| Arsenic contamination has attracted worldwide concerns,owing to its toxicity and severe threat to human and environment.So far,many techniques like oxidation,precipitation,coagulation,co-precipitation,sorption,membrane have been adopted to achieve arsenic removal.Among these methods,adsorption is regarded as a promising technique due to its low cost,simple operation,no need of expensive reagents.Traditional adsorbents are facing some problems like low adsorption capacity,and slow adsorption rate.It is still important and challenging to explore efficient and eco-friendly adsorbents for the superior decontamination of arsenic in water.Within this work,several metal-organic frameworks?MOFs?and MOFs/cotton fibers have been synthesized and characterized.Their adsorptive activities and the mechanism were also studied.The main content of this work was listed as the following:1.A 2D metal-organic framework?SO4?3?BUC-17?has been synthesized by hydrothermal method,and was utilized as an efficient adsorbent to remove As?V?from contaminated water.The results showed that BUC-17 have higher adsorption capacity toward As?V?than most counterpart adsorbents,its maximum uptake capacity reached 129.2 mg g-1 at 298 K.The adsorption kinetics and isotherm behaviors were well fitted with pseudo-second-order and Langmuir model,respectively.The thermodynamic parameters suggesting that the adsorption process of BUC-17 towards As?V?was spontaneous and exothermal.The influence of pH and foreign ions on the adsorptive removal of As?V?using BUC-17 were investigated.The results showed that pH values have significant influence while co-existed anions?unless phosphate?exert slight effect on adsorption capacity.Finally,a corresponding adsorption mechanism was proposed and confirmed by characterization analysis.2.Both pristine MIL-88A?Fe?and MIL-88A?Fe?decorated on cotton fibers were successfully fabricated using an eco-friendly method.The pristine MIL-88A?Fe?displayed outstanding adsorption performances towards four selected arsenic pollutants,in which the adsorption capacities toward As?III?,As?V?,ROX and ASA were 126.5,164.0,261.4 and 427.5 mg g-1,respectively.Additionally,MIL-88A?Fe?exhibited excellent removal efficiencies in a wide pH range and with the presence of different co-existing ions.It was proposed that the coordinative interactions of As-O-Fe between arsenic pollutants and MIL-88A?Fe?contributed to the superior adsorption performances.Furthermore,two MIL-88A?Fe?/cotton fibers composites were synthesized by both post synthesis?MC-1?and insitu synthesis?MC-2?,which demonstrated identically outstanding adsorption activities toward four selected arsenic pollutants.MC-1 and MC-2 enhanced the stability and reusability of MIL-88A?Fe?,which was challenging issues of pristine MIL-88A?Fe?powder.Additionally,the fixed-bed column packed by MC-1 or MC-2 can continuously eliminate arsenic pollutants from the water flow.This work provided a new possibility of metal-organic frameworks to accomplish potentially large-scale application to purify the arsenic-contaminated water.3.In this study,one of the zeolitic imidazolate frameworks?ZIFs?-ZIF-67 were prepared by using an eco-friendly method,which was further used to carry out the adsorptive removal of roxarsone from simulated wastewater.The adsorption kinetics,adsorption isotherm and possible adsorption mechanism were investigated.The results revealed that ZIF-67 exhibited good adsorption performance towards roxarsone,with maximum uptake capacity being 172.45 mg g-1 at pH = 6.The adsorption kinetics and isotherm behaviors were well fitted with pseudo-second-order kinetic model and Langmuir model,respectively.The possible adsorption mechanism of ZIF-67 towards roxarsone was proposed,in which the electrostatic interaction and ion-exchange contributed the efficient adsorption activity.Finally,the fixed-bed column experiments implied that ZIF-67 could be potentially applied to achieve large-scale roxarsone removal from the real polluted water. |
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