In order to recover the antimony from wastewater, a custom-designed fluidized-bed reactor (FBR) was employed to treat antimony-containing wastewater. By single-factor experiments, the effects of the solution pH, the molar ratio of [TA]/[Sb3+], the seed size and dosage, the up-flow velocity (U), and the hydraulic retention time (HRT) on antimony recovery were investigated based on the antimony removal and granulation efficiency. The optimum conditions for antimony recovery were obtained at pH 9.0, the molar ratio of [TA]/[Sb3+] of 2, 6 g/L of 13–38 μm Sb2O3as the fluidized seed, and the U and HRT of 42 m/h and 40 min, respectively; the antimony removal and granulation efficiency reached 95% and 91%, respectively. The granular products were analyzed by an X-ray polycrystalline diffractometer (XRD) and scanning electron microscopy (SEM) as cubic Sb2O3, widely used in various industries. The fluidized-bed reactor was operated continuously for 7 days, during which the antimony removal and granulation efficiency were stable at 96% and 93%, respectively. This study demonstrated the feasibility of the fluidized-bed granulation process for the recovery of antimony from wastewater. It provides a novel approach for retrieving and managing antimony-containing wastewater.
Bu Daolu,Yang Hu,Zhang Haibo,Wang Liang,Wang Jiao,Liao Jie
The present study investigates the efficacy of newly developed Zr-based metal–organic frameworks, specifically MIP-206, and its amine-modified counterpart, MIP-206-NH 2 , for the re-covery of antimony (Sb) from both synthetic and actual mining wastewater. Batch method studies were employed to examine the effect of waste media pH, Sb concentration, process kinetics, and the performance of the regeneration solution. MIP-206-NH 2 exhibited impressive separation capabilities, achieving 102.18 mg/g and 63.23 mg/g for Sb (V) and Sb (III), respectively. In contrast, the pristine MIP-206 reached maximum values of 26.26 mg/g for Sb (V) and 16.95 mg/g for Sb (III). The separation process was well-described by the Langmuir equation, and the kinetics followed the pseudo-second-order model. Although the amine modification resulted in a decrease in the surface area of MIP-206 from 1345.21 to 1169.86 m 2 /g, SEM and XRD analyses confirmed that the structural integrity of MIP-206-NH 2 remained unchanged. In terms of reusability, MIP-206-NH 2 maintained up to 90% of its separation performance over 9 cycles, while MIP-206 demonstrated effectiveness for 7 cycles. The regeneration solution exhibited a capacity of approximately 0.63 mol/L for Sb (V) and 0.71 mol/L for Sb (III). Furthermore, MIP-206 and MIP-206-NH 2 demonstrated successful application in selectively separating Sb from real mining wastewater.
Exhausted adsorbents from Sb-laden wastewater are hazardous and generally landfilled. This study presents that exhausted Sb adsorbents can be thermally reduced and recycled as supercapacitor electrode. Specifically, ordered hierarchical porous amidoxime-polyacrylonitrile (OHPAPAN) is synthesized for highly efficient Sb(V) ions adsorption and then thermal conversion of exhausted OHPAPAN to Sb-contained char, rendering excellent electrochemical activity. Sb 0 atom clusters are found to form during recycling process by X-ray absorption spectroscopy (XAFS), along with Sb oxide with average valence of +2.63. The 4d and 4p orbital of Sb cluster exhibits abundant electron state in Fermi level and valence band, making a pseudocapacitive contribution. Moreover, ordered hierarchical pore is confirmed to be inherited in the char from OHPAPAN, further enhancing electrical double layer capacitance. Coordination configuration of Sb and N/O becomes more stable from sexadentate (coordinate atom distance of 1.98 and 2.66 Å) in OHPAPAN to ≈2 N/O ligands in Sb-contained char (1.97 Å), underlining the shorter atom distance and higher orbital energy for Sb immobilization. Consequently, the capacitance maintains 96.1% after 6000 cycles, indicating that its excellent stability can rival relevant commercial electrode. This study offers a novel insight that Sb mineral sources can be derived from industrial wastewater, not just mining activity.
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