Multi-walled carbon nanotubes modified with iron oxide and silver nanoparticles (MWCNT-Fe3O4/Ag) as a novel adsorbent for determining PAEs in carbonated soft drinks using magnetic SPE-GC/MS method

Green preparation of activated carbon from pomegranate peel coated with zero-valent iron nanoparticles (nZVI) and isotherm and kinetic studies of amoxicillin removal in water

In present research, the activated carbon was prepared by a green approach from pomegranate peel coated with zero-valent iron nanoparticles (AC-nZVI) and developed as adsorbent for the removal of amoxicillin from aqueous solution. The physicochemical properties of the AC-nZVI were investigated using XRD, FTIR, and FESEM techniques. The optimal values of the parameters for the best efficiency (97.9%) were amoxicillin concentration of 10 mg/L, adsorbent dose of 1.5 g/L, time of 30 min, and pH of 5, respectively. The adsorption equilibrium and kinetic data were fitted with the Langmuir monolayer isotherm model (qmax 40.282 mg/g, R² 0. 0.999) and pseudo-first order kinetics (R² 0.961). The reusability of the adsorbent also revealed that the adsorption efficiency decreased from 83.54 to 50.79% after five consecutive repetitions. Overall, taking into account the excellent efficiency, availability, environmental friendliness, and good regeneration, AC-nZVI can be introduced as a promising absorbent for amoxicillin from aquatic environments.

Recent Applications of Magnetic Nanoparticles in Food Analysis

Nanotechnology has become a topic of interest due to the outstanding advantages that the use of nanomaterials offers in many fields. Among them, magnetic nanoparticles (m-NPs) have been one of the most widely applied in recent years. In addition to the unique features of nanomaterials in general, which exclusively appear at nanoscale, these present magnetic or paramagnetic properties that result of great interest in many applications. In particular, in the area of food analysis, the use of these nanomaterials has undergone a considerable increase since they can be easily separated from the matrix in sorbent-based extractions, providing a considerable simplification of the procedures. This allows reducing cost and giving fast responses, which is essential in the food trade to guarantee consumer safety. These materials can also be easily tunable, providing higher selectivity. Moreover, their particular electrical, thermal and optical characteristics allow enhancing sensor signals, increasing the sensitivity of the approaches based on this type of device. The aim of this review article is to summarise the most remarkable applications of m-NPs in food analysis in the last five years (2016–2020) showing a general view of the use of such materials in the field.

The concentration of polycyclic aromatic hydrocarbons (PAHs) in the processed meat samples collected from Iran's market: a probabilistic health risk assessment study

The concentration of PAHs among raw and cooked meat products (sausages and burgers), randomly collected from five regions of Tehran, Iran, was investigated by the aid of a gas chromatography-mass spectrometry (GC-MS), and the risk assessment was conducted. The concentration of 16 types of PAHs in sausage and burger samples was found in the range of 8.08 to 29.55 and 10.18 to 29.85 μg/kg, respectively. The concentrations of some PAHs such as anthracene (A) (14.12 μg/kg) and acenaphthylene (Acl) (13.4 μg/kg) were higher than the European Standard (2 μg/kg). Among the meat products with different meat percentages (50, 70, and 90), the highest level of total PAHs was noted in the product containing 90% meat (19.34 μg/kg), while the highest mean level of PAHs was noted in fried meat products (23.31 μg/kg). A positive and significant correlation between cooking method and brand of product with the concentration of PAHs (p-value < 0.05) was noted. Also, no concern regarding the non-carcinogenic risk due to the ingestion of PAHs via consumption of the meat products was demonstrated by the health risk. However, the carcinogenic risk due to the consumption of sausage and burger was at the tolerable (1E-6 to 1E-4) and considerable (> 1E-4) risk levels, respectively. In this regard, further assessments to control and modify the cooking method among the Iranian population were recommended.

Properties Analysis and Preparation of Biochar–Graphene Composites Under a One-Step Dip Coating Method in Water Treatment

In order to improve the adsorption efficiency of biochar in water treatment, biochar–graphene (BG) composites were prepared by the one-step dip coating method and applied to remove phthalates from water. Firstly, the materials and equipment needed for the experiment are introduced. The steps of preparing graphene oxide (GO) by the improved Hummers method and BG composites by one-step dip coating are discussed. Then, the morphology characterization, adsorption performance measurement, and isothermal model of BG composites are introduced. Finally, the structure characterization, adsorption kinetics, and adsorption isotherms of BG composites are analyzed. The results show that the properties of biochar could be changed by one-step dip coating, and the biochar could form composites with graphene. Compared with biochar, biochar–graphene composites have greater surface area and porosity. When the pyrolysis temperature was 600 °C, the specific surface area of biochar was 8.4 m2g−1, and the specific surface area of the biochar–graphene composite was 221.3 m2g−1. When the temperature was 300 °C, the specific surface area of biochar was 11.01 m2g−1, and the specific surface area of biochar–graphene composite was 251.82 m2g−1. The formation of graphene on the surface of biochar can increase the stability of the composite and acts as a very high potential active site. The porous structure and surface properties of biochar–graphene composites regulate the adsorption rate of pollutant molecules, thereby improving the adsorption performance. When the adsorption equilibrium was reached, the adsorption effect of phthalate esters on the biochar/graphene composite at the pyrolysis temperature of 600 °C was the best, and the adsorption capacity of Dimethyl phthalate (DMP)was 35.2 mg/g, that of Diethyl phthalate (DEP) was 26.4 mg/g, and that of Dibutyl phthalate (DBP) was 25.1 mg/g. The adsorption effect of DMP was the best. The results of the isotherm study indicate that the adsorption of phthalates by BG composites has great potential, which provides a good theoretical basis for the application of BG composites in environmental protection in China.

Production and characterisation of activated carbon and carbon nanotubes from potato peel waste and their application in heavy metal removal

Herein, activated carbon (AC) and carbon nanotubes (CNTs) were synthesised from potato peel waste (PPW). Different ACs were synthesised via two activation steps: firstly, with phosphoric acid (designated PP) and then using potassium hydroxide (designated PK). The AC produced after the two activation steps showed a surface area as high as 833 m2 g-1 with a pore volume of 0.44 cm3 g-1, where the raw material of PPW showed a surface area < 4 m2 g-1. This can help aid and facilitate the concept of the circular economy by effectively up-cycling and valorising waste lignocellulosic biomass such as potato peel waste to high surface area AC and subsequently, multi-walled carbon nanotubes (MWCNTs). Consequently, MWCNTs were prepared from the produced AC by mixing it with the nitrogen-based material melamine and iron precursor, iron (III) oxalate hexahydrate. This produced hydrophilic multi-wall carbon nanotubes (MWCNTs) with a water contact angle of θ = 14.97 °. Both AC and CNT materials were used in heavy metal removal (HMR) where the maximum lead absorption was observed for sample PK with a 84% removal capacity after the first hour of testing. This result signifies that the synthesis of these up-cycled materials can have applications in areas such as wastewater treatment or other conventional AC/CNT end uses with a rapid cycle time in a two-fold approach to improve the eco-friendly synthesis of such value-added products and the circular economy from a significant waste stream, i.e., PPW. Graphical abstract .

Direct growth of oriented nanocrystals of gamma-iron on graphene oxide substrates. Detailed analysis of the factors affecting unexpected formation of the gamma-iron phase

Substrate-oriented nanocrystals of room-temperature-stable gamma-iron have been synthesized by a two-step impregnation/annealing method on a graphene oxide surface.