Abdelkrim Bouzaza

PHOTOCATALYTIC DEGRADATION OF TOLUENE IN THE GAS PHASE: COMPARATIVE STUDY OF SOME TIO2 SUPPORTS

The Langmuir–Hinshelwood (L–H) kinetic model has been used to describe the degradation of the toluene on three TiO2-based photocatalysts supports. The determination of the L–H rate constant (k) showed that the UV illumination parameter seems to be more important than the quantity of TiO2 per unit area. The constant k is the greatest for the less density TiO2 photocatalyst. The comparison between the Langmuir adsorption constant (K) in the dark and under UV irradiation shows that the adsorption constant for the high kinetic catalyst increases while it decreases for the other two.

Photo-oxidation process of indole in aqueous solution with ZnO Catalyst: Study and optimization

The photo-oxidation of indole has been investigated using the catalytically active ZnO in aqueous solution, under various physical and chemical conditions. First of all, a structural analysis with X ray diffraction (XRD) shows that ZnO powder crystallizes in wurtzite with a main grain size estimated to be about 270 nm. An increase in catalyst loading greatly enhances the process efficiency until a certain. limit. Indole photodegradation improves with increasing air flow. The effect of the pH on the photo-oxidation efficiency was carried out from 3.88 to 11.16. The activity exhibits its maximal value around the natural pH (6.68). Photocatalytic degradation showed that the activity of ZnO improved with increasing light intensity. This was ascribed to the fact that there was a more efficient generation of electron-hole pairs used in the degradation process.

Kinetic study of spiramycin removal from aqueous solution using heterogeneous photocatalysis

Spiramycin macrolide antibiotic (SPM) can be photocatalytically degraded on TiO2 (anatase variety). The experiments are done in a batch reactor and the effect of some key parameters is investigated under low energy of artificial UV light. The reaction rate is affected by varying TiO2 dose, pH and SPM concentration. Under optimized conditions, a photodegradation efficiency of 98% is achieved and the SPM photodegradation follows pseudo-first order kinetics. The Langmuir–Hinshelwood (L–H) model is successfully used to fit the experimental data, indicating the dependence of the reaction rate on the chemical reaction step. The L–H model led to the determination of both reaction kinetic and adsorption/desorption equilibrium constants. In order to give an overall estimate of the by-products, chemical oxygen demand, total organic carbon, and calculated average oxidation state monitor the photodegradation process.

Macrolide antibiotics removal using a circulating TiO2-coated paper photoreactor: parametric study and hydrodynamic flow characterization.

The present work investigates the photocatalytic degradation efficiency of biorecalcitrant macrolide antibiotics in a circulating tubular photoreactor. As target pollutants, spiramycin (SPM) and tylosin (TYL) were considered in this study. The photoreactor leads to the use of an immobilized titanium dioxide on non-woven paper under artificial UV-lamp irradiation. Maximum removal efficiency was achieved at the optimum conditions of natural pH, low pollutant concentration and a 0.35 L min(-1) flow rate. A Langmuir-Hinshelwood model was used to fit experimental results and the model constants were determined. Moreover, the total organic carbon analysis reveals that SPM and TYL mineralization is not complete. In addition, the study of the residence time distribution allowed us to investigate the flow regime of the reactor. Electrical energy consumption for photocatalytic degradation of macrolides using circulating TiO2-coated paper photoreactor was lower compared with some reported photoreactors used for the elimination of pharmaceutic compounds. A repetitive reuse of the immobilized catalyst was also studied in order to check its photoactivity performance.

Pilot scale degradation of mono and multi volatile organic compounds by surface discharge plasma/TiO 2 reactor: Investigation of competition and synergism

This paper mainly deals with the isovaleraldehyde degradation with the help of a nonthermal plasma surface discharge (NPSD) coupled with photocatalysis. The efficiency of NPSD reactor, for gas treatment, was studied for different binary mixtures: (1) mixture of aldehydes (Isovaleraldehyde and Butyraldehyde) and (2) mixture of aldehyde and amine (Isovaleraldehyde and Trimethylamine). A planar continuous reactor is used to investigate the effect of addition of another pollutant on the performance of oxidation process. A synergetic effect was observed by combining NPSD and photocatalysis for the degradation of mixture of pollutants. In addition, combined NPSD/photocatalysis has significantly enhanced the CO2 selectivity, as compared to NPSD alone. This is attributed to the formation of more reactive species due to the presence of TiO2 in the plasma discharge zone. Moreover, ozone and UV light on TiO2, produced by plasma, have activated the surface leading to enhanced mineralization. In addition, the byproducts of each binary mixture were identified and evaluated.

Interactions between Cd, Cu, Pb, and Zn and four different mine soils

The chemical associations of Cd, Cu, Pb, and Zn in four mine soil samples from the Amizour-Bejaia Pb/Zn mine (Algeria) have been investigated by a five-step sequential extraction procedure. Although Cd preferentially binds to carbonates, Cu, Pb, and Zn are mainly associated with the organic and reducible fractions. Batch adsorption experiments with either mono- or multi-metallic solutions are described with the Freundlich isotherm model. Whatever the nature of the soil sample, the sorption behavior for each given metal except Pb is very similar, indicating that the binding sites at the soil surface are progressively occupied by the metal from the solution. On each soil sample, the decreasing order of sorption can be established as Pb >> Cu > Cd > Zn. When the four metals are simultaneously applied to each soil sample, their specific behavior is strongly affected by their interactions and/or competition for the available surface sites: we generally observed isotherm curves with a slight maximum before the plateau at higher solution concentration. Although Cu is only slightly affected by the other metals, in the case of Pb, Cd, and Zn, the sorbed amounts strongly decreased.

Photocatalytic treatment of petroleum industry wastewater using recirculating annular reactor: comparison of experimental and modeling

In this study, the treatment of petroleum wastewater has been investigated by applying heterogeneous photocatalytic process using a recirculating annual reactor. An attempt has been made to study the effect of operating parameters such as TiO2 load, initial concentration of the pollutant, emitted photonic flux, and pH of the solution. The degradation efficiency of toluene and benzene, as target molecules, was studied. In fact, result showed that the toluene is better degraded alone than when it is in a mixture. The rate of elimination of toluene separately was 89.5%, while it was 76.19 and 79.55% in the binary (toluene/benzene) and the ternary mixtures (toluene/benzene/xylene), respectively. Moreover, the mineralization of the solution decreased more rapidly when toluene was pure with a rate of 83.13% compared to binary and ternary mixtures. A mathematical model is proposed taking into account the parameters influencing the process performances. The mass transfer step, the degradation, and the mineralization kinetics of the pollutants were defined as model parameters. To build the model, mass balances are written in bulk region and catalyst phase (solid phase). The degradation mechanism on solid phase is divided in two stages. Firstly, the removal of toluene gives an equivalent intermediate (EI). Secondly, EI is oxidized into carbon dioxide (CO2). This approach gives a good agreement between modeling and empirical data in terms of degradation and mineralization. It also allows for the simulation of toluene kinetics without knowing the plausible chemical pathway. A satisfactory fit with experimental data was obtained for the degradation and mineralization of toluene.

Removal of lead(II) from water using activated carbon developed from jujube stones, a low-cost sorbent

ABSTRACT The preparation of activated carbon from jujube stones with H2SO4 activation and its ability to remove lead from aqueous solutions were reported in this study. The surface structure of the activated carbon was characterized by various physico-chemical methods. Sorption studies were carried out by varying the initial metal ion and the pH: the amount of sorbed Pb(II) ions increased with increasing pH and initial Pb(II) ions concentration. The removal of lead ions was rapid and the kinetic of sorption can be well described by pseudo-second order modelling. The Langmuir model conveniently fits the data of isotherm experiments and the monolayer sorption capacity of Pb(II) ions was determined as 71.43 mg/g at pH 6.0 and 25°C. These results showed that activated carbon prepared from jujube stones could be considered for application as a potential sorbent for the removal of lead from wastewaters.