ABSTRACT
Boron-doped diamond (BDD) was modified with copper and gold particles by using an electrodeposition technique to improve its catalytic effect on CO2 reduction in a flow system. The system was optimized based on the production of formic acid by the electroreduction process. At the optimum applied potential of -1.0 V (vs. Ag/AgCl) and flow rate of 50 mL min-1, the copper-gold-modified BDD produced formic acid at the highest rate of 4.88 mol m-2 s-1 and a concentration of 15.93 ppm, while acetic acid was produced with a rate of 0.11 mol m-2 s-1 and a concentration of 0.47 ppm. An advantage of the flow system using the modified BDD was that it was found to accelerate the production rate of acetic acid as well as to decrease the reduction potential of CO2. Furthermore, better stability of the metal particles was observed when using mixed copper-gold modification on the BDD surface than single modification by either metal. The results indicated that a flow system is suitable to be employed for electroreduction of CO2 using the bimetal-modified BDD electrodes, especially with copper and gold as the modifying particles.
ABSTRACT
BACKGROUND AND OBJECTIVE: Reutealis trisperma (Blanco) is a non-edible biodiesel producer plant that has a good prospect due to the higher seed production capacity and oil content. In addition, it also able to grow well under unfavourable environment. The study aimed to analyze the response of Reutealis trisperma (R. trisperma) to gold mined wastewater. MATERIALS AND METHODS: Five varieties of R. trisperma i.e., Kemiri Minyak-1 (KM1), Kemiri Minyak-2 (KM2), Kermindo-1 (KD1), Kermindo-2 (KD2) and Harapan (HR) grown in water culture, were treated with wastewater from gold mining industry with concentration of 0, 125, 250, 500 and 1000 mL for 2 weeks. Shoot and root growth, anatomy as well as some physiological characters were analyzed during the treatment. RESULTS: Wastewater treatments for 14 days caused decrease of shoot growth and induced leaf yellowing of the plants. The treatments caused increase in malondialdehyde content up to 4 fold, while chlorophyll a, chlorophyll b and total chlorophyll of the plants decreased significantly. TEM analysis indicated that the root cell of plants exposed to highest concentration of wastewater started to degenerate and had higher number of mitochondria and peroxisome vesicles suggesting that the cellular respiration and anti-oxidative mechanism presumably became more active due to the accumulation of reactive oxygen species. CONCLUSION: Gold mine wastewater treatment caused all the plants to undergo stress characterized by the increase of malondialdehyde and the decrease of chlorophyll content and leaf growth of R. trisperma, even though there was variation among the varieties. KM2 and KD2 had the best performance among all varieties in response to gold-mine wastewater.
