RESUMO
The production of low-cost solid adsorbents for carbon dioxide (CO2) capture has gained massive consideration. Biomass wastes are preferred as precursors for synthesis of CO2 solid adsorbents, due to their high CO2 adsorption efficiency, and ease of scalable low-cost production. This review particularly focuses on waste biomass-derived adsorbents with their CO2 adsorption performances. Specifically, studies related to carbon (biochar and activated carbon) and silicon (silicates and geopolymers)-based adsorbents were summarized. The impact of experimental parameters including nature of biomass, synthesis route, carbonization temperature and type of activation methods on the CO2 adsorption capacities of biomass-derived pure carbon and silicon-based adsorbents were evaluated. The development of various enhancement strategies on biomass-derived adsorbents for CO2 capture and their responsible factors that impact adsorbent's CO2 capture proficiency were also reviewed. The possible CO2 adsorption mechanisms on the adsorbent's surface were highlighted. The challenges and research gaps identified in this research area have also been emphasized, which will help as further research prospects.
RESUMO
The subject of water contamination and how it gets defiled to the society and humans is confabulating from the past decades. Phenolic compounds widely exist in the water sources and it is emergent to determine the toxicity in natural and drinking water, because it is hazardous to the humans. Among these compounds, catechol has sought a strong concern because of its rapid occurrence in nature and its potential toxicity to humans. The present work aims to develop an effective electrochemical sensing of catechol using mesoporous structure of Fe3O4-TiO2 decorated on glassy carbon (GC) electrode. The creation of pure TiO2 using the sol-gel technique was the first step in the synthesis protocol for binary nanocomposite, which was then followed by the loading of Fe3O4 nanoparticles on the surface of TiO2 using the thermal decomposition method. The resultant Fe3O4-TiO2 based nanocomposite exhibited mesoporous structure and the cavities were occupied with highly active magnetite nanoparticles (Fe3O4) with high specific surface area (90.63 m2/g). When compared to pure TiO2, catechol showed a more prominent electrochemical response for Fe3O4-TiO2, with a significant increase in anodic peak current at a lower oxidation potential (0.387 V) with a detection limit of 45 µM. Therefore, the prepared magnetite binary nanocomposite can serve as an efficient electroactive material for sensing of catechol, which could also act as a promising electrocatalyst for various electrocatalytic applications.
Assuntos
Carbono , Nanopartículas de Magnetita , Humanos , Carbono/química , Nanopartículas de Magnetita/química , Catecóis , ÁguaRESUMO
This study addresses the significance of wastewater recuperation by a simple and facile treatment process known as photocatalyst technology using visible light. Titanium di-oxide (TiO2) is the most promising photocatalyst ever since longing decades, has good activity under UV light, owing to its small band gap. Hence, TiO2 has been modified with metal oxides for the positive response against visible light. Since this is an efficient process, the novelty has been made on nanometal oxide CdO (cadmium oxide) combined with TiO2 to acquire the best efficiency of degrading organic chlorophenol contaminant. Initially, the composites were synthesized by sol-gel and thermal decomposition methods and investigated for their various outstanding properties. The characterized outcomes have exhibited heterostructures with reduced crystallite size from the X-ray diffraction studies. Then, the determination of nanoporous feature was recognized through HR-TEM analysis which was also detected with some dislocations. The EDX spectrum was identified the perfect elemental composition. The nitrogen adsorption-desorption equilibrium was attained that offers many pores measured with high surface area. The XPS result convinced that Ti3+ was accessible along with TIO2/CdO composite. Further the absorption towards higher wavelength was obtained from UV-vis spectra. Finally, for the photocatalytic application of chlorophenol, the composite shows higher percentage of degrading efficiencies than the pristine TiO2. The photocatalytic mechanism was discussed in detail.
Assuntos
Clorofenóis , Poluentes Ambientais , Nanoporos , Catálise , Clorofenóis/química , Óxidos/química , Titânio/químicaRESUMO
The treatment of industrial waste and harmful bacteria is an important topic due to the release of toxins from the industrial pollutants that damage the water resources. These harmful sources frighten the life of every organism which was later developed as the carcinogenic and mutagenic agents. Therefore, the current study focuses on the breakdown or degradation of 4-chlorophenol and the antibacterial activity against Escherichia coli (E. coli). As a well-known catalyst, pure titanium-di-oxide (TiO2) had not shown the photocatalytic activity in the visible light region. Hence, band position of TiO2 need to be shifted to bring out the absorption in the visible light region. For this purpose, the n-type TiO2 nanocrystalline material's band gap got varied by adding different ratios of p-type CuO. The result had appeared in the formation of p (CuO) - n (TiO2) junction synthesized from sol-gel followed by chemical precipitation methods. The optical band gap value was determined by Kubelka-Munk (K-M) plot through UV-Vis diffusive reflectance spectroscopy (DRS). Further, the comprehensive mechanism and the results of photocatalytic and antibacterial activities were discussed in detail. These investigations are made for tuning the TiO2 catalyst towards improving or eliminating the existing various environmental damages.
Assuntos
Escherichia coli , Titânio , Antibacterianos , Catálise , Clorofenóis , Cobre , Luz , FotóliseRESUMO
In recent times, cost effective synthesis of semiconductor materials has been a subject of concern for the day to today applications. In this work, novelty has been made on the facile synthesis of metal oxides (TiO2 and CeO2) and nanocomposites (TiO2-CeO2) through sol-gel and precipitation methods of imparting lemon extract. The synthesized materials behave as the functional catalysts which has been further carried out for the photocatalytic degradation against 2,4-Dichlorophenol (2,4-DCP). The materials are then valued for the structural and optical properties. The lemon extract used in synthesis has played a premier role in upgrading the charge carrier separation, bandgap, and size reduction of the composite system. Further, the CeO2 supported TiO2 sample acts as the better visible light catalyst, due to the prevention of aggregation and existence of line dislocation that supported to access the additional electron trap sites.