In this study, the surface modification of graphene (SMG) was developed for efficient speciation and determination of chromium in water and wastewater samples. By procedure, the chromium ions were extracted from water/wastewater samples based on sulfonated and amine graphene (S-NG, N-NG) by suspension solid-phase microextraction procedure (SMSPE). Hydrophobic ionic liquid ([HMIM] [PF6]) was used for separation graphene from 10 mL of water. After shaking and centrifuging, the phase of Cr→ S-NG, Cr→N-NG was back-extracted by 0.2 mL of HNO3 (0.4 mol L-1) and finally chromium concentration determined with ET-AAS. The results showed the sulfonated and amine graphene can successfully extract Cr(III) and Cr(VI) from water and wastewater samples at pH=3.5-5.5 and pH<3, respectively. Also, the most Cr(VI) extracted by N-graphene at pH=2(NH3+→Cr2O7─). Under the optimal conditions, the linear range, LOD, and preconcentration factor were obtained 0.02–2.4 µg L−1, 5.0 ng L−1 and 20.2, respectively for Cr(III, VI) (%RSD<5%).
In this study, the effects of nanostructure absorbent of ZnO in graphene bed for a wastewater treatment unit in weaving are evaluated. Initial analysis was undertaken to identify the existing metals and their concentration in the prepared wastewater. It was seen that the diluted solution consisted of the ambivalence ions of lead, copper, nickel, cadmium, and silver with the concentration of 73/31, 81/19, 54/6, 98/1and 76/1 milligram per liter, respectively. Trivalent chrome, with a concentration of 98/1 milligram per liter was also observed. Therefore, by adding various amounts of absorbent (20, 30 and 50 milligrams) to the wastewater sample and adjusting the PH to 5 and 6, each metal was separately absorbed.
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