Functionalization of Shorea faguetiana biochar using Fe2O3 nanoparticles and MXene for rapid removal of methyl blue and lead from both single and binary systems.

The synthesis of polymeric magnetic composites is a promising strategy for the rapid and efficient treatment of wastewater. Lead and methyl blue are extremely hazardous to living organisms. The sorption of Pb2+ and the dye methyl blue (MB) by biochar is an ecologically sustainable method to remediate this type of water pollution. We functionalized Shorea faguetiana biochar with Fe2O3 and MXene, resulting in Fe2O3/BC/MXene composites with an efficient, rapid, and selective adsorption performance. Based on X-ray photoelectron and Fourier transform infrared spectrometry, we found that the Fe2O3/BC/MXene composites had an increased number of surface functional groups (F-, C[double bond, length as m-dash]O, CN, NH, and OH-) compared with the original biochar. The batch sorption findings showed that the maximum sorption capacities for Pb2+ and MB at 293 K were 882.76 and 758.03 mg g-1, respectively. The sorption phenomena obeyed a pseudo-second-order (R2 = 1) model and the Langmuir isotherm. There was no competition between MB and Pb2+ in binary solutions, indicating that MB and Pb2+ did not influence each other as a result of their different adsorption mechanisms (electrostatic interaction for Pb2+ and hydrogen bonding for MB). This illustrates monolayer sorption on the Fe2O3/BC/MXene composite governed by chemical adsorption. Thermodynamic investigations indicated that the sorption process was spontaneous and exothermic at 293-313 K, suggesting that it is feasible for practical applications. Fe2O3/BC/MXene can selectively adsorb Pb2+ ions and MB from wastewater containing multiple interfering metal ions. The sorption capacities were still high after five reusability experiments. This work provides a novel Fe2O3/BC/MXene composite for the rapid and efficient removal of Pb2+ and MB.

First-Principles Investigation of Novel Alkali-Based Lead-Free Halide Perovskites for Advanced Optoelectronic Applications.

Lead-free halide perovskites are considered promising candidates as visible light absorbers with outstanding optoelectronic properties. In this work, novel kinds of lead-free halide perovskites were studied for their electronic, optical, and thermoelectric properties by employing the most precise and enhanced modified Trans-Blaha Beck-Johnson potential. The estimated band spectra of the studied materials were comparable. The materials are confirmed to have an indirect band gap semiconducting nature due to the existence of energy band gaps. Among the studied materials, CsSnI3 has a smaller band gap, confirming the excitation to be more energy efficient. Examining the predicted density of states and true electronic orbital contributions, we observed a progressive fluctuation along the energy axis was observed. Furthermore, the linear optical properties are calculated and studied in terms of possible optoelectronic applications. The absorption in KSnI3 was greater compared to the other two materials. The studied materials could be used for antireflecting coatings against UV radiation, owing to the prominent peaks in their reflectivity spectra. The Seebeck coefficient and electrical properties, as well as the positive value of RH all pointed to a p-type nature in these materials. From the anticipated thermoelectric properties, the materials also appear to be suitable for application in thermoelectric devices.