Effect of NaOH concentration on structure and phosphate adsorption of polymer-based hydrated ferric oxide composite adsorbents
-
摘要: 树脂基水合氧化铁(Hydrated ferric oxide,HFO)复合吸附剂以磷吸附容量大、吸附速率快、洗脱率高等特点,受到广泛关注,但不同NaOH浓度制备的复合吸附剂结构和吸附性能是否一样尚不清楚。通过考察NaOH浓度对树脂基HFO复合吸附剂的结构和除磷性能影响,为优化D213-HFO复合吸附剂制备提供依据。结果表明,NaOH浓度从1 mol·L−1增加至6 mol·L−1,复合吸附剂的HFO负载量(约为16wt%,以Fe质量分数计)和晶体结构无显著差异,但复合吸附剂负载纳米HFO颗粒团聚程度降低,分布更均匀。此外,随着NaOH浓度增加,复合吸附剂的磷吸附容量先增加后稳定(18 mg·g−1)。另外,复合吸附剂吸附磷的平衡时间为240 min,更符合准一级动力学模型(R2 > 0.99),最佳吸附pH为6~8,相同浓度时共存离子对磷吸附影响程度为SO42−>Cl−>NO3−。在连续5个吸附洗脱周期内,复合吸附剂的磷洗脱率均接近100%。实验表明,随NaOH浓度增加,复合吸附剂负载HFO颗粒分布更均匀,磷吸附容量先增加后稳定,但晶体结构、吸附平衡时间、最佳pH范围、共存离子影响趋势及洗脱效果均无显著差异。Abstract: Polymer-based hydrated ferric oxide (HFO) composite adsorbents had attracted extensive attention because of large phosphate adsorption capacity, rapid adsorption rate and high regeneration efficiency. Nevertheless, whether the same structure and phosphate adsorption could be performed by composite adsorbents prepared at different NaOH concentration was still unclear. In order to provide evidence for optimization of polymer-based hydrated ferric oxide composite adsorbents preparation, the structure and phosphate adsorption of composite adsorbents prepared by regulating NaOH concentration were studied. The results show that when NaOH concentration increases from 1 mol·L−1 to 6 mol·L−1, there are no significantly effect on the HFO loadings (approximately 16wt%, mass fraction in Fe) and crystal structure of composite adsorbents. However, the considerable self-agglomerate of HFO nanoparticles decrease, and HFO nanoparticles distribute evenly. Moreover, phosphate adsorption capacity is increased with NaOH concentration and then remains the same (18 mg·g−1). Additionally, adsorption equilibrium times are 240 min, and the adsorption kinetic curves are fitted well with pseudo-first order kinetic model (R2 > 0.99). The optimal pH value for phosphate adsorption is 6-8, and the influence degree of phosphate adsorption by co-existing ions is SO42−>Cl−>NO3− under the same concentration. The regeneration efficiencies of composite adsorbents approach 100% during 5 continuous adsorption regeneration cycles. The experiments show that the HFO nanoparticles distribute evenly with the increase of NaOH concentration, and the phosphate adsorption capacity of composite adsorbents is increased and then remains the same, while there is no significant difference in crystal structure, adsorption equilibrium time, optimal pH, effect of coexisting anions, and elution effect.
-
Key words:
- sodium hydroxide /
- hydrated ferric oxide /
- anion exchange resin /
- composite adsorbents /
- phosphate
-
表 1 不同NaOH浓度制备的复合吸附剂
Table 1. Composite adsorbents prepared with various NaOH concentrations
Adsorbent NaOH concentration/
(mol·L−1)HFO loadings/
(Fe wt%)D213-HFO-1 1 15.7 D213-HFO-3 3 16.0 D213-HFO-6 6 15.9 Note: HFO—Hydrated ferric oxide. 表 2 D213-HFO复合吸附剂的Freundlich模型和Langmuir模型拟合参数
Table 2. Isothermal adsorption model fitting parameters of Langmuir and Freundlich model by D213-HFO composite adsorbents
Adsorbents Langmuir model Freundlich model qm/(mg·g−1) b/(L·mg−1) R2 K/(mg1-1/n·L1/n·g−1) 1/n R2 D213-HFO-1 13.31 0.26 0.970 4.34 0.30 0.955 D213-HFO-3 17.94 0.20 0.973 4.90 0.34 0.939 D213-HFO-6 18.07 0.15 0.977 4.39 0.37 0.926 Notes: qm―Maximum adsorption capacity; b—Adsorption energy; K and n―Isotherm constants; R2—Degree of fitting. 表 3 D213和D213-HFO复合吸附剂的吸附动力学拟合参数
Table 3. Kinetic fitting parameters of D213 and D213-HFO composite adsorbents
Adsorbents Pseudo-first-order Pseudo-second-order Intra-particle diffusion qe/
(mg·g−1)k1/
min−1R2 qe/
(mg·g−1)k2/
(g·mg−1·min−1)R2 C1 kd1/
(mg·g−1·min−1/2)R12 C2 kd2/
(mg·g−1·min−1/2)R22 D213 15.23 0.028 0.998 17.31 20.90 0.978 −1.91 1.83 0.972 13.53 0.11 0.616 D213-HFO-1 19.73 0.015 0.999 20.26 6.69 0.988 −3.39 1.95 0.995 9.23 0.67 0.893 D213-HFO-3 19.87 0.016 0.999 24.49 6.87 0.989 −3.31 1.97 0.995 9.22 0.69 0.881 D213-HFO-6 19.84 0.017 0.999 25.47 7.38 0.989 −3.31 2.01 0.996 10.06 0.64 0.870 Notes: k1―Pseudo-first-order kinetic constant; k2―Pseudo-second-order kinetic constant; qe―Phosphate adsorption capacity in equilibrium; kd―Intra-particle diffusion rate constant; C―Reaction constant. -
[1] 赵治国, 袁林江, 王骞, 等. 废水中有机物对铁盐除磷的影响[J]. 中国环境科学, 2020, 40(1):288-293. doi: 10.3969/j.issn.1000-6923.2020.01.032ZHAO Zhiguo, YUAN Linjiang, WANG Qian, et al. Effects of organic substance on ferric ion-dependent phosphorus removal in wastewaters[J]. China Environmental Science,2020,40(1):288-293(in Chinese). doi: 10.3969/j.issn.1000-6923.2020.01.032 [2] ZHANG H, ELSKENS M, CHEN G, et al. Influence of seawater ions on phosphate adsorption at the surface of hydrous ferric oxide (HFO)[J]. Science of the Total Environment,2020,721:137826. doi: 10.1016/j.scitotenv.2020.137826 [3] 董浩, 花铭. 树脂基纳米复合材料吸附水中As(III)的性能比较研究[J]. 离子交换与吸附, 2017, 33(5):385-394.DONG Hao, HUA Ming. Comparative study of arsenite removal from water by polymer-supported hydrated metallic oxides[J]. Ion Exchange and Adsorption,2017,33(5):385-394(in Chinese). [4] MAHARDIKA D, PARK H S, CHOO K H. Ferrihydrite-impregnated granular activated carbon (FH@GAC) for efficient phosphorus removal from wastewater secondary effluent[J]. Chemosphere,2018,207:527-533. doi: 10.1016/j.chemosphere.2018.05.124 [5] LIU T, WANG H, ZHANG Z, et al. Application of synthetic iron-oxide coated zeolite for the pollution control of river sediments[J]. Chemosphere,2017,180:160-168. doi: 10.1016/j.chemosphere.2017.04.023 [6] WANG Z, LIN Y, WU D, et al. Hydrous iron oxide modified diatomite as an active filtration medium for phosphate capture[J]. Chemosphere,2016,144:1290-1298. doi: 10.1016/j.chemosphere.2015.10.015 [7] WIRIYATHAMCHAROEN S, SARKAR S, JIEMVARANGKUL P, et al. Synthesis optimization of hybrid anion exchanger containing triethylamine functional groups and hydrated Fe(III) oxide nanoparticles for simultaneous nitrate and phosphate removal[J]. Chemical Engineering Journal,2020,381:122671. doi: 10.1016/j.cej.2019.122671 [8] MUHAMMAD A, SOARES A, JEFFERSON B. The impact of background wastewater constituents on the selectivity and capacity of a hybrid ion exchange resin for phosphorus removal from wastewater[J]. Chemosphere,2019,224:494-501. doi: 10.1016/j.chemosphere.2019.01.085 [9] CUMBAL L, SENGUPTA A K. Arsenic removal using polymer-supported hydrated iron(III) oxide nanoparticles: Role of Donnan membrane effect[J]. Environmental Science & Technology,2005,39(17):6508-6515. [10] BLANEY L M, CINAR S, SENGUPTA A K. Hybrid anion exchanger for trace phosphate removal from water and wastewater[J]. Water Research,2007,41(7):1603-1613. doi: 10.1016/j.watres.2007.01.008 [11] MARCUS Y. Thermodynamics of solvation of ions. Part 5. —Gibbs free energy of hydration at 298.15 K[J]. Journal of the Chemical Society, Faraday Transactions,1991,87(18):2995-2999. doi: 10.1039/FT9918702995 [12] GU B H, BROWN G M, MAYA L, et al. Regeneration of perchlorate (ClO4−)-loaded anion exchange resins by a novel tetrachloroferrate (FeCl4−) displacement technique[J]. Environmental Science & Technology,2001,35(16):3363-3368. [13] PAN B, WU J, PAN B, et al. Development of polymer-based nanosized hydrated ferric oxides (HFOs) for enhanced phosphate removal from waste effluents[J]. Water Research,2009,43(17):4421-4429. doi: 10.1016/j.watres.2009.06.055 [14] PAN B, CHEN D, ZHANG H, et al. Stability of hydrous ferric oxide nanoparticles encapsulated inside porous matrices: Effect of solution and matrix phase[J]. Chemical Engineering Journal,2018,347:870-876. doi: 10.1016/j.cej.2018.04.130 [15] 刘艳, 高洋, 赵昕, 等. 凝胶型树脂载纳米水合氧化铁复合材料的制备与除As(V)特性[J]. 高分子学报, 2018(7):939-948.LIU Yan, GAO Yang, ZHAO Xin, et al. A gel resin-supported nano-hydrated iron oxide for arsenate sorption from water[J]. Acta Polymerica Sinica,2018(7):939-948(in Chinese). [16] 赵继旭, 胡建龙, 邵立南, 等. HCl浓度对水合氧化铁复合吸附剂磷吸附效能的影响[J]. 复合材料学报, 2021, 38(4):1139-1146.ZHAO Jixu, HU Jianlong, SHAO Li'nan, et al. Effect of HCl concentration on phosphate adsorption behavior of hydrated ferrous oxide composite adsorbents[J]. Acta Materiae Compositae Sinica,2021,38(4):1139-1146(in Chinese). [17] 孙健, 徐兆郢, 赵平歌, 等. 水合氧化铁负载量对丙烯酸树脂基复合吸附剂的结构及除磷影响[J]. 复合材料学报, 2021, 38(8):2595-2604.SUN Jian, XU Zhaoying, ZHAO Pingge, et al. Effect of hydrated ferric oxide loadings on structure and phosphate adsorption of acrylic polymer-supported composite adsorbents[J]. Acta Materiae Compositae Sinica,2021,38(8):2595-2604(in Chinese). [18] KOCIOŁEK-BALAWEJDER E, STANISŁAWSKA E, CIECHANOWSKA A. Iron(III) (hydr)oxide loaded anion exchange hybrid polymers obtained via tetrachloroferrate ionic form—Synthesis optimization and characterization[J]. Journal of Environmental Chemical Engineering,2017,5(4):3354-3361. doi: 10.1016/j.jece.2017.06.043 [19] LI S, YANG Q, ZHONG Y, et al. Adsorptive bromate removal from aqueous solution by commercial strongly basic resin impregnated with hydrated ferric oxide (HFO): Kinetics and equilibrium studies[J]. Journal of Chemical & Engineering Data,2016,61(3):1305-1312. [20] 中国石油和化学工业联合会. 离子交换树脂预处理方法: GB/T 5476—2013[S]. 北京: 中国标准出版社, 2013.China Petroleum and Chemical Industry Federation. Methods of pretreating ion exchange resin: GB/T 5476—2013[S]. Beijing: China Standards Press, 2013(in Chinese). [21] 国家环境保护局标准处. 钼酸铵分光光度法: GB/T 11893—1989[S]. 北京: 中国标准出版社, 1989.Standards Division of State Environmental Protection Administration. Ammonium molybdate spectrophotometric method: GB/T 11893—1989[S]. Beijing: China Standards Press, 1989(in Chinese). [22] SU Y, CUI H, LI Q, et al. Strong adsorption of phosphate by amorphous zirconium oxide nanoparticles[J]. Water Research,2013,47(14):5018-5026. doi: 10.1016/j.watres.2013.05.044 [23] ALSHEHRI S M, NAUSHAD M, AHAMAD T, et al. Synthesis, characterization of curcumin based ecofriendly antimicrobial bio-adsorbent for the removal of phenol from aqueous medium[J]. Chemical Engineering Journal,2014,254:181-189. doi: 10.1016/j.cej.2014.05.100 [24] GONG C, CHEN D, JIAO X, et al. Continuous hollow α-Fe2O3 and α-Fe fibers prepared by the sol-gel method[J]. Journal of Materials Chemistry,2002,12(6):1844-1847. doi: 10.1039/b201243j [25] ZHOU K, WU B, SU L, et al. Enhanced phosphate removal using nanostructured hydrated ferric-zirconium binary oxide confined in a polymeric anion exchanger[J]. Chemical Engineering Journal,2018,345:640-647. doi: 10.1016/j.cej.2018.01.091 [26] WANG J, ZHANG S, PAN B, et al. Hydrous ferric oxide-resin nanocomposites of tunable structure for arsenite removal: Effect of the host pore structure[J]. Journal of Hazardous Materials,2011,198:241-246. doi: 10.1016/j.jhazmat.2011.10.036 [27] KARIM A H, JALIL A A, TRIWAHYONO S, et al. Amino modified mesostructured silica nanoparticles for efficient adsorption of methylene blue[J]. Journal of Colloid and Interface Science,2012,386(1):307-314. doi: 10.1016/j.jcis.2012.07.043 [28] 高源, 贺维鹏, 施周, 等. 聚硫酸铁强化混凝除锑(V)作用机制探讨[J]. 中国环境科学, 2015, 35(11):3346-3351. doi: 10.3969/j.issn.1000-6923.2015.11.020GAO Yuan, HE Weipeng, SHI Zhou, et al. Discussion on action mechanisms of antimony(V) removal by enhanced coagulation with polymeric ferric sulphate[J]. China Envi-ronmental Science,2015,35(11):3346-3351(in Chinese). doi: 10.3969/j.issn.1000-6923.2015.11.020 [29] ZENG H, FISHER B, GIAMMAR D E. Individual and competitive adsorption of arsenate and phosphate to a high-surface-area iron oxide-based sorbent[J]. Environmental Science & Technology,2008,42(1):147-152. [30] KHARE N, HESTERBERG D, MARTIN J D. XANES investigation of phosphate sorption in single and binary systems of iron and aluminum oxide minerals[J]. Environmental Science & Technology,2005,39(7):2152-2160. [31] LEFEVRE G. In situ Fourier-transform infrared spectroscopy studies of inorganic ions adsorption on metal oxides and hydroxides[J]. Advances in Colloid and Interface Science,2004,107(2):109-123.