A composite of clay, cement, and wood as natural support material for the immobilization of commercial titania (P25, P90, PC500, C-TiO2) towards photocatalytic phenol degradation.

Different types of commercial titania (P25, P90, PC500, and C-TiO2) were immobilized as single or mixed photocatalyst onto the surface of a natural support material made of cement, clay, and wood fibers. The successful immobilization was studied by different techniques showing a composite material with the mechanical properties of the support material and the photocatalytic behavior of the immobilized titania. The supported photocatalyst showed high mechanical stability and was applied to the photocatalytic degradation of phenol as a model pollutant under UV light irradiation. As the most active photocatalytic material, a mixture PC500 and P90 (comp-PC500/P90) was identified with an apparent pseudo first-order kinetic rate constant (kapp) of 0.010 min-1 at a degradation efficiency of 100%. The catalyst was used several times and showed minor loss in activity during four runs due to degradation intermediates adsorbed to the surface, shown by a color change from white to yellow.

Biosorptive uptake of methylene blue using Mediterranean green alga Enteromorpha spp.

Batch biosorption experiments were carried out for the removal of methylene blue, a basic dye, from aqueous solution using raw and dried Enteromorpha spp., Mediterranean green alga. A series of assays were undertaken to assess the effect of the system variables, i.e. contact time, solution pH and sorbent amount. The results had showed that sorption capacity was optimal using 6-10 solution pH range (i.e. maximum adsorption capacity of 274 mg/g). The minimum sorbent concentration experimentally found to be sufficient to reach the total removal of the dye molecules from the aqueous solution was 5 g/L. Besides, equilibrium data were fitted using five linearisable isotherm models. The related results showed that the experimental data were very well represented by the Langmuir model for the linear regression analysis and both the Langmuir and Redlich-Peterson isotherm models for the non-linear analysis. In both cases, such modelling behaviour confirms the monolayer coverage of methylene blue molecules onto energetically homogenous Enteromopha surface. In addition, an exhaustive comparative study was done to situate this marine biomass among other proposed sorbents.

Preparation and characterisation of raw chars and physically activated carbons derived from marine Posidonia oceanica (L.) fibres.

Industrial valorisation of low cost and renewable biomass as raw precursor of activated carbon for environmental applications is an interesting alternative to costly commercial activated carbons. In this study, the possible use of Mediterranean, Posidonia oceanica fibrous biomass, as a precursor for chars and physically activated carbons, is investigated. Firstly, the raw marine material was chemically and biochemically characterised throughout dry-basis elemental, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis. Then, several P. oceanica chars were prepared and characterised under different pyrolysis times and temperatures. In addition, physically activated carbons (PACs) were produced via water steam flow under various activation periods. The results showed that the pyrolysis induces the creation of pores at different levels with respect to the involved temperature. Thereafter, the physical activation tends to enhance the development of the porous structure. In that issue, the performed Brunauer-Emmett-Teller (BET) and Barrett-Joiner-Halenda (BJH) analysis revealed that the prepared PACs have a mainly mesoporous inner morphology with a varying fraction of micropores.