Nitrogen Elemental Composition Research Articles

Characterization of novel solar based nitrogen doped titanium dioxide photocatalytic membrane for wastewater treatment

The increasing presence of microbial and emerging organic contaminants pose detrimental effects on the environment and ecosystem such as diseases, pandemics and toxicity. Most of these synthetic pollutants are biorecalcitrant and therefore persist in the environment. Conventional water treatment methods are not effective thereby necessitating the development of advanced techniques such as photocatalysis and membrane processes. In this study, visible light-driven photocatalytic membrane was synthesized through the immobilization of nitrogen-doped nanoparticles onto the polyvinylidene fluoride (PVDF) membrane and performance evaluated with E.coli microbial contaminant removal. Characterization was done using Fourier transform infrared spectra, X-ray diffraction (XRD), water contact angle, Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX). The Nitrogen-doping of titanium dioxide red-shifted the light absorption to a visible range of 440 nm from 400 nm. Nitrogen dopant was detected at 1420 cm−1and 1170 cm−1 for nitrogen doped nanoparticles and 1346-1417 cm−1 for nitrogen doped titanium dioxide PVDF membrane. SEM-EDX confirmed presences of nitrogen in nitrogen doped titanium dioxide nanoparticles on membrane surface with nitrogen elemental composition of 0.01 % wt. The water contact angle reduced by 81.39o from 120.14o to 38.75o because of PVA immobilization of nitrogen-doped titanium dioxide and glutaraldehyde crosslinking. Nitrogen doping resulted in visible light active photocatalytic membranes with better hydrophilicity and fouling resistance. 8.42 E.coli log removal and a relative flux of 0.35 was obtained within 75 min. The developed photocatalytic membrane enables the use of sunlight hence a less costly method for decontamination of wastewater.

Mesoporous silica nanoparticles modified with N-rich polymer as a potentially environmentally-friendly delivery system for pesticides

The focus of the article is on the design of environmentally-friendly nanocarriers for improved controlled pesticide release, which have low environmental toxicity and nitrogen elemental composition as the most important components of fertilisers. In this study, a novel delivery system was developed for post-loading a biopesticide to mesoporous silica nanoparticles (MeSiNPs) functionalised with N-rich derived polymer. Initially, MeSiNPs were synthesised by the template-assisted method, which yielded MeSiNPs in the nm range, together with highly ordered mesoporous channels with a pore size of 2.9 nm. Subsequently, the water-soluble branched polyethyleneimine (bPEI) was derived systematically with epoxy organosilicate, and functionalised on MeSiNPs to create a source of N-nutrients. The carefully designed novel nano-carrier was analysed by several physicochemical and structural analyses, which confirmed the successful attachment of the derived bPEI to MeSiNPs. Further, the novel nano-synthesised system was used as a delivery for the model biopesticide citridiol. The loading efficiency of citridiol in/on MeSiNPs@bPEI was 19%, while the loading capacity of citridiol was proven to be 5 mg biopesticide/1 mg MeSiNPs@bPEI. The MeSiNPs@bPEI with loaded citridiol was investigated for kinetic release. The system showed a fast initial release behaviour in the first 300 min, which was continued by slow release behaviour and started to reach equilibrium after 10 days. It has been shown that the MeSiNPs@bPEI showed an excellent potential for use in agrochemical applications, not only as a nanocarrier for controlled and slow pesticide release, but may also act as a soil improver by providing Si and N as key nutrient sources. • Novel hybrid nanomaterial was developed by modifying MeSiNPs with N-rich polymer. • Derived bPEI was grafted systematically to MeSiNPs that provide N as a key nutrient. • MeSiNPs@bPEI was used for the first time as a mesoporous nanocarrier for biopesticide. • MeSiNPs@bPEI-citridiol showed burst release followed by sustained release behaviour. • An MeSiNPs@bPEI pesticide nanocarrier represents a sustainable and green approach.

Fabrication of hexagonal boron nitride quantum dots via a facile bottom-up technique

The smaller size of the Boron nitride quantum dots (BNQDs) leads to the quantization of energy due to the confinement of electrons and holes. As a result, it behaves like an artificial atom with higher quantum yield. Unlike, previously used complex and lengthy experimental procedures, a facile bottom-up technique based on nanoscale precursors and dual roles of ammonia gas has been developed to synthesize BNQDs in 25 min growth duration at 1200 °C. Shape and morphology of the synthesized BNQDs look like beads of different sizes. Fast Fourier transform (FFT) shows a hexagonal atomic structure of the synthesized BNQDs whereas XPS, Raman, and XRD confirms the Boron and Nitrogen elemental compositions and hexagonal phase of the synthesized sample. The as-synthesized BNQDs has excellent properties for a variety of potential applications in the fields of biomedical (for bioimaging and drug delivery), microelectromechanical systems (MEMS), catalysis, sensors, and solid-state neutron detectors.

Exploring the potential of human bone and teeth collagen from Prehistoric Cyprus for isotopic analysis

This pilot study attempts to document the potential of Prehistoric human bone and teeth collagen from Cyprus (9th-2nd mill. BC), for isotopic analysis and palaeodietary reconstruction. We sampled archaeological human skeletons and some faunal remains coming from six sites located in different locations, with different burial modes. The analysis of carbon and nitrogen elemental compositions and stable isotope ratios (δ13C, δ15N), indicate an extremely poor preservation of collagen, probably in relationship with burying conditions. Although very few individuals were successfully analysed, stable isotope data from this study allow a discussion on different protein food resources intake by humans in comparison with some other published data in the Near East (Greece, Cyprus, Turkey) from the Neolithic to the Bronze Age. These diachronic data provide documentations for future studies, including palaeodietary and environmental field research.

Decomposition-adsorption-deposition: An effective and novel technique for synthesis of hexagonal boron nitride microsheets

Magnesium diboride as a precursor with dual role of Nitrogen introduces a simple “decomposition-adsorption-deposition (DAD)” technique for the synthesis of Hexagonal Boron nitride microsheets (BNMSs) on silicon (Si) substrate at 1100 °C. The synthesized BNMSs has the apparent morphology like the white dispersed feathers on a plate surface with diameter in the range of 3–15 µm and lengt greater than 30 µm. All the BNMSs has the characteristics of h-BN lattice with an interlayer spacing of 0.34 nm. Boron and Nitrogen elemental compositions and h-BN phase of the synthesized BNMSs are verified from its characterization by X-ray photoelectron spectroscopy (XPS), Fourier transformed infrared (FTIR) spectroscopy and Raman.

Characterization of surface marine sediments from Ría de Arousa estuary according to extractable humic matter content

Surface marine sediments from Ría de Arousa estuary were analyzed for humic and fulvic acids by UV–visible spectrometry and have been characterized using elemental analysis (carbon, hydrogen and nitrogen elemental composition) and spectrometric data (A2/A4 ratio, absorbancies at 270 and 407 nm and E4/E6 ratio, absorbancies at 465 and 665 nm). These variables have been used as discriminating factors to distinguish of marine and terrestrial origin of humic and fulvic acids in Ría de Arousa surface marine sediments. Principal component analysis, PCA, and cluster analysis, CA, have been used as unsupervised pattern recognition procedures. The half-range central value transformation was used as data pre-treatment to homogenize data. After a Varimax rotation, PCA applied to humic acid data has reveled that spectrometric A2/A4 and E4/E6 ratios are the main dominating features in the first principal component (48.6% of total variance), the humic acid content is the feature with the highest weight in the second principal component (22.9% of the total variability) and the carbon elemental composition domain in the third principal component (13.3% of total variance). Results from PCA have revealed that surface sediments collected at inner-left part of the estuary and at the mouth of the river Ulla belong to the same group. Similarly, PCA has shown that surface sediments from the right mouth of the estuary form a compact group. Taking in account the water circulation in Ría de Arousa estuary, these findings mean that the organic matter in surface sediments from the inner-left part of the estuary derived mainly from terrestrial organic matter while the organic matter in surface sediments from the right mouth of the estuary is mainly derived from marine sources. Finally, it must be noticed that any classification of surface sediments was assessed when applying of PCA and CA from fulvic acids data.