The adsorption of bixin in aprotic solvents onto acid- and alkali-treated kaolinite was investigated. Kaolinite was treated three times, for 6 h each, with 8 M HCl or 5 M KOH. The adsorbents were characterized by XRD, FT-IR, EDS, and BET-N2. The effects of contact time and dye concentration on adsorption capacity and kinetics, electronic transition of bixin before and after adsorption, and also mechanism of bixin-kaolinite adsorption were investigated. Dye adsorption followed pseudo-second order kinetics and was faster in acetone than in dimethyl carbonate. The best adsorption results were obtained for KOH-treated kaolinite. In both of the solvents, the adsorption isotherm followed the Langmuir model and adsorption capacity was higher in dimethyl carbonate (q
m = 0.43 mg/g) than in acetone (0.29 mg/g). The adsorption capacity and kinetics of KOH-treated kaolinite (q
m = 0.43 mg/g, k
2 = 3.27 g/mg·min) were better than those of HCl-treated kaolinite (q
m = 0.21 mg/g, k
2 = 0.25 g/mg·min) and natural kaolinite (q
m = 0.18 mg/g, k
2 = 0.32 g/mg·min). There are shift in the band position of maximum intensity of bixin after adsorption on this adsorbent. Adsorption in this system seemed to be based essentially on chemisorption due to the electrostatic interaction of bixin with the strong basic and reducing sites of kaolinite.
Bixin is one of the potential natural sensitizers used in dye-sensitized solar cells (DSSCs). In this study, bixin was complexed with Cu(II) and Zn(II) to increase its stability. The formation of the complexes was indicated by shifting peaks absorption and the changes in the fine spectral structure observed from the UV-Vis absorption spectra. The metal-bixin complex occurs due to the interaction between the ester groups of bixin and the metal. Bixin, Cu-bixin, and Zn-bixin were used separately as sensitizers in DSSCs. The DSSCs performance was then improved by adding 1-methyl-3-propylimidazolium iodide (MPII) to the electrolyte system. The presence of MPII 0.4 M in KI-I2 electrolyte produced a higher ionic conductivity value (20.44 mS cm–1) than that without MPII (11.14 mS cm–1). This electrolyte system significantly improved DSSCs performance. Under a light intensity of 300 W/m2, the maximum energy conversion efficiencies of DSSC with bixin, Cu-bixin, and Zn-bixin as sensitizers are 0.084, 0.081, and 0.005%, respectively. The Zn-bixin-based DSSC was stable under high light intensity. Under 700 W/m2, its maximum energy conversion efficiency reaches 0.125%. There was a synergistic work observed between the metal-bixin complex and the MPII based electrolyte. This result can open the way for constructing functional materials for solar cell applications.
In this research, treated metakaolinite (TMK) was introduced into the TiO2 photoelectrode to fabricated dye-sensitized solar cells (DSSCs). The photovoltaic cells have four main natural components, i.e., a photosensitizer (carotenoid bixin), photoelectrode (TiO2/kaolinite), electrolyte (glycerine carbonate derivative), and counter-electrode (carbon). Their stability, reusability, and equivalent circuit were studied. The presence of 5% of TMK in anatase TiO2 paste decreased the TiO2 band gap from 3.21 to 3.16 eV. The result showed that the presence of 5% of TMK in TiO2 paste was more favorable to obtain higher energy conversion efficiency. Under a light intensity of 200 W/m2, it produced an energy conversion yield of 0.086%. The combination of the electrolyte and the TMK demonstrated a synergistic effect to improve the electrical properties of the DSSC. The energy storage function worked well until the third day of analysis. The DSSC based on TiO2/TMK photoelectrode exhibited 16 times better stability than pure TiO2-based photoelectrode. The Faraday charge transfer processes showed that the TiO2/TMK photoelectrode is not in direct contact with the carbon counter-electrode.
Shrimp species have been reported to contain astaxanthin, which has high antioxidant activities. They also contain omega-3 in the form of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which can act as photoprotective agents that maintain healthy skin from reactive oxygen species (ROS) due to exposure to UV rays. In addition, fermentation has become an essential pre-treatment to extract the bioactive components in shrimp more easily. This study aims to extract oil from cincalok, a traditional Indonesian (especially in West Kalimantan) food made from Acetes shrimp fermented for 7–15 days. Cincalok oil was added to the lotion as a bioactive additive and sunscreen. Cincalok oil was extracted by the soxhletation method using n-hexane as solvent. The oil was then analyzed for its physicochemical properties, including density, viscosity, possible heavy metal contamination, and the profile of the fatty acids contained. The yield of cincalok oil extraction was 1.09 ± 0.05%, with the highest fatty acid content of 21.70% palmitic acid, 10.99% DHA, and 10.33% EPA. Cincalok oil also contains astaxanthin of 0.38 ± 0.02 mg/L oil. It has a viscosity of 69.71 ± 0.12 cP with a density of 0.93 ± 0.03 g/cm3. The analysis data of ICP-AES shows that there is no heavy metal contamination. The SPF value produced from cincalok oil lotion at 5 and 10% variations of cincalok oil was 15.17 ± 0.09 and 30.28 ± 0.49, respectively. The SPF value of lotion with the addition of cincalok oil was much greater than that of the base lotion, which was 2.16 ± 0.12.
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