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1.
A novel nanoadsorbent for the removal of heavy metal ions is reported.Cotton was first hydrolyzed to obtain cellulose nanocrystals(CNCs).CNCs were then chemically modified with succinic anhydride to obtain SCNCs.The sodic nanoadsorbent(NaSCNCs) was further prepared by treatment of SCNCs with saturated NaHCO 3 aqueous solution.Batch experiments were carried out with SCNCs and NaSCNCs for the removal of Pb 2+ and Cd 2+.The effects of contact time,pH,initial adsorption concentration,coexisting ions and the regeneration performance were investigated.Kinetic studies showed that the adsorption equilibrium time of Pb 2+ and Cd 2+ was reached within 150 min on SCNCs and 5 min on NaSCNCs.The adsorption capacities of Pb 2+ and Cd 2+ on SCNCs and NaSCNCs increased with increasing pH.The adsorption isotherm was well fitted by the Langmuir model.The maximum adsorption capacities of SCNCs and NaSCNCs for Pb 2+ and Cd 2+ were 367.6 mg/g,259.7 mg/g and 465.1 mg/g,344.8 mg/g,respectively.SCNCs and NaSCNCs showed high selectivity and interference resistance from coexisting ions for the adsorption of Pb 2+.NaSCNCs could be efficiently regenerated with a mild saturated NaCl solution with no loss of capacity after two recycles.The adsorption mechanisms of SCNCs and NaSCNCs were discussed.  相似文献   

2.
利用离子交联和自由基聚合反应制备了一种海藻酸锆/聚(N-异丙基丙烯酰胺)半互穿网络凝胶球(ZA/PNIPAM),用于吸附水中的磷酸盐.考察了溶液初始pH、吸附剂投加量、初始磷酸盐浓度和共存阴离子等因素对凝胶球吸附性能的影响.结果表明:ZA/PNIPAM在pH=2时可获得较大的吸附能力;随着投加量的减少、初始磷酸盐浓度的升高,凝胶球的吸附性能逐渐增大;SO_4~(2-)对吸附性能影响较Cl~-和NO_3~-明显.准二级动力学模型和颗粒内部扩散模型可以较好地拟合动力学吸附数据,表明表面吸附和颗粒内部扩散是吸附速率的主要控制步骤.吸附等温线数据可以较好地被Freundlich模型描述,表明吸附过程为非均匀多分子层吸附.FTIR、XPS、零电荷点(pH_(pzc))的结果以及相关吸附数据揭示凝胶球吸附磷酸盐的机制为静电吸附(物理吸附)以及配位交换(化学吸附)的共同作用.经过4次循环再生后,ZA/PNIPAM吸附性能保持稳定,具有良好的重复使用性.  相似文献   

3.
非活性黑根霉菌对废水中重金属离子的吸附   总被引:18,自引:1,他引:17  
屠娟  张利  赵力  俞耀庭 《环境科学》1995,16(1):12-15
为探讨发酵工业中废弃的菌丝体黑根霉菌(Rhizopusnigricans)对水中重金属离子的吸附特性,考察pH、浓度、共存离子等因素对吸附能力的影响,进行了实验室吸附试验,绘制出吸附等温线,并由Langmuir曲线和Freundlich曲线求出相应参数。对化学改性前后的黑根霉进行了吸附对比。初步分析了吸附机理。结果表明,黑根霉在pH=3—6.5范围内,对Pb2+、Cu2+、Mn2+、Cr(VI)几种主要重金属离子都有吸附作用,其中吸附Pb2+能力最高,饱和吸附量可达88mg/g。经化学改性的黑根霉可不同程度地提高吸附能力。用0.5mol/LHCI和NaoH可以洗脱和再生。  相似文献   

4.
The adsorption behavior of 2-mercaptobenzothiazole onto organo-bentonite was investigated.Natural bentonite from Gaozhou in Guangdong Province,China was collected.Organo-bentonite was prepared by intercalation of cetyltrimethyl ammonium bromide into the natural bentonite.The physicochemical properties of the prepared organo-bentonite were characterized by X-ray diffraction,N2 adsorption-desorption isotherm and Fourier transform infrared spectroscopy.The results showed that montmorillonite is the main component of the natural bentonite.The basal spacing of the natural bentonite is 1.47 nm,which increased to 1.98 nm on intercalation with cetyltrimethyl ammonium bromide.Moreover,both the surface area and pore volume increased with intercalation.Clear CH2 stretching(3000-2800 cm-1) and scissoring(1480-1450 cm-1) modes of the intercalated surfactants were observed for organobentonite.Compared with the pseudo first-order kinetic model,the pseudo second-order kinetic model is more suitable to describe the adsorption kinetics of 2-mercaptobenzothiazole onto organo-bentonite.The adsorption capacity of 2-mercaptobenzothiazole onto organo-bentonite increased with increasing initial concentration of 2-mercaptobenzothiazole,but decreased with increasing adsorbent dosage.The adsorption isotherm of 2-mercaptobenzothiazole onto organo-bentonite fits well with the Langmuir model.The maximum adsorption capacity of organo-bentonite for 2-mercaptobenzothiazole was 33.61 mg/g,indicating that organo-bentonite is a promising adsorbent for 2-mercaptobenzothiazole.  相似文献   

5.
Low-cost activated carbons (ACs) were prepared from four kinds of solid wastes: petroleum coke, Enteromorpha prolifera, lignin from papermaking black liquid and hair, by pyrophosphoric acid (H4P2O7) activation. Thermo-gravimetric analysis of the pyrolysis of H4P2O7-precursor mixtures implied that H4P2O7 had different influences on the pyrolysis behavior of the four raw materials. N2 adsorption/desorption isotherms, scanning electron microscopy, Fourier transform infrared spectroscopy and adsorption capacities for dyes were used to characterize the prepared activated carbons. AC derived from E. prolifera exhibited the highest surface area (1094 m2/g) and maximum monolayer adsorption capacity for malachite green (1250 mg/g). Kinetic studies showed that the experimental data were in agreement with the pseudo-second-order model. The adsorption isotherms were well described by the Langmuir isotherm model, indicating the adsorption of dye onto the ACs proceeded by monolayers.  相似文献   

6.
Accelerating the (NH4)2SO3 oxidation gives rise to the reclaiming of byproduct, while there are secondary environmental risks from reduction of the coexisted selenium species by sulfite. In this study, a bi-functional Co-SBA-15-SH, were synthesized through Co impregnation and sulfhydryl (-SH) decoration, which can simultaneously uptake Se and accelerate sulfite oxidation efficiently. Meanwhile, the adsorption kinetics and migration mechanism of Se species were revealed through characterization and density functional calculations, with maximum adsorption capacity of 223 mg/g. The inhibition of Se0 re-emission and poisonous effect of Se on sulfite oxidation was also investigated. Using the findings of this study, the ammonia desulfurization can be improved by enabling purification of the byproduct and lowering the toxicity of effluent by removing toxic pollutants.  相似文献   

7.
Na-rich birnessite (NRB) was synthesized by a simple synthesis method and used as a high-efficiency adsorbent for the removal of ammonium ion (NH4+) from aqueous solution. In order to demonstrate the adsorption performance of the synthesized material, the effects of contact time, pH, initial ammonium ion concentration, and temperature were investigated. Adsorption kinetics showed that the adsorption behavior followed the pseudo second-order kinetic model. The equilibrium adsorption data were fitted to Langmuir and Freundlich adsorption models and the model parameters were evaluated. The monolayer adsorption capacity of the adsorbent, as obtained from the Langmuir isotherm, was 22.61 mg NH4+-N/g at 283 K. Thermodynamic analyses showed that the adsorption was spontaneous and that it was also a physisorption process. Our data revealed that the higher NH4+ adsorption capacity could be primarily attributed to the water absorption process and electrostatic interaction. Particularly, the high surface hydroxyl-content of NRB enables strong interactions with ammonium ion. The results obtained in this study illustrate that the NRB is expected to be an effective and economically viable adsorbent for ammonium ion removal from aqueous system.  相似文献   

8.
通过批量吸附实验考察了锆负载颗粒沸石改良底泥对水中磷酸盐的吸附特征,并采用分级提取法分析了被改良底泥中锆负载颗粒沸石所吸附磷酸盐的形态分布特征.结果发现,与Freundlich和Dubinin-Radushkevich模型相比,Langmuir模型可以更好地用于描述改良底泥对水中磷酸盐的吸附等温行为.改良底泥对水中磷酸盐的吸附动力学过程可以较好地采用准二级动力学模型和Elovich模型加以描述,膜扩散和颗粒内扩散共同构成了缓慢吸附阶段速率的限制步骤.溶液共存的SO_4~(2-)和HCO_3~-降低了改良底泥对水中磷酸盐的吸附,而共存的Na~+、K~+、Mg~(2+)和Ca~(2+)却增强了对磷酸盐的吸附,且Ca~(2+)的增强效果大于Mg~(2+),后者的增强效果又大于Na~+和K~+.改良底泥对水中磷酸盐的吸附能力明显强于未改良底泥,前者的最大单位吸附量为336 mg·kg~(-1),明显高于后者的最大单位吸附量(215 mg·kg~(-1)).被改良底泥中锆负载颗粒沸石所吸附的磷酸盐主要以较为稳定的NaOH-P和最为稳定的Res-P形态存在,不容易被重新释放出来.上述的研究结果显示,向底泥中添加锆负载颗粒沸石可以显著增加底泥对水中磷酸盐的吸附能力,锆负载颗粒沸石是一种有希望的可以用于底泥内源磷释放控制的底泥改良剂.  相似文献   

9.
A fibrous strong base anion exchanger (QAPPS) was prepared for the first time via chloromethylation and quaternary amination reaction of polyphenylene sulfide fiber (PPS), and its physical-chemical structure and adsorption behavior for Cr(VI) were characterized by FT-IR, Energy Dispersive Spectrometry, TG-DTG, elemental analysis and batch adsorptive technique, respectively. The novel fibrous adsorbent could effectively adsorb Cr(VI) over the pH range 1-12, the maximum adsorption capacity was 166.39 mg/g at pH 3.5, and the adsorption behavior could be described well by Langmuir isotherm equation model. The adsorption kinetics was studied using pseudo first-order and pseudo second-order models, and the t1/2 and equilibrium adsorption time were 5 and 20 min respectively when initial Cr(VI) concentration was 100 mg/L. The saturated fibers could be regenerated rapidly by a mixed solution of 0.5 mol/L NaOH and 0.5 mol/L NaCl, and the adsorption capacity was well maintained after six adsorption-desorption cycles.  相似文献   

10.
郑雯婧  林建伟  詹艳慧  王虹 《环境科学》2015,36(6):2185-2194
采用锆(Zr)和阳离子表面活性剂十六烷基三甲基氯化铵(CTAC)对活性炭进行联合改性,考察了所制备的Zr-CTAC改性活性炭对水中硝酸盐和磷酸盐的吸附去除作用,并探讨了相关的吸附去除机制.结果表明,Zr-CTAC改性活性炭对水中硝酸盐和磷酸盐均具备较好的吸附去除能力.Zr-CTAC改性活性炭对硝酸盐和磷酸盐吸附动力学过程满足准二级动力学模型.Langmuir、Freundlich和Dubinin-Radushkevich(D-R)等温吸附模型可以较好地描述Zr-CTAC改性活性炭对水中硝酸盐的等温吸附过程,Langmuir和D-R等温吸附模型可以较好地描述Zr-CTAC改性活性炭对水中磷酸盐等温吸附过程,通过Langmuir模型计算得到吸附剂对硝酸盐和磷酸盐的最大单位吸附量分别为7.58 mg·g-1和10.9 mg·g-1.高的p H会抑制Zr-CTAC改性活性炭对水中硝酸盐和磷酸盐的吸附.水中共存的Cl-、HCO-3和SO2-4等阴离子均会抑制Zr-CTAC改性活性炭对硝酸盐和磷酸盐的吸附,且对吸附硝酸盐的抑制作用较强而对吸附磷酸盐的抑制作用较弱.水中共存的磷酸盐对Zr-CTAC改性活性炭吸附硝酸盐的抑制作用较强,而水中共存的硝酸盐对Zr-CTAC改性活性炭吸附磷酸盐的抑制作用较弱.1 mol·L-1Na Cl溶液可以使90%左右被吸附到Zr-CTAC改性活性炭表面上的硝酸盐解吸下来.1 mol·L-1的Na OH溶液可以使78%左右被吸附到Zr-CTAC改性活性炭表面上的磷酸盐解吸下来.Zr-CTAC改性活性炭对硝酸盐的吸附机制主要包括阴离子交换作用和静电吸引作用,对磷酸盐的吸附机制主要包括配位体交换作用、阴离子交换作用和静电吸引作用.上述结果说明Zr-CTAC改性活性炭适合作为一种吸附剂去除废水中的硝酸盐和磷酸盐.  相似文献   

11.
Phosphate is one of the most predominant pollutants in natural waters. Laboratory experiments were conducted to investigate the phosphate adsorption performance of a(NFS) made from drinking water treatment residuals. The adsorption of phosphate on the NFS fitted well with the Freundlich isotherm and pseudo second-order kinetic models. At p H 7.0, the maximum adsorption capacity of 1.03 mg/g was achieved at 15°C corresponding to the wastewater temperature in cold months, and increased notably to 1.31 mg/g at 35°C.Under both acidic conditions(part of the adsorption sites was consumed) and basic conditions(negative charges formed on the surface of NFS, which led to a static repulsion of PO43-and HPO42-), the adsorption of phosphate was slightly inhibited. Further study showed that part of the adsorption sites could be recovered by 0.25 mol/L Na OH. The activation energy was calculated to be above 8.0 k J/mol, indicating that the adsorption of phosphate on NFS was probably a chemical process. Considering the strong phosphate adsorption capacity and recoverability, NFS showed great promise on enhancing phosphate removal from the secondary treated wastewater in the filtration process.  相似文献   

12.
The development of low-cost and efficient new mineral adsorbents has been a hot topic in recent years. In this study, Friedel’s salt (FS:3CaO·A12O3 ·CaCl2 ·10H2O), a hexagonal layered inorganic absorbent, was synthesized to remove Cd2+ from water. The adsorption process was simulated by Langmuir and Freundlich models. The adsorption mechanism was further analyzed with TEM, XRD, FT-IR analysis and monitoring of metal cations released and solution pH variation. The results indicated the adsorbent FS had an outstanding ability for Cd(Ⅱ) adsorption. The maximum adsorption capacity of the FS for Cd(Ⅱ) removal can reach up to 671.14 mg/g. The nearly equal numbers of Cd2+ adsorbed and Ca2+ released demonstrated that ion-exchange (both surface and inner) of the FS for Cd(Ⅱ) played an important role during the adsorption process. Furthermore, the surface of the FS after adsorption was microscopically disintegrated while the inner lamellar structure was almost unchanged. The behavior of Cd(Ⅱ) adsorption by FS was significantly affected by surface reactions. The mechanisms of Cd2+ adsorption by the FS mainly included surface complexation and surface precipitation. In the present study, the adsorption process was fitted better by the Langmuir isotherm model (R2 = 0.9999) than the Freundlich isotherm model (R2 = 0.8122). Finally, due to the high capacity for ion-exchange on the FS surface, FS is a promising layered inorganic adsorbent for the removal of Cd(Ⅱ) from water.  相似文献   

13.
灼烧净水污泥对外源磷的吸附和固定作用   总被引:1,自引:1,他引:0  
于胜楠  李勇  李大鹏  黄勇 《环境科学》2017,38(9):3962-3969
研究了不同投加方式下(混匀和覆盖)灼烧净水污泥对外源磷的累积吸附效果,以及吸附外源磷后底泥等温吸附效果和在厌氧条件下内源磷释放情况.结果表明,混匀和覆盖条件下,底泥对上覆水中磷的累积吸附量分别为11.496 mg和11.042 mg,明显高于对照实验(7.219 mg).通过对吸附外源磷后的底泥进行等温吸附实验,发现混匀条件和覆盖条件下磷最大吸附量(Smax)均有所增加,并且前者(7.795 mg·g~(-1))要高于后者(6.807 mg·g~(-1)),但磷平衡浓度(EPC0)前者(0.83mg·L~(-1))却明显大于后者(0.64 mg·L~(-1)),表明混匀条件下内源磷更容易释放.在厌氧环境下,混匀方式内源磷释放量仅为0.93 mg,不仅低于覆盖(1.49 mg),也明显低于对照实验(7.76 mg).覆盖条件下比释放速率的平均值(0.006 14)大于混匀(0.003 96),并均低于对照实验.这说明混匀对内源磷的持留能力更强.暗示了单纯用EPC0值来评价底泥对磷的固定能力是不妥的.  相似文献   

14.
研究了沉淀pH值分别为4.8、8.0和10.6条件下制备的水合氧化锆对水中磷酸盐的吸附作用,结果表明,共存的Na~+仅仅略微促进了沉淀pH值为4.8和8.0时所得水合氧化锆对水中磷酸盐的吸附,却明显促进了沉淀pH值为10.6时所得水合氧化锆对磷酸盐的吸附.共存的Ca~(2+)仅仅略微促进了沉淀pH值为4.8时水合氧化锆对磷酸盐的吸附,却极大地促进了沉淀pH值为8.0和10.6时水合氧化锆对磷酸盐的吸附.共存的HCO_3~-和SO_4~(2-)抑制了水合氧化锆对磷酸盐的吸附,且它们对沉淀pH值为4.8时水合氧化锆吸磷的抑制作用明显大于对沉淀pH值为8.0和10.6时水合氧化锆的抑制作用.不同沉淀pH值条件下制备的水合氧化锆对水中磷酸盐的吸附能力均随着溶液pH值的增加而降低.不同沉淀pH值条件下所得水合氧化锆对水中磷酸盐的吸附平衡数据可以采用Langmuir、Freundlich和Dubinin-Redushckevich(D-R)等温吸附模型加以描述.存在Na+而不存在Ca~(2+)情况下,3种不同沉淀pH值条件下所得水合氧化锆对中性溶液中磷酸盐的最大单层吸附容量差别不大;存在Ca~(2+)情况下,沉淀pH值为8.0和10.6时所得水合氧化锆对中性溶液中磷酸盐的最大单层吸附容量远远高于沉淀pH值为4.8时制备的水合氧化锆.沉淀pH值为4.8和8.0时所得水合氧化锆的吸磷机制主要是表面氯和羟基基团与磷酸盐之间的配位体交换作用,而沉淀pH值为10.6时所得水合氧化锆的吸磷机制主要是表面羟基基团与磷酸盐之间的配位体交换作用.以上研究结果显示,与沉淀pH值为4.8时制备的水合氧化锆相比,沉淀pH值为8.0和10.6时制备的水合氧化锆更加适合作为吸附剂去除废水中的磷酸盐.  相似文献   

15.
In this work, magnesium silicate-based sulfonated polystyrene sphere composites (SPS/MgSi) were synthesized by one-step (SMD1) and two-step (SMD2) methods. For SMD1, MgSi particles were densely assembled on the surface of SPS, assisted by complexation between Fe3+ and hydroxyl phenol. For SMD2, SPS/SiO2 was firstly obtained by the same method as SMD1, and then SPS/SiO2 was transformed directly to SPS/MgSi under hydrothermal conditions. Therefore, MgSi obtained by the two-step method had an interwoven structure. Compared to SPS, MgSi and SMD1, SMD2 presented a larger specific surface area and more negative surface charges. Therefore, SMD2 showed superior adsorption performance toward CIP with concentrations of 5, 10 and 50 mg/L, and for 50 mg/L, the equilibrium adsorption capacity could reach 329.7 mg/g. The adsorption process is fast and can be described by the pseudo-second-order kinetic model. The relationship between pH value and Zeta potential demonstrated that electrostatic interaction dominated the adsorption process. In addition, competitive adsorption showed that the effect of Na+ was negligible but the effect of Ca2+ was dependent on its concentration. Humid acid (HA) could slightly promote the absorption of CIP by SMD2. After five rounds of adsorption-desorption, the equilibrium adsorption capacity of SMD2 still remained at 288.6 mg/L for 50 mg/L CIP. Notably, SMD2 presented likewise superior adsorption capacity for CIP with concentrations of 10 and 50 mg/L in Minjiang source water. All the results indicated that this synthesis method is universal and that SMD2 has potential as an adsorbent for CIP removal from aquatic environments.  相似文献   

16.
选用阳离子表面活性剂十六烷基三甲基氯化铵(CTAC)改性膨润土以提高膨润土对ClO4-的吸附能力.试验结果表明,CTAC改性能显著提高膨润土对ClO4-的吸附能力,在0.1~l mmol·L-1的C1O4-溶液中,6h内能迅速达到吸附平衡.有机膨润土对ClO4-的吸附最符合Langmuir等温吸附模型,其吸附容量可达0.48 mmol·g-1.pH值在4~10范围内变化对ClO-的吸附几乎没有影响.高的分配系数(Kd>1.5×103cm3·g-1)表明有机膨润土对ClO4-有很高的选择性,各阴离子的分配系数从小到大的顺序为HPO42-< SO42-< NO3-< ClO4-,这与阴离子的自由水合能大小相一致.1 mol·L-1 HCl溶液对吸附剂的再生效率在96%左右,可直接使用,不用再改性.  相似文献   

17.
一种纳米级不定形碳对水中四环素的吸附研究   总被引:1,自引:0,他引:1  
研究了一种新型纳米级不定形碳对水中四环素的吸附作用.结果表明,在Li-Na-K碳酸盐的共熔体系中生成的碳粉对四环素表现出了良好的吸附性能.在298K下,碳粉对四环素的吸附行为更符合拟二级动力学模型和Freundlich吸附等温线,最大吸附容量达到127.76 mg·g-1.热力学计算结果表明,吸附过程是吸热的、自发的,以化学吸附为主.吸附行为表现出明显的p H依赖性,当溶液的起始p H在2~11,p H为4时碳粉对四环素的吸附量最大.溶液中的阳离子对吸附有一定的影响,但影响不大,随着阳离子浓度的增加,吸附量在一定程度上逐渐减小.离子交换作用可能是吸附的原理之一,还可能同时存在静电引力、氢键等作用.分别使用0.25 mol·L-1的Ca Cl2和Na Cl溶液进行解吸实验,解吸效率在7.42%~25%,解吸效率较低,说明吸附的化学作用较强.  相似文献   

18.
黑藻吸附Cu2+机制研究   总被引:3,自引:0,他引:3  
生物吸附法是一种经济有效的去除废水中有害重金属离子的方法.以黑藻(Hydrilla verticillata)干样为生物吸附材料,研究了黑藻对水体中Cu<'2+>等温吸附的基本特征,并通过测定吸附前后溶液离子浓度变化以及pH值、基团屏蔽对Cu<'2+>吸附的影响,结合红外光谱技术,从静电吸附作用、离子交换作用、基团作用...  相似文献   

19.
Pollution of antibiotics, a type of emerging contaminant, has become an issue of concern, due to their overuse in human and veterinary application, persistence in environment and great potential risk to human and animal health even at trace level. In this work, a novel adsorbent, Fe3O4 incorporated polyacrylonitrile nanofiber mat (Fe-NFM), was successfully fabricated via electrospinning and solvothermal method, targeting to remove tetracycline (TC), a typical class of antibiotics, from aqueous solution. Field emission scanning electron microscopy and X-ray diffraction spectroscopy were used to characterize the surface morphology and crystal structure of the Fe-NFM, and demonstrated that Fe-NFM was composed of continuous, randomly distributed uniform nanofibers with surface coating of Fe3O4 nanoparticles. A series of adsorption experiments were carried out to evaluate the removal efficiency of TC by the Fe-NFM. The pseudo-second-order kinetics model fitted better with the experimental data. The highest adsorption capacity was observed at initial solution pH 4 while relative high adsorption performance was obtained from initial solution pH 4 to 10. The adsorption of TC on Fe-NFM was a combination effect of both electrostatic interaction and complexation between TC and Fe-NFM. Freundlich isotherm model could better describe the adsorption isotherm. The maximum adsorption capacity calculated from Langmuir isotherm model was 315.31 mg/g. Compared to conventional nanoparticle adsorbents which have difficulties in downstream separation, the novel nanofiber mat can be simply installed as a modular compartment and easily separated from the aqueous medium, promising its huge potential in drinking and wastewater treatment for micro-pollutant removal.  相似文献   

20.
Synthesis and high adsorption and selectivity performance of lead ion-imprinted micro-beads with combination of two functional monomers.  相似文献   

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