Colored cotton crop wastes valorization through pyrolysis: a study of energetic characterization and analytical Py-GC/MS.

The present work aimed to study different parts of colored cotton waste through energetic characterization and analytical flash pyrolysis. Stalks and bolls of BRS cotton cultivars from Sementes do Brasil (Green, Ruby, Topaz and Jade) were studied, using white cotton (BRS 286) as a comparison. The energetic potential of biomass was evaluated by bulk density, High Heating Value (HHV), proximate and ultimate analysis, compositional and thermogravimetric analysis (TGA). Pyrolysis was performed in a micro-pyrolyzer and the products were identified by gas chromatography and mass spectroscopy (Py-GC/MS). The results indicated a significant energetic potential, suggesting that can be used as an alternative energy source for thermochemical processes. The results of conventional pyrolysis indicated the presence of oxygenated compounds of different organic groups: aldehydes, ketones, phenols, furans and ethers, characteristic of the decomposition of lignocellulosic materials. Light organic acids in the C1-C4 range stood out the most, followed by phenols that appeared in a considerable proportion. Finally, it is concluded that the energy potential and pyrolysis products of the different parts (stalks and bolls) of colored cotton waste can be used to generate bioenergy and various chemical compounds of plant origin from green chemistry.

Biosorption of nickel and cadmium using Pachira aquatica Aubl. peel biochar.

This study aimed to assess the value of Pachira aquatica Aubl. fruit peels by exploring their applicability in the biosorption process for the removal of Ni(II) and Cd(II) metal ions. The Pachira aquatica Aubl. fruit peel biochar (PAB) was extensively characterized through various techniques, including proximate analysis, helium pycnometer, XRD, SEM, point of zero charge determination, zeta potential measurement, and Boehm titration. Subsequently, kinetic, isotherm, and thermodynamic batch biosorption studies were conducted, followed by column biosorption tests. The characteristics of PAB, including low moisture content, a neutral point of zero charge, porosity, an irregular and heterogeneous structure, a negatively charged surface, and the presence of functional groups, indicate its remarkable capacity for efficiently binding with heavy metals. Biosorption equilibrium time was achieved at 300 min for both ions, fitting well with a pseudo second-order kinetic model and Langmuir isotherm model. These data suggest that the biosorption process occurred chemically in monolayer. The column C presented an exhaust volume of 1200 mL for Ni(II) and 1080 for Cd(II) and removal of 98% and 99% of removal for Ni(II) and Cd(II), respectively. In summary, PAB demonstrates substantial potential as a biosorbent for effectively removing heavy metals, making a valuable contribution to the valorization of this co-product and the mitigation of environmental pollution.

Advancements and Prospects in Perovskite Solar Cells: From Hybrid to All-Inorganic Materials.

Hybrid perovskites, materials composed of metals and organic substances in their structure, have emerged as potential materials for the new generation of photovoltaic cells due to a unique combination of optical, excitonic and electrical properties. Inspired by sensitization techniques on TiO2 substrates (DSSC), CH3NH3PbBr3 and CH3NH3PbI3 perovskites were studied as a light-absorbing layer as well as an electron-hole pair generator. Photovoltaic cells based on per-ovskites have electron and hole transport layers (ETL and HTL, respectively), separated by an ac-tive layer composed of perovskite itself. Major advances subsequently came in the preparation methods of these devices and the development of different architectures, which resulted in an efficiency exceeding 23% in less than 10 years. Problems with stability are the main barrier to the large-scale production of hybrid perovskites. Partially or fully inorganic perovskites appear promising to circumvent the instability problem, among which the black perovskite phase CsPbI3 (α-CsPbI3) can be highlighted. In more advanced studies, a partial or total substitution of Pb by Ge, Sn, Sb, Bi, Cu or Ti is proposed to mitigate potential toxicity problems and maintain device efficiency.

Renewable aromatics through catalytic flash pyrolysis of pineapple crown leaves using HZSM-5 synthesized with RHA and diatomite.

The influence of reactor temperature of 300  and 600 °C and the acidity of the ZSM-5 and HZSM-5 catalysts on the pyrolysis product yields of the pineapple crown leaves have been investigated in a fixed bed reactor Py-GC/MS. The ZSM-5 catalyst was hydrothermally synthesized with a Si/Al ratio 50, using residual diatomite and rice husk ash as alternative sources of Al and Si for catalyst cost reduction. For the HZSM-5 synthesis, calcined ZSM-5 was activated by ion exchange between Na+ and H+. The catalysts structure was confirmed by the XRD and Rietveld treatment, SEM, FTIR, FRX, TGA and BET results. Analytical pyrolysis of the biomass was carried out at 500 °C in a Py-5200 HP-R pyrolyzer connected to the GC/MS and the pyrolysis vapors were transported to a catalytic bed at 300 and 600 °C. The results showed that the increase in the catalytic bed temperature promoted increased the aromatic content. The main pyrolysis products of the PCL were oxygenated compounds that were converted at 600 °C using the HZSM-5 catalyst into high value renewable aromatic compounds for the chemical industry, such as benzene, toluene, xylene, etilbenzene, thereby confirming the deoxygenation activity of synthesized catalyst to produce renewable aromatics compounds which are important platform chemicals and precursors for jet fuels, gases, polymers and solvents.

Ex situ catalytic biomass pyrolysis using mesoporous Ti-MCM-41.

Biomass has attracted considerable attention as energy, economic, and environmental asset, as result of its abundance and range of properties. The use of mesoporous catalysts during fast pyrolysis has been a highly important route to improve efficiency as well adding value to biomass. The addition of titanium to molecular sieves increases the efficiency of the pyrolysis reaction by improving production and selectivity of products of interest. This study aims at analyzing the catalytic pyrolysis products of elephant grass using titanium catalysts prepared at different Si/Ti molar ratios, i.e., 25 and 50. The material was supported on MCM-41 for the catalytic pyrolysis of biomass. The biomass pyrolysis reactions were performed in a micropyrolyzer coupled to a GC/MS analyzer. The Ti-MCM-41 samples were characterized by XRD, BET-specific area, and UV-visible. The distribution of pyrolysis products depended on process parameters such as temperature and catalyst type. The highest yield for hydrocarbon production, such as styrene, benzene, methylbenzene, and naphthalene, was observed at 600 °C using Si/Ti equal to 50.