In this work, wet oxidative decomposition of (NH₄)₂SO₄ in an air and Ar atmosphere was conducted in a lab-scale airtight glass vessel reactor by adding Na₂S₂O₈ and H₂O₂ as oxidative agents to (NH₄)₂SO₄ solution. The initial concentration of NH₄⁺ in (NH₄)₂SO₄ aqueous solution was set to 1,000 mg-NH₄⁺/dm³. The experiments were conducted at temperatures of 343–363 K, keeping the initial pH at a prescribed value between 5.5 and 13.5. The mixing molar ratio of (NH₄)₂SO₄/oxidant was set to 1/1 – 1/10.
Results show that the decomposition of (NH₄)₂SO₄ by Na₂S₂O₈ in an alkaline region was more significant than that by H₂O₂ because most H₂O₂ disappeared by self-decomposition under the present conditions. Results further showed that (NH₄)₂SO₄ was almost decomposed completely in about 150 min reaction time by adding Na₂S₂O₈ at a molar ratio of (NH₄)₂SO₄/Na₂S₂O₈=1/3 at 363 K in an alkaline condition of pH=13.5. The rates of decomposition of Na₂S₂O₈ and (NH₄)₂SO₄ were expressed by the first-order kinetics with respect to the concentrations of Na₂S₂O₈ and (NH₄)₂SO₄ with constant initial concentrations of (NH₄)₂SO₄ and Na₂S₂O₈, respectively.
When Na₂S₂O₈ was added to (NH₄)₂SO₄ solution, NH_3(aq) was decomposed by reactive oxygen species such as • SO₄⁻, • OH⁻, • O⁻, • O₃⁻, etc. in an alkaline condition, producing the main reaction product of N₂ and small amounts of NO₂⁻ and NO₃⁻ by-products. In this oxidative decomposition of (NH₄)₂SO₄, O₂ formation was suppressed by the consumption of these reactive oxygen species.

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The inhibitory effect of BTA on the anodic dissolution of copper in an acid solution was studied using a channel flow double electrode. Electrochemical measurements obtained using channel flow double electrode enable the determination of dissolution currents of cuprous or cupric ions with the measurement of the potentiodynamic polarization curve. The diffusion-limiting current decreased remarkably in an acid solution containing BTA. Results show that the actions of BTA on the dissolution mechanisms of cuprous and cupric ions are different. Potential-pH diagrams were constructed and compared with the experimental data. CuCl and Cu(I)-BTA are in equilibrium at the forming potential of Cu(I)-BTA film. The decrease of the dissolution current of cuprous ions by the addition of BTA originates from the formation of Cu(I)-BTA film by reacting CuCl and BTA. Cupric ions dissolve at the noble potential in the presence of Cu(I)-BTA film on the copper surface. For the measurement of transient current at potentiostatic polarization, the time at which the initial current value becomes 1/10 was defined as the film formation time(t_1/10), which was evaluated at various potentials. The competitive reactions of copper dissolution and Cu(I)-BTA film formation were investigated based on the potential dependence on t_1/10.

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It is well known that bulk Pd-Ni-P metallic glass with a wide range of compositions (Pd: 25–60 at%; Ni: 20–57 at%; P 16–22 at%) can be prepared. In the present study, we investigated the method of production of electrodeposited Pd-Ni-P metallic glass films whose composition range is the same as that of bulk Pd-Ni-P metallic glass. The composition of electrodeposited Pd-Ni-P films were controlled by adjusting the concentrations of PdCl₂, NiSO₄·6H₂O and H₃PO₃ in the Pd-Ni-P bath. X-ray diffraction patterns and transmission electron microscopy images showed that the electrodeposited Pd-Ni-P films were amorphous. The results of differential scanning calorimetry indicated that the electrodeposited Pd-Ni-P films were metallic glass with Pd, Ni, and P compositions of 36–57 at%, 25–43 at%, and 17–20 at%, respectively, which were almost identical to those in bulk Pd-Ni-P metallic glass. Furthermore, we succeeded in producing a Pd₄₂Ni₃₇P₂₁ metallic glass film by electrodeposition. The alloy composition of this film was very similar to that of Pd₄₀Ni₄₀P₂₀, which is one of the best bulk metallic glasses because of its glass forming ability (GFA).

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