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In the present work, we study the ability of materials based on hydroxyapatite to be developed as a sensing materials toward relative humidity. Natural (NHAp) and synthetic (SHAp) hydroxyapatites are used as sensitive layers on interdigitated copper electrodes. The morphological structure and composition of HAp are characterized by X-ray diffraction analysis (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy EDS. The capacitive and impedance responses of the humidity sensors are analyzed at frequencies ranging from 0.1 kHz to 1 MHz at different humidity values varying from 16 to 87%. Other properties and characteristics of moisture detection are studied for both sensors such as sensitivity, hysteresis, response and recovery times and conduction mechanisms. The results showed that the best performance of all our manufactured sensors is obtained for the NHAp sensor. This sensitivity is around 17900pF/%RH, whereas the response and recovery times are approximately 8 s and 11 s, respectively, the hysteresis value was very low. The obtained results proved that the natural hydroxyapatite is a good candidate and suitable for moisture sensing application.

The biosorption of methylene blue (MB) from aqueous solution by leaf residues of Thymus numidicus (RTN), Origanum glandulosum (ROG) and Sapindus mukorossi pericarp fibre (SMPF) was investigated in batch experiments. The effects of contact time, initial MB concentration, pH and biomass dosage on the biosorption capacity were investigated. Moreover, kinetic and equilibrium models were used to fit the experimental data. Equilibrium data were analysed using the Freundlich and Langmuir isotherms. Results show that the adsorption capacity increases until equilibrium is reached after 10 min of contact time. Furthermore, the amount of MB adsorbed per gram of biosorbent increases with pH in the pH range 2–5 but tends to decrease with pH in the pH range 7–10. Under optimal conditions, equilibrium sorption data are accurately represented by a pseudo-second-order kinetic model. The results show that the Langmuir model best describes the adsorption of methylene blue on the three biosorbents. At neutral pH and ambient temperature, the maximum adsorption capacities reached are 24.2, 33.3 and 41 mg of MB per gram of biosorbent, respectively, for SMPF, ROG and RTN. Thermodynamic studies showed that adsorption was spontaneous and endothermic with residues of ROG and SMPF but exothermic with RTN. Our results clearly reveal that RTN, ROG and SMPF act as effective adsorbents for the removal of methylene blue from aqueous solutions.

Permeable reactive barrier (PRB) containing zero valent iron (ZVI), plaster and additives to make a porous composite structure was tested to remove an organic nitro compound as model pollutant. An aqueous solution of 4-nitroaniline (PNA) was passed through a porous plaster composite column and chemical degradation quantified by UV-Vis spectroscopy. PNA was reduced to p-phenylenediamine and the rate of the reduction was strongly related to ZVI amount, pollutant volume, and the contact rate with metal particles. The parameters could be controlled by reactor design and operation. The columns were made to test the materials for making precast plaster blocks containing ZVI. The results showed that such porous plaster blocks could be efficient as retaining walls for environmental applications.

The present study has been carried on Numidian thyme (Thymus numidicus), a medicinal plant belonging to the Lamiaceae family. Numidian thyme is an Algero-Tunisian endemic species. The essential oil was extracted from the leaves of the plant harvested in wild habitat at Tifrit (Tizi Ouzou, Algeria), by steam hydrodistillation with 1.58% yield. Analysis by GC–MS (Gas chromatography-mass spectrometry) of the essential oil helped to identify more than 70 compounds and to classify it as a thymol chemotype. The major components of the oil were: thymol (40.40%) and carvacrol (13.37%). Antibacterial and antifungal activities of Thymus numidicus essential oil was studied in vitro on three bacterial (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa) and one fungal strains (Candida albicans). The results showed that this essential oil has a wide spectrum of antimicrobial activity on Gram-negative and Gram-positive bacteria and possesses strong antifungal activity on Candida. This activity is probably due mainly to the predominant presence of thymol, and it is more important on fungi than bacteria. Results of this study look promising for the valuation of medicinal plants with the aim of promoting the Algerian pharmaceutical industry.

Hydroxyapatite (HAP) is considered to be a stable mineral under surface Earth conditions and adopted as a proxy for paleo-environmental reconstructions and in choice of remediation strategies. A clear description of the solubility properties for HAP is fundamental and can be gained by understanding the basic principals governing the solid-solution interface. In this study we investigated the early stage of HAP dissolution at 25°, 50° and 70 °C using solubility and ATR-FTIR spectroscopy measurements. We found a non-stoichiometric release of calcium and total phosphorus in solution in the experimental close to neutral pH conditions. The ATR-FTIR measurements revealed the presence of new peaks corresponding to the vibrations of HPO42 − group. Comparing HAP spectra of the pristine surface to those obtained after 7 days of hydration we propose the presence of monetite (CaHPO4). This rapidly formed new phase would affect the observed low solubility of HAP and its presence could validate the use of this mineral in paleo-environmental reconstructions and ecological remediation strategies.

The sorption of divalent copper and nickel ions from aqueous solutions on natural and synthetic hydroxyapatites was investigated in batch mode at 25 and 40°C and over metal concentration range of 20–800 mg/L. Effect of initial pH solution was also investigated for two values pH 4.5 and pH 6. The sorption equilibrium data were well fitted by Langmuir’s model. Both hydroxyapatites are efficient to remove copper and nickel ions, despite their different compositions and morphologies. The sorption mechanism involved an ion exchange between calcium ions of hydroxyapatite and metal ions along with pronounced precipitation, particularly in case of the synthetic hydroxyapatite. Higher sorption efficiencies were observed with the synthetic hydroxyapatite towards copper ions, similar values for both synthetic and natural hydroxyapatites were found towards Ni ion’s sorption and lower values at pH 6.

A survey of the fungal contamination and occurrence of aflatoxins and ochratoxin A (OTA) in 50 pistachio nut samples collected from commercial stores around Catalonia (Spain) was carried out. Aspergillus flavus was found in 30% of samples, whereas Aspergillus section Nigri, Aspergillus ochraceus, and Penicillium verrucosum were found in 40%, 2% and 26% of samples, respectively. A total of 204 fungal isolates were obtained; 70.8% of A. flavus isolates were able to produce aflatoxin B1 and B2, whereas OTA production capacity was detected in 54.4% of the A. section Nigri biseriate isolates. Aflatoxins were detected in five samples (10% of total), all exceeding the maximum legal limit set for aflatoxin B1 (2 µg kg(-1)) or for total aflatoxins (4 µg kg(-1)), with one sample having a very high level of contamination (1134.5 µg kg(-1)). Only one sample of pistachio showed OTA contamination at 0.67 µg kg(-1). Simultaneous contamination by aflatoxins and OTA was not observed in these samples. It was concluded that the frequency of aflatoxins and OTA contamination in pistachio samples available in the Spanish market is relatively low. Thus, no significant contribution to health risk should be expected from aflatoxin consumption through pistachios among healthy consumers. However, the existence of single samples with an extremely high aflatoxin concentration reinforces the need for effective prevention strategies in pistachio processing and commercialization.

The sorption of divalent cadmium and copper ions from aqueous solutions on natural and synthetic hydroxyapatite was investigated by the batch method and under dynamic conditions in columns at 22 °C and pH 5. The effect of cadmium and copper concentration on sorption was studied. Both types of apatites are efficient, despite their different composition and morphology. The sorption mechanism involves an ion exchange for Cd(II), while Cu(II) leads to precipitation of a newly formed solid. Thus, the sorption efficiency depends on the experimental conditions and the specific physicochemical properties of the apatites used. The sorption isotherms were fitted to the Langmuir equation.

Des méthodes relativement récentes, comme l’échange d’ions et l’extraction liquide-liquide, ont été largement utilisées pour séparer des métaux à l’état de traces. Pour ceux qui présentent notamment des propriétés analogues, la complexation par des agents chélatants s’avère nécessaire. Du fait de leur grande stabilité thermique et de la diversité des groupements fonctionnels des produits commerciaux disponibles, les résines ont été d’une grande utilité en analyse et dans l’industrie. Cette étude a trait à la rétention de métaux comme le cadmium et le zinc sur les résines acides Amberlite IRC-50, Dowex-50 X8 et Permutit C‑67. Les études en flacon ont mis en évidence une grande affinité de ces éléments pour les résines utilisées, et que l’équilibre est atteint rapidement (30 à 60 min). Les ions Zn2+ et Cd2+ n’utilisaient au maximum que 88 à 91 % de capacité totale des résines étudiées. Le traitement des résultats pour les faibles concentrations a montré que les isothermes sont du type Langmuir comme ceux obtenus par ailleurs sur des échangeurs minéraux.

Synthetic and natural calcium phosphates were tested for removal metallic pollution in aqueous solution. Calcium phosphates with Ca/P ratio between 1,33 and 1,67 are fluently called apatite. They have a strong capacity to immobilize metallic ions when they are brought into contact with aqueous solutions. Ca2+ ions can substituted completely or partly by cations such as metallic ions (Ni2+; Cu2+; Co2+ and Cd2+). PO43− ions can be replaced by anions such as AsO43−, CO32−, … etc. Sorption of Cu2+ and Ni2+ from aqueous solutions on natural (NA) and synthetic (SA) apatite was investigated in batch mode at 25 ∘C and 40 ∘C and over metal concentration range of 20–800 mg/L. Other experiments of co-precipitation metal-apatite (metal-TCP) were investigated in static mode at 25 ∘C. The results characterization of NA and SA apatite by FTIR, SEM, and ICP confirm their composition and apatitic structure. The results confirm efficiency of these calcium phosphates to decontaminate, by adsorption or co-precipitation, metallic ions such as Ni2+ or Cu2+ present in aqueous solution at concentrations between 20–800 mg/L.

Mycotoxin contamination of pistachios represents a serious food safety hazard. The aim of this study was to evaluate fungal contamination and aflatoxin (AF) and ochratoxin A (OTA) occurrence in pistachio sampled in Algeria and to study the mycotoxigenic capacities of the isolates. A total of 31 pistachio samples were collected from retail outlets from different regions of Algeria. The most frequently found fungi were Penicillium spp. (38%), Aspergillus section Nigri (30%) and A. flavus (22%). A total of 56.5% of A. flavus isolates were able to produce AFB1 and AFB2. No A. section Nigri uniseriate isolate was OTA producer, whereas OTA production capacity was detected in 33.3% of the A. section Nigri biseriate. At least one of the potentially ochratoxigenic species was found in 64.5% of samples. Despite the high number of pistachio samples containing AFs and OTA-producing isolates, only two samples contained AFs (always below the EU maximum tolerable level) and only one sample showed OTA contamination. This is the first report on the occurrence of toxigenic moulds and mycotoxins in pistachios from Algerian market. The authors are grateful to the EC (Project KBBE 2007- 222738), Spanish (Project AGL2007-66416-C05-03) and Catalonian (XaRTA—Reference Network on Food Technology) Governments for their financial support. F. Fernane is grateful to the Agencia Española de Cooperación Internacional para el Desarrollo (MAEC-AECID) for their financial support.