Thiosemicarbazide and thiocarbohydrazide functionalized chitosan as ecofriendly corrosion inhibitors for carbon steel in hydrochloric acid solution.

Organically functionalized chitosan macromolecules namely Chitosan-Thiosemicarbazide (CS-TS) and Chitosan-Thiocarbohydrazide (CS-TCH) were synthesized and evaluated as new corrosion inhibitors for mild steel corrosion in 1M HCl. The FTIR and 1H NMR studies confirmed the formation of the derivatives. The corrosion tests were performed using weight loss method, electrochemical measurements, surface morphology (AFM), quantum chemical investigation and molecular dynamics simulation methods. The maximum efficiency of 92% was obtained at a concentration as low as 200mgL-1. The inhibitors were found to obey Langmuir adsorption isotherm and exhibited both physical and chemical adsorption. Electrochemical impedance spectroscopy (EIS) results showed an increase in polarization resistance which supported the adsorption of inhibitors on the mild steel surface. Tafel data showed a mixed type behavior with cathodic predominance. The data of quantum chemical calculations and molecular dynamics simulation supported the experimental findings.

Preparation and characterization of biodegradable nanocomposites derived from carboxymethyl cellulose and hydroxyapatite.

Development of a cost-effective technology for extraction and quantification of carcinogenic and toxic organic materials which are widely used in the industry are critical to humans. Membrane technology received much attention and has already been widely used in this area. In this work, we offer a newly developed bio-based nanocomposite membrane for removal of bisphenol-A (BPA) from water. Three natural components hydroxyapatite (HAp), carboxymethyl cellulose and lysine as a diluent were used for making the bio-based membrane. The membrane was fabricated by two different methods, the conventional casting method and the double decomposition method. Analysis and testing results showed that, membrane produced by the casting method is rough, stiff and partially soluble in water. However, the film made by the double decomposition method is smooth, flexible, and has low water solubility. The physicochemical characteristics of the prepared membranes were determined by Fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric analysis (TGA/DTA). The morphology and components interface were observed by X-ray wide angle (WAXD), scanning electron microscopy (SEM) and electron microscopy (SEM/FEG). The spectral and crystallographic data showed the presence of an effective interaction between hydroxyapatite and CMC plasticized with lysine. Results also show that, the particles size of the composite decrease as the content of CMC increases, with an increase of a 2% by weight of CMC the size increases by 18±3nm. Produced membrane composite could be classified as tri-functional material: it could be useful for extracting toxic material bisphenol A (BPA) from baby food containers; has antimicrobial and antifungal properties; and a valuable candidate for use in bone tissue engineering.

Pesticide residue levels in green beans cultivated in Souss Masa valley (Morocco) after multiple applications of bifenthrin and λ-cyhalothrin.

Dissipation of bifenthrin and λ-cyhalothrin pyrethroid insecticides, under environmental conditions, was evaluated on green beans grown in experimental greenhouses (Souss Massa valley, Morocco). Pesticide residues were determined by gas chromatography with micro electron-capture detector (GC-µECD) after dichloromethane extraction and cleanup on florisil phase cartridges. In the case of field experiments, a random block scheme was employed. Each block contained 25 plants in a single row and tests were carried out in triplicates applying pesticides at the recommended doses by the manufacturers. Fruit samples were periodically taken until the end of the preharvest interval (p.i.). The results obtained showed that the p.i of bifenthrin in green bean were 4 days in the winter and 3.5 days in the spring, whereas that for λ-cyhalothrin 8 days was found in the winter and 7.5 days in the spring. Consequently, it is possible to consider the European Union maximum residue limit (EU MRL) values compatible with the proper agricultural practices used for growing green bean in the plastic greenhouse of Souss Massa valley in South Morocco. Bifenthrin had a degradation of first-order kinetics, whereas that of levels for λ-cyhalothrin residue can not be interpreted by the use of a first order model.

Pesticide residues in tomatoes from greenhouses in Souss Massa Valley, Morocco.

Eight pesticide residues in tomato samples collected in the area of Souss Massa Valley (Southern Morocco) were analyzed. The detected residue levels ranged from 0.001 to 0.400 mg kg(-1) for dicofol, from 0.003 to 0.170 mg kg(-1) for procymidone, from 0.001 to 0.250 mg kg(-1) for chlorothalonil, from 0.050 to 0.500 mg kg(-1) for bifenthrin, from 0.001 to 0.010 mg kg(-1) for λ-cyhalothrin, from 0.001 to 0.300 mg kg(-1) for cypermethrin, from 0.010 to 1 mg kg(-1) for deltamethrin and from 0.003 to 1.123 mg kg(-1) for endosulfan. European MRL for endosulfan in tomatoes set in 0.500 mg kg(-1), was exceeded in 8 samples, and MRL for deltamethrin set in 0.300 mg kg(-1) for tomatoes was exceeded in 2 samples.

Nanoparticle-based assay for the detection of virgin argan oil adulteration and its rapid quality evaluation.

A new method, based on the formation of gold nanoparticles (AuNPs) and spectrophotometric analysis, is proposed to determine total phenolic acids in virgin argan oil samples. These compounds have reducibility due to the presence of the phenol group in their molecular structure, and a redox reaction occurs in the presence of HAuCl(4). The formation of AuNPs as a result of the redox reaction leading to colour changes can be visually observed, resulting in strong light signals that show absorption at 555 nm. As ferulic acid represents more than 95% of the total phenolic acid content of virgin argan oil, this compound was used as an adulteration marker to carry out the screening of samples for the evaluation of the authenticity of virgin argan oils. The analytical features of this screening method also allowed a low precision quantization of the quality of the product. Then, a reference HPLC-DAD/FD method was used to confirm the potential adulterated samples, as well as to provide a detailed quantitative analysis of the most representative phenolic compounds in the samples. The overall screening-confirmation strategy was validated by analysing pure virgin argan oil samples and argan oil samples adulterated with other commercial vegetable oils, demonstrating the reliability of the results. This approach is characterised by its simplicity, low cost, rapid information and responded to practical laboratories needs.

Supercritical fluid extraction as an on-line clean-up technique for rapid amperometric screening and alternative liquid chromatography for confirmation of paraquat and diquat in olive oil samples.

A rapid and simple method for the direct screening of paraquat (PQ) and diquat (DQ) in olive oil samples is proposed. The sample screening method involves supercritical fluid extraction (SFE) (clean-up followed by the extraction of the analytes) followed by continuous flow electrochemical detection. Those samples for which the total concentration is close to or above the threshold limit established by the Columbian Society for Social Protection (0.05 microg g(-1)) are subsequently analyzed by liquid chromatography (LC) with diode array detection (DAD). This confirmation method allows the determination of PQ and DQ in the range between 0.04 and 1.0 microg g(-1), with average relative standard deviations lower than 3.5%, and 0.003 and 0.002 microg g(-1) detection limits for PQ and DQ, respectively. The proposed arrangement opens up interesting prospects for the direct determination of polar pesticides in complex samples with a good throughput and a high level of automation.