Organic and heavy metal pollutants in dredged sediment of Oran Harbor, Algeria.

Harbors on all coasts regularly silt up, receiving sedimentary inputs that progressively reduce the water depths available for navigation. Consequently, they are routinely dredged to guarantee the depths necessary for navigation. Sediments act as a reservoir for anthropogenic contaminants such as heavy metals and persistent organic pollutants (POPs) that enter the aquatic system associated with particles or in solution. The objective of this study is to assess the state of pollution by POPs and heavy metals such as copper and zinc, used in large quantities in antifouling paints, in the sediments of the port of Oran. These were characterized by different methods: size, XRD, calcination, FTIR, NMR, GC-MS, and AAS, in order to determine their main characteristics and heavy metals and POPs content. The particle size is determined by laser particle size distribution. Thus, sediments from Oran port are composed of means and end sands, silt, and clay. The XRD analysis shows that the sediments consist mainly of silicates and calcite. The organic matter was determined by ignition loss at 450 and 550 °C; it is about 7%. Analysis by FTIR, 1H and 13C NMR, and GC-MS of POPs excerpts shows that the sediments are highly polluted by aliphatic and aromatic hydrocarbons (3372 mg/kg). Finally, metals were determined by AAS method. The results show significant pollution of Zn (313.5 mg/kg) and moderate pollution by Cu (75.6 mg/kg).

Green Copolymers and Nanocomposites from Myrcene and Limonene Using Algerian Nano-Clay as Nano-Reinforcing Filler.

In this work, we report a new facile method for the preparation of myrcene-limonene copolymers and nanocomposites using a Lewis acid as a catalyst (AlCl3) and organo-modified clay as a nano-reinforcing filler. The copolymer (myr-co-lim) was prepared by cationic copolymerization using AlCl3 as a catalyst. The structure of the obtained copolymer is studied and confirmed by Fourier Transform Infrared spectroscopy, Nuclear Magnetic Resonance spectroscopy, and Differential Scanning Calorimetry. By improving the dispersion of the matrix polymer in sheets of the organoclay, Maghnite-CTA+ (Mag-CTA+), an Algerian natural organophilic clay, was used to preparenanocomposites of linear copolymer (myr-co-lim). In order to identify and assess their structural, morphological, and thermal properties, the effect of the organoclay, used in varyingamounts (1, 4, 7, and 10% by weight), and the preparation process were investigated. The Mag-CTA+ is an organophylic montmorillonite silicate clay prepared through a direct exchange process in which they were used as green nano-reinforcing filler. The X-ray diffraction of the resulting nanocomposites revealed a considerable alteration in the interlayer spacing of Mag-CTA+. As a result, interlayer expansion and myr-co-lim exfoliation between layers of Mag-CTA+ were observed. Thermogravimetric analysis provided information on the synthesized nanocomposites' thermal properties. Fourier transform infrared spectroscopy and scanning electronic microscopy, respectively, were used to determine the structure and morphology of the produced nanocomposites (myr-co-lim/Mag). The intercalation of myr-co-lim in the Mag-CTA+ sheets has been supported by the results, and the optimum amount of organoclay needed to create a nanocomposite with high thermal stability is 10% by weight. Finally, a new method for the preparation of copolymer and nanocomposites from myrcene and limonene in a short reaction time was developed.

Synthesis and Characterization of Copolymers and Nanocomposites from Limonene, Styrene and Organomodified-Clay Using Ultrasonic Assisted Method.

In the present work, we report a simple synthesis method for preparation of copolymers and nanocomposites from limonene and styrene using clay as a catalyst. The copolymerization reaction is carried out by using a proton exchanged clay as a catalyst called Mag-H+. The effect of temperature, reaction time and amount of catalyst were studied, and the obtained copolymer structure (lim-co-sty) is characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1H-NMR) and differential scanning calorimetry (DSC). The molecular weight of the obtained copolymer is determined by gel permeation chromatography (GPC) and is about 4500 g·mol-1. The (lim-co-sty/Mag 1%, 3%, 7% and 10% by weight of clay) nanocomposites were prepared through polymer/clay mixture in solution method using ultrasonic irradiation, in the presence of Mag-CTA+ as green nano-reinforcing filler. The Mag-CTA+ is organophilic silicate clay prepared through a direct exchange process, using cetyltrimethylammonuim bromide (CTAB). The prepared lim-co-sty/Mag nanocomposites have been extensively characterized by FT-IR spectroscopy, X-ray diffraction (XRD), scanning electronic microscopy (SEM) and transmission electronic microscopy (TEM). TEM analysis confirms the results obtained by XRD and clearly show that the obtained nanocomposites are partially exfoliated for the lower amount of clay (1% and 3% wt) and intercalated for higher amounts of clay (7% and 10% wt). Moreover, thermogravimetric analysis (TGA) indicated an enhancement of thermal stability of nanocomposites compared with the pure copolymer.

Tough Hydrogels Based on Maleic Anhydride, Bulk Properties Study and Microfiber Formation by Electrospinning.

Hydrogels present a great number of advantages, such as their swelling capacity or their capability to mimic tissues, which make them very interesting biomaterials. However, one of their main disadvantages is their lack of good mechanical properties, which could limit some of their applications. Several strategies have been carried out to develop hydrogels with enhanced mechanical properties, but many of the suggested synthetic pathways to improve this property are expensive and time consuming. In this work, we studied an easy synthetic path to produce tough hydrogels based on different maleic anhydride copolymers crosslinked with polyethylenglycol. The effect of the comonomers in the mechanical properties has been studied, their excellent mechanical properties, good swelling behavior and thermal stability being remarkable. In addition, in order to evaluate their possible applications as scaffolds or in wound healing applications, microsized fibers have been fabricated by electrospinning.

Polycarbazole and Its Derivatives: Synthesis and Applications. A Review of the Last 10 Years.

Polycarbazole and its derivatives have been extensively used for the last three decades, although the interest in these materials briefly decreased. However, the increasing demand for conductive polymers for several applications such as light emitting diodes (OLEDs), capacitators or memory devices, among others, has renewed the interest in carbazole-based materials. In this review, the synthetic routes used for the development of carbazole-based polymers have been summarized, reviewing the main synthetic methodologies, namely chemical and electrochemical polymerization. In addition, the applications reported in the last decade for carbazole derivatives are analysed. The emergence of flexible and wearable electronic devices as a part of the internet of the things could be an important driving force to renew the interest on carbazole-based materials, being conductive polymers capable to respond adequately to requirement of these devices.

Green Nanocomposites from Rosin-Limonene Copolymer and Algerian Clay.

Green nanocomposites from rosin-limonene (Ros-Lim) copolymers based on Algerian organophilic-clay named Maghnite-CTA+ (Mag-CTA+) were prepared by in-situ polymerization using different amounts (1, 5 and 10% by weight) of Mag-CTA+ and azobisisobutyronitrile as a catalyst. The Mag-CTA+ is an organophilic montmorillonite silicate clay prepared through a direct exchange process; the clay was modified by ultrasonic-assisted method using cetyltrimethylammonuim bromide in which it used as green nano-filler.The preparation method of nanocomposites was studied in order to determine and improve structural, morphological, mechanical and thermal properties ofsin.The structure and morphology of the obtained nanocomposites(Ros-Lim/Mag-CTA+) were determined using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electronic microscopy and transmission electronic microscopy. The analyses confirmed the chemical modification of clay layers and the intercalation of rosin-limonene copolymer within the organophilic-clay sheets. An exfoliated structure was obtained for the lower amount of clay (1% wt of Mag-CTA+), while intercalated structures were detected for high amounts of clay (5 and 10% wt of Mag-CTA+). The thermal properties of the nanocomposites were studied by thermogravimetric analysis (TGA) and show a significant improvement inthe thermal stability of the obtained nanocomposites compared to the purerosin-limonene copolymer (a degradation temperature up to 280 °C).

Structural, morphological and thermal properties of nanocomposites poly(GMA)/clay prepared by ultrasound and in-situ polymerization.

This work focuses on the preparation and characterization of nanocomposites poly(glycidylmethacrylate)/organoclay. Effect of the organoclays nature and the preparation method were investigated in order to evaluate their structural, morphological and thermal properties. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nitrogen sorption at 77 K, scanning and transmission electronic microscopy (SEM, TEM) and thermogravimetric analysis (TGA) were employed to determine the features of the obtained materials. In the first step, the Algerian clay was modified by ultrasonic-assisted method using different concentrations of CTAB or TBAHS in which were used as green nano-filler. A series of nanocomposites were prepared by two different methods. The first deals the in-situ polymerization of GMA within the organoclay galleries and the second pathway involves the use of solution blending of poly(GMA) assisted by ultrasound. The obtained results confirm the intercalation of surfactants within the clay layers, while the nanocomposites obtained by the both methods showed different morphologies and structures in which the exfoliated and intercalated forms were obtained. Both nanocomposites displayed significant enhancement in the thermal stabilities compared to the unmodified poly(GMA). The best results in terms of reaction time, clay dispersion and nanocomposite yield were obtained by the ultrasound method.