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排序方式: 共有1345条查询结果,搜索用时 15 毫秒
1.
利用无毒交联剂制备壳聚糖微球并负载稀土元素,制得新型除氟吸附剂。配制水除氟实验中,Ce-CEB对F^-(纯NaF溶液)的静态吸附容量为17.7 mgF^-/g微球,F^-的脱除率为93.4%;对于具有复杂阴离子的配制水,Ce-CEB对F^-的动态饱和吸附量为12.3 mgF^-/g微球。 相似文献
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Hector Iván Meléndez-Ortiz Bertha Puente-Urbina Jesus Alfonso Mercado-Silva Lorena García-Uriostegui 《International Journal of Applied Ceramic Technology》2019,16(4):1533-1543
The dye adsorption performance of four mesoporous silicas with different structure and textural properties, MCM-41, MCM-48, SBA-15 and mesocellular silica foam (MCF), was studied and compared by using toluidine blue O (TBO) as dye model in aqueous solution. These materials were characterized by X-ray diffraction (XRD), small-angle X-ray scattering, nitrogen adsorption-desorption analyses, and transmission electron microscopy (TEM). The effect of some parameters such as adsorbent dosage, contact time, temperature, and pH on the TBO removal in aqueous solution was studied. Results showed that adsorption capacity raised when adsorbent dosage, contact time and pH solution were increased while an increase in temperature decreased the adsorption of TBO. Langmuir, Freundlich and Temkin isotherm models were employed to elucidate the adsorption mechanism while the adsorption rate data were analyzed according to the pseudo-first and second-order kinetic models. Results showed that adsorption of TBO onto MCM-48, SBA-15, and MCF fitted well the Freundlich isotherm model while the kinetic studies showed that adsorption process could be better described by the pseudo-second-order model for all mesoporous silicas. Finally, some solvents were evaluated to carried out dye desorption from the TBO-loaded mesoporous silicas founding that acetic acid was the most efficient. 相似文献
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《水科学与水工程》2021,14(4):286-294
Fruit peels, which are common agricultural byproducts, have been extensively used as abandoned or low-cost biosorbents to remove heavy metals. In this study, dragon fruit peel (DFP), rambutan peel (RP), and passion fruit peel (PFP) were used to remove Cu(II) ions from an aqueous solution. Concentrations of the adsorbed metal ions were determined using the atomic absorption spectroscopic method. Adsorption experiments were performed with different adsorbent dosages, pH values, contact times, and initial copper concentrations. The optimum set of conditions for biosorption of Cu(II) ions was found to be an adsorbent dosage of 0.25 g, a contact time of 180 min, an initial concentration of 100 mg/L, a pH value of 4 for RP and PFP, and a pH value of 5 for DFP. The adsorption conformed with the pseudo-second-order kinetic model. The adsorption data were consistent with the Langmuir and Freundlich isotherm models, but the best fit was with the Langmuir model. The Langmuir monolayer adsorption capacity values of DFP, RP, and PFP were calculated to be 92.593, 192.308, and 121.951 mg/g, respectively. RP showed a higher adsorption capacity of Cu(II) ions than PFP and DFP for all parameters. The results indicate that these biosorbents might be used to effectively adsorb Cu(II) ions from wastewater treatment plants. 相似文献
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Coal fly ash(CFA)is composed of minerals containing some oxides in crystalline phase(i.e.,quartz and mullite),as well as unburned carbon as mesoporous material,thus enabling CFA to act as a dual-sites adsorbent with unique properties.This work focused on the adsorption of Pb(Ⅱ)and Zn(Ⅱ)from binary system,a mixture containing two metal ion solutions present simultaneously,onto NaOH-modified CFA(MCFA).Several adsorption tests were conducted to evaluate the effect of several parameters,includ-ing pH and contact times.The experiment results indicated that chemical treatment of CFA with NaOH increased pore volume from 0.021 to 0.223 cm3 g-1.In addition,it could also enhance the availability of functional groups on both minerals and unburned carbon,resulting in almost 100%Pb(Ⅱ)and 97%Zn(Ⅱ)adsorbed.The optimum pH for adsorption system was pH=3 and quasi-equilibrium occurred in 240 minutes.Equilibrium data from the experimental results were analyzed using Modified Extended Langmuir(MEL)and Competitive Adsorption Langmuir-Langmuir(CALL)isotherm models.The analysis results showed that the CALL isotherm model could better describe the Pb(Ⅱ)and Zn(Ⅱ)adsorption pro-cess onto MCFA in binary system compared with MEL isotherm model. 相似文献
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研究制备了海绵负载纳米Al2O3微球的复合吸附剂(NAS),并用于对Se(Ⅳ)和Se(Ⅵ)的吸附。结果表明,合成的纳米Al2O3微球(NAO)的平均尺寸为200~400 nm,在海绵上负载NAO会使其分散性更好。当NAO负载量分别为80 mg/g和60 mg/g时,NAS对Se(Ⅳ)和Se(Ⅵ)的吸附性能为佳,分别需要60、120 min达到平衡,适应pH为2~5;两者均符合准2级动力学模型;NAS对Se(Ⅳ)、Se(Ⅵ)的最大吸附容量分别为137.2、143.9 mg/g,能很好地与Freundlich模型拟合,说明NAS表面不均匀,且属于多层吸附。经过2次的循环,对Se(Ⅳ)和Se(Ⅵ)的去除率有所降低,但均仍保持在一定的水平,说明NAS可再生循环利用。NAS作为一种新型吸附剂去除水中Se具有较好的应用前景。 相似文献
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Hydrogels for absorbing metal ions in wastewater have attracted more attentions in the environmental field especially for recent years. The removal efficiency of hydrogel adsorbents for eliminating metal ions is highly related with the effective contact between adsorbents and adsorbates. However, poor water absorption capacity of the hydrogel adsorbents would restrict on the expose of adsorption sites to the targeted subjects, causing undesirable removal ratio (RR) especially for metal ions at trace level. Thereby, the reported hydrogel adsorbents mainly focus on the removal of high content but not the trace level of metal ions so far. In this work, poly(acrylamide) (PAM)/poly(acrylic acid) (PAA)/Ca(OH)2 composite hydrogel is applied to adsorb trace metal ions. Swelling ratio of such PAM/PAA/Ca(OH)2 gel reaches 2,530 g/g, resulting in effective exposure of active sites and further expected RR for trace metal ions. The RRs of such adsorbent for Cu2+ (initial concentration C0 = 0.064 mg/L), Al3+ (C0 = 0.27 mg/L), Co2+ (C0 = 0.59 mg/L), Cr6+ (C0 = 0.52 mg/L), Mn2+ (C0 = 0.55 mg/L), Ni2+ (C0 = 0.59 mg/L), Zn2+ (C0 = 0.65 mg/L), Ag+ (C0 = 1.08 mg/L), and La3+ (C0 = 1.39 mg/L) are 56.6, 80.8, 41.3, 29.3, 34.6, 44.6, 55.9, 45.8, and 35.5%, respectively. This work broadens the application of hydrogel adsorbent for eliminating trace metal ions from polluted water. 相似文献
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Yanan Zhang Wei Kang Hongjing Han Haiying Wang Yanguang Chen Xuzhong Gong Changxiu Zhai Hua Song 《Journal of the American Ceramic Society》2019,102(12):7665-7677
Here, a novel approach has been proposed to synthesize NaP zeolite adsorbents doped with transition metals (M-NaP) using the Na2SiO3 and NaAlO2 compounds extracted from fly ash via activation and stage treatment. The preparation process of M-NaP employed the in-situ synthesis in combination with organic complexation method. The effects of the addition amounts and valence state of transition metals on the zeolite products were investigated. The crystalline phase, morphology, and particle size of M-NaP were characterized using X-ray diffractometry (XRD), Scanning electron microscopy (SEM), and Laser particle size analyzer (PSD). The doping process was investigated using X-ray photoelectron spectroscopy (XPS) and Materials Studio. The adsorption performance of M-NaP was tested by the adsorption of Zn2+. The optimal molar ratio of n(Al2O3)/n(M) was identified as 8:1 for Co–NaP, Ni–NaP, and Fe–NaP, compared with 6:1 for Ti–NaP. The influence of transition metals on adsorption was: Co–NaP > Ni–NaP > Ti–NaP > Fe-NaP. Due to largest surface area of Co–NaP (162.5 m2/g, five times than that of NaP-RAW), the maximum removal rate of Zn2+ was above 99.50% at 25°C. The existence state of transition metals in M-NaP primarily included: isomorphous substitution and balance of the skeletal charge, with the latter in majority. The simulation of Materials Studio indicates that Si at T4 was first substituted and then, Si at T3 opposite T4 was replaced when the replacement of Si in different sites occurred. 相似文献