A combined bioprocess for integrated removal of copper and organic pollutant from copper-containing municipal wastewater

Experimental design for the optimization of copper biosorption from aqueous solution by Aspergillus terreus

An experimental design methodology was applied to study the effects of temperature, pH, biomass dose, and stirring speed on copper removal from aqueous solutions by Aspergillus terreus in a biosorption batch system. To identify the effects of the main factors and their interactions on copper removal efficiency and to optimize the process, a full 2(4) factorial design with central points was performed. Four factors were studied at two levels, including stirring speed (50-150 min(-1)), temperature (30-50°C), pH (4-6) and biosorbent dose (0.01-0.175 g). The main factors observed were pH and biomass dose, along with the interactions between pH and biomass, and stirring speed. The optimal operational conditions were obtained using a response surface methodology. The adequacy of the proposed model at 99% confidence level was confirmed by its high adjusted linear coefficient of determination (R(Adj)(2)=0.9452). The best conditions for copper biosorption in the present study were: pH 6, biosorbent dose of 0.175 g, stirring speed of 50 min(-1) and temperature of 50°C. Under these conditions, the maximum predicted copper removal efficiency was 68.52% (adsorption capacity of 15.24 mg/g). The difference between the experimental and predicted copper removal efficiency at the optimal conditions was 4.8%, which implies that the model represented very well the experimental data.

Immobilization of 2,2'-dipyridyl onto bentonite and its adsorption behavior of copper(II) ions

In this study, the immobilization of 2,2'-dipyridyl onto bentonite was firstly carried out and it was then used for the adsorption of copper(II) ions from aqueous solutions. The variation of the parameters of pH, contact time, initial copper(II) concentration and temperature were investigated in the adsorption experiments. The XRD, FTIR, elemental and thermal analyses were performed to observe the immobilization of 2,2'-dipyridyl onto natural bentonite. The adsorption data obtained were well described by the Langmuir adsorption isotherm model at all studied temperatures. The results indicated that the maximum adsorption capacity was 54.07 mg g(-1) from the Langmuir isotherm model at 50 degrees C. The thermodynamic parameters indicated that the adsorption process is spontaneous, endothermic and chemical in nature. The kinetic parameters of the adsorption were calculated from the experimental data. According to these parameters, the best-fit was obtained by the pseudo-second-order kinetic model. The results showed that 2,2'-dipyridyl-immobilized bentonite can be used as the effective adsorbent for the removal of heavy metal contaminants.