2.3. Bimetallic Chitosan PreparationChitosan modified by Cu/Mg particles was prepared by using a modified water-based approach [16]. The preparation selleck screening library was performed in a 250mL flask attached to a vacuum line. In particular, a given amount of chitosan particles was immersed in double distilled water and was then purged with purified N2 for 45min in order to remove the dissolved oxygen. In a typical preparation, first, a stock solution of 0.21M MgCl2?6H2O was prepared right before use and then added to the chitosan solution to yield the desired concentration of Mg2+ and chitosan. The mixture was purged with N2 in an ultrasonic bath for 1h to ensure the complete formation of the Mg2+-chitosan complex. Second, the Mg2+ ions were reduced to Mg0 by adding a certain amount of sodium borohydride (BH4?/Mg2+ = 2.

0) dropwise to the above Mg2+-chitosan solution under inert conditions through continuous vacuuming.Then, the bimetallic chitosan particles were synthesized by mixing a solution of secondary metal (copper) with Mg0-chitosan particles. The copper metal stock solution was prepared by dissolving CuCl2 in double distilled water. The bimetallic chitosan was prepared using copper bulk loadings of 1wt.% by diluting the appropriate amount of the copper stock solution to 100mL with double distilled water and then adding this solution to 10g of fresh Mg0-chitosan particles according to the following redox reaction (1):Chitosan?Mg0+Cu2+��Mg2++Chitosan?Cu0/Mg0.(1)The samples were then shaken for 5min, after which they were allowed to stand for 5min at 25��C to enable the reduction of Cu2+ to Cu0.

The resultant mixture was filtered by vacuum filtration through 0.2��m cellulose acetate filter paper. To get rid of the excess chemicals, the particles were washed with an excess amount of deoxygenated double distilled water and rinsed with ethanol and acetone before being dried at 50��C under vacuum overnight. Finally, the modified chitosan was stored under vacuum conditions for further use.2.4. Experimental DesignAzo removal experiments with the prepared BCP were carried out as a batch test in a 100mL flask while agitating on a shaker-incubator instrument (Pars Azma Co., Iran). The solution pH (3�C10), BCP dosage (0.25�C1.5mg/L), pollutant concentration (50�C200mg/L), and contact time (1�C60min) were the selected variables in this step of the work.

Each test consisted of preparing 50mL of the azo Cilengitide solution with a desired initial concentration; the initial pH of the solution was adjusted by adding 0.1N HCl and NaOH solutions. The shaking rate for all samples was 100rpm. Aliquots were carefully withdrawn from the solution at various time intervals, and the solution absorbance was determined in the UV-visible range at the maximum absorption (�� = 483nm) using a PuXi UV-vis spectrophotometer (TU-1900, China).