Factors Influencing the Photocatalytic Degradation of Reactive Yellow 145 by TiO₂-Coated Non-Woven Fibers

The photocatalytic degradation of the synthetic textile dye Reactive Yellow 145 (RY 145) in aqueous solution, using TiO2 coated non-woven fibers as photocatalyst, under UV-lamp irradiation, was studied. The effects of the operational parameters such as initial dye concentration, pH, addition of oxidant hydrogen peroxide and addition of ethanol on the reaction rate were investigated. The effect of some inorganic ions such as and , commonly present in real effluents, on the photodegradation of RY 145 was also examined. The experimental results showed that the photocatalytic degradation rate was favoured by a high concentration of solution in respect to Langmuir-Hinshelwood model. The maximum rate of complete decolorization of RY 145 was observed in the acidic medium at pH 3. The presence of and anions led to an increase of the effectiveness of the photocatalytic degradation. However, the presence of and anions decreased differently the photodegradation reaction rate. TiO2/UV process was proved to be capable of the complete degradation of the RY 145.

Removal of Carbaryl Pesticide from Aqueous Solution by Adsorption on Local Clay in Agadir

This study was conducted to assess the removal efficiency of pesticide (Carbaryl) used in Souss Massa region (Agadir city), on a clay originated from barrage situated in Agadir. The adsorption of Carbaryl from aqueous solution by local clay as a low-cost, natural and eco-friendly adsorbent was investigated. Different physicochemical parameters were analyzed: adsorbent mass, ionic strength (NaNO3), initial concentration of pollutant, temperature, and pH. The empirical results showed that all these parameters have an impact on the retention of pesticide on the clay. The equilibrium uptake was increased with an increase in the initial pesticide concentration in solution. The results of adsorption were fitted to the Langmuir and Freundlich isotherms. The Freundlich model represented the adsorption process better than Langmuir model, with correlation coefficients (R2) values ranged from 0.97 to 0.99. This study has shown that the natural clay is a solid that has got an important adsorption capacity, which may be used in treatment and depollution of water.

Modeling Experimental Design for Photo-Fenton Degradation of Methomyl

Modeling experimental design was used to study the main effects and the interaction effects between operational parameters in the photocatalytic degradation of pesticide methomyl. The important parameters which affect the removal efficiency of methomyl such as concentration of Fe(NO3)3, concentration of H2O2, initial concentration of the pesticide and pH. The parameters were coded as x1, x2, x3 and x4, consecutively, and were investigated at two levels (–1 and +1). The effects of individual variables and their interaction effects for dependent variables, namely, photocatalytic degradation efficiency (%) were determined. From the statistical analysis, the most effective parameters in the photocatalytic degradation efficiency were initial concentrations of the methomyl and Fe(NO3)3. The interaction between initial concentration of the pesticide and Fe(NO3)3 was the most influencing interaction. The optimum conditions that were obtained for the photocatalytic degradation of methomyl were: minimum quantity of contaminant: 6 × 10–5 mol.L–1, maximum quantity of Fe(NO3)3: 5 × 10–4 mol.L-1, initial pH of the solution: 3 and maximum quantity H2O2: 10–2 mol.L–1.

Effective Removal of Nitrates Ions from Aqueous Solution Using New Clay as Potential Low-Cost Adsorbent

In the present study, we investigated the performance of clay mineral originated from a dam situated in Morocco (Agadir city), as natural, low-cost, alternative and eco-friendly adsorbent for removal of nitrates ions from aqueous solution within a batch process. The clay was characterized by X-ray diffraction, Scanning Electron Microscopy (SEM), Dispersive Energy of Spectroscopy (EDS), Fourier Transform Infrared (FTIR) and surface area analysis (BET). The effects of various experimental parameters are examined such as contact time, initial concentration of pollutant, adsorbent mass and solution pH. The removal of nitrate was 71.89% at natural pH (pH = 5.1) using 1 g/l of adsorbent in 500 ml of nitrate solution having initial concentration of 300 mg/l (effect of contact time). Adsorption kinetic study revealed that the adsorption process followed first order kinetic. Theoretical correlation of the experimental equilibrium adsorption data for the Nitrate-New Clay system was properly explained by the Langmuir isotherm model. The maximum adsorption capacity was Qm, exp = 244.06 mg/g at 20℃ and at natural pH (with Qm, cal = 250 mg/g). An increase in adsorbent dosage increased the percent removal of nitrate, R = 1 g/l was considered as optimum dose and was used for further study. The pH heavily affected the adsorption capacity, and the percentage removal was found to decrease with increase in pH. The obtained results indicated that this New Clay (NC) was very good adsorbent for NO3-, interesting alternative material with respect to more costly adsorbent used, and could be used as a highly efficient adsorbent for the separation of nitrate from drinking or waste water.