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This research, for the first time, reports the fabrication of dodecylamine-capped hafnium oxide nanomaterial onto gold (Au) electrodes for the efficient detection of sulfide (HS−) electrochemically.

A theoretical Density-functional theory (DFT) study has been carried out to explore the interaction of highly toxic gases carbon monoxide (CO), phosphine (PH3) and stibine (SbH3) with pristine (AGNR) and manganese (Mn) doped armchair graphene nanoribbon (AGNR-Mn). The adsorption behaviour of these gases has been analyzed by calculating the binding distance, adsorption energy (Eads), band structure, density of state spectrum, and current-voltage characteristics. In the case of AGNR, the highest Eads = −0.19 eV has been observed for the CO gas. The Mn doping leads to the high stability and substantial improvement in adsorption performance due to covalent interaction with gas molecules. The enhancement in adsorption energy by 19, 26 and 23 times for CO, PH3 and SbH3 respectively has been observed using AGNR-Mn instead of AGNR. The adsorption of these gases shows a considerable enhancement in the DOS around Fermi level. Furthermore, using I-V characteristics, the response of all these gases is observed and it has been found that the response of PH3 and SbH3 gas to AGNR-Mn are 48% and 45% respectively. These findings indicate that the AGNR-Mn system can be explored as a highly sensitive material for potential gas sensing of PH3 and SbH3.

Mononitrotoluenes (MNTs) can cause methemoglobinemia, liver/kidney damage, and skin/eye/throat irritation. Monitoring of MNTs in real and laboratory samples is necessary to maintain levels below permissible limits. Herein, silver oxide quantum dots (Ag2O QDs) were synthesized using a chemical method and were well characterized using transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and UV–visible spectroscopy. The characterized QDs were coated on a gold (Au) electrode using a binder (Nafion). This modified electrode was evaluated and standardized for redox-based sensing against 2-nitrotoluene. Cyclic voltammetry (CV) was optimized for electrochemical determination of 2-nitrotoluene. The effects of various factors like scan rate, solution pH, analyte concentration, and possible interferants were also evaluated for sensing performance of 2-nitrotoluene. The fabricated sensor displayed a high sensitivity of 100 μA cm−2 ppm−1 with a limit of detection of 4.3 ppm and a linear range of 5–40 ppm. The proposed technique was reliable for monitoring real as well as laboratory samples of 2-nitrotoluene.

Heterostructured α-Bismuth zinc oxide (α-Bi2O3–ZnO) photocatalyst was fabricated by a facile and cost-effective, ultrasound assisted chemical precipitation method followed by hydrothermal growth technique. As synthesized α-Bi2O3–ZnO photocatalyst showed enhanced photocatalytic performance for the MB dye degradation in contrast to pure ZnO and α-Bi2O3. Light emitting diodes (UV-LED) were used in the experimental setup, which has several advantages over conventional lamps like wavelength selectivity, high efficacy, less power consumption, long lifespan, no disposal problem, no warming-up time, compactness, easy and economic installation. XRD study confirmed the presence of both the lattice phases i.e. monoclinic and hexagonal wurtzite phase corresponding to α-Bi2O3 and ZnO in the α-Bi2O3–ZnO composite photocatalyst. FESEM images showed that α-Bi2O3–ZnO photocatalyst is composed of dumbbell like structures of ZnO with breadth ranging 4–5 μm and length ranging from 10 to 11 μm respectively. It was observed that α-Bi2O3 nanoparticles were attached on the ZnO surface and were in contact with each other. Low recombination rate of photo-induced electron-hole pairs, due to the migration of electrons and holes between the photocatalyst could be responsible for the 100% photocatalytic efficiency of α-Bi2O3–ZnO composite. In addition, photocatalyst was also observed to show the excellent antimicrobial activity with 1.5 cm zone of inhibition for 1 mg L−1 dose, against the human pathogenic bacteria (S. aureus).

Copper oxide (CuO) nanomaterials (NMs) of different size and morphology were synthesized by Chemical precipitation, Microwave irradiation and Hydrothermal method and characterized by TEM, BET, FTIR, XRD and EDX analysis. As synthesized CuO NMs were utilized for elimination of harmful dyes viz. Direct Red 81 (DR-81) and Coomassie Brilliant blue R-250 (BBR-250) and pathogenic bacteria (Staphylococcus aureus). Owing to their morphology, smaller size and relatively high surface area (40.320 m2 g−1), CuO NMs prepared by chemical precipitation method were observed to show better adsorption capacity for both the dyes (68.70 (DR-81) and 73.04 (BBR-250) mg g−1). The influence of different experimental conditions was studied by the methodical assessments of various parameters such as pH, adsorbent dose, concentration and contact time. Moreover, different adsorption isotherms and pseudo-second order kinetic model were applied to understand the adsorption mechanism. Langmuir model was found to be best fit thus confirming the monolayer adsorption process. To ensure the practical utility of CuO NMs for organic waste removal, the adsorption studies were performed in the presence of different inorganic ions and real water samples. In addition, recovery of the dye and NMs were also carried out effectively by simple method, thus avoiding the secondary pollution. CuO NMs were observed to exhibit significant antibacterial activity against the human pathogenic bacteria. These studies demonstrated that synthesized CuO NMs showed good adsorption efficiency for the removal of harmful dyes and antimicrobial activity against the pathogenic bacteria, which vary as a function of size and surface area.

Nanotechnology is the ability to understand, control, and manipulate matter at nanoscale dimension (i.e., 1–100 nm). At these dimensions, nanomaterials exhibit unique properties, in comparison to their bulk equivalents, such as lower melting points, higher specific surface areas, specific optical properties, mechanical strengths, and chemical reactivity. Unique properties of nanomaterials have increased their production and applications in many areas (e.g., cosmetics, drug delivery, electronics, imaging, textiles, biotechnology, and medicines). However, while nanoparticles can lead to breakthrough applications, they may also cause some serious environmental problems which not only pollute air, water, and soil but also causes various hazardous health effects. Humans are already exposed to the danger of variety of nanomaterials, whether natural or human-made, such as carbon nanotubes, quantum dots, metal oxide nanoparticles, zero-valence metals, and dendrimers by air, water, food, and numerous commercial products available. Due to greater surface-to-volume ratio, biopersistence, and greater oxidant capacity, nanoparticles are primary source for toxicity, which can easily penetrate epithelium and reach interstitial pulmonary area. There are needs to protect public and environmental health and safety. Standards or guidelines, which can directly refer to nanomaterials effect, do not presently exist. Thus, this present chapter provides an outline of all the toxic effects of nanomaterials, their type including their transportation and decomposition, and how adversely they affect the various physical factors of environment.

Since the onset of industrial revolution is up till the recent surge in technological processes, environmental pollution has grown at an alarming rate causing distress to living beings and irreplaceable damage to the earth. With the recognition of the severity of this environmental damage and increase in interest of using technological advancement, a number of successful pollution control strategies have emerged over the years. However, the measurement and quantification of environmental pollution is the most pragmatic first step for identifying various management and mitigation strategies to control environmental pollution. This chapter aims to study a range of proven measurement techniques for quantitatively determining the concentration of various environmental pollutants in the atmosphere. This is particularly important in the formulation of cost-effective control measures and strategies for environmental pollution. Furthermore, to elucidate the concept of pollution measurement, certain parameters which are considered of high importance for environmental monitoring and reflect the quality of a healthy (or unhealthy) environment, especially with respect to soil, water and air, are also discussed in the initial parts of the chapter.