Evaluation of Phenol/Aniline (Single and Binary) Removal from Aqueous Solutions onto Hyper-cross-linked Polymeric Resin (Macronet MN200) and Granular Activated Carbon in Fixed-Bed Column

This work was conducted to evaluate the sorption performance of hyper-cross-linked Macronet resin (MN200) compared to the granular activated carbon in order to remove phenol and aniline from aqueous solution in both single and binary solutions. Fixed-bed column experiments were used to obtain the breakthrough curves. The experimental data were fitted to the Thomas, Bed Depth Service Time and Yoon?CNelson models, well-established fixed-bed sorption models. The theoretical sorption capacities obtained by the Thomas model were in good agreement to the breakthrough capacities determined from the sorption data. The sorption capacity decreased in binary sorption for resin MN200, while activated carbon reported similar (aniline) or higher (phenol) sorption performance indicating a synergistic effect between both solutes on the activated carbon surface. A good prediction of the breakthrough curves in binary solution was obtained by using an approach that considers a simple model to describe a breakthrough curve (Thomas) and modified isotherm equilibrium. The resin MN200 fixed-bed columns were easily regenerated by using a methanol solution, reporting more above of 90% of recovery for both solutes, while about 50% was the recovery of activated carbon after single experiments. The regeneration after the binary sorption experiments reported a decrease in the solute recovery, effect that was especially evident for activated carbon.     

Removal of Arsenic from Aqueous Solutions by Sorption onto Sewage Sludge-Based Sorbent

This study aimed at evaluating and comparing the removal of arsenic from solutions by a low-cost waste-based sorbent, produced by pyrolysing sewage sludge under appropriate conditions, and by a commercially activated carbon. Batch sorption experiments were performed under isothermal conditions (20°C), in order to evaluate the effect of pH on the arsenic sorption kinetics and on the equilibrium sorption capacity of the materials under study. Kinetic data revealed that the arsenic sorption was faster onto the activated carbon than onto the pyrolysed sludge. The sorption process was well described by both the pseudo-first and pseudo-second-order kinetics equations for both materials. Changes in the initial solution pH have distinct effects on the removal of arsenic onto pyrolysed sludge and activated carbon. While for pyrolysed sludge, pH affects essentially the equilibrium time, for activated carbon it affects the sorption capacity. Equilibrium results were well described by both Freundlich and Langmuir isotherm models, although fittings corresponding to the Langmuir isotherm were slightly better. The Langmuir maximum sorption capacity determined for the pyrolysed sludge was 71???g?g^?1, while for activated carbon was 229???g?g^?1. Despite the relative lower capacity of the pyrolysed sludge, the considerable lower cost and the valorisation of the sludge may justify further research on its use for water decontamination.     

Effects of Municipal Sewage Sludge Application on Soil and Purple Moor-grass (Molinia caerulea) Contamination by Metals in a Maritime Pine Forest

Granular bentonite has been assessed regarding its capacity to remove Hg(II), Cd(II) and Pb(II) from aqueous solutions. Sorption capacities, kinetics and the dependence of the sorption process on pH were determined. Fractional power, pseudo-first-order, pseudo-second-order and intra-particle diffusion equations were used to model the kinetics of metal adsorption. The pseudo-second-order model showed the best fit to experimental data. Different two-parameter sorption isotherm models (Langmuir, Freundlich, Temkin and Dubinin?CRadushkevich) were used to fit the equilibrium data. Freundlich's isotherm model gave the best fit to experimental data. The selectivity of granular bentonite towards these metals is Pb(II)?>?Cd(II)?>?Hg(II). The adsorption capacities of granular bentonite towards the metals expressed in milligramme metal per gramme granular bentonite are 19.45, 13.05 and 1.7 for Pb(II), Cd(II) and Hg(II), respectively (for an initial concentration of 100 mg metal/L).     

Equilibrium Isotherm Studies for the Sorption of Divalent Metal Ions onto Peat: Copper,Nickel and Lead Single Component Systems

The sorption of three divalent metal ions — copper, nickel and lead — from aqueous solution onto peat in single component systems has been studied and the equilibrium isotherms determined. The experimental data have been analysed using the Langmuir, Freundlich, Redlich-Peterson, Toth, Temkin, Dubinin-Radushkevich and Sips isotherm models. In order to determine the best fit isotherm for each system, six error analysis methods were used to evaluate the data: the coefficient of determination, the sum of the errors squared, a hybrid error function, Marquardt's percent standard deviation, the average relative error and the sum of absolute errors. The error values demonstrated that the Sips equation provided the best model for the three sets of experimental data overall.     

Behavior of phenol and aniline on selected sorbents and energy-related solid wastes

The sorption and desorption of phenol and aniline on selected soils and soil components and on some energy-related solid wastes were investigated. Isotherms were generally nonlinear and were described usually by the Freundlich equation. Most partition coefficients were low, and no significant correlation was shown with organic C content, pH, cation exchange capacity, or particle-size of the sorbent. It appears that sorption of small polar aromatic compounds, such as phenol and aniline, cannot be defined by a single sorbent characteristic, but is affected by both the organic and mineral components of the sorbents. Hysteresis was observed in most sorption-desorption experiments; a fraction of the sorbate was irreversibly held by the sorbent.     

Equilibrium and Kinetic Characteristic of Adsorption of Cu2+, Pb2+ on a Novel Anionic Starch Microspheres

Neutral starch microspheres (NSMs) were synthesized with epichlorohydrin as the cross-linking agent from soluble starch by inverse microemulsion method. Anionic starch microspheres (ASMs) were prepared from NSMs by the secondary polymerization with chloroacetic acid as the anionic etherifying agent. Scanning electron microscopy (SEM) revealed that microspheres had good sphericity and fine dispersibility, and the average particle size was about 75 ??m. The adsorption procedure of Cu²⁺, Pb²⁺ on ASMs was carried out by batch experiments, Langmuir and Freundlich adsorption models were applied to describe the experimental isotherms, the adsorption equilibrium data were found to fit the Langmuir and Freundlich isotherm model, the Freundlich isotherm was more adequate than the Langmuir isotherm in simulating the adsorption isotherm of Cu²⁺,the adsorption of Cu²⁺, Pb²⁺ on ASMs was a spontaneous, the isosteric heat of adsorption at different adsorption levels was always negative and indicative of an exothermic process. The pseudo first- and second-order kinetic models were used to describe the kinetic data, and the rate constants were evaluated. The experimental data fitted well to the second-order kinetic model, which indicated that the chemical sorption was the rate-limiting step, instead of mass transfer.     

高酸度芦苇活性炭的制备及其吸附性能

为实现湿地植物资源化,解决重金属废水难处理问题,本文采用青贮活化法制备高酸度湿地植物质活性炭作为吸附材料去除废水中重金属离子镍Ni(Ⅱ)和镉Cd(Ⅱ),通过XRD、N2吸附/脱附、Boehm滴定和元素分析等表征方法,探究湿地植物在青贮过程中结构变化,以及高酸度活性炭比表面积、孔径结构、官能团数量及表面元素。通过批次实验,研究活性炭对重金属离子镍和镉吸附特性,用Langmuir和Freundlich模型对实验数据进行拟合。结果表明:青贮活化法能够有效地提高活性炭的表面酸度,从而提升对重金属离子的吸附能力。通过吸附实验,高酸度活性炭对Ni(Ⅱ)和Cd(Ⅱ)的吸附过程可以用Langmuir模型进行很好的描述,并且活性炭对重金属离子的吸附过程主要由化学吸附控制。     

Evaluation of phosphorus sorption by an allophanic soil

Solutions containing different P concentrations were equilibrated with samples of an allophanic soil from Navarra (Spain) to determine whether P sorption conformed qualitatively and quantitatively to the Langmuir, Freundlich and Sokolowska isotherms.Phosphorus sorption conformed to the Langmuir isotherm. When the sorption d data were plotted according to the conventional and Hofstee forms, two linear relationships were obtained. At the lower equilibrium P concentrations the K₁ parameter determined by regression analysis was higher than those corresponding to higher equilibrium P concentrations. The values obtained for K₁ and K₂ by the conventional and Hofstee equations were different. A procedure for evaluating the coefficients for higher equilibrium P concentrations was proposed. The K₁ and K₂ values so obtained allowed us to generate an experimental curve by addition of calculated adsorption data. This suggests that the curve-splitting technique is satisfactory.The sorption data also conformed to the Freundlich and Sokolowska equations, but in the latter it was necessary to evaluate two different sets of parameters.The same experimental data can be adjusted to the three different equations, in one case with only one set of constants and in the other two cases with two different sets of parameters, one for the lower P concentrations and the other for the higher ones. Besides, to fit the experimental data to the Langmuir and Sokolowska equations, it was necessary to split the isotherm into two regions and these two regions were different for the Langmuir and the Sokolowska equations. This suggests that the parameters do not have any chemical signification and that they are only “curve fitting”.A study of the effect of pH on the P sorption indicated that low pH notably increased the P sorption.The soil samples had very high phosphate sorption capacity probably due to the very large specific surface and reactivity of the allophane.     

SOME NEW EQUATIONS TO DESCRIBE PHOSPHATE SORPTION BY SOILS

Phosphate sorption was studied on surface and subsurface soils sampled from the old field experiments at Askov, Denmark. Two empirical three-parameter equations, an extended Freundlich and an extended Langmuir equation are proposed and compared with the Langmuir, the Freundlich, the ‘double’ Langmuir, the Gunary, and the Fitter-Sutton equations. In the proposed equations the affinity parameter of the Langmuir equation and the exponent of the Freundlich equation are replaced by the term Bc ^?D the value of which decreases with increasing phosphate concentration, c. On average the Freundlich equation thus modified yielded the closest fit to the sorption data. This was followed by the Fitter-Sutton, the modified Langmuir, the ‘double’ Langmuir, the Gunary, the Freundlich, and finally the Langmuir equation. Out of the three equations that yielded the closest fit to the sorption data the correlation between the parameters within the equations, furthermore, was least for the proposed extended Freundlich equation. Therefore, this equation may be generally suitable for describing phosphate sorption by soils.     

Sorption Behaviors of Sodium Dodecylbenzene Sulfonate (SDBS) on Marine Sediments

The sorption behavior of sodium dodecylbenzene sulfonate (SDBS), an anionic surfactant, on marine sediments was systematically investigated. The experimental results showed that 100 min was required for the adsorption equilibrium. For the sediments treated by HCl and H₂O, sorption behavior of SDBS was fit with linear isotherm very well over the concentration range studied at 298 K. The sorption occurred primarily due to partition function of hydrophobic chains into organic carbon of sediments. Sorption of SDBS on H₂O₂-treated sediments was satisfactorily fit with Freundlich isotherm model and mainly through surface function of clay minerals in the sediment. The sorption was favorably influenced by the increased salinity, deceased pH and decreased temperature of seawater.     

Sorption of Selected Aromatic Substances��Application of Kinetic Concepts and Quantum Mechanical Modeling

Prediction of the sorption behavior of environmental pollutants is of utmost importance within the framework of risk assessments. In this work two approaches are presented with the aim to describe sorption of aromatic substances to geosorbents. First, analytical solutions of kinetic models were fitted to experimental data of batch sorption experiments with aniline and 1-naphthylamine onto animal manure-treated soil and the soil mineral montmorillonite. The models, accounting for equilibrium and nonequilibrium sorption coupled to transformation and/or irreversible sorption processes, could well reproduce the concentration course of the sorbates. Results suggest that the amounts transformed/degraded and irreversibly bound were higher for the soil than for the clay mineral. In the second part, quantum chemical calculations were performed on aniline and 1-naphthylamine interacting with acetic acid, acetamide, imidazole, and phenol as models of functional groups present in humic substances. Molecular modeling showed that formation of hydrogen bonds is the dominating binding mechanism in all modeled complexes, which are energetically very similar between aniline and 1-naphthylamine.     

Complexation Study of Humic Acids Extracted from Forest and Sahara Soils with Zinc (II) and Cadmium (II) by Differential Pulse Anodic Stripping Voltammetry (DPASV) and Conductimetric Methods

Safranin was used as a model reactive dye for biosorption studies onto various forms of chemically modified biomass of Aspergillus wentii. The experimental equilibrium data was analyzed by various single-, two-, three-, four-, and five-parameter isotherms to understand the biosorption process. Biosorption isotherms modeling shows that the interaction of safranin with A. wentii surface is localized monolayer sorption. Results show that in general the accuracy of models to fit experimental data improves with the degree of freedom. The interaction among adsorbed molecules is repulsive having no association between them and sorption is carried out on energetically different sites and is an endothermic process. The five-parameter Fritz?CSchluender model gives the most accurate fit with high regression coefficients (0.9902?C0.9941), low standard errors (0.0389?C0.0758), and sum of squares error (0.0075?C0.0230) values to all experimental data in comparison to other models. The results disclose that the sorption isotherm models fitted the experimental data in the order: Fritz?CSchluender (five-parameter) > Langmuir > Khan > Fritz?CSchluender (four-parameter) > Temkin. This systematic evaluation of the more important equilibrium isotherm models provided the general basis for making a preliminary selection of an effective model for a given application.     

Preparation of High Surface Area Oxidized Activated Carbon from Peanut Shell and Application for the Removal of Organic Pollutants and Heavy Metal Ions

A peanut shell-derived oxidized activated carbon (OAC) with high surface area was prepared by zinc chloride (ZnCl₂) chemical activation and subsequent nitric acid oxidation. OAC was characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and N₂ adsorption-desorption. The results showed that OAC had the surface area of 1807 m² g^?1, with the total pore volume of 0.725 cm³ g^?1 and average pore diameter of 3.8 nm. More importantly, when OAC acted as an adsorbent, it exhibited high efficiency to remove basic blue 41 (BB-41), congo red (CR), phenol, Cr(VI), and Pb(II) from aqueous solution due to its universality in adsorption. Batch adsorption experiments were carried out to study the effect of various parameters such as pH, initial concentration, temperature, and contact time. Also, the isotherms, kinetic models, and thermodynamics of adsorption process were investigated. The equilibrium data for CR and Pb(II) were fitted to Langmuir isotherm model, while Freundlich model was suitable for the equilibrium isotherm of BB-41, phenol, and Cr(VI), respectively. As the result indicated, peanut shell was a suitable raw material to synthesize OAC which could be employed as an efficient and universal adsorbent for removing organic pollutants and heavy metal ions from wastewater.     

Sorption and Desorption of Dye Remazol Yellow onto a Mexican Surfactant-modified Clinoptilolite-rich Tuff and a Carbonaceous Material from Pyrolysis of Sewage Sludge

The sorption behavior of dye remazol yellow using surfactant modified zeolitic rock and a carbonaceous material obtained by pyrolysis of sewage sludge and treated with HCl (1.0%) solution was determined. The kinetic and sorption isotherms experimental results were best adjusted to the pseudo-second order model and to the Langmuir–Freundlich isotherm model which indicate that the sorption process is chemisorption on heterogeneous materials. Remazol yellow could be removed from the saturated modified zeolitic material by different processes, unfortunately, the surfactant was removed together with the dye, the best results were found using Fenton’s reagent. Thermal treatment was the best method found to remove the dye from the carbonaceous material.     

诺氟沙星在胡敏酸上的吸附热力学与动力学特征研究

根据OECD Guideline106批平衡实验,研究了诺氟沙星在胡敏酸上的吸附热力学和动力学,并探讨了其可能吸附机理。结果表明,诺氟沙星在经过约12h的快速吸附阶段后,进入缓慢吸附阶段,其吸附平衡时间为48h。伪二级动力学方程能够较好地描述不同pH条件下诺氟沙星在胡敏酸上的吸附动力学特性。诺氟沙星在胡敏酸上的吸附等温线符合Freundlich方程,该方程的拟合系数1/n〈0.5,表明诺氟沙星在胡敏酸上为非线性吸附。ΔH0=-48.85kJ·mol-1和ΔG0〈0,表明诺氟沙星在胡敏酸上的吸附是自发进行的放热过程,且离子交换是其主要吸附机理,同时也可能存在着偶极间作用力、氢键力和电荷转移等吸附机理;ΔS0〈0表明吸附过程中熵在减小。吸附位点的能量随着吸附量的增大而降低,也表明胡敏酸的异质性和吸附的非线性。     

Removal of Zn2+ from Aqueous Solution using Castor Seed Hull

The effects of various experimental parameters on adsorption of Zn²⁺ metal ion from its aqueous solution by castor seed hull and also by activated carbon have been investigated using batch adsorption experiments. It has been found that the amount of zinc adsorbed per unit mass of the hull increases with the initial metal ion concentration, contact time, solution pH and with the amount of the adsorbent. Kinetic experiments clearly indicate that adsorption of zinc on both castor hull and activated carbon is a three-step process??a rapid adsorption of the metal ion, a transition phase, and an almost flat plateau. This has also been confirmed by the intraparticle diffusion model. It has also been found that the zinc adsorption process followed pseudo-second order kinetics. The kinetic parameters including rate constants have been determined at different initial metal ion concentration, pH, amount, and type of adsorbent, respectively. The Langmuir and Freundlich adsorption isotherm models have been used to interpret the equilibrium adsorption data. The Langmuir model yields better correlation coefficients. The monolayer adsorption capacities (q _m ) of castor hull and activated carbon have been compared with those for others reported in the literature. The value of separation factor (R _L ) derived from the Langmuir model gives an indication of favorable adsorption. Finally, from comparative studies, it has been found that castor hull is a potentially attractive adsorbent as compared to commercial activated carbon for the removal of zinc from aqueus effluents.     

Removal of Tartrazine from Aqueous Solution by Adsorption on Activated Red Mud

In this study, activated red mud was used to develop an effective adsorbent in order to remove a toxic azo dye (tartrazine E102) from aqueous solutions. To increase the adsorption capacity, the red mud was activated by acid-heat treatment using 20 wt.% HCl (RM-HCl). To establish the optimum operating parameters, the influence of pH, adsorbent dose, contact time, initial dye concentration, and stirring rate was investigated. The adsorption equilibrium was studied using Langmuir, Freundlich, Dubinin-Radushkevich, Temkin isotherm models, and the characteristic parameters for each adsorption isotherm were determined. The kinetics of the adsorption process was analyzed by means of pseudo-first-order and pseudo-second-order models. The maximum removal efficiency obtained under optimum conditions was 84.72%. These results were in accordance with the isotherm and kinetic data. The results suggested that tartrazine adsorption process follows the pseudo-second-order kinetic model and also that fits Langmuir isotherm model. The maximum monolayer adsorption capacity was 136.98 mg/g.     

Evaluation of Activated Carbon-Coated Electrode in Electrostatic Precipitator and Its Regeneration for Volatile Organic Compounds Removal

Activated carbon-coated electrode was developed and applied in electrostatic precipitator to remove volatile organic compound gases simultaneously with dust particles from a contaminated air. The activated carbon coating mixture was made up of powdered activated carbon (AC), carbon black (CB), and polyvinyl acetate (PVA), and methanol was added as a solvent to control the thickness of the mixture for best coating performance. During the coating process, the Brunauer-Emmett-Teller (BET) surface decreased to 86% of the original AC while pore volume percentages of macro pore increased, compared to micro- and meso-sized pores. The adsorption isotherm of benzene, toluene, ethyl benzene, and xylene (BTEX) gases onto the original AC and AC coating mixture (AC thoroughly mixed with PVA and methanol for coating and powdered again after dry) were tested and compared to each other, and it was found that both isotherm were best fitted to Freundlich and Langmuir isotherm with the order of adsorption capacities; ethyl benzene?>?m-xylene?>?toluene?>?benzene. The difference between adsorption capacities was clearer with the absorbent AC but became little with the AC coating mixture. In removing BTEX at increasing linear velocities up to 6.7 cm/s, it appeared that the surface area of AC electrode was directly proportional to its removal rate of BTEX. The thermal desorption was applied to regenerate the AC electrode, and 200 °C was found to be most efficient for benzene desorption, but higher temperature would be required for entire BTEX gases desorption.     

Efficiency of rice bran for the removal of selected organics from water: kinetic and thermodynamic investigations

The sorption efficiency of indigenous rice (Oryza sativa) bran for the removal of organics, that is, benzene, toluene, ethylbenzene, and cumene (BTEC), from aqueous solutions has been studied. The sorption of BTEC by rice bran is observed over a wide pH range of 1-10, indicating its high applicability to remove these organics from various industrial effluents. Rice bran effectively adsorbs BTEC of 10 microg mL(-1) sorbate concentration from water at temperatures of 283-323 +/- 2 K. The effect of pH, agitation time between solid and liquid phases, sorbent dose, its particle size, and temperature on the sorption of BTEC onto rice bran has been studied. The pore area and average pore diameter of rice bran by BET method are found to be 19 +/- 0.7 m(2) g(-1) and 52.8 +/- 1.3 nm. The rice bran exhibits appreciable sorption of the order of 85 +/- 3.5, 91 +/- 1.8, 94 +/- 1.4, and 96 +/- 1.2% for 10 microg mL(-1) concentration of benzene, toluene, ethylbenzene, and cumene, respectively, in 60 min of agitation time using 0.1 g of rice bran at pH 6 and 303 K. The sorption data follow Freundlich, Langmuir, and Dubinin-Radushkevich (D-R) models. Sorption capacities have been computed for BTEC by Freundlich (32 +/- 3, 61 +/- 14, 123 +/- 28, and 142 +/- 37 m mol g(-1)), Langmuir (6.6 +/- 0.1, 7.5 +/- 0.13, 9.5 +/- 0.22, and 9.4 +/- 0.18 m mol g(-1)), and D-R isotherms (11 +/- 0.5, 16 +/- 1.3, 30 +/- 2.2, and 33 +/- 2.5 m mol g(-1)), respectively. The Lagergren equation is employed for the kinetics of the sorption of BTEC onto rice bran and first-order rate constants (0.03 +/- 0.002, 0.04 +/- 0.003, 0.04 +/- 0.003, and 0.05 +/- 0.004 min(-1)) have been computed for BTEC at their concentration of 100 mug mL(-1) at 303 K. Studies on the variation of sorption with temperatures (283-323 K) at 100 mug mL(-1) sorbate concentration gave thermodynamic constants DeltaH (kJ mol(-1)), DeltaG (kJ mol(-1)), and DeltaS (J mol(-1) K(-1)). The results indicate that the sorption of organics onto rice bran is exothermic and spontaneous in nature under the optimized experimental conditions selected. This sorbent has been used successfully to accumulate and then to determine benzene, toluene, and ethylbenzene in wastewater sample.     

Adsorption of Copper in the Different Sorbent/Water Ratios of Soil Systems

While sorbate/sorbent, sorbate/water, and sorbent/water (S/W)ratios in a batch system are known to affect the adsorption ofsorbate, the effect of different S/W ratios on the adsorptionof inorganic sorbates has seldom been addressed. This studyinvestigates the adsorption phenomena of Cu²⁺ in differentsorbate/sorbent/water ratios in a batch system. Batch experimentsare performed to examine the adsorption, and the linear (K _D), Langmuir (K _L), and Freundlich (K _F) adsorption coefficients of Cu²⁺ in lateritic soil. These experiments are conducted using solutions with initial concentrations of 0.5 to 50 mg Cu²⁺ L^-1 equilibratedwith an appropriate amount of soil to give S/W ratios of 0.1 to 2 g mL^-1. Although the variations in the sorbed amountand adsorption coefficients apparently originate from a changein the sorbate/sorbent/water ratio, only the equilibrium concentration significantly affects adsorption. On the otherhand, the linear and Langmuir isotherm cannot adequately describethe adsorption data. In this study, the Freundlich equation gavean excellent fit to the adsorption data with a goodness-of-fit(R²) > 0.984. However, adsorption isotherms should be regarded as only a curve-fitting model or a mathematical tool and cannot be employed to interpret any particular adsorptionmechanism. Meanwhile, the solids effect reveals that K _F andmaximum adsorption (b) of the Langmuir equation increase when S/W ratio decreases. The sorbate in the stagnant phase must beconsidered as part of the equilibrium concentration in the solidphase to avoid underestimating the sorbed amount at a lower S/Wratio and/or a higher sorbate concentration level.