Adsorption of branched alkylbenzene sulfonate onto styrene and acrylic ester resins

In this study, a series of acrylic ester resins were prepared and characterized. The adsorption behaviors of sodium 6-dodecyl benzenesulfonate (6-NaDBS) on styrene resin XAD-4 and acrylic ester resins have been studied. As compared to commercial acrylic ester resins Amberlite XAD-7 and Diaion HP2MG, YWB-38, one of the as-prepared resins, exhibits better adsorption properties toward 6-NaDBS. The experimental equilibrium data were fitted to the Langmuir and double-Langmuir models. The two models provide very good fit for all acrylic ester resins over the temperature range studied, whereas fitted results for styrene resin XAD-4 are less accurate. The investigation indicates that the adsorbate molecules are directly adsorbed on acrylic ester resins as a bi-layer, while the molecules are adsorbed on XAD-4 as monolayer formation followed by the establishment of bi-layer. Adsorption kinetics and elution processes were also investigated for further exploring the adsorption behavior and mechanism on styrene resin XAD-4 and YWB-38.     

Adsorption of bentazon and propanil from aqueous solutions at the high area activated carbon-cloth

Removal of the pesticides bentazon and propanil from single and bisolute solutions by adsorption at the high area activated carbon-cloth was investigated. Kinetics of adsorption was followed and adsorption isotherms of the two pesticides were determined. A special V-shaped cell with an UV cuvette attached to it was used for adsorption studies. With this cell it was possible to follow the concentration of pesticide molecule by in situ UV spectroscopy as it is adsorbed at the carbon-cloth. It was found that concentration of pesticides decreased from the same initial concentration of 4.5 x 10(-5) to 1.1 x 10(-5) for bentazon and to 9.5 x 10(-6) for propanil in about 2 h. The fits of experimental adsorption isotherm data to Langmuir and Freundlich isotherm equations were almost equally successful. Monolayer capacities determined from Langmuir isotherms of pesticides showed that bentazon has greater monolayer capacity than propanil. This conclusion was also confirmed through the 1/n parameter of Freundlich equation.     

大孔树脂吸附去除水中的2,4,6-三硝基甲苯

研究了2种大孔树脂XAD-4和NDA-804对水中的TNT的吸附行为。2种树脂对TNT的吸附等温线表明,温度的升高有利于吸附,在35℃条件下XAD-4树脂与NDA-804树脂对TNT的最高平衡吸附量分别达82.86 mg/g和94.26mg/g。采用Langmuir方程和Freundlich方程用于吸附等温线的解释,结果表明,吸附等温线更加符合Langmuir模型,相关系数均大于0.99。TNT在2种树脂上的吸附符合准二级动力学方程,TNT初始浓度越低,达到吸附平衡所需时间越短,在1 h内可达到吸附平衡。采用NDA-804处理对TNT废水,废水中TNT浓度由103.58 mg/L降至0.4 mg/L,去除率达99.6%,吸附后的树脂采用pH=2的乙醇和盐酸的混合液脱附可再生,高浓度再生溶液经蒸馏可回收TNT,实现了废水治理与资源化。     

Adsorption characteristics of Ni(II) on gamma-type alumina particles and its determination of overall adsorption rate by a differential bed reactor

The adsorption experiment of nickel ion [Ni(II)] on gamma-type alumina by a differential bed reactor in aqueous solutions was investigated to determine the adsorption characteristics and overall adsorption rate. The adsorbed amount increased rapidly with pH from pH 2 to 6 and kept constant over pH 6. The adsorbed amount of Ni(II) increased with temperature from 20 to 50 degrees C. Correlation coefficients (R2) of Langmuir and Freundlich adsorption isotherms were 0.9268 and 0.9489, respectively, and Freundlich isotherm was more suitable for adsorption on gamma-type alumina than Langmuir isotherm.The overall adsorption rate of Ni(II) on gamma-type alumina at pH 6 by a differential bed rector was determined as follows: r = 68.77Ce(1.61) - 17.60qe(0.36). Al(III) ions in solutions were away from the alumina surface during the adsorption of Ni(II) and Al(III) concentration increased with an increasing Ni(II) adsorbed amount on alumina.     

超高交联吸附树脂对有机物质甲苯的吸附热力学研究

比较了2种超高交联聚苯乙烯吸附树脂NDa99与ZH-04对甲苯的静态吸附行为.结果表明,在288～293 K和研究的浓度范围内,ZH-04、NDa99对甲苯的吸附平衡数据符合Freundlich和Langmuir吸附等温方程.吸附为放热过程,适当降低温度有利于吸附,并计算了甲苯在ZH-04和NDa99树脂上的吸附焓变、自由能变和熵变,对吸附行为进行了合理的解释,为废水处理提供一定的理论依据.     

超高交联吸附树脂对有机物质甲苯的吸附热力学研究

比较了2种超高交联聚苯乙烯吸附树脂NDa99与ZH-04对甲苯的静态吸附行为.结果表明,在288～293 K和研究的浓度范围内,ZH-04、NDa99对甲苯的吸附平衡数据符合Freundlich和Langmuir吸附等温方程.吸附为放热过程,适当降低温度有利于吸附,并计算了甲苯在ZH-04和NDa99树脂上的吸附焓变、自由能变和熵变,对吸附行为进行了合理的解释,为废水处理提供一定的理论依据.     

Adsorption of 2,4-dichlorophenoxyacetic acid and 4-chloro-2-metylphenoxyacetic acid onto activated carbons derived from various lignocellulosic materials

Adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-metylphenoxyacetic acid (MCPA) from aqueous solution onto activated carbons derived from various lignocellulosic materials including willow, miscanthus, flax, and hemp shives was investigated. The adsorption kinetic data were analyzed using two kinetic models: the pseudo-first order and pseudo-second order equations. The adsorption kinetics of both herbicides was better represented by the pseudo-second order model. The adsorption isotherms of 2,4-D and MCPA on the activated carbons were analyzed using the Freundlich and Langmuir isotherm models. The equilibrium data followed the Langmuir isotherm. The effect of pH on the adsorption was also studied. The results showed that the activated carbons prepared from the lignocellulosic materials are efficient adsorbents for the removal of 2,4-D and MCPA from aqueous solutions.     

Adsorption of phenolic compounds from aqueous solutions by a water-compatible hypercrosslinked polymeric adsorbent

A water-compatible hypercrosslinked polymeric adsorbent (NJ-8) for adsorbing and removing phenolic compounds from their aqueous solutions was prepared. This product can be used directly without a wetting process. Its adsorption property toward four phenolic compounds, phenol, p-cresol, p-chlorophenol, and p-nitrophenol was tested using the commercial Amberlite XAD-4 as a reference. The capacities of equilibrium adsorption for all four phenolic compounds on the NJ-8 from their aqueous solutions are around two times as high as that of Amberlite XAD4 within the temperature range 283-323 K, which may contribute to their micropore structure and the partial polarity on the network. Freundlich isotherm equations, as well as relative adsorption capacities and isosteric adsorption enthalpies for the four phenolic compounds, indicate that the adsorption of phenolic compounds on the NJ-8 resin is a physical adsorption process. Mini-column adsorption studies for phenol on Amberlite XAD4 and NJ-8 resins show that the breakthrough adsorption capacities are 0.54 and 0.99 mmol/ml, and the total capacities are 0.62 and 1.37 mmol/ml, while no extra acetone was needed to remove the adsorbed phenol from NJ-8 as from Amberlite XAD4.     

Multi-component sorption isotherms of basic dyes onto peat

The adsorption of basic dyes onto peat from single component and multi-component solution is reported. The adsorption is presented in the form of the equilibrium isotherms. The Freundlich, Langmuir and Redlich-Peterson isotherm equations are fitted to the results and the isotherm constants obtained.     

In vitro study of oxytetracycline adsorption on activated charcoal

In vitro adsorption experiments simulating pH in gastric environment and using Langmuir isotherm, showed that 408 mg of oxytetracycline was adsorbed per gram of activated charcoal. Langmuir isotherm fitted adsorption data better than a Freundlich isotherm. Freundlich isotherm showed a specific adsorption capacity of 518 mg/g for activated charcoal. Both isotherm parameters indicated a strong oxytetracycline adsorption on activated charcoal in terms of quantity and binding strength. The results demonstrate that the concomitant use of oxytetracyline and activated charcoal should be avoided.     

Removal of congo red from aqueous solution by bagasse fly ash and activated carbon: kinetic study and equilibrium isotherm analyses

Present investigation deals with the utilisation of bagasse fly ash (BFA) (generated as a waste material from bagasse fired boilers) and the use of activated carbons-commercial grade (ACC) and laboratory grade (ACL), as adsorbents for the removal of congo red (CR) from aqueous solutions. Batch studies were conducted to evaluate the adsorption capacity of BFA, ACC and ACL and the effects of initial pH (pH(0)), contact time and initial dye concentration on adsorption. The pH(0) of the dye solution strongly affected the chemistry of both the dye molecules and BFA in an aqueous solution. The effective pH(0) was 7.0 for adsorption on BFA. Kinetic studies showed that the adsorption of CR on all the adsorbents was a gradual process. Equilibrium reached in about 4h contact time. Optimum BFA, ACC and ACL dosages were found to be 1, 20 and 2 g l(-1), respectively. CR uptake by the adsorbents followed pseudo-second-order kinetics. Equilibrium isotherms for the adsorption of CR on BFA, ACC and ACL were analysed by the Freundlich, Langmuir, Redlich-Peterson, and Temkin isotherm equations. Error analysis showed that the R-P isotherm best-fits the CR adsorption isotherm data on all adsorbents. The Freundlich isotherm also shows comparable fit. Thermodynamics showed that the adsorption of CR on BFA was most favourable in comparison to activated carbons.     

Predictions of binary sorption isotherms for the sorption of heavy metals by pine bark using single isotherm data

The adsorption of three heavy metal ions by pine bark was studied. The study was divided into two parts; single component adsorption of the metals Cu2+, Cd2+ and Ni2+ and bisolute adsorption of the three binary systems Cu2+-Cd2+, Cu2+-Ni2+ and Cd2+-Ni2+. Extended Langmuir model, extended Freundlich model. Sips model and ideal adsorption solution theory (IAST) models were used to predict the equilibrium uptake for Cu2+, Cd2+ and Ni2+ in the binary diluted solutions using the single adsorption constants. The experimental data of single isotherm adsorption process were found to follow Langmuir isotherm model with less accuracy than Freundlich and Sips models. Whereas, the predictions of bisolute adsorption isotherms of the mentioned three systems, Cu2+-Cd2+, Cu2+-Ni2+ and Cd2+-Ni2+, showed good agreement with experimental data when using Extended-Langmuir, Extended-Freundlich and IAST. However, the only good fit of the Sips model was with the Cu2+-Cd2+ system.     

Adsorption of glyphosate on resin supported by hydrated iron oxide: equilibrium and kinetic studies

Hydrated iron oxide supported on resin (D301) was prepared as a new sorbent for the removal of glyphosate from wastewater. Batch adsorption studies were performed on glyphosate aqueous solutions with different initial glyphosate concentrations and temperatures. Experimental data were analyzed using the Langmuir and Freundlich isotherms, and the adsorption data were best fit to the Langmuir isotherm model. The thermodynamic parameters AG, AH, and AS also were calculated for the adsorption processes. Adsorption rate constants were determined using the pseudo-first-order and pseudo-second-order rate equations and Kannan-Sundaram intraparticle diffusion models. Adsorption of glyphosate clearly followed the pseudo-second-order model and was controlled by both film diffusion and intraparticle diffusion.     

改性粉煤灰吸附稀土废水中的氨氮

用硫酸和氢氧化钠对粉煤灰进行酸改性和碱改性处理,研究改性前后粉煤灰对稀土废水中氨氮的吸附效果变化及最佳吸附条件,并从吸附等温线入手探讨吸附机理。结果显示,经碱改性后粉煤灰对氨氮的吸附性能有明显改善,当最佳吸附条件确定为投加量2 g,吸附时间2 h,初始pH 7～8时,碱改性粉煤灰对氨氮的吸附过程符合Freundlich等温方程式和Langmuir等温方程式。碱改性粉煤灰对氨氮的吸附属于良性吸附,且为吸热过程,室温下理论饱和吸附量为1.9066mg/g。     

Determination of the adsorptive capacity and adsorption isotherm of vapor-phase mercury chloride on powdered activated carbon using thermogravimetric analysis

This study investigated the use of thermogravimetric analysis (TGA) to determine the adsorptive capacity and adsorption isotherm of vapor-phase mercury chloride on powdered activated carbon (PAC). The technique is commonly applied to remove mercury-containing air pollutants from gas streams emitted from municipal solid waste incinerators. An alternative form of powdered activated carbon derived from a pyrolyzed tire char was prepared for use herein. The capacity of waste tire-derived PAC to adsorb vapor-phase HgCl2 was successfully measured using a self-designed TGA adsorption system. Experimental results showed that the maximum adsorptive capacities of HgCl2 were 1.75, 0.688, and 0.230 mg of HgCl2 per gram of powdered activated carbon derived from carbon black at 30, 70, and 150 degrees C for 500 microg/m3 of HgCl2, respectively. Four adsorption isotherms obtained using the Langmuir, Freundlich, Redlich-Peterson, and Brunauer-Emmett-Teller (BET) models were used to simulate the adsorption of HgCl2. The comparison of experimental data associated with the four adsorption isotherms indicated that BET fit the experimental results better than did the other isotherms at 30 degrees C, whereas the Freundlich isotherm fit the experimental results better at 70 and 150 degrees C. Furthermore, the calculations of the parameters associated with Langmuir and Freundlich isotherms revealed that the adsorption of HgCl2 by PAC-derived carbon black favored adsorption at various HgCl2, concentrations and temperatures.     

In vitro study of oxytetracycline adsorption on activated charcoal

Abstract

In vitro adsorption experiments simulating pH in gastric environment and using Langmuir isotherm, showed that 408 mg of oxytetracycline was adsorbed per gram of activated charcoal. Langmuir isotherm fitted adsorption data better than a Freundlich isotherm. Freundlich isotherm showed a specific adsorption capacity of 518 mg/g for activated charcoal. Both isotherm parameters indicated a strong oxytetracycline adsorption on activated charcoal in terms of quantity and binding strength. The results demonstrate that the concomitant use of oxytetracyline and activated charcoal should be avoided.     

腐熟污泥对废水中Cd(Ⅱ)与Zn(Ⅱ)的吸附性能研究

利用腐熟污泥作为一种重金属吸附剂,考察其对水中重金属锌和镉的吸附过程.实验数据的拟合采用了Pseudo-first Order-和Pseudo-second Order 2种动力学模型以及Langmuir和Freundlich 2种吸附等温线模型;拟合结果表明,腐熟污泥对锌与镉的吸附过程符合Pseudo-second ...     

Dynamic behaviour of Cd2+ adsorption in equilibrium batch studies by CaCO3 −-rich Corbicula fluminea shell

This work presents the structural and adsorption properties of the CaCO₃ ^?-rich Corbicula fluminea shell as a natural and economic adsorbent to remove Cd ions from aqueous solutions under batch studies. Experiments were conducted with different contact times, various initial concentrations, initial solution pH and serial biosorbent dosage to examine the dynamic characterization of the adsorption and its influence on Cd uptake capacity. The characterization of the C. fluminea shell using SEM/EDX revealed that the adsorbent surface is mostly impregnated by small particles of potentially calcium salts. The dominant Cd adsorption mechanism is strongly pH and concentration dependent. A maximum Cd removal efficiency of 96.20 % was obtained at pH 7 while the optimum adsorbent dosage was observed as 5 g/L. The Langmuir isotherm was discovered to be more suitable to represent the experimental equilibrium isotherm results with higher correlation coefficients (R ²?>?0.98) than Freundlich (R ²?<?0.97).The correlation coefficient values (p?<?0.01) indicated the superiority of the Langmuir isotherm over the Freundlich isotherm.     

Kinetics and isotherm modeling of azoxystrobin and imidacloprid retention in biomixtures

The paper reports the kinetics and adsorption isotherm modeling for imidacloprid (IMIDA) and azoxystrobin (AZOXY) in rice straw (RS)/corn cob (CC) and peat (P)/compost (C) based biomixtures. The pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich and intraparticle diffusion models were used to describe the kinetics. The adsorption data were subjected to the Langmuir and the Freundlich isotherms. Results (r²_Adj values) suggested that the modified Elovich model was the best suited to explain the kinetics of IMIDA sorption while different models explained AZOXY sorption kinetics in different biomixtures (PFO in RS?+?C and RS?+?P; PSO in CC?+?P and Elovich in CC?+?C). Biomixtures varied in their capacity to adsorb both pesticides and the adsorption coefficient (K_d) values were 116.8–369.24 (AZOXY) and 24.2–293.4 (IMIDA). The Freundlich isotherm better explained the sorption of both pesticides. Comparison analysis of linear and nonlinear method for estimating the Freundlich adsorption constants was made. In general, r²_Adj values were higher for the nonlinear fit (AZOXY?=?0.938–0.982; IMIDA?=?0.91–0.970) than the linear fit (AZOXY?=?0.886–0.993; IMIDA?=?0.870–0.974) suggesting that the nonlinear Freundlich equation better explained the sorption. The rice straw-based biomixtures performed better in adsorbing both the pesticides and can be used in bio-purification systems.     

改性玉米秸秆吸附Cu^2＋的动力学和热力学

本研究用ZnCl2作为活化剂,使用功率640W的微波照射4min的方法制备改性玉米秸秆。考察投加量、pH、吸附时间对吸附性能的影响,并对等温吸附特征、吸附动力学和热力学进行了系统研究。结果表明：投加量为0．2g,pH为6,改性玉米秸秆对Cu^2＋具有很好的吸附效果,吸附在8h后达到平衡。该吸附过程符合Langmuir及Freundlich等温吸附模型和准二级动力学方程,其反应的吉布斯自由能△G〈0,为自发反应过程。