Strontium titanates were prepared with different morphologies by varying the ratio of solvents used during the synthesis. The effects of morphology and solvent (ethylene glycol to water) ratio were investigated both on the structure and photocatalytic activity of the samples. Structural properties were determined by X-ray diffraction, scanning electron microscopy, diffuse reflectance spectroscopy, and nitrogen adsorption measurements. The photocatalytic activity of the samples was evaluated by the photocatalytic oxidation of phenol and by the photocatalytic reduction of carbon dioxide. The ratio of solvents notably influenced the morphology, strontium carbonate content, primary crystallite size, and specific surface area of the samples. Samples prepared at low ethylene glycol to water ratios were spherical, while the ones prepared at high ethylene glycol to water ratios could be characterized predominantly by lamellar morphology. The former samples were found to have the highest efficiency for phenol degradation, while the sample with the most well-defined lamellar morphology proved to be the best for CO₂ reduction.

Strontium titanate (STO) photocatalysts were prepared via a slightly modified Pechini sol–gel method. A unique rapid calcination technique with a short exposure time was used to obtain crystalline products. The samples were characterized by X-ray diffractometry, scanning electron microscopy, diffuse reflectance spectroscopy, infrared spectroscopy, nitrogen adsorption–desorption measurements, and X-ray photoelectron spectroscopy. Their photocatalytic activity was evaluated by the photocatalytic oxidation of phenol, oxalic acid, and chlorophenol under UV light irradiation using commercial STO as a reference. These pollutants, together with glucose and propanol, were used to investigate the stability of the samples against various functional groups. All our samples exhibited higher photocatalytic activity than the commercial STO reference. With increasing calcination temperature, the crystallinity and primary crystallite sizes increased while the band gaps and specific surface areas decreased. The photocatalytic activity of the most efficient sample was explained by the presence of SrCO₃ on its surface. The STO catalysts were highly stable as they largely retained their crystalline composition after exposure to chemicals with different functional groups. Finally, we compared the costs associated with the unique calcination technique with a more conventional one and found that our method is ~35% more cost-effective.

Calcium titanate (CTO) photocatalysts were synthesized using a sol-gel method by adopting a cost-efficient, rapid calcination technique. The CTOs were characterized by X-ray diffractometry, X-ray photoelectron spectroscopy, infrared spectroscopy, nitrogen adsorption, porosimetry measurements, scanning/transmission electron microscopy, and diffuse reflectance spectroscopy. Their photocatalytic activity was assessed through the photocatalytic degradation of phenol, oxalic acid, and chlorophenol under UV light exposure, using a commercial CTO as a reference. The stability of the samples was evaluated using compounds with -OH, -COOH, and -Cl functional groups. Characterization results showed that CTO composites containing anatase, rutile, and brookite titania were obtained. Increasing the calcination temperature led to various crystalline compositions, higher crystallinity, larger primary crystallite sizes, and smaller specific surface areas. The photocatalytic activity of all CTO/TiO₂ composites was superior compared to the commercial CTO we used as a reference. The high photocatalytic activity of the best-performing composites was attributed to their higher specific surface areas and the synergistic effect between the crystal phases. A cost comparison was also made between our unique calcination technique and conventional calcination, and it was found that our method is approximately 35% more cost-effective, while retaining the photocatalytic activity.

Barium titanate photocatalysts were synthesized via a sol–gel method involving a unique, cost-effective calcination technique that includes rapid heating and short exposure. The samples were characterized by X-ray diffractometry, scanning electron microscopy, diffuse reflectance spectroscopy, photoluminescence spectroscopy, infrared spectroscopy, and nitrogen adsorption–desorption measurements. The photooxidation activity and stability of the samples were evaluated by the degradation of phenol, oxalic acid, and chlorophenol. Their photoreduction activity was also investigated by the photocatalytic conversion of CO₂ to CO. In both cases, UV irradiation was applied to activate the catalysts. As references, commercially available cubic and tetragonal barium titanates were used, with the addition of benchmark P25 TiO₂ in some cases. Increasing the calcination temperature resulted in increased primary crystallite sizes, decreased specific surface areas, and slightly redshifted band gaps. On the one hand, the overall photooxidation activity of the samples for pollutant degradation was rather low, possibly due to their unfavorable valence band maximum position. On the other hand, our samples displayed significantly superior photoreduction activity, surpassing that of all the references, including P25 TiO₂. The high photoactivity was mainly attributed to the specific surface areas that changed per the efficiency of the samples. Last, the cost comparison calculations showed that applying our calcination technique is 29.5% more cost-efficient than conventional calcination, and the same amount of energy is sufficient for preparing even a 1.4 times higher amount of barium titanite.

آب شیرین کمتر از 1% منابع آبی جهان را تشکیل می‏دهد، برداشت بی ‏رویه از این منبع و نفوذ آب دریا در مناطق تحت تنش آب به‏ سرعت در حال تخلیه آن می‏ باشد. روند تخلیه‏ آب در خاورمیانه به سطح بحرانی رسیده است، زیرا سرانه‏ آب در این منطقه بسیار پایین‏ تر از میانگین سرانه‏ جهان می‏ باشد. نمک‏ زدایی آب با تولید آب شیرین از آب دریا، آب‏ های لب ‏شور زیرزمینی، آب زهکشی و پساب حاصل از تصفیه‎‏ی آب، رهیافتی برای کاهش تنش آب است. طی این فرآیندها، جریان زائدی با شوری بالا به ‏عنوان محصول فرعی تولید می‌شود که دفع آن هزینه ‏بر است. حجم عظیمی از آب تغلیظ‏ شده که حاوی ترکیبات باقی‌ مانده است به محیط تخلیه می‏شود و معضلی جدی محسوب می‏شود. به‏ دلیل عدم امکان دفع شورابه تولیدی، نمک‌زدایی درون ‌سرزمینی با نمک‌زدایی ساحلی متفاوت است. در شیرین‌سازی آب‌های زیرزمینی، املاح محلول در آب موجب گرفتگی می‌شودو رسوب‏گذاری منجر به کاهش تولید آب با انرژی مشخصی طی این فرآیندها می‌شود. از این‏ رو تکامل فرآیندهای نمک‌زدایی، این فناوری را ارزان‌تر، مطمئن‌تر و کم‌مصرف‌تر می‌سازد.