Effect of microstructural evolution of natural kaolinite due to MWCNT doping: a futuristic ‘green electrode’ for energy harvesting applications

Superbugs, also known as multidrug-resistant bacteria, have become a lethal and persistent threat due to their unresponsiveness toward conventional antibiotics. The main reason for this is that superbugs can rapidly mutate and restrict any foreign drug/molecule in their vicinity. Herein, nanomaterial-mediated therapies have set their path and shown burgeoning efficiency toward the ablation of superbugs. Notably, treatment modalities like photothermal therapy (PTT) have shown prominence in killing multidrug-resistant bacteria with their ability to generate local heat shock-mediated hyperthermia in such species. However, photothermal treatment has some serious limitations, such as high cost, complexity, and even toxicity to some extent. Hence, it is important to resolve such shortcomings of PTTs as they provide substantial tissue penetration. This is why multimodal PTTs have emerged and taken over this domain of research for the past few years. In this work, we have summarized and critically reviewed such exceptional works of recent times and provided a perspective to enhance their efficiencies. Profoundly, we discuss the design rationales of some novel photothermal agents (PTAs) and shed light on their mechanisms. Finally, challenges for PTT-derived multimodal therapy are presented, and capable synergistic bactericidal prospects are anticipated.

Nanomaterials as multimodal photothermal agents (PTAs) against 'Superbugs'.

Real-time sensitive detection of Cr (VI) in industrial wastewater and living cells using carbon dot decorated natural kyanite nanoparticles.

This work reports a solvothermal synthesis of ferromagnetic bismuth ferrite (BFO) nanoparticle and its piezo activity in the domain of catalytic degradation of carcinogenic and genotoxic rhodamine B (RhB) dye and pathogenic Escherichia coli bacteria as well. After synthesis and characterization, the structural and morphological features of the catalyst were further investigated using density functional theory (DFT), which enabled us to estimate the polarizability and many other important electrical properties of the synthesized material. The DFT study reveals remarkably high polarizability and dipole moment, which were utilized to validate the generation of piezo response by the synthesized material. Interestingly, we found enhanced piezo catalytic degradation efficiency (η ∼ 99%) along with a high rate constant (k ∼ 2.259 × 10-2 min-1), indicating a fast and efficient degradation process. In the case of pathogenic bacteria E. coli, the degradation efficacy was found to be ∼94%. Moreover, the extraction of this catalyst is quite simple. Due to its high remanent magnetization (retentivity ∼0.08 emu g-1), the catalyst can be extracted from the treated water sample by using external magnetic stimulation, making it a potential candidate for sustainable wastewater treatment.

Piezo-responsive bismuth ferrite nanoparticle-mediated catalytic degradation of rhodamine B and pathogenic E. coli in aqueous medium and its extraction using external magnetic stimulation after successful treatment.

Natural hematite-based self-poled piezo-responsive membrane for harvesting energy from water flow and catalytic removal of organic dye

The present study describes the variation of grain size of natural hematite (α-Fe2O3) from bulk to nano-scale, owing to fractionation by ball milling and also the change in vital electrical properties of the products with respect to their bulk counterpart. Hematite, an important iron ore, is present in abundance in the deposits of most parts of the world. This fact was the rationale behind the selection of this mineral for the study. A gradual decrease in size via top-down synthesis technique was confirmed and the morphological parameters of the materials were analyzed using field emission scanning electron microscopy (FESEM) and corresponding pore diameter and surface area were determined by BET-BJH analysis. The studies were performed on three size fractions, namely, S1 (bulk mineral), S2 (bulk mineral, ball milled for 3 h) and S3 (bulk mineral, ball milled for 12 h). The purities of the natural mineral and its fractionated end products were estimated by using x-ray diffraction (XRD) and x-ray fluorescence (XRF) techniques. Increase in purity with decline in the particle size, especially in the nano-domain, was observed. The changes in dielectric properties of the materials with varying temperature were studied. Temperature dependence of the dielectric constant and ac conductivity were recorded, which indicated a remarkable augmentation in dielectric permittivity with reduction in size of the material. High dielectric constants of the smaller sized materials (S2 and S3) at low frequency signified their potential use in energy storage devices. Thus, using an easily available natural mineral as the starting material, an efficient energy storage appliance can be devised with a low-cost substance, synthesized by the simple approach of fractionation without employing any chemicals.

Barsha Bhowal

Papers

Effect of Size Fractionation on Purity, Thermal Stability and Electrical Properties of Natural Hematite