Sains Malaysiana 47(6)(2018): 1085–1091

http://dx.doi.org/10.17576/jsm-2018-4706-02

Oxidation of p-Cresol by Ozonation

(Pengoksidaan p-Cresol oleh Pengozonan)

SU-HUAN KOW*, MUHAMMAD RIDWAN FAHMI, CHE ZULZIKRAMI AZNER ABIDIN, SOON-AN ONG, ABDUL HAQI IBRAHIM, SITI NASUHA SABRI & NUR AQILAH RAZALI

School of Environmental Engineering, Universiti Malaysia Perlis (UniMAP), Kompleks Pusat Pengajian Jejawi 3, 02600 Arau, Perlis Indera Kayangan, Malaysia

Diserahkan: 22 Disember 2017/Diterima: 7 Februari 2018

ABSTRACT

Oxidation of p-Cresol was investigated by using ozonation process. The aim of this research is to assess the effectiveness of ozonation on oxidation of micropollutant such as p-Cresol. Ozonation performance was evaluated based on p-Cresol concentration reduction and chemical oxidation demand (COD) reduction. It was found ozonation at pH11 achieved the highest p-Cresol degradation, with 95.8% of p-Cresol reduced and 96.0% of COD reduced, for an initial 50 mgL-1 of p-Cresol. The degradation of p-Cresol could be expressed by second-order of kinetic model. The second-order rate constant k increases as the initial pH increased, but decreases with the increasing of initial p-Cresol concentrations. Besides, the absorption spectra of p-Cresol over ozonation time were analyzed by spectrophotometry. The evolution of absorption spectra of p-Cresol degradation suggests that the oxidation of p-Cresol follows three stages mechanisms with cycloaddition as the first step to produce aromatic intermediates followed by ring-opening reactions, degradation of the intermediates, and subsequently achieved mineralization.

Keywords: Absorption spectra; mechanism; micropollutant; ozonation; p-Cresol

ABSTRAK

Pengoksidaan p-Cresol dikaji dengan menggunakan proses pengozonan. Tujuan penyelidikan ini adalah untuk menilai keberkesanan pengozonan terhadap pengoksidaan pencemar mikro seperti p-Cresol. Prestasi pengozonan dinilai berdasarkan pengurangan kepekatan p-Cresol dan pengurangan permintaan oksigen kimia (COD). Didapati pengozonan pada pH11 mencapai kemerosotan p-Cresol tertinggi, dengan 95.8% p-Cresol dikurangkan dan 96.0% COD dikurangkan, untuk awalan 50 mgL-1 p-Cresol pada suhu bilik. Degradasi p-Cresol boleh dinyatakan oleh model kedua kinetik. Pesanan laju pesanan kedua k meningkat apabila pH awal meningkat, tetapi berkurangan dengan peningkatan kepekatan p-Cresol awal. Selain itu, spektrum penyerapan p-Cresol ke atas masa pengozonan dianalisis spektrofotometri. Evolusi spektrum penyerapan degradasi p-Cresol menunjukkan bahawa pengoksidaan p-Cresol mengikuti tiga peringkat mekanisme dengan pensiklotambahan sebagai langkah pertama untuk menghasilkan perantara aromatik diikuti oleh reaksi pembukaan cincin, kemerosotan perantaraan dan seterusnya pemineralan.

Kata kunci: Mekanisme; pencemar mikro; pengozonan; p-Cresol; spektrum penyerapan

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*Pengarang untuk surat-menyurat; email: suhuan_kow@yahoo.com