Peanut Shell Activated Carbon： Characterization,Surface Modification and Adsorption of Pb^2＋ from Aqueous Solution

Metal ion contamination of drinking water and waste water, especially with heavy metal ion such as lead, is a serious and ongoing problem. In this work, activated carbon prepared from peanut shell （PAC） was used for the removal of Pb^2＋ from aqueous solution. The impacts of the Pb25 adsorption capacities of the acid-modified carbons oxidized with HNO3 were also investigated. The surface functional groups of PAC were confirmed by Fourier transform infrared （FTIR） spectroscopy, X-ray photoelectron spectroscopy （XPS）, Boehm titration. The textural properties （surface area, total pore volume） were evaluated from the nitrogen adsorption isotherm at 77 K. The experimental results presented indicated that the adsorption data fitted better with the Langmuir adsorption model. A comparative study with a commercial granular activated carbon （GAC） showed that PAC was 10.3 times more efficient compared to GAC based on Langmuir maximum adsorption capacity. Further analysis results by the Langmuir equation showed that HNO3 [20% （by mass）] modified PAC has larger adsorption capacity of Pb^2＋ from aqueous solution （as much as 35.5 mg·g^-1）. The adsorption capacity enhancement ascribed to pore widening, increased cation-exchange capacity by oxygen groups, and the promoted hydrophilicity of the carbon surface.     

含酚废水处理的吸附和臭氧氧化动力学模型

A three phase fluidized bed reactor was used to investigate the combined effect of adsorption and oxidation for phenolic wastewater treatment.Aqueous solutions containing 10 mg·L 1of phenol and ozone were continuously fed co-currently as upward flow into the reactor at constant flow rate of 2 and 1 L·min1,respectively.The phenolic treatment results in seven cases were compared:(a)O3 only,(b)fresh granular activated carbon(GAC),(c) 1st reused GAC,(d)2nd reused GAC,(e)fresh GAC enhanced with O3,(f)1st reused GAC enhanced with O3,and (g)2nd reused GAC enhanced with O3.The phenolic wastewater was re-circulated through the reactor and its concentration was measured with respect to time.The experimental results revealed that the phenolic degradation using GAC enhanced with O3 provided the best result.The effect of adsorption by activated carbon was stronger than the effect of oxidation by ozone.Fresh GAC could adsorb phenol better than reused GAC.All cases of adsorption on GAC followed the Langmuir isotherm and displayed pseudo second order adsorption kinetics.Finally,a differential equation for the fluidized bed reactor model was used to describe the phenol concentration with respect to time for GAC enhanced with O3.The calculated results agree reasonably well with the experimental results.     

污泥含炭吸附剂的制备及其吸附模拟烟气中汞蒸汽的应用(英文)

The carbonaceous adsorbent was prepared from mixtures of dewatered sludge and sawdust with enhanced ZnCl2 chemical activation.Characteristics of the adsorbent were studied using scanning electron microscope(SEM) ,Fourier transform infrared spectroscopy(FT-IR) ,and adsorption of nitrogen.The surface analysis showed that the carbonaceous adsorbent had good specific surface and porosity(394 m 2 ·g-1of BET surface,0.12 and 0.10 ml·g-1of microporous and mesoporous volume,respectively) .The oxygen functional groups such as OH,C O and C O were found on the surface by FTIR and XPS(X-ray photoelectron spectroscopy) .The adsorption of elemental mercury(Hg0) on the carbonaceous adsorbent was studied in a fixed bed reactor.The dynamic adsorption capacity of carbonaceous adsorbent increased with influent mercury concentration,from 23.6μg·g-1at 12.58μg·m-3to 87.9μg·g-1at 72.50μg·m-3,and decreased as the adsorption temperature increased,from 246 μg·g-1 at 25°C to 61.3μg·g-1 at 140°C,when dry nitrogen was used as the carrier gas.The carbonaceous adsorbent presented higher dynamic adsorption capacity than activated carbon,which was 81.2μg·g-1and 53.8μg·g-1respectively.The adsorption data were fitted to the Langmuir adsorption model.The physical and chemical adsorption were identified on the adsorbent.     

Hierarchical pore structure of activated carbon fabricated by CO2/microwave for volatile organic compounds adsorption

An activated carbon pore-expanding technique was achieved through innovative reactivation by CO_2/microwave.The original and modified activated carbons were characterized by nitrogen adsorption–desorption,scanning electron microscopy,transmission electron microcopy,and Fourier transform infrared spectroscopy.The mesopore volume increased from 0.122 cm~3·g~(-1) to 0.270 cm~3·g~(-1),and a hierarchical pore structure was formed.A gradual decrease in the phenolic hydroxyl and carboxyl groups on the surface of activated carbon enhanced the surface inertia of granular activated carbon(GAC).The toluene desorption rate of the modified sample increased by 8.81% compared with that of the original GAC.Adsorption isotherm fittings revealed that the Langmuir model was applicable for the original and modified activated carbons.The isosteric adsorption heat of toluene on the activated carbon decreased by approximately 50%,which endowed the modified sample with excellent stability in application.The modified samples showed an enhanced desorption performance of toluene,thereby opening a way to extend the cycle life and improve the economic performance of carbon adsorbent in practical engineering applications.     

Kinetic and thermodynamic studies of acid scarlet 3R adsorption onto low-cost adsorbent developed from sludge and straw简

A low-cost adsorbent was prepared from sludge and straw by pyrolysis in a dried state with the surface area of the adsorbent of 829.49 ma. g-l, micropore volume of 0.176 cm2·g-1 and average pore radius of 5.0 nm. The kinetic, equilibrium isotherm and thermodynamic characteristics of trisodium 1-（1-naphthylazo）-2-hydroxynaphthalene- 4＇,6,8-trisulphonate （acid scarlet 3R） onto the adsorbent from sludge and straw were investigated. The results indicated that the pseudo second order adsorption was the predominant adsorption mechanism of acid scarlet 3R. Thus, the adsorption phenomenon was suggested as a chemical process. The adsorption data were fitted better with Langmuir model than Freundlich model, indicating that the adsorption of acid scarlet 3R belonged to the monolayer adsorption and mainly occurred in micropores.     

Modified activated carbons with amino groups and their copper adsorption properties in aqueous solution

Activated carbons were prepared by two chemical methods and the adsorption of Cu (II) on activated carbons from aqueous solution containing amino groups was studied. The first method involved the chlorination of activated carbon following by substitution of chloride groups with amino groups, and the second involved the nitrilation of activated carbon with reduction of nitro groups to amino groups. Resultant activated carbons were characterized in terms of porous structure, elemental analysis, FTIR spectroscopy, XPS, Boehm titration, and pHzpc. Kinetic and equilibrium tests were performed for copper adsorption in the batch mode. Also, adsorption mechanism and effect of pH on the adsorption of Cu (II) ions were discussed. Adsorption study shows enhanced adsorption for copper on the modified activated carbons, mainly by the presence of amino groups, and the Freundlich model is applicable for the activated carbons. It is suggested that binding of nitrogen atoms with Cu (II) ions is stronger than that with H+ions due to relatively higher divalent charge or stronger electrostatic force.     

二苯并呋喃在活性炭床层中的吸附动力学

The adsorption of dibenzofuran （DBF） on three commercial granular activated carbons （GAC） was investigated to correlate the adsorption equilibrium and kinetics with the morphological characteristics of activated carbons. Breakthrough experiment was conducted to determine the isotherm and kinetics of dibenzofuran on the activated carbons. All-the experiment runs were performed in a fixed bed with a process temperature of 368 K. The effects of adsorbent morphological properties on the kinetics of the adsorption process were studied. The equilibrium data are found satisfactory fitted to the Langmuir isotherm. An intraparticle diffusion model based on the obtained Langmuir isotherm was＇developed for predicting the fixed bed adsorption of dibenzofuran. The result indicated that this model fit all the breakthrough curves well. The surface diffusion coefficients of dibenzofuran on the activated carbon are calculated, and a relationship with the microporosity is found. As it was expected, the dibenzofuran molecule finds more kinetic restrictions for the diffusion in those carbons with narrower pore diameter.     

Regulation of isobutane/1-butene adsorption behaviors on the acidic ionic liquids-functionalized MCM-22 zeolite

The adsorption ratio of isobutane/1-butene on the catalyst surface is one of the most important factors for the C4 alkylation process.Regulation of isobutane/1-butene adsorption ratio on the zeolite-supported acid catalyst is a big challenge for catalyst preparation.To regulate the isobutane/1-butene adsorption ratio,four types of ionic liquid (i.e.,IL) with different alkyl chain lengths and different acid group numbers were synthesized and were subsequently immobilized onto the MCM-22 zeolite.The as-synthesized IL-immobilized MCM-22 (i.e.,MCM-22-IL) was characterized by FTIR,TGA,BET,XPS and XRD,and their adsorption capacities and adsorption molar ratios of isobutane to 1-butene (I/O) were investigated to correlate with surface features of MCM-22-IL Results showed that the immobilization of ILs led to a decrease of specific surface area and pore volume.But the surface density of acid groups was increased and the adsorption molar ratio of isobutane/1-butene (I/O) was significantly improved by the immobilization of ionic liquids.The adsorption molar ratio of I/O is substantially improved from 0.75 to above 0.9 at 300 kPa upon immobilizing ILs.Although the alkyl chain length of ILs was found to have little effect on the adsorption molar ratio of I/O,the increase of acid group numbers led to a dramatic decrease in the adsorption I/O ratio.The results illustrated that immobilizing ionic liquids is an effective way to modify the textural,chemical and morphological properties of MCM-22.Accordingly,the immobilization of ionic liquids provides a novel and a feasible way to regulate the adsorption I/O ratio on an adsorbent or a solid catalyst.     

Adsorption equilibrium of citric acid from supercritical carbon dioxide/ethanol on cyano column

Supercritical adsorption equilibrium has a significant role in defining supercritical adsorption behavior. In this paper, the adsorption equilibrium of citric acid from supercritical CO2/ethanol on a cyano column was systemat-ical y investigated with the elution by characteristic point method. Equilibrium loading was obtained at 313.15 K and 321.15 K with supercritical CO2/ethanol densities varying from 0.7068 g·cm?3 to 0.8019 g·cm?3. The exper-imental results showed that the adsorption capacity of citric acid decreased with increasing temperature and in-creasing density of the supercritical CO2/ethanol mobile phase. The adsorption equilibrium data were fitted wel by the Quadratic Hill isotherm model and the isotherms showed anti-Langmuir behavior. The monolayer satura-tion adsorption capacity of citric acid is in the range of 44.54 mg·cm?3 to 64.66 mg·cm?3 with an average value of 56.86 mg·cm?3.     

CO2和N2吸附的研究札记

Experiments were made for the adsorption of CO2 and N2 on typical adsorbents to investigate the effects of porous structure and surface affinity of adsorbents as well as those of adsorption temperature and pressure that might cause the variation of adsorption mechanism. It is shown that polar surface tends to enlarge the adsorption difference between CO2 and N2, and the difference is more sensitive to temperature than the adsorbents with non-polar surface. The adsorbents with non-polar surface are not much sensitive to the effect of water vapor, though the water vapor interferes the separation remarkably. The separation coefficient linearly increases with the micropore volume per unit surface area of activated carbons, but no rule is shown on mesoporous silicon materials. The function of adsorption mechanism on the separation is not as much as expected.     

Effect of the chelating agents on bio-sorption of hexavalent chromium using Agave sisalana fibers

The current work is focused on the study of the bio-sorption of hexavalent chromium from aqueous solution using sisal natural fiber(Agave sisalana) treated by various chelating agents(ligands) such as urea(UR),thiocarbamide(TC), ethylenediaminetetraacetic acid(EDTA), and diphenyl carbazide(DCZ). The fiber treatments were investigated using Fourier Transform Infrared Spectroscopy(FTIR) and Scanning electron microscope(SEM). The kinetics of chromium bio-sorption was studied in batch presses under the effect of some physicochemical factors such as the nature of chelating agent(F@UR, F@TC, F@DCZ, and F@EDTA),adsorbent dose(2–10 g·L~(-1)), chromium initial concentration(100–500 mg·L~(-1)), solution pH(1–6), and batch temperature(20 ℃–50 ℃). This study resulted in an optimum adsorption at a chromium initial concentration of 100 mg·L~(-1), at pH 2, and at 20 ℃. The obtained results showed clearly that the treatment with chelating agent boosts the adsorptive capacity of A. sisalana fibers Cr(VI) 10.9 mg·g~(-1) to 58.6 mg·g~(-1). The modeling study showed that the adsorption kinetics obey the pseudo-second-order model, with an R2 in the range of 0.991 and 0.999. The bio-sorption isotherms followed the Langmuir model; the maximum uptake capacity of(F@N, F@UR,F@TC, F@DCZ, and F@EDTA) was found to be respectively, 12.3 mg·g~(-1), 25.33 mg·g~(-1), 28.73 mg·g~(-1),42.54 mg·g~(-1), and 61.45 mg·g~(-1). The determined adsorption thermodynamics parameters such as enthalpy,free energy, and entropy showed that the adsorption process is exothermic, spontaneous, and has a stable configuration.     

茶叶对氟的吸附研究

以茶叶为吸附材料,研究了改性前后的茶叶对氟的吸附,探讨了氟化钠模拟废水溶液的pH值、初始浓度及吸附时间对吸附效果的影响,同时,时改性前后的茶叶进行吸附动力学拟合和吸附等温线拟合.结果表明,在pH值为4、茶叶投加量为1.0 g、室温条件下,改性前后的茶叶对50 mL 0.1 mol·L-1氟化钠模拟废水中氟的最大吸附量分...     

Adsorption characteristics of a novel ceramsite for heavy metal removal from stormwater runoff

Urban sediments have rapidly increased in recent years around the world,and their effective management has become an important problem.To remove heavy metals from stormwater runoff and use sediments as a resource,a novel ceramsite was developed using sewer pipe sediments(SPS),river bed sediments(RBS),urban water supply treatment sludge(WSTS),and wastewater treatment plant excess sludge(WWTS).The optimal composition was determined based on the Brunauer–Emmett–Teller specific surface area and an orthogonal test design.The adsorption characteristics of the novel ceramsite for dissolved heavy metals(Cu~(2+)and Cd~(2+)) were investigated through adsorption isotherms and kinetic experiments at(25±1)℃.Both Cu~(2+) and Cd~(2+) were effectively removed by the novel ceramsite,and their equilibrium adsorption was 4.96 mg·g~(-1) and 3.84 mg·g~(-1),respectively.Langmuir isotherms and a pseudo-first-order kinetic equation described the adsorption process better than other techniques.Characterization analysis of the ceramsite composition before and after heavy metal adsorption showed that the Cu~(2+) and Cd~(2+) contents in the ceramsite increased after adsorption.The results revealed that adsorption is both a physical and chemical process,and that ceramsite can be used as a bioretention medium to remove heavy metals from stormwater runoff while simultaneously converting problematic urban sediments into a resource.     

Synthesis of zinc oxide nanoparticles reinforced clay and their applications for removal of Pb (Ⅱ) ions from aqueous media

The aim of the study was to synthesize zinc oxide nanoparticles (ZnONPs) composite with clay by a novel route and then to explore the capability of composite of ZnONPs and silty clay (SC) as adsorbents for Pb (Ⅱ) eradication from aqueous media by batch adsorption method. The effect of different operating factors like temperature, pH, dose and time of contact on the adsorption process were studied to optimize the conditions. Langmuir, Freundlich, Dubinin–Radushkevich (D-R) and Temkin isotherms were applied for the interpretation of the process. The R2 and q values obtained from Langmuir model suggested that the process is best interpreted by this model. The values of adsorption capacity (qm) noted were 12.43 mg·g-1 and 14.54 mg·g-1 on SC and ZnONPs-SC respectively. The kinetic studies exposed that pseudo second order (PSO) kinetics is followed by the processes suggesting that more than one steps are involved to control the rate of reactions. Various thermodynamic variables such as change in free energy (ΔGΘ), change in enthalpy (ΔHΘ) and change in entropy (ΔSΘ) were calculated. Thermodynamic data suggested that Pb (Ⅱ) adsorption on SC and ZnONPs-SC are spontaneous, endothermic and feasible processes.     

花生壳活性炭的表征,表面改性及吸附脱除水中Pb2+离子

Metal ion contamination of drinking water and waste water, especially with heavy metal ion such as lead, is a serious and ongoing problem. In this work, activated carbon prepared from peanut shell (PAC) was used for the removal of Pb2 from aqueous solution. The impacts of the Pb2 adsorption capacities of the acid-modified carbons oxidized with HNO3 were also investigated. The surface functional groups of PAC were confirmed by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Boehm titration. The textural properties (surface area, total pore volume) were evaluated from the nitrogen adsorption isotherm at 77K. The experimental results presented indicated that the adsorption data fitted better with the Langmuir adsorption model. A comparative study with a commercial granular activated carbon (GAC) showed that PAC was 10.3 times more efficient compared to GAC based on Langmuir maximum adsorption capacity. Further analysis results by the Langmuir equation showed that HNO3 [20% (by mass)] modified PAC has larger adsorption capacity of Pb2 from aqueous solution (as much as 35.5mg.g1). The adsorption capacity enhancement ascribed to pore widening, increased cation-exchange capacity by oxygen groups, and the promoted hydrophilicity of the carbon surface.     

甲烷、乙烷、丙烷和丁烷在中孔活性炭上的吸附平衡

以活性炭AC1为吸附剂,在体积法实验装置上分别测定了其对甲烷、乙烷、丙烷和丁烷4种气体的吸附等温线,吸附温度分别为283、293、303和313 K。利用77 K吸附氮气数据表征AC1,得到其比表面积为956 m²·g^-1,孔体积为1.36 mL·g^-1,孔径分布在1~5 nm,中孔的比例达到了61%。AC1对4种气体的吸附等温线均为I型等温线,分别采用Langmuir方程和Langmuir-Freundlich方程(简称L-F方程)对吸附平衡数据进行拟合,结果表明,L-F方程具有更好的拟合效果,为后序的多组分吸附平衡研究提供了基础数据。AC1对乙烷/丙烷的吸附平衡选择性系数在1.7~2.5,吸附选择性随吸附压力的增大而减小,吸附温度对吸附选择性无明显影响。     

磁性交联壳聚糖对水溶液中铀(Ⅵ)离子的吸附行为

采用纳米Fe₃O₄作为磁流体包埋、戊二醛和硫脲进行交联壳聚糖,制备磁性交联壳聚糖（TTG-MCTS）。红外光谱（FTIR）和X射线能谱（EDS）分析结果表明,壳聚糖改性后,吸附能力得到提高,铀(Ⅵ)成功地被吸附在TTG-MCTS上。系统研究了溶液pH值、铀(Ⅵ)初始浓度及振荡时间对吸附容量的影响,继而得到最佳工艺条件。吸附过程用Langmuir等温式拟合优于用Freundlich等温式,最大吸附容量为161.3 mg·g^-1。较之拟一级动力学模型,拟二级动力学模型能更好地拟合实验数据。     

微生物-化学耦合法再生活性炭的研究(英文)

In this study,spent activated carbon(AC) saturated with caramel was regenerated by using yeast and NaOH.The efficiency of regeneration was evaluated under parameters such as amount,treatment time,temperature,pH value,stirring temperature of yeast and NaOH concentration.The optimum condition for AC regeneration was 8 h for yeast treatment time,35 ℃ for 0.075% yeast culture temperature,a pH value of 6 for the yeast dealing with the spent AC,90 ℃ for NaOH stirring temperature of AC and 6% NaOH for washing after the spent AC was treated by yeast.Under these conditions,methylene blue(MB) adsorption was 213 mg·g-1 in comparison with 60 mg·g-1 of spent AC.The micro structure and surface area of the regenerated AC were characterized by scanning electron mi-croscope(SEM) and N2 sorption,respectively.The pore size distributions of virgin and regenerated AC were ana-lyzed by means of H-K equation,resulting in a mean pore diameter of 1.28 nm and a pore volume of 1.13 cm3·g-1.This study provides data for theoretical support of the AC regeneration technology.     

Ozonation of 1,3,6-naphthalenetrisulphonic acid catalysed by activated carbon in aqueous phase

This paper presents experimental results of the ozonation of a model aromatic sulphonic compound, 1,3,6-naphthalenetrisulphonic acid (NTS), in the presence of different activated carbons with different physical and chemical surface properties. Carbons used were commercial activated carbons (Ceca AC40, Norit, Merck, Witco, Ceca GAC, Filtrasorb 400, Sorbo) with or without demineralisation pre-treatment. Carbon samples were texturally and chemically characterised using N₂ adsorption isotherms, mercury porosimetry, pH_PZC, selective neutralisation and elemental analysis. Results show that NTS was degraded by ozone at a faster rate in the presence of activated carbon, especially in the case of Sorbo, Ceca GAC and Norit carbons, which display catalytic activity, probably by enhancing ozone decomposition in aqueous phase in highly oxidative species. These catalytic properties seem to be favoured by both the basicity of the carbon surface and the higher macropore volume. Dissolved total organic carbon from the NTS degradation compounds was removed in the presence of activated carbon through both the catalytic activity of activated carbon to mineralise organic matter and the adsorption of these organic compounds on activated carbon.