Kajian telah dijalankan menggunakan sistem cahaya, mangkin serbuk TiO₂, hidrogen peroksida, H₂O₂ dan ion logam. Penambahan ion logam seperti Ni²⁺, Cu²⁺, Ag⁺, Mn²⁺, Co²⁺, Fe²⁺ dan Cd²⁺ dan agen pengoksidaan, iaitu hidrogen peroksida adalah untuk mendapatkan kaedah yang paling cekap. Keputusan menunjukkan penambahan H₂O₂ dan ion Fe²⁺ dan Ni²⁺ berjaya meningkatkan kecekapan proses degradasifoto tirosina. Ion Ni²⁺ memberikan keputusan terbaik berbanding ion-ion lain. Ion Cu²⁺, Ag⁺, Mn²⁺ dan Cd²⁺ merencat proses degradasi. Keputusan juga menunjukkan cahaya matahari adalah setanding dengan cahaya ultralembayung. Kepekatan H₂O₂ terbaik adalah 5.0 x 10^-2M dan semakin banyak TiO₂ digunakan semakin baik peratus degradasi tirosina. Oleh itu kaedah optimum untuk proses degradasifoto ialah Tr 2.5 x 10^-4 M + TiO₂ + H₂O₂5.0 x 10^-3 M + Mⁿ⁺ 1.0 x 10^-2 M. Proses degradasifoto dikaji menggunakan spektroskopi ultralembayung-nampak pada julat panjang gelombang 400-200 nm. Kata kunci: Tirosina; degradasifoto; serbuk TiO; akueus Amino acid is a basic component in plant or animal tissue. Tyrosine (Tr), an amino acid which contains aromatic ring, was chosen as a sample for a photodegradation process in an aqueous system. The purpose of the experiment is to study the effect of photocatalysis under UV (λ < 400 nm) or sunlight on tyrosine. The experiment was carried out by using UV light, catalyst powder (TiO₂), hidrogen peroxide H₂O₂ and metal ions system. The addition of oxidising agent H₂O₂ and metal ions such as Ni²⁺, Cu²⁺, Ag⁺, Mn²⁺, Co²⁺, Fe²⁺ and Cd²⁺ were used in order to achieve the most efficient system. Results showed that the system with added H₂O₂ and metal ions such as Ni²⁺ and Fe²⁺ had successfully enhanced the process of the tyrosine photodegradation. Other metal ions system such as Cu²⁺, Ag⁺, Mn²⁺ and Cd²⁺ were found to inhibit the degradation process. The results also showed that sunlight was comparable to ultraviolet light. The best H₂O₂ concentration was 5.0 x 10^-2 M and the percentage of tyrosine degradation increased with the addition of more TiO₂) by mass. Therefore, the optimum condition for tyrosine photodegradation process was in Tr 2.5 x 10^-4 M + TiO₂ + H₂O₂ 5.0 x 10^-3 M + H₂O₂ 1.0 x 10^-2 M. The dissappearance of tyrosine in the photo degradation process was monitored by UV-visible spectroscopy between 400-200 nm. Key words: Tyrosine; photodegradation; TiO2 powder; akueus