Carboxylated nanodiamonds@CuAl2O4@TiO2 nanocomposite for the dispersive micro-solid phase extraction of nickel at trace levels from food samples

Heavy metal pollution poses a significant health risk, necessitating regular environmental monitoring for public safety. Elevated nickel concentrations can disrupt ecosystems and impact human health. This study presents a nano-sorbent can be used for dispersive micro-solid phase extraction of nickel. The nano-sorbent was characterized using FT-IR, XRD, FESEM, BET, and BJH. It demonstrated remarkable efficiency due to its nanoscale properties, optimizing results in exceptional extraction performance with minimal interference from common ions. A flame atomic absorption spectrometer was utilized for all measurements. It has a low LOD (0.29 μg L-1) and RSDs% (7.3 % and 6 % intra-day and inter-day, respectively), minimal variation, and a precisely accurate correlation (0.997). It can be used on black tea, green tea, carrots, coffee beans, tuna fish, herring fish, tobacco, soil, natural water, and wastewater samples. The accuracy of the method was assessed by analyzing TMDA-64.3 fortified water and NIST 1573a tomato leaves certified reference materials.

Advanced development of dairy farm waste-based biocarbon-reinforced unsymmetrical structured bio-phenolic polybenzoxazine composites

In the present work, an attempt has been made to develop cow manure carbon-reinforced hybrid biophenol-based benzoxazine composites for antifouling coating applications. Bio-based benzoxazine with unsymmetrical molecular structure was synthesized using the mixture of a combination of cardanol and eugenol with diaminodiphenyl methane and paraformaldehyde, and the hybrid-benzoxazine obtained was characterized using different analytical techniques, viz., Fourier transform infrared, nuclear magnetic resonance and MALDI mass. Bio-based benzoxazine was further reinforced with varying weight percentages (1, 3 and 5 wt%) of biocarbon derived from cow manure to obtain hybrid composite coatings. The hybrid benzoxazine matrix and composites were studied for their thermal behaviour, contact angle (CA), morphology, corrosion-resistant behaviour and antifouling character to utilize them as coatings materials for different industrial applications. Results obtained from different studies inferred that the biocarbon-reinforced composites possess an enhanced value of glass transition temperature (249°C), high char yield (38.4%), improved CA (105.6°), higher efficiency of corrosion protection against mild steel surface (98%) and improved antimicrobial activity.

Green Dispersive Micro Solid-Phase Extraction using Multiwalled Carbon Nanotubes for Preconcentration and Determination of Cadmium and Lead in Food, Water, and Tobacco Samples

Background:

Cadmium (Cd2+) and lead (Pb2+) have acute and chronic effects on humans and other living organisms. In the present work, new, green and accurate dispersive micro solid-phase extraction (DμSPE) method for the separation and preconcentration of trace amounts of cadmium (Cd2+) and lead (Pb2+) ions in various food, water and tobacco samples collected from Saudi Arabia prior to its Flame Atomic Absorption Spectrometric (FAAS) determinations was developed.

Methods:

The proposed method was based on a combination of oxidized multiwalled carbon nanotubes (O-MWCNTs) with a new chelating agent 5-benzyl-4-[4-methoxybenzylideneamino)-4H- 1,2,4-triazole-3-thiol (BMBATT) to enrich and separate trace levels of Cd2+ and Pb2+. The effect of separation parameters was investigated. The validation of the proposed preconcentration procedure was performed using certified reference materials.

Results:

Analyte recovery values ranged from 95-102%, indicating that the method is highly accurate. Furthermore, precision was demonstrated by the relative standard deviation (RSD < 3.0%). The limits of detection were 0.08 and 0.1 μg L−1 for Cd2+ and Pb2+ ions, respectively. The preconcentration factor was 200.

Conclusion:

The proposed method was used for the estimation of Cd2+ and Pb2+ ion content in various real samples, and satisfactory results were obtained. The proposed method has high adsorption capacity, rapid adsorption equilibrium, extremely low LODs, high preconcentration factors and shortens the time of sample preparation in comparison to classical SPE.

A tunable nanopore sensor for the detection of metal ions using translocation velocity and biphasic pulses

A tunable resistive pulse sensor, utilising a polyurethane nanopore, has been used to characterise nanoparticles as they traverse the pore opening. Herein we demonstrate that the translocation speed, conductive and resistive pulse magnitude, can be used to infer the surface charge of a nanoparticle, and act as a specific transduction signal for the binding of metal ions to ligands on the particle surface. Surfaces of silica nanoparticles were modified with a ligand to demonstrate the concept, and used to extract copper(ii) ions (Cu²⁺) from solution. By tuning the pH and ionic strength of the solution, a biphasic pulse, a conductive followed by a resistive pulse is recorded. Biphasic pulses are becoming a powerful means to characterise materials, and provide insight into the translocation mechanism, and herein we present their first use to detect the presence of metal ions in solution. We demonstrate how combinations of translocation speed and/or biphasic pulse behaviour are used to detect Cu²⁺ with quantitative responses across a range of pH and ionic strengths. Using a generic ligand this assay allows a clear signal for Cu²⁺ as low as 1 ppm with a short 5-minute incubation time, and is capable of measuring 10 ppm Cu²⁺ in the presence of 5 other ions. The method has potential for monitoring heavy metals in biological and environmental samples.

Modified surface-active ionic liquid-coated magnetic graphene oxide as a new magnetic solid phase extraction sorbent for preconcentration of trace nickel

General procedure for preconcentration/recovery of nickel ions using modified surface-active ionic liquid-coated magnetic graphene oxide nanocomposite.