聚多巴胺包覆的磁性碳纳米管对水中Ni~(2+)的吸附作用

以碳纳米管(MWNTs)、多巴胺、硫酸亚铁铵、硫酸铁铵为主要原材料,采用化学共沉淀法制备磁性碳纳米管(mMWNTs),通过多巴胺原位氧化聚合到磁性碳纳米管表面上,生成改性材料聚多巴胺(PDA)包覆的磁性碳纳米管(mMWNTs@PDA)。并采用红外光谱(FTIR)、扫描电镜(SEM)对其进行表征。考察了改性后材料在pH、反应时间、温度、初始浓度因素下对水中Ni⁽²⁺⁾的吸附,同时对吸附数据进行吸附动力学和吸附等温线分析。结果表明,改性材料对水溶液中Ni(2+)的吸附,同时对吸附数据进行吸附动力学和吸附等温线分析。结果表明,改性材料对水溶液中Ni⁽²⁺⁾的吸附过程更符合准二级动力学模型(R(2+)的吸附过程更符合准二级动力学模型(R²=0.998 9)和Freundlich等温吸附模型(R2=0.998 9)和Freundlich等温吸附模型(R²=0.996 1)。最后考察改性材料的重复利用性能,实验结果证明经循环再生5次后仍然具有较好的吸附性能。     

CTAB改性铁柱撑膨润土对苯酚的吸附

为了研究膨润土对含酚废水的吸附性能,采用羟基铁柱撑剂对钠基膨润土进行预改性,随后用十六烷基三甲基溴化铵(CTAB)改性,制备CTAB改性铁柱撑膨润土。利用X射线衍射仪(XRD)、红外光谱仪(FTIR)和场发射扫描电镜(FESEM)对改性膨润土的结构和性能进行表征。考察了吸附剂用量、吸附时间、吸附温度、苯酚初始浓度和pH值对吸附性能的影响,研究了吸附热力学和吸附动力学规律。结果表明,CTAB进入铁柱撑膨润土的层间和表面。当吸附剂用量为3 g·L^-1、吸附时间为60 min、吸附温度为25 ℃、苯酚初始浓度为300 mg·L^-1、苯酚初始pH值为7时,改性膨润土吸附量达到29.7 mg·g^-1,吸附过程符合准二级动力学模型和Freundlich热力学模型。     

盐酸改性膨润土处理含镉废水的研究

用盐酸对膨润土进行活化改性制得酸改性膨润土,在静态吸附条件下研究其对模拟水样中镉离子的吸附条件和吸附机理。结果表明,经盐酸改性后的膨润土对镉离子的吸附性能得到一定程度提高,吸附最佳条件:pH=8,模拟水溶液中镉离子浓度20 mg/L,反应时间30 min。二级动力学方程和Freundlich吸附等温线方程能较好地描述酸改性膨润土吸附镉离子的反应过程。     

盐酸改性膨润土处理含镉废水的研究

用盐酸对膨润土进行活化改性制得酸改性膨润土,在静态吸附条件下研究其对模拟水样中镉离子的吸附条件和吸附机理。结果表明,经盐酸改性后的膨润土对镉离子的吸附性能得到一定程度提高,吸附最佳条件:pH=8,模拟水溶液中镉离子浓度20 mg/L,反应时间30 min。二级动力学方程和Freundlich吸附等温线方程能较好地描述酸改性膨润土吸附镉离子的反应过程。     

玉米秸秆活性炭的制备及其吸附含氮废水性能探析

采用玉米秸秆作为制备原料,KHCO₃为活化剂、HCl作为改性试剂制备改性玉米秸秆活性炭,吸附含氮废水,进行物理表征以及吸附动力学性能分析。本实验采取Freundlich与Langmuir模型对等温吸附曲线进行线性拟合,实验数据结果表明,玉米秸秆活性炭对氮素的吸附更加符合Freunglich方程,拟合相关性较好,R²=0.998。随后采用Lagergren准一级及准二级动力学速率模型对活性炭吸附氮素溶液动力学拟合,实验结果表明,Lagergren准二级速率模型可以最准确地描述吸附过程,其中R²=0.95。玉米秸秆活性炭对氨氮的最大吸附量常数达到407.51 mg·g^-1,表明吸附能力较强。     

复合改性膨润土的制备及吸附苯胺的特性

选用不同碳链长度及不同类型的表面活性剂与聚合羟基铝对膨润土进行复合改性,表明长碳链表面活性剂制备的复合改性样品相对于短碳链表面活性剂制备的复合改性样品对苯胺有较好的吸附效果,阴离子表面活性剂制备的复合改性样品比阳离子表面活性剂制备的复合改性样品对苯胺有更好的吸附效果。采用正交试验得到的最优复合改性样品吸附苯胺,表明样品对苯胺的吸附符合准二级动力学模型(R2≈1),粒内扩散并不是控制吸附的惟一限速步骤,Freundlich等温线模型比Langmuir等温线模型更适合描述吸附过程,吸附过程为吸热物理过程(△Hθ=9.39 k J·mol-1)。     

铅在土壤中的吸附特性及形态分布研究

采用动力学吸附模型和等温吸附模型,并结合BCR形态法和红外光谱方法,探究土壤对铅的吸附效果以及在土壤中的形态分布。结果表明,土壤中有机物质活性位点发生偏移,有机质组分能够吸持部分铅,但所吸附铅含量较少;铅在土壤中的吸附符合准二级动力学(R²=0.997 6)和Freundlich等温模型(R²=0.988 2),铅的最大吸附量为72.68 mg/g,主要以化学吸附为主;土壤中的铁锰氧化物对铅的吸附量最高能达到85.27%,因此,土壤中的铁锰氧化物可以作为良好的稳定化药剂运用于修复铅污染土壤。     

改性膨润土对重金属的吸附性能研究

膨润土是垃圾填埋场垫层的主要吸附、防渗材料之一,对土进行不同程度改性可提高对垃圾渗滤液中含量较高的重金属(Cr⁶⁺、Cu²⁺、Zn²⁺)的吸附性能。采用十六烷基三甲基溴化铵(CTMAB)对钠基膨润土进行有机改性制得CTMAB-Bent,再利用聚丙烯酰胺(CPAM)对CTMAB-Bent复合改性后制得CPAM-Bent。通过设计正交实验,研究了不同因素(改性剂浓度、膨润土用量、吸附时间、吸附温度和离子浓度)对吸附性能的影响,以探讨吸附机理。结果表明,CPAM-Bent与CTMAB-Bent和钠基膨润土相比,吸附性能最优,三种重金属吸附率均高于90%,且最优条件为：改性剂浓度为5.5%,膨润土用量0.5 g,时间45 min,温度25℃;吸附过程符合准二级动力学模型,吸附等温线与Langmuir模型相符,说明吸附过程按照单分子层吸附机理进行的,进一步通过拟合实验得知重金属(Cr⁶⁺、Cu²⁺、Zn²⁺)平衡吸附量分别为0.629、0.807、1.134 mg/...     

改性煤气化灰渣吸附重金属离子的研究

以煤气化灰渣为原料,采用酸改性法(HF酸)制备改性煤气化灰渣。通过静态实验研究了改性煤气化灰渣对溶液中Pb⁽²⁺⁾、Cu(2+)、Cu⁽²⁺⁾、Cd(2+)、Cd⁽²⁺⁾的吸附特性,测定了溶液pH值、吸附时间、金属离子初始浓度对吸附的影响。结果表明,二级动力学方程很好的描述溶液中重金属离子在改性煤气化灰渣上的吸附过程;吸附等温线符合Langmuir模型,Pb(2+)的吸附特性,测定了溶液pH值、吸附时间、金属离子初始浓度对吸附的影响。结果表明,二级动力学方程很好的描述溶液中重金属离子在改性煤气化灰渣上的吸附过程;吸附等温线符合Langmuir模型,Pb⁽²⁺⁾、Cu(2+)、Cu⁽²⁺⁾、Cd(2+)、Cd⁽²⁺⁾的静态饱和吸附量分别为112.07,40.18,31.21 mg/g。     

CTAB改性膨润土对苯酚的吸附

制备了有机改性膨润土—十六烷基三甲基溴化铵改性膨润土(CTAB-膨润土)。对CTAB-膨润土进行了表征,研究了影响CTAB-膨润土吸附苯酚的主要因素。结果表明,CTAB已成功进入了膨润土表面和层间,CTAB-膨润土的比表面积为53. 12 m~2/g。用5 g/L的吸附剂处理300 mg/L的苯酚,苯酚的去除率可达到92. 6%。CTAB-膨润土对苯酚的吸附符合Langmuir吸附等温模型,吸附量为55. 6 mg/g;苯酚的吸附符合拟二级动力学模型,吸附过程以表面吸附为主。     

Adsorption of Bezanyl Red and Nylomine Green from aqueous solutions by natural and acid-activated bentonite

The adsorption of two acid dyes, namely, Red Bezanyl and Green Nylomine, onto natural bentonite and acid activated bentonite from aqueous solutions were studied in a batch system. The kinetic data show that at the equilibrium, the acid-activated bentonite fixes more Bezanyl Red and Nylomine Green than the natural bentonite. Adsorption equilibrium was reached within 2 h. The results also showed that the kinetics of adsorption is best descibed by a pseudo second-order expression than a first or second-order model. Adsorption isotherms of acid dyes onto bentonite and acid-activated bentonite were determined and correlated with common isotherm equations such as the Langmuir and Freundlich models. The Langmuir model agrees very well with the experimental data. For better explanation of these results, the natural bentonite and acid-activated bentonite have been examined in detail through FTIR, BET and XRD analyses.     

Adsorption characteristics of metal-capture-agent immobilized PAC for low concentration Cr(Ⅵ) in water at low temperature

针对低温微污染水中(275 K)低浓度Cr(Ⅵ)离子(0.500 mg·L^-1),制备基于表面负载食品级单宁酸为金属捕获剂的改性PAC(TA-PAC),以HNO₃、NaOH氧化改性PAC为对照,研究了TA-PAC的表面物理化学特性和吸附性能,并进行了pH影响和吸附等温线拟合研究。结果表明:TA-PAC的比表面积、总孔容积和表面极性大小最佳。TA-PAC对低温水中Cr(Ⅵ)及总铬的去除效果优于N-PAC和OH-PAC。酸性范围内(pH=3.0~6.0)TA-PAC对Cr(Ⅵ)及总铬的去除率均大于碱性范围(pH=7.0~10.0)。Freundlich 双参数吸附等温式对TA-HNC吸附水中低浓度总铬的吸附等温线拟合效果最好(R²=0.9941)。TA-PAC吸附低温水中低浓度Cr(Ⅵ)是一个极为复杂的过程,主要吸附机理可能包括表面还原作用、酯化/螯合作用和离子交换作用等。     

Adsorption of phenol onto activated carbons having different textural and surface properties

Adsorption of phenol in aqueous phase onto activated carbons (ACs) having different textural and surface properties has been considered. Six types of ACs were used: three were commercial, and three were obtained from Kraft lignin chemically activated with sodium hydroxide, potassium hydroxide or ortho-phosphoric acid. The apparent surface areas of the commercial ACs varied from 620 to 1320 m²/g, while ACs made from lignin presented surface areas as high as 1300 m²/g and 2900 m²/g when prepared with H₃PO₄ and alkaline hydroxides, respectively; moreover, the highest proportion of microporosity was found for ACs derived from lignin. A kinetic study was carried out, showing that the phenol adsorption data may be correctly adjusted, for all the ACs tested, by an equation corresponding to a pseudo second-order chemical reaction. Freundlich, Langmuir and Tempkin equations were tested for modelling the adsorption isotherms at equilibrium, and it was concluded that Langmuir model fitted adequately the experimental data. However, Tempkin model fitted even better the adsorption data obtained with ACs derived from lignin activated with alkaline hydroxides, which are characterized by the highest number of surface groups. Remarkably high phenol adsorption capacities were found for the ACs prepared by activation of Kraft lignin with NaOH and KOH: 238 and 213 mg/g of AC, respectively. Finally, the adsorption of phenol was found to depend not only on the micropore volume, but also on the total amount of carbonyl and basic groups and on the ratio of acid to basic groups.     

Sulfamic acid functionalized slag for effective removal of organic dye and toxic metal from the aqueous samples

Surface functionalization of blast furnace slag with sulfamic acid(a zwitterion) was performed for the removal of Cr~(3+) and methylene blue dye(MB) from water samples. The slag functionalization process was optimized using Response Surface Methodology Design. Statistical analysis of the parameters that include the sulfamic acid amount(A), reaction time(B), and temperature(C) revealed that(A) increase had a negative effect on the adsorption of both pollutants by the zwitterion slag, whereas(B) and(C)increase presented a positive impact. At the optimum condition of 2 g sulfamic acid amount, 50 min reaction time and 37 °C temperature, the prepared slag showed a removal efficiency of more than 90% for both Cr~(3+) and MB. Surface characterization by SEM/EDS, FTIR, XPS and surface area analyser, showed an improvement in surface properties and the incorporation of zwitterionic NH_2~+ and S@O groups of sulfamic acid. Adsorption isotherm and kinetic studies conducted with the zwitterion slag showed the adsorption process was suited to Freundlich isotherm model and pseudo-second-order kinetic model.The thermodynamic study conducted revealed the spontaneity of the process based on the calculated negative DG(Gibb's free energy) values. The prepared zwitterion slag offered easy regeneration with dilute HCl solution and showed a considerable removal(Cr3+: 65% and MB: 80%) for both pollutants even after 3 cycles of usage.     

Adsorption equilibrium for Z-ligustilide on C18-bonded silica from supercritical carbon dioxide

Adsorption equilibrium is of great importance for the preparative supercritical fluid chromatography(pre-SFC) in defining supercritical adsorption behavior and the industrial amplification.This paper presents adsorption isotherms of Z-ligustilide from supercritical carbon dioxide(SC-CO_2) on C18-bonded silica.Adsorption behavior was studied at 305.15 K,313.15 K and 323.15 K with SC-CO_2 density varying from 0.687 g·cm~(-3) to0.863 g·cm~(-3) with the elution by characteristic points(ECP) method.The adsorption amount of Z-ligustilide from SC-CO_2 on C18-bonded silica decreased with the increasing density of the mobile phase as well as the increasing temperature.Adsorption equilibrium data were fitted by Langmuir and Freundlich isotherm models,and the Langmuir isotherm model performed better for describing the whole adsorption process on the column.The monolayer saturation adsorption capacity of Z-ligustilide is in the range of 3.0 × 10~(-4) mg·cm~(-3) to5.5 × 10~(-4) mg·cm~(-3) with an average value of 4.0 × 10~(-4) mg·cm~(-3).     

From pollutant to solution of wastewater pollution: Synthesis of activated carbon from textile sludge for dye adsorption

Adsorption is an important process in wastewater treatment,and conversion of waste materials to adsorbent offers a solution to high material cost related to the use of commercial activated carbon.This study investigated the adsorption behaviour of Reactive Black 5(RB5)and methylene blue(MB)onto activated carbon produced from textile sludge(TSAC).The activated carbon was synthesized through chemical activation of precursor followed with carbonization at 650°C under nitrogen flow.Effects of time(0–200 min),pH(2–10),temperature(25–60°C),initial dye concentration(0–200 mg·L~(-1)),and adsorbent dosage(0.01–0.15 g)on dye removal efficiency were investigated.Preliminary screening revealed that TSAC synthesized via H_2SO_4activation showed higher adsorption behaviour than TSAC activated by KCl and ZnCl_2.The adsorption capacity of TSAC was found to be 11.98 mg·g~(-1)(RB5)and 13.27 mg·g~(-1)(MB),and is dependent on adsorption time and initial dye concentration.The adsorption data for both dyes were well fitted to Freundlich isotherm model which explains the heterogeneous nature of TSAC surface.The dye adsorption obeyed pseudo-second order kinetic model,thus chemisorption was the controlling step.This study reveals potential of textile sludge in removal of dyes from aqueous solution,and further studies are required to establish the applicability of the synthesized adsorbent for the treatment of waste water containing toxic dyes from textile industry.     

Lead removal from aqueous medium using fruit peels and polyaniline composites in aqueous and non-aqueous solvents in the presence of polyethylene glycol

In the present study, composites of Polyaniline and some fruit peels were synthesized in various conditions and used for lead removal from aqueous solutions. Adsorption tests were conducted in batch mode using the most efficient adsorbent, and the effects of medium pH, initial lead concentration, contact time, adsorbent dosage, and adsorption isotherms were investigated. The results showed that all composites were more efficient in lead removal compared to the fruit peels alone. The highest removal percentage was related to the composite of banana peel and Polyaniline that synthesized in the aqueous solution in the presence of 2 g·L^-1 Poly ethylene glycol. This composite showed 95.96% lead adsorption at pH = 6, the contact time of 90 min, the initial lead concentration of 25 mg·L^-1, and an adsorbent concentration of 8 g·L^-1. Adsorption isotherm study showed that adsorption of lead by synthesized composite could be fitted by both Langmuir and Freundlich models, but the Langmuir model was more fitted than Freundlich. Besides, some characteristics of the composites, such as chemical composition (XRD analysis), structure, and morphology (SEM analysis) and functional groups (FTIR analysis), were studied.     

中药渣基活性炭的制备及其对头孢拉定的吸附研究

以香橼、桂枝和板蓝根3种中药渣为原料,Na₂CO₃为活化剂,800℃下活化1.5 h制备了香橼活性炭（AC-CM）、桂枝活性炭（AC-RC）和板蓝根活性炭（AC-IT）3种活性炭。采用扫描电镜、红外光谱、比表面积分析、pH值和pH_pzc测定等表征手段考察了活性炭的特性。研究了3种活性炭对头孢拉定的吸附动力学与吸附等温线,考察了不同初始pH值和NaCl质量浓度对吸附过程的影响。结果发现,AC-CM、AC-RC和AC-IT的比表面积分别为453.32、413.78和230.06 m²/g,pH值分别为9.70、8.23和9.24,pH_pzc值分别为9.28、9.21和9.38,活性炭表面主要含有C=O、C=C以及含N基团,SEM分析显示活性炭表面存在大量的孔结构。AC-CM、AC-RC和AC-IT对头孢拉定的吸附过程均符合伪二级动力学与粒内扩散模型,吸附速率受粒内扩散机制和化学吸附共同控制。Freundlich模型能较好地描述3种活性炭的等温吸附过程,n均大于1,说明吸附过程容易进行。溶液初始pH值对活性炭吸附影响较大,pH值为3（在100 mg/L头孢拉定溶液中,添加0.1 g活性炭,吸附48 h）时,AC-CM、AC-RC和AC-IT对头孢拉定的吸附量最大,分别达到74.76、79.44和62.55 mg/g。溶液中NaCl的存在也增加了活性炭的吸附量。