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The growing volume of plastics derived from electronic waste (e-waste) underscores the imperative for environmentally sustainable strategies for the management of this waste. In light of the paramount importance of this issue, a pilot demonstrator for the decontamination of polymers containing Brominated Flame Retardants (BFRs) has been developed. The objective is to investigate the potential for decontaminating BFR-containing polymers from e-waste via UV-visible irradiation using a rotatory laboratory pilot operating under primary vacuum conditions. This report focuses on binary model blends composed of 90 weight% (wt%) poly(Acrylo-Butadiene-Styrene) (ABS) pellets and 10 wt% Deca-Bromo-Diphenyl Ether (DBDE), which is one of the most toxic BFRs. The efficiency of the irradiation process was evaluated as a function of pellet diameter and irradiation time using Fourier Transform InfraRed spectroscopy (FTIR) and High-Resolution Laser Desorption/Ionization Mass Spectroscopy (HR-LDI-MS). As a consequence, ABS + DBDE achieved a decontamination efficiency of 97% when irradiated with pellets of less than 1 mm in diameter for a period of 4 h. Additionally, the thermal behavior of the irradiated samples was investigated through thermogravimetric analysis and differential scanning calorimetry. It was thus established that the application of UV-visible irradiation had no significant impact on the overall thermal properties of ABS. [ABSTRACT FROM AUTHOR]

In this study, the preparation and characterisation of a new adsorbent prepared by hetero-coagulation of Algerian bentonite and double hydroxide are reported. The nanocomposite BNa/LDH is used as an adsorbent for the removal of copper ions. The XRD and FTIR analyse show that the BNa/LDH material is formed of LDH particles enveloped by layers of bentonite. Batch experiments were carried out to study the relationship between copper removal and various parameters such as pH solution, copper concentration, contact time and temperature. The maximum amount of copper adsorbed by the BNa/LDH hybrid material is recorded at pH 4 (67 mg/g). Adsorption equilibrium is reached after 30 minutes of contact for an initial copper concentration varying between 50 and 250 mg/L. The kinetic study indicates that the limiting step of copper adsorption by the BNa/LDH material is chemical. The intraparticle diffusion models and Elovich confirm this result. The adsorption of copper by the hybrid material in the presence of anions of different nature follows the sequence: SO42-> Ac−> Cl−. A comparison of the adsorption isotherms of nickel and iron with that of copper shows that the latter has an affinity for the hybrid material. The recycling of the adsorbents was carried out by calcining the adsorption products at 500°C and the results showed a progressive reduction of the adsorption capacity. In general, we could conclude that the adsorbents studied here could be successfully applied in the cleaning of the wastewaters. The characteristics of this new material encourage promising future use in wastewater treatment applications. [ABSTRACT FROM AUTHOR]

Water pollution caused by dyes poses a significant threat to life on earth. Poly(acrylamide-co-acrylic acid) hydrogels are widely used to treat wastewater from various pollutants. This study aims to examine the removal of malachite green (MG), a harmful and persistent dye that could cause extensive environmental damage, from an aqueous solution by adjusting the initial concentration of acrylamide (AM) and the degree of copolymer crosslinking. The copolymer hydrogels efficiently eliminate MG in a brief timeframe. The most successful hydrogel accomplished a removal rate exceeding 96%. The copolymer of 4 wt % 1,6-hexanediol diacrylate and a concentration of 100 mg/mL AM was effective. The degree of swelling was affected by crosslinking density as expected, with low crosslinking ratios resulting in significant swelling and high ratios resulting in less swelling. To evaluate the results, a docking approach was used which presented three crosslinked models: low, medium, and high. The copolymer–dye hydrogel system displayed robust hydrogen bonding interactions, as confirmed by the high quantities of both donors and acceptors. It was determined that MG contains six rotatable bonds, enabling it to adapt and interact with the copolymer chains. The dye and copolymer enhance H-bond formation by providing two hydrogen bond donors and 16 hydrogen bond acceptors, respectively. Through capitalizing on cationic and anionic effects, the ionic MG/copolymer hydrogel system improves retention efficiency by enhancing attraction between opposing charges. It is interesting to note that the synthesized copolymer is able to remove 96.4% of MG from aqueous media within one hour of contact time. [ABSTRACT FROM AUTHOR]

Due to their significant disposal problem during oil extraction and biofuel production, Eucalyptus camaldulensis leaves as an abundant forestry waste in the Mediterranean region, was investigated in this study as a precursor for the preparation of a low-cost adsorbents for the treatment of water laden with ascorbic acid (AA) as contaminant. A single step involving activation and carbonization in which the raw material was impregnated with chemical agent (KOH 20% and 40%) and then thermally decomposed at 600°C to produce K-Eucal-20 and K-Eucal-40 adsorbents, respectively. Prior to adsorption tests, Fourier-transform infrared analysis, pHzpc determination, scanning electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller surface area, iodine number and methylene blue index were performed for structural and surface characterization. Important parameters affecting AA uptake including equilibrium time, adsorbent dose, solution pH and temperature were also evaluated. Adsorption isotherms were better described by the Langmuir model than those of Freundlich and Temkin. The maximum adsorption capacities achieved for AA were 190.80 and 305.78 mg/g, by K-Eucal-20 and K-Eucal-40, respectively. Kinetics was found to obey the pseudo-second-order model. Thermodynamic analysis confirms the spontaneity and endothermicity of AA adsorption process. This study shows that activated Eucalyptus camaldulensis leaves can be successfully used as an alternative to the commercially available adsorbents for the removal of such pollutant from liquid media. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) were broadly applied worldwide as electrical insulators in transformers and power capacitors, due to their high dielectric constant and non-flammability. They were often added to mineral oils (MOs) and used as dielectric fluids, which are nowadays classified as hazardous waste. Indeed, the Stockholm Convention aims to eliminate the use of equipment with PCB content greater than 0.005 wt-% (=50 ppm) by 2025. Accurate identification and quantification of small traces of PCBs contained in MO thus represent a great analytical challenge. To achieve this goal, a simple, cost-effective and fast chromatographic process was developed to separate PCBs from MO, allowing to obtain reliable data to determine the concentration of PCBs, reduced to 2–3 ppm. Experimental and analytical methods, such as thin layer chromatography, column chromatography as well as gas chromatography coupled with mass spectroscopy, were applied to acquire a high level of qualitative and quantitative determination of PCBs in transformer MOs. [ABSTRACT FROM AUTHOR]

A clay-based TiO2 nanocomposite material was synthesized by a facile method, to investigate its structure and photocatalytic efficiency. The supported TiO2 nanoparticles were generated using a sol-gel method, and subsequently, mixed with a suspension of sepiolite. The material was recovered in powder form (Mc-80) and then calcined to properly arrange the crystal lattice of the TiO2 particles for use in heterogeneous photocatalysis (Mc-80-500). A powder X-ray diffractogram of Mc-80-500 revealed a dispersion of anatase and rutile phase TiO2 particles on the clay surface, exhibiting a size in the order of 4–8 nm. TEM images of Mc-80-500 confirmed the presence of isolated TiO2 beads on the surface of the fibrous sepiolite. The specific surface area of Mc-80-500 was larger than that of raw sepiolite and that of free TiO2 nanoparticles. Mc-80-500 was found to be more efficient in heterogeneous photocatalysis compared to other TiO2 materials based on sepiolite. Total depollution of a reactive dye (Orange G) was achieved after 1 h irradiation time, which is relatively quick compared to previous reports. The photocatalyst material can be washed with distilled water without chemical additives or calcination, and can be reused several times for photocatalysis, without loss of efficiency. [ABSTRACT FROM AUTHOR]

Amoxicillin (AMX) removal from aqueous media by MgAl-Layered double hydroxide (LDH) was investigated. LDH material with Mg2+/Al3+molar ratio of 2 was synthesised by co-precipitation at pH 9. The resulting material was characterised by thermogravimetry (TG), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction and scanning electron micrograph (SEM). The surface charge of LDH was measured using zeta potential technique. AMX adsorption tests were achieved at different pHs, temperatures, contact time and initial AMX concentrations. The adsorption process turned out to be spontaneous and endothermic. AMX was found to adsorb according to pseudo-second-order kinetics, while adsorption isotherms agree with Sips model, suggesting that the adsorption of AMX onto MgAl-LDH occurs predominantly by chemisorption mechanism, showing a maximum monolayer adsorption capacity of 30.42 mg/g at 30°C. Triplicate regeneration tests did not reduce the retention capacity. [ABSTRACT FROM AUTHOR]

In this work, a detailed study on the electrochemical degradation of an azo dye, Orange G is performed using a platinum electrode. Indeed, the influence of the dye concentration (50-150 mg/L), the pH of the medium and the density of the electric current is studied on the rate of discoloration, the rate of mineralization, the efficiency of the electric current and the energy consumption. The UV-visible spectra of OG plotted against the degradation time show the decrease of the intensity of the characteristic dye peaks. In an environment rich in chlorides, all peaks disappear after 15 min of degradation. However, the peaks at wavelengths of 200 and 290 nm appeared after one hour of treatment. In K2SO4, the eliminated percentages are respectively 46, 54 and 61% for wavelengths of 245, 330 and 480 nm. This suggests that the degradation mechanisms in K2SO4 and KCl environments are not the same. In the middle rich in chlorides, the eliminated percentage of OG did not seem to be affected by the concentrations increase. These results confirm the hypothesis that electrochemical oxidation process is very favorable for concentrated pollutants discharge. [ABSTRACT FROM AUTHOR]

ABSTRACT The dynamic swelling behavior of chemically crosslinked poly( n-butylacrylate/1,6-hexanedioldiacrylate) [poly(Abu-HDDA)] networks, immersed in an nematogenic and two isotropic solvents, was experimentally analyzed. These networks were elaborated by ultraviolet (UV)-visible light-induced radical polymerization/crosslinking reactions of Abu/HDDA mixtures, to yield poly(Abu/0.5 wt % HDDA) and poly(Abu/5 wt % HDDA) networks corresponding to weakly and strongly crosslinked systems, respectively. The swelling behavior of these poly(Abu-HDDA) networks was investigated by immersion in excess solvent, followed by subsequent measurements of the variation of the sample size by means of optical microscopy, depending on temperature and immersion time. Methanol and toluene were employed as isotropic solvents and the nematic liquid crystal molecule 4-cyano-4 ′- n-pentyl-biphenyl, was considered as anisotropic medium. Swelling ratios were calculated by taking into account diameter sizes as function of immersion time compared to the dry state. Experimental data were analyzed using the Komori-Sakamoto approach and the results of this model were found to be in good agreement with the obtained data. The plateau values of the swelling curves at equilibrium were used to establish phase diagrams as function of temperature and solvent concentration. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45452. [ABSTRACT FROM AUTHOR]