Ratnam, Sree Amertharaj
(2016)
Electrochemical Reduction Of Nitrates And Nitrites Using Copper Modified Platinum Electrode.
Masters thesis, Universiti Sains Malaysia.
Abstract
Elektropenurunan nitrat dan nitrit dalam kajian ini dijalankan dengan menggunakan elektrod platinum terubahsuai dengan kuprum di dalam larutan 0.05 M KCl melalui teknik voltammetri kitaran. Satu perbandingan telah dilakukan dengan menggunakan pelbagai elektrod kerja seperti kuprum, elektrod kuprum terubahsuai dengan kuprum (Cu-Cu) dan elektrod pensil grafit terubahsuai kuprum (PG-Cu). Proses permendapan zarah kuprum ditetapkan sebanyak 30 kitaran/ 18 saat untuk semua elektrod yang diubahsuai dengan kuprum bagi mendapatkan nisbah yang terbaik. Luas permukaan sebenar bagi elektrod Pt, Cu, Cu-Cu, PG-Cu dan Pt-Cu dianggarkan sebanyak 1.747 cm2, 0.814 cm2, 0.988 cm2, 1.146 cm2 and 2.259 cm2. Aktiviti dan pemilihan elektropenurunan nitrat dan nitrit adalah lebih memuaskan jika menggunakan elektrod Pt-Cu. Plot ip vs. ν1/2 menunjukkan bahawa elektron yang dipindahkan dalam langkah penentu kadar tindakbalas adalah 1.51, 1.66, 1.88 dan 2.05 melalui elektrod Cu, Cu-Cu, PG-Cu dan Pt-Cu yang menunjukkan penurunan kepada nitrit.
The electroreduction of nitrates and nitrites were carried out in this study using a copper modified platinum (Pt-Cu) electrode in the presence of 0.05 M KCl solution using cyclic voltammetry. Comparison was carried out using various working electrodes such as Cu, copper modified copper electrode (Cu-Cu) and copper modified pencil graphite electrode (PG-Cu). For the copper modified electrodes, the deposition of the copper particles was maintained at 30 cycles/ 18 seconds as the best ratio. The real surface area Pt, Cu, Cu-Cu, PG-Cu and Pt-Cu electrodes were estimated to be 1.747 cm2, 0.814 cm2, 0.988 cm2, 1.146 cm2 and 2.259 cm2 respectively. The activity and selectivity for electroreduction of both nitrates and nitrites were better at the Pt-Cu electrode. The plot ipvsν1/2 shows that the electrons transferred in the rate determining step was 1.51, 1.66, 1.88 and 2.05 on the Cu, Cu-Cu, PG-Cu and Pt-Cu respectively indicating the electroreduction of nitrate to nitrite. At more negative overpotentials, the number of electrons transferred was approximately 5.15, 5.26, 5.35 and 6 on the Cu, Cu-Cu, PG-Cu and Pt-Cu electrodes respectively, corresponding to the production of ammonia.
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