Zohra Bouberka

Adsorption of Two Dyes by Mg(OH)2: Procion Blue HB and Remazol Brilliant Blue R

The use of low-cost and ecofriendly adsorbents has been investigated as an ideal alternative to the current expensive methods of removing dyes from wastewater. Mg(OH)2 sludge was produced from precipitation of magnesium ions (Mg2+) with NaOH in pH = 10 and investigated as a low-cost adsorbent. This paper deals with the removal of textile dyes from aqueous solutions by Mg(OH)2. Reactive Procion blue HB (PR) and Acid Remazol brilliant blue R (RB) were used as model compounds. The adsorption capacity was found as 43.47 and 26.89 mg/g at initial pH 6.5.

Optical properties of electron beam- and UV-cured polypropyleneglycoldiacrylate/liquid crystal E7 systems

This contribution focuses on a detailed investigation of the relationship between the method of polymerisation/cross-linking, such as slow and rapid UV radiation, and high voltage accelerated electron beam (EB), and the obtained physical properties including phase diagrams, polymerisation and phase separation kinetics, morphologies and electro-optic responses of polypropyleneglycoldiacrylate (PPGDA) monomers, in the presence of the nematic liquid crystal E7. The longer the spacing between double bonds, the more rapid was the photopolymerisation under both UV systems; however, the reverse was proved under EB. More homogenous and regular morphologies were obtained under EB curing. The electro-optical responses of various polymer dispersed liquid crystals (PDLCs) systems exhibited remarkable differences between the UV-cured samples and those cured by the EB technique. It was found that the threshold and saturation voltages considerably increased in the case of the UV-cured systems. Other results involving the contrast ratio, which is higher for EB-cured systems, confirm their higher quality, although the rapid photopolymerisation UV source was employed, which slightly improved the electro-optical responses. Moreover, EB curing leads to high enough conversions without a photoinitiator, which may act as an impurity that might have a strong impact on the electro-optical performance of the obtained PDLCs.

Photochemical Degradation of Polybrominated Diphenylether BDE209 Under Ultraviolet Irradiation

The photodegradation of decabromodiphenylether (BDE209) in Tetrahydrofuran was investigated under UV light, employing a xenon source with 150 W. The degradation reactions obey a first-order rate law. The photolytic chemical reduction of BDE209 in THF under UV irradiation can rapidly degrade BDE209 to form lower bromine substituted diphenylethers. The reductive debromination mechanism of the photolytic degradation of BDE209 can facilitate the design of remediation processes and help to predict their fate in the environment.

Deactivation of Polybrominated Flame Retardants by Ultraviolet Radiation

The European directive RoHS (Restriction of the use of certain Hazardous Substances) limits the use of specific toxic substances for example a number of flame retardants. In the light of this context, this work handles with the implementation of a methodology of deactivation by radiative exposure of Tetrabromobisphenol A bis-(2,3-dibromopropylether) (TBBPA-DBPE), concerned by the RoHS directive. It has been shown that the photodegradation by UV-visible irradiation of TBBPA-DBPE in Tetrahydrofuran as organic environment generates less brominated thus less toxic congeners. Physico-chemical analyses were realized by means of a spectroscopic technique that allows to characterize products before and after irradiation under UV-visible light.

Adsorption Study of Reactive Blue 2 Dye on CTAB-Bentonite in Aqueous Solution

Cetyltrimethylammoniumbromide-bentonite (CTAB-bentonite) was synthesized by placing alkylammonium onto B-Na+, and investigated for adsorption of reactive Blue 2 dye from aqueous solution. The adsorption capacity of reactive blue 2 onto organo-bentonite was found to increase with the dye concentration. The evaluated activation energy was found as 8.02 kJ/mol. Equilibrium adsorption isotherms were satisfactorily described by Langmuir model.