In this work, TiO2 nanoparticles were successfully synthesized with narrow size distribution via a wet ball milling sol-gel method. The effect of calcination temperature on photocatalytic activity was observed from particle size, crystallite size, and phase transition of TiO2 nanoparticles. Increasing calcination temperature increased particle size, crystallite size, and the crystallinity of synthesized TiO2. Phase transition depended on variation in calcination temperatures. A two-phase mixture of anatase and brookite was obtained with lower calcination temperature whereas a three-phase mixture appeared when calcination temperature was 500–600 °C. With higher temperature, the rutile phase kept increasing until it was the only phase observed at 800 °C. Anatase strongly affected the photocatalytic activity from 300 °C to 600 °C while the particle size of TiO2 was found to have a dominant effect on the photocatalytic activity between 600 °C and 700 °C. A mixture of three phases of TiO2-600 exhibited the highest methylene blue degradation with the rate constant of 9.46 × 10−2 h−1 under ultraviolet (UV) irradiation.

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Lithium extraction is currently too inefficient to be economical or marketable. The objective of this work was to find the best extractant and the most inexpensive approach to recover lithium chemically from lithium ion batteries containing other desired metals using the solvent extraction technique. The extraction efficiency of various extracting types was investigated. The highest extraction efficiency of lithium ion from aqueous solution was obtained with bis(2-ethylhexyl) phosphate (DEHPA), with 75% recovery. Studying the effects of selected extractants in this experiment, it was found that the acidic extractant group provided better extraction efficiency than solvating extractants. Further investigation of influential variables was carried out, including extraction time, pH of aqueous solution, and initial concentration. The results indicate that 6 h of extraction brings the system to equilibrium, and pH 1.5 is the best for extraction efficiency.

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To control the water quality in the intensive shrimp mariculture pond by uptaking the total ammonia-nitrogen with sterile Ulva sp., the growth rate of sterile Ulva sp. was experimentally measured and the influence of the rate on the water quality control evaluated. The specific growth rate constant of the seaweed increased with the total ammonia-nitrogen concentration, photosynthetic photon flux density and operating temperature. Then the dynamics of ammonia-nitrogen in the modeled culture pond for the intensive shrimp farming in the tropical region were numerically simulated, in which the seaweed was used to uptake ammonia-nitrogen. The seaweed could uptake ammonia-nitrogen effectively during daytime mainly due to the high intensity of sun light, and the total ammonia-nitrogen concentration in the shrimp pond could be kept very low. The required seaweed density to control the total ammonia-nitrogen concentration less than the recommended maximum concentration of 1.0 ⋅ 10 -3 kg N m -3 was estimated to be reasonable.