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A B S T R A C TMulti-walled carbon nanotubes (MWCNTs) are a highly effective adsorbent of methylene blue (MB), and they can be used to remove MB from aqueous solutions. In this study, we used MWCNTs that were synthesized by chemical vapor deposition method. The physicochemical properties of MWCNTs were characterized by Brunauer-Emmett-Teller (BET) surface area, surface functional group analysis by fourier transform infrared (FTIR) analysis, zero point charge (pH zpc ), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The factors that affected the adsorption properties of MB onto MWCNTs were investigated, including initial pH, contact time, dosage, initial concentration, and temperature. The equilibrium adsorption data were analyzed using two common adsorption models, i.e. the Langmuir and Freundlich models. The results indicated that the Langmuir isotherm fits the experimental results well. The maximum adsorption capacity obtained from the equation of the Langmuir isotherm at 323 K was 95.30 mg/g, indicating that the MWCNTs adsorbed MB effectively. The kinetic study illustrated that the adsorption of MB onto MWCNTs fits the pseudo-second-order kinetic model. The thermodynamic parameters indicated that the adsorption of MB onto MWCNTs was a spontaneous, endothermic process.

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Response surface methodology (RSM) was used to optimize the medium components of˛-amylase production using solid substrate fermentation (SSF). Hazelnut cake (HC), peptone, yeast extract (YE), and (NH 4 ) 2 SO 4 were selected as independent variables for optimization. Central composite design (CCD) was used in design experiments and analysis results. This procedure limited the number of actual experiments performed while allowing possible interactions between the independent variables. By using CCD, 30 experiments were performed for determining the interaction of independent variables and optimization of fermentation medium. The P-value of the coefficient of linear effect of (NH 4 ) 2 SO 4 concentrations, which was obtained as 0.0001 has shown that this parameter has the greatest effect on the production of˛-amylase. Model F-value (5.62) implies that the model is significant. The highest˛-amylase activity (4895 IU) was measured when the HC, peptone, YE, and (NH 4 ) 2 SO 4 concentrations in the medium were 22.62, 5.20, 1.62, and 6.81 g L −1 , respectively.On a eu recoursà la méthodologie de surface de réponse (RSM) dans le but d'optimiser les composants du milieu lors de la production d'amylase-ą l'aide de la fermentationà substrat solide (SSF). Le gâteau de noix (HC), le peptone, l'extrait de levure (YE) et le (NH4) 2 SO 4 ontété sélectionnés comme variables indépendantes pour l'optimisation. On a utilisé une méthode de conception composite centrée (CCD) dans les expériences de conception et les résultats d'analyse. Cette procédure limite le nombre d'expériences effectivement réalisées tout en permettant des interactions entre les variables indépendantes. Trente expériences de CCD ontété menées pour déterminer l'interaction des variables indépendantes et l'optimisation du milieu de fermentation. Les valeurs P du coefficient pour l'effet linéaire des concentrations de (NH 4 ) 2 SO 4 , qui s'avèrentêtre de 0,0001, montrent que ce paramètre a le plus grand effet sur la production d'amylase-˛. La valeur F du modèle (5,62) démontre l'importance du modèle. Cette plus grande activité (4895 IU) aété mesurée lorsque les concentrations de HC, de peptone, de YE et de (NH 4 ) 2 S0 4 dans le milieu sont de 22,62, 5,20, 1,62 et 6,81 (gL −1 ), respectivement.

The photocatalytic performance of TiO2 and ZnO was comparatively studied for photocatalytic degradation of reactive black 5 (RB5) under artificial UVC irradiation. The effect of initial solution pH, catalyst concentration, initial RB5 concentration, purging oxygen rate, stirring rate, and process temperature on the degradation process by TiO2 and ZnO was investigated. In addition, total organic carbon (TOC) analysis has been employed for each parameter to detect the presence of organic intermediates and the photodegradation performance of catalysts simultaneously with the photocatalytic degradation process. The RB5 photodegradation was more rapid in the aqueous medium by TiO2 under UVC irradiation compared to the catalysis by ZnO. On the other hand, the slower photocatalysis by ZnO resulted in generating more organic intermediates. The structural and morphological analyses of photocatalysts TiO2 and ZnO were performed using XRD and FE‐SEM techniques. The UV‐vis spectroscopy measurements supported that the TiO2 demonstrated evidently better photocatalytic activity than ZnO for RB5 degradation.