Elaboration and characterization of photobiocomposite beads, based on titanium (IV) oxide and sodium alginate biopolymer, for basic blue 41 adsorption/photocatalytic degradation.

This study provides the preparation and profound characterization of an eco-friendly photobiocomposite beads named, titanium (IV) oxide/calcium alginate (TiO2/CaAlg), and the examination of their effectiveness for Basic Blue 41 (BB 41) adsorption/ photocatalytic degradation using sunlight like a renewable energy source. Chemical and physical characteristics of pure TiO2, pure CaAlg and TiO2/CaAlg beads were investigated using; X-ray diffraction (XRD), UV-visible diffuse reflectance spectra (UV-Vis DRS), scanning electron microscopy (SEM), attenuated total reflection spectroscopy (ATR), X-Ray photoelectron spectrometer (XPS), thermogravimetry (TGA) derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC) analysis. Kinetic and isotherm models were evaluated using the non-linear model fitting analysis method. Effect of experimental parameters such as solution initial pH, BB 41 initial concentration, photobiocomposite dose on the BB 41 adsorption/photocatalytic degradation was investigated. Recycling capacity of TiO2/CaAlg photobiocomposite beads was tested. Results show that TiO2/CaAlg photobiocomposite is promising material for the BB 41 adsorption/photocatalytic degradation.

Kinetic and equilibrium study for the sorption of cadmium(II) ions from aqueous phase by eucalyptus bark.

The efficiency of eucalyptus bark as a low cost sorbent for removing cadmium ions from aqueous solution has been investigated in batch mode. The equilibrium data could be well described by the Langmuir isotherm but a worse fit was obtained by the Freundlich model. The five linearized forms of the Langmuir equation as well as the non-linear curve fitting analysis method were discussed. Results show that the non-linear method may be a better way to obtain the Langmuir parameters. Maximum cadmium uptake obtained at a temperature of 20 degrees C was 14.53mgg(-1). The influence of temperature on the sorption isotherms of cadmium has been also studied. The monolayer sorption capacity increased from 14.53 to 16.47 when the temperature was raised from 20 to 50 degrees C. The DeltaG degrees values were negative, which indicates that the sorption was spontaneous in nature. The effect of experimental parameters such as contact time, cadmium initial concentration, sorbent dose, temperature, solution initial pH, agitation speed, and ionic strength on the sorption kinetics of cadmium was investigated. Pseudo-second-order model was evaluated using the six linear forms as well as the non-linear curve fitting analysis method. Modeling of kinetic results shows that sorption process is best described by the pseudo-second-order model using the non-linear method. The pseudo-second-order model parameters were function of the initial concentration, the sorbent dose, the solution pH, the agitation speed, the temperature, and the ionic strength.

Batch sorption dynamics and equilibrium for the removal of cadmium ions from aqueous phase using wheat bran.

Studies on a batch sorption process using wheat bran as a low cost sorbent was investigated to remove cadmium ions from aqueous solution. The influence of operational conditions such as contact time, cadmium initial concentration, sorbent mass, temperature, solution initial pH, agitation speed and ionic strength on the sorption kinetics of cadmium was studied. Pseudo-second-order model was evaluated using the six linear forms as well as the non-linear curve fitting analysis method. Modeling of kinetic results shows that sorption process is best described by the pseudo-second-order model using the non-linear method. The sorption of cadmium was found to be dependent on initial concentration, sorbent mass, solution pH, agitation speed, temperature, ionic strength and contact time. The value of activation energy (12.38 kJ mol(-1)) indicates that sorption has a low potential barrier corresponding to a physical process. Sorption equilibrium isotherms at different temperatures was determined and correlated with common isotherm equations such as Langmuir and Freundlich models. It was found that the Langmuir model appears to well fit the isotherm data but a worse correlation was obtained by the Freundlich model. The five Langmuir linear equations as well as the non-linear curve fitting analysis method were discussed. Results show that the non-linear method may be a better way to obtain the Langmuir parameters. Thermodynamic parameters such as DeltaH degrees, DeltaS degrees and DeltaG degrees were calculated. These parameters indicate that the sorption of cadmium by wheat bran is a spontaneous process and physical in nature involving weak forces of attraction and is also endothermic.

Optimization of a novel biocomposite synthesis (Ammi Visnaga extraction waste/alginate) for Cd(2+) biosorption.

A novel environmentally friendly biocomposite namely calcium alginate immobilized Ammi Visnaga (Khella) extraction waste was prepared by electrostatic extrusion method. A full factorial design 2(3) was used to optimize the beads preparation conditions. The effect of sodium alginate concentration (X1), biomass concentration (X2) and cross-linker concentration (X3) on the Cd(2+) removal efficiency was examined in a batch system with a fixed biocomposite dose of 1g/L. Using the experimental results, a linear mathematical model representing the influence of different variables and their interactions was obtained. The optimized values of X1, X2 and X3 were found to be 4.35%, 2.5% and 1.99% respectively. The biocomposite beads were characterized by ATR spectroscopy, scanning electron microscopy for the surface morphology and optical microscopic for the particles size measurements.

Ultrasonication-assisted sorption of cadmium from aqueous phase by wheat bran.

In the present study, the sorption of cadmium from aqueous phase by wheat bran was investigated with and without the assistance of ultrasound. Kinetic data and sorption equilibrium isotherms were carried out in batch conditions. The influence of different operating parameters such as ultrasonic power, cadmium initial concentration, sorbent mass, temperature, and the combination of ultrasound and mechanical stirring on the kinetics of cadmium removal was studied. The obtained results show that the ultrasonic irradiation significantly enhances and improves the efficiency of the removal of cadmium, especially in the combined method. The sorption kinetic data were found to be well-represented by the pseudo-second-order rate equation, both in the absence and presence of ultrasound as well as in the combined process (stirring and ultrasonication). Ultrasonic power played a key role in the removal of cadmium. Equilibrium isotherm results could be well described by the Langmuir model both with and without the assistance of ultrasound. The effect of temperature on the sorption isotherms of cadmium in the absence and presence of ultrasound has been also studied and the thermodynamic parameters DeltaG degrees, DeltaH degrees, and DeltaS degrees were determined. The monolayer sorption capacities were 51.81, 35.09, and 22.78 mg g(-1) for experiments conducted by the combined process, in the presence of ultrasound, and in passive conditions, respectively. The combination ultrasound-stirring for the sorption process was shown to be of interest for the treatment of wastewaters contaminated with cadmium.