Simultaneous speciation of inorganic rhenium and molybdenum in the industrial wastewater by amino-functionalized nano-SiO2

• A nano-SiO2 modified by octylamine was developed.
• Octylamine modified nano-SiO2 was employed for simultaneous separation/preconcentration of ReO4− and MoO42– from aqueous solution.
• Several models were applied to obtain kinetics and equilibrium parameters.
• The recovery of Re(VII) and Mo(VI) from recontaining wastewater was possible.

A novel adsorbent was prepared by octylamine modified nano-SiO2 and was employed for simultaneous separation/preconcentration of ReO4− and MoO42– from aqueous solution. It was found that ReO4− could be adsorbed quantitatively (above 92%) on amino modified nano-SiO2 in the pH range of 1.0–3.0, while MoO42− almost was not adsorbed, while 94% of MoO42– could be quantitatively adsorbed at pH 6.0–8.0. A new method of separation/ preconcentration was developed for simultaneous speciation of inorganic rhenium and molybdenum in the industrial wastewater. These two ions adsorbed could be recovered quantitatively. Adsorption kinetics for ReO4−/MoO42– were shown to be very fast, and equilibrium was reached within 5 min/10 min following the pseudo-second-order model with observed rate constants (k2) of 6.455 g/(mg min)/12.472 g/(mg min) respectively at 298 K. The sorption data could be well interpreted by the Langmuir model with a maximum adsorption capacity of 4.93 mg/g ReO4−/16.85 mg/g MoO42– on modified nano-SiO2. Furthermore, modified nano-SiO2 was of high stability in eight times removal-regeneration recycles. In summary, modified nano-SiO2 is an excellent adsorbent which can be successfully applied to the separation of ReO4− and MoO42– from the samples with satisfactory results.

Modified nano-SiO2 shows high adsorption efficiency for ReO4− and MoO42− ions, and tuning the pH of the solution will allow exclusive, efficient extraction of either ReO4− or MoO42– from solutions.Figure optionsDownload as PowerPoint slide