合成时间对钛酸盐纳米材料的影响及其吸附水中铅的性能研究
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摘要
以Ti O2(ST-01)和Na OH为原料,采用碱性水热法通过调节反应时间合成不同形貌的钛酸盐纳米材料(TNs),利用XRD、SEM、BET对材料的形貌、结构、比表面积和化学组成等物化性能进行表征,并通过其对水中Pb(Ⅱ)的静态吸附实验,考察材料对Pb(Ⅱ)的吸附性能和吸附规律.结果表明,12~72 h合成的TNs均为纯净的单斜相钛酸盐,比表面积为243.05~286.20 m2·g-1;12~36 h合成的TNs主要为片状结构,48 h以上的TNs为线状结构.TNs-12、TNs-24、TNs-36、TNs-48、TNs-60和TNs-72对Pb(Ⅱ)的吸附量分别为479.40、504.12、482.00、388.10、364.60和399.00 mg·g-1,片状的TNs对Pb(Ⅱ)具有比线状更高的吸附能力,其中以TNs-24对Pb(Ⅱ)的吸附量最高.TNs-24对Pb(Ⅱ)的吸附结果符合准二级动力学模型和Langmuir模型,吸附平衡时间为120 min;TNs对Pb(Ⅱ)的吸附为放热过程,低温或室温便有较高的吸附量;最佳吸附p H为5.0;当p H为1.0时,TNs-24的解析率可达到99.00%;再生的TNs对Pb(Ⅱ)循环吸附6次的去除率仍可达到97%以上,可见TNs可很好地去除水中重金属Pb(Ⅱ).因此,最佳合成时间可控制在12~24 h;当溶液中存在共存Cd(Ⅱ)或Ni(Ⅱ)时,TNs-24对Pb(Ⅱ)的平衡吸附量及去除率均有所下降;吸附机制主要是Pb(Ⅱ)与TNs层间的H+和Na+发生离子交换作用.
Titanate nanomaterials( TNs) were synthesized via a simple hydrothermal method using Ti O2( ST-01) and Na OH as the raw materials,and presented different morphologies by adjusting the reaction time. The physico-chemical properties of the as-prepared TNs,such as morphology,structure,surface area,and chemical composition were characterized by XRD,SEM and BET. The adsorption capability and rules of Pb( Ⅱ) in aqueous solutions were tested in the static system. The results showed that the TNs prepared with 12-72 h reaction time were pure monoclinic phase titanate and their specific surface areas were in the range from 243. 05m2·g- 1to 286. 20 m2·g- 1. TNs with reaction time between 12-36 h mainly showed sheet structure,and those with reaction time higher than 48 h showed linear structure. The adsorption capacity of Pb( Ⅱ) by TNs-12,TNs-24,TNs-36,TNs-48,TNs-60 and TNs-72 was 479. 40,504. 12,482. 00,388. 10,364. 60 and 399. 00 mg·g- 1,respectively. The sheet TNs had a better adsorption capacity than the linear TNs. TNs-24 had the highest adsorbing capacity. The adsorption kinetics of Pb( Ⅱ) by TNs-24 followed the pseudosecond-order model,and the equilibrium data was best fitted with the Langmuir isotherm model. The equilibrium adsorption time of TNs-24 was 120 min,and the adsorption was an exothermic process,with a high adsorption capacity at low temperature or room temperature; the optimal adsorption p H was 5. 0. When p H was 1. 0,the desorption rate of TNs-24 could reach 99. 00%,and the removal efficiency of Pb( Ⅱ) by regenerated TNs was still more than 97% after six times of usage. Therefore,TNs could efficiently remove Pb( Ⅱ) in aqueous solutions,and the optimal reaction time should be controlled to 12-24 h. When Cd( Ⅱ) or Ni( Ⅱ)existed in the solution,the equilibrium adsorption capacity and removal rate of TNs-24 were decreased. The adsorption mechanism was mainly ion-exchanged between Pb( Ⅱ) and H+/ Na+in TNs.
Titanate nanomaterials( TNs) were synthesized via a simple hydrothermal method using Ti O2( ST-01) and Na OH as the raw materials,and presented different morphologies by adjusting the reaction time. The physico-chemical properties of the as-prepared TNs,such as morphology,structure,surface area,and chemical composition were characterized by XRD,SEM and BET. The adsorption capability and rules of Pb( Ⅱ) in aqueous solutions were tested in the static system. The results showed that the TNs prepared with 12-72 h reaction time were pure monoclinic phase titanate and their specific surface areas were in the range from 243. 05m2·g- 1to 286. 20 m2·g- 1. TNs with reaction time between 12-36 h mainly showed sheet structure,and those with reaction time higher than 48 h showed linear structure. The adsorption capacity of Pb( Ⅱ) by TNs-12,TNs-24,TNs-36,TNs-48,TNs-60 and TNs-72 was 479. 40,504. 12,482. 00,388. 10,364. 60 and 399. 00 mg·g- 1,respectively. The sheet TNs had a better adsorption capacity than the linear TNs. TNs-24 had the highest adsorbing capacity. The adsorption kinetics of Pb( Ⅱ) by TNs-24 followed the pseudosecond-order model,and the equilibrium data was best fitted with the Langmuir isotherm model. The equilibrium adsorption time of TNs-24 was 120 min,and the adsorption was an exothermic process,with a high adsorption capacity at low temperature or room temperature; the optimal adsorption p H was 5. 0. When p H was 1. 0,the desorption rate of TNs-24 could reach 99. 00%,and the removal efficiency of Pb( Ⅱ) by regenerated TNs was still more than 97% after six times of usage. Therefore,TNs could efficiently remove Pb( Ⅱ) in aqueous solutions,and the optimal reaction time should be controlled to 12-24 h. When Cd( Ⅱ) or Ni( Ⅱ)existed in the solution,the equilibrium adsorption capacity and removal rate of TNs-24 were decreased. The adsorption mechanism was mainly ion-exchanged between Pb( Ⅱ) and H+/ Na+in TNs.
引文
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[2]Tofighy M A,Mohammadi T.Adsorption of divalent heavy metal ions from water using carbon nanotube sheets[J].Journal of Hazardous Materials,2011,185(1):140-147.
[3]Wang T,Liu W,Xiong L,et al.Influence of p H,ionic strength and humic acid on competitive adsorption of Pb(Ⅱ),Cd(Ⅱ)and Cr(Ⅲ)onto titanate nanotubes[J].Chemical Engineering Journal,2013,215-216:366-374.
[4]Hernández-Hipólito P,García-Castillejos M,Martínez-Klimova E,et al.Biodiesel production with nanotubular sodium titanate as a catalyst[J].Catalysis Today,2014,220-222:4-11.
[5]Lee C K,Lai L H,Liu S S,et al.Application of titanate nanotubes for ammonium adsorptive removal from aqueous solutions[J].Journal of the Taiwan Institute of Chemical Engineers,2014,45(6):2950-2956.
[6]Liu W,Sun W L,Han Y F,et al.Adsorption of Cu(Ⅱ)and Cd(Ⅱ)on titanate nanomaterials synthesized via hydrothermal method under different Na OH concentrations:Role of sodium content[J].Colloids and Surfaces A:Physicochemical and Engineering Aspects,2014,452:138-147.
[7]Liu W,Wang T,Borthwick A G L,et al.Adsorption of Pb2+,Cd2+,Cu2+and Cr3+onto titanate nanotubes:Competition and effect of inorganic ions[J].Science of the Total Environment,2013,456-457:171-180.
[8]Niu G J,Liu W,Wang T,et al.Absorption of Cr(Ⅵ)onto amino-modified titanate nanotubes using 2-Bromoethylamine hydrobromide through SN2 reaction[J].Journal of Colloid and Interface Science,2013,401:133-140.
[9]Nie X T,Teh Y L.Titanate nanotubes as superior adsorbents for removal of lead(Ⅱ)ions from water[J].Materials Chemistry and Physics,2010,123(2-3):494-497.
[10]Chen Y C,Lo S L,Kuo J.Pb(Ⅱ)adsorption capacity and behavior of titanate nanotubes made by microwave hydrothermal method[J].Colloids and Surfaces A:Physicochemical and Engineering Aspects,2010,361(1-3):126-131.
[11]Xiong L,Chen C,Chen Q,et al.Adsorption of Pb(Ⅱ)and Cd(Ⅱ)from aqueous solutions using titanate nanotubes prepared via hydrothermal method[J].Journal of Hazardous Materials,2011,189(3):741-748.
[12]Liu W,Ni J R,Yin X C.Synergy of photocatalysis and adsorption for simultaneous removal of Cr(Ⅵ)and Cr(Ⅲ)with Ti O2and titanate nanotubes[J].Water Research,2014,53:12-25.
[13]Liu W,Chen H,Borthwick A G L,et al.Mutual promotion mechanism for adsorption of coexisting Cr(Ⅲ)and Cr(Ⅵ)onto titanate nanotubes[J].Chemical Engineering Journal,2013,232:228-236.
[14]Liu W,Borthwick A G L,Li X Z,et al.High photocatalytic and adsorptive performance of anatase-covered titanate nanotubes prepared by wet chemical reaction[J].Microporous and Mesoporous Materials,2014,186:168-175.
[15]Liu W,Sun W L,Borthwick A G L,et al.Comparison on aggregation and sedimentation of titanium dioxide,titanate nanotubes and titanate nanotubes-Ti O2:Influence of p H,ionic strength and natural organic matter[J].Colloids and Surfaces A:Physicochemical and Engineering Aspects,2013,434:319-328.
[16]Wang T,Liu W,Xu N,et al.Adsorption and desorption of Cd(Ⅱ)onto titanate nanotubes and efficient regeneration of tubular structures[J].Journal of Hazardous Materials,2013,250-251:379-386.
[17]Santos-López I A,Handy B E,García-de-León R.Titanate nanotubes as support of solid base catalyst[J].Thermochimica Acta,2013,567:85-92.
[18]Manfroi D C,Dos Anjos A,Cavalheiro A A,et al.Titanate nanotubes produced from microwave-assisted hydrothermal synthesis:Photocatalytic and structural properties[J].Ceramics International,2014,40(9):14483-14491.
[19]Li X Z,Liu W,Ni J R.Short-cut synthesis of tri-titanate nanotubes using nano-anatase:Mechanism and application as an excellent adsorbent[J].Microporous and Mesoporous Materials,2015,213:40-47.
[20]Yang W D,Nam C T,Chung Z J,et al.Synthesis and metal ion sorption properties of peroxide-modified sodium titanate materials using a coprecipitation method[J].Surface and Coatings Technology,2015,271:57-62.
[21]Wei M D,Konishi Y,Arakawa H.Synthesis and characterization of nanosheet-shaped titanium dioxide[J].Journal of Materials Science,2007,42(2):529-533.
[22]Chang Y F,Xing S T,Wei X R,et al.Lignosulfanate-assistant hydrothermal method for synthesis of titanate nanotubes with improved adsorption capacity for metal ions[J].Materials Letters,2014,132:353-356.
[23]Zhang X M,Liu J Y,Kelly S J,et al.Biomimetic snowflakeshaped magnetic micro-/nanostructures for highly efficient adsorption of heavy metal ions and organic pollutants from aqueous solution[J].Journal of Materials Chemistry A,2014,2(30):11759-11767.
[24]Sounthararajah D P,Loganathan P,Kandasamy J,et al.Adsorptive removal of heavy metals from water using sodium titanate nanofibres loaded onto GAC in fixed-bed columns[J].Journal of Hazardous Materials,2015,287:306-316.
[25]Huang J Q,Cao Y G,Liu Z G,et al.Efficient removal of heavy metal ions from water system by titanate nanoflowers[J].Chemical Engineering Journal,2012,180:75-80.
[26]Sheng G D,Ye L,Li Y M,et al.EXAFS study of the interfacial interaction of nickel(Ⅱ)on titanate nanotubes:Role of contact time,p H and humic substances[J].Chemical Engineering Journal,2014,248:71-78.
[27]Jayaram K,Murthy I Y L N,Lalhruaitluanga H,et al.Biosorption of lead from aqueous solution by seed powder of Strychnos potatorum L[J].Colloids Surfaces B:Biointerfaces,2009,71(2):248-254.
[28]Lagergreen S.Zur Theorie der sogenannten Adsorption gelster Stoffe[J].Zeitschrift für Chemie und Industrie der Kolloide,1907,2(1):15.
[29]Ho Y S,Mc Kay.Sorption of dye from aqueous solution by peat[J].Chemical Engineering Journal,1998,70(2):115-124.
[30]Langmuir I.The adsorption of gases on plane surfaces of glass,mica and platinum[J].Journal of the American Chemical Society,1918,40(9):1361-1403.
[31]Hall K R,Eagleton L C,Acrivos A,et al.Pore-and soliddiffusion kinetics in fixed-bed adsorption under constant-pattern conditions[J].Industrial&Engineering Chemistry Fundamentals,1966,5(2):212-223.
[32]Freundlich H.ber die adsorption in lsungen[M].Leipzig:Wilhelm Engelmann,1906.385-470.
[33]Tempkin M J,Pyzhev V.Recent modifications to Langmuir isotherms[J].Acta Physico-Chimica Sinica,1940,12:217-222.
[34]Li N,Zhang L D,Chen Y Z,et al.Adsorption behavior of Cu(Ⅱ)onto titanate nanofibers prepared by alkali treatment[J].Journal of Hazardous Materials,2011,189(1-2):265-272.