Offretite zeolite synthesis in the presence of cetyltrimethylammonium bromide (CTABr) is reported. The offretite crystals were synthesized with a high crystallinity and hexagonal prismatic shape after only 72 h of hydrothermal treatment at 180 °C. The CTABr has dual-functions during the crystallization of offretite, viz. as structure-directing agent and as mesoporogen. The resulting offretite crystals, with a Si/Al ratio of 4.1, possess more acid sites than the conventional offretite due to their high crystallinity and hierarchical structure. The synthesized offretite is also more reactive than its conventional counterpart in the acylation of 2-methylfuran for biofuel production under non-microwave instant heating condition, giving 83.5% conversion with 100% selectivity to the desired product 2-acetyl-5-methylfuran. Hence, this amphiphile synthesis approach offers another cost-effective and alternative route for crystallizing zeolite materials that require expensive organic templates.
Microalgae is an autotrophic organism with fast growth, short reproduction cycle, and strong environmental adaptability. In recent years, microalgae and the bioactive ingredients extracted from microalgae are regarded as potential substitutes for raw materials in the pharmaceutical and the cosmetics industry. In this review, the characteristics and efficacy of the high-value components of microalgae are discussed in detail, along with the sources and extraction technologies of algae used to obtain high-value ingredients are reviewed. Moreover, the latest trends in biotherapy based on high-value algae extracts as materials are discussed. The excellent antioxidant properties of microalgae derivatives are regarded as an attractive replacement for safe and environmentally friendly cosmetics formulation and production. Through further studies, the mechanism of microalgae bioactive compounds can be understood better and reasonable clinical trials conducted can safely conclude the compliance of microalgae-derived drugs or cosmetics to be necessary standards to be marketed.
Hydrazine borane (HB) is a chemical hydrogen storage material with high gravimetric hydrogen density of 15.4 wt%, containing both protic and hydridic hydrogen. However, its limitation is the formation of unfavorable gaseous by-products, such as hydrazine (N2H4) and ammonia (NH3), which are poisons to fuel cell catalyst, upon pyrolysis. Previous studies proved that confinement of ammonia borane (AB) greatly improved the dehydrogenation kinetics and thermodynamics. They function by reducing the particle size of AB and establishing bonds between silica functional groups and AB molecules. In current study, we employed the same strategy using MCM-41 and silica aerogel to investigate the effect of nanosizing towards the hydrogen storage properties of HB. Different loading of HB to the porous supports were investigated and optimized. The optimized loading of HB in MCM-41 and silica aerogel was 1:1 and 0.25:1, respectively. Both confined samples demonstrated great suppression of melting induced sample foaming. However, by-products formation was enhanced over dehydrogenation in an open system decomposition owing to the presence of extensive Si-O···BH3(HB) coordination that further promote the B-N bond cleavage to release N2H4. The Si-OH···N(N2H4) hydrogen bonding may further promote N-N bond cleavage in the resulting N2H4, facilitating the formation of NH3. As temperature increases, the remaining N-N-B oligomeric chains in the porous silica, which are lacking the long-range structure may further undergo intramolecular B-N or N-N cleavage to release substantial amount of N2H4 or NH3. Besides open system decomposition, we also reported a closed system decomposition where complete utilization of the N-H from the released N2H4 and NH3 in the secondary reaction can be achieved, releasing mainly hydrogen upon being heated up to high temperatures. Nanosizing of HB particles via PMMA encapsulation was also attempted. Despite the ester functional group that may favor multiple coordination with HB molecules, these interactions did not impart significant change towards the decomposition of HB selectively towards dehydrogenation.
Acetylation of glycerol to yield monoacetin (MAT), diacetin (DAT), and triacetin (TAT) over NiO-supported CeO2 (xNiO/CeO2) catalysts is reported. The catalysts were synthesized utilizing a sol-gel technique, whereby different quantities of NiO (x = 9, 27, and 45 wt%) were supported onto the CeO2 substrate, and hexadecyltrimethylammonium bromide (CTABr) served as a porogen. The utilization of EDX elemental mapping analysis confirmed the existence of evenly distributed Ni2+ ion and octahedral NiO nanoparticles on the CeO2 surface through the DRS UV-Vis spectroscopy. The most active catalyst is 27NiO/CeO2 based on TAT selectivity in the glycerol acetylation with ethanoic acid, attaining 97.6% glycerol conversion with 70.5% selectivity to TAT at 170 °C with a 1:10 glycerol/ethanoic acid molar ratio for 30 min using a non-microwave instant heating reactor. The 27NiO/CeO2 is reusable without significant decline in catalytic performance after ten consecutive reaction cycles, indicating high structure stability with accessible active acidity.
Biofertilizers encompass microorganisms that can be applied to plants, subsequently establishing themselves within the plant's rhizosphere or internal structures. This colonization stimulates plant development by enhancing nutrient absorption from the host. While there is growing literature documenting the applications of microalgae-based and bacterial-based biofertilizers, the research focusing on the effectiveness of consortia formed by these microorganisms as short-term plant biofertilizers is notably insufficient. This study seeks to assess the effectiveness of microalgae-bacterial biofertilizers in promoting plant growth and their potential contribution to the circular economy. The review sheds light on the impact of microalgae-bacterial biofertilizers on plant growth parameters, delving into factors influencing their efficiency, microalgae-bacteria interactions, and effects on soil health. The insights from this review are poised to offer valuable guidance to stakeholders in agriculture, including farmers, environmental technologists, and businesses. These insights will aid in the development and investment in more efficient and sustainable methods for enhancing crop yields, aligning with the Sustainable Development Goals and principles of the circular economy.
The demand for astaxanthin has been increasing for many health applications ranging from pharmaceuticals, food, cosmetics, and aquaculture due to its bioactive properties. Haematococcus pluvialis is widely recognized as the microalgae species with the highest natural accumulation of astaxanthin, which has made it a valuable source for industrial production. Astaxanthin produced by other sources such as chemical synthesis or fermentation are often produced in the cis configuration, which has been shown to have lower bioactivity. Additionally, some sources of astaxanthin, such as shrimp, may denature or degrade when exposed to high temperatures, which can result in a loss of bioactivity. Producing natural astaxanthin through the cultivation of H. pluvialis is presently a demanding and time-consuming task, which incurs high expenses and restricts the cost-effective industrial production of this valuable substance. The production of astaxanthin occurs through two distinct pathways, namely the cytosolic mevalonate pathway and the chloroplast methylerythritol phosphate (MEP) pathway. The latest advancements in enhancing product quality and extracting techniques at a reasonable cost are emphasized in this review. The comparative of specific extraction processes of H. pluvialis biological astaxanthin production that may be applied to large-scale industries were assessed. The article covers a contemporary approach to optimizing microalgae culture for increased astaxanthin content, as well as obtaining preliminary data on the sustainability of astaxanthin production and astaxanthin marketing information.