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.     

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).     

Evaluating Binary Sorption of Phenol/Aniline fromAqueous Solutions onto Granular Activated Carbon and Hypercrosslinked Polymeric Resin (MN200)

Sorption equilibrium of phenol and aniline onto the granular activated carbon and hyperreticulated un-functionalized polymeric resin (MN200) was investigated in single and binary component aqueous systems. Higher loading was obtained for aniline than phenol onto both sorbents, which is probably due to hydrophobic difference between both solutes and the greater electronic density of the aromatic ring of the aniline. Granular activated carbon reported larger uptake than resin MN200 for both solutes, which may be attributed to the better physical properties of the granular activated carbon, for instance, larger surface area. The experimental sorption could be properly described by the Langmuir and Freundlich isotherms. Five models for predicting the binary equilibrium sorption isotherm were compared in order to determine the best fit model to correlate binary experimental data: the extended Langmuir isotherm with and without a constant interaction factor, a simplified model based on the single equilibrium factors, the empirical extended Freundlich isotherm and the modified extended Langmuir equation, which considers the synergistic interactions between sorbate–sorbate and not only the competition between them defined by the extended Langmuir model. The modified extended Langmuir model provides the best agreement between predicted and experimental data indicating that the synergistic interactions between solutes play an important role in the binary phenol/aniline sorption system.     

THE USE OF THE FREUNDLICH ISOTHERM FOR SOIL PHOSPHATE SORPTION DATA

Phosphate sorption data for twenty-nine soils were found to fit the Freundlich adsorption isotherm better if a measure of native labile P was first added to the sorption data, and this sum plotted against intensity. The exponent from the isotherm thus obtained was closely related to exchangeable A1 (in acid soils) and exchangeable Ca (in neutral and calcareous soils), with a mole ratio of one P to 6 A1 or Ca.     

土壤吸附铜离子的研究进展

对土壤吸附Cu的研究进行了综述。主要讨论了吸附速率,吸附等温线,表面络合模式和影响吸附量的因子等方面的问题。目前对土壤吸附Cu的速率研究主要有两种方法:一是根据实验数据绘制吸附量随时间变化的曲线,根据所绘制的曲线斜率来研究吸附动力学过程;二是选择经验性的化学动力学方程对数据进行拟和,依据较高的相关系数和较低的标准误差选择最优方程,根据吸附速率系数来进行定量的研究。土壤对Cu吸附的定量描述,经验性的吸附等温式仍不失为一个十分有用的方法;考虑到土壤性质和环境因子对吸附的影响,模型中应该加入这些参数使其更能反映土壤对重金属的吸附过程,但这方面的研究相对较少。土壤表面电荷特征、低分子有机酸对土壤吸附Cu的影响和吸附过程中Cu形态的变化等方面研究也较少。     

Spreadsheet Optimization for Parameter Estimation of Pressure–Saturation Equations Used for Two-Phase Groundwater Flow

Spreadsheet optimization using a range of nonlinear error functions was utilized for parameter estimation of the two-phase pressure–saturation models developed by van Genuchten, Brutsaert, Russo and Kosugi. The data was obtained from the UNSODA database (US Salinity Laboratory, Riverside, California). Results show that spreadsheet optimization is a practical platform for evaluations based on minimizing nonlinear error functions, consequently allowing for a broader mathematical approach to parameter estimation. An error function representing the sum of the squares of errors provided the best fit for a majority of the soils evaluated, although the fractional error function provided the best fit for silts and loams. Outcomes indicated that the van Genuchten parameters m and n may also be estimated individually as opposed to following the published relationship of m=1?1/n.     

Sorption of polycyclic aromatic hydrocarbons to mineral surfaces

Minerals contribute crucially to the retention of polycyclic aromatic hydrocarbons (PAHs) in subsurface environments. To investigate the sorption behaviour to mineral surfaces batch sorption experiments were conducted using three PAHs (phenanthrene, pyrene, benzo(a)pyrene) and three mineral sorbents that were representative of subsurface materials (quartz, goethite‐coated quartz, quartz‐montmorillonite mixture). Sorption kinetics showed an instantaneous, considerable PAH sorption to all minerals, except for phenanthrene sorption to quartz at small aqueous‐phase concentrations. Apparent sorption equilibrium was achieved after 4 hours of contact time. The sorption characteristics were fitted to six isotherm models by applying Monte Carlo simulation and nonlinear regression. Best‐fit models were obtained by a model discrimination approach. Phenanthrene and pyrene sorption were best described by the Freundlich isotherm model, with the exception of phenanthrene sorption to quartz (linear isotherm). Good fit results for quartz were also obtained for the combined linear‐Freundlich isotherm. Benzo(a)pyrene sorption to all minerals followed linear high‐affinity isotherms. In the case of phenanthrene and pyrene, the Monte Carlo simulations resulted in mean values with small standard deviations for the isotherm parameters, indicating a negligible influence of the experimental uncertainties on the accuracy of the fitted parameters. For phenanthrene, (i) linear isotherms to quartz and goethite‐coated quartz and (ii) a nonlinear concave‐shaped isotherm to quartz–montmorillonite, assuming a pore‐filling process to micropores formed by clay aggregates, were confirmed. For pyrene, nonlinear convex‐shaped isotherms to the mineral surfaces were assessed. A specific sorption affinity of pyrene to the goethite surface indicated a non‐covalent cation‐π interaction. Small sorption affinities to quartz–montmorillonite support an unfavourable partitioning into the adjacent water.     

菲和Cu^2＋在黑垆土上的吸附及其交互影响

采用批平衡法,研究了菲和Cu2＋在黑垆土上的吸附及其交互影响。结果表明,菲和Cu2＋在黑垆土上的吸附动力学曲线较好符合一级动力学方程,菲在黑垆土上的吸附主要通过分配作用,其吸附等温曲线符合线性Henry方程,Cu2＋的存在抑制菲在黑垆土上的吸附;而Cu2＋在黑垆土上的吸附主要通过表面吸附和专性吸附作用,其吸附等温曲线符合Freundlich方程,菲的存在促进了Cu2＋的吸附;对菲和Cu2＋来说,pH均是影响黑垆土吸附的主要因素,黑垆土对Cu2＋的吸附量随着土壤溶液pH值的增加而增加,而对菲的吸附量随着pH增加而降低。     

A Novel Pretreatment Method of Lignocellulosic Material as Adsorbent and Kinetic Study of Dye Waste Adsorption

Sulphuric acid-modified bagasse has been used as low-cost adsorbent for the removal of methylene blue (MB) dye from aqueous solution. In order to remove organic compounds that contribute to chemical oxygen demand (COD), pretreatment with thorough washing of adsorbent using boiling distilled water was performed instead of conventional washing using distilled water at room temperature only. This has resulted in the highest efficiency of color removal of 99.45% and COD reduction of 99.36% for MB dye solution at pH 9. Effects of initial pH, dye concentration, adsorbent dosage, temperature, and contact time have been studied. The adsorption of MB dye was pH dependent. Langmuir and Freundlich isotherm models were tested on the adsorption data. The kinetic experimental data were analyzed using pseudo-first order, pseudo-second order, and the intraparticle diffusion model in order to examine the adsorption mechanisms. The adsorption process followed the Langmuir isotherm as well as the Freundlich isotherm and pseudo-second-order kinetic model. The process was found to be endothermic in nature.     

Reducing nitrogen loss by application of natural clinoptilolite modified with quaternary N-Alkyl agent as controlled-release fertilizer in two species of beans (P. Vulgaris and Vigna Unguiculata)

In this work, a novel controlled-release fertilizer (CRF) was designed by using new quaternary N-alkyl as an innovative surface modifier for clinoptilolite in order to adsorb the nitrate anion. So far, a few number of commercial cationic surfactants have been introduced for engineered zeolites to adsorb and slow release anions. Therefore, an organic ligand was synthesized for the first time and was applied for modification of clinoptilolite. Investigating the effect of pH and adsorbent dosage showed that the experimental adsorption data were fitted well with the Langmuir and Freundlich isotherm models. Moreover, nitrate leaching tests were performed and the results confirmed that nitrate concentration of the leachate from the soil amended with novel fertilizer was 42% lower than that of the urea fertilizer. The growth parameters including were studied and the results showed that the red beans planted in the soil amended with modified fertilizer had the best results.     

蔬菜氮磷钾三元肥效模型的MonteCarlo建模法

应用"3414"设计的田间肥料试验结果,探讨蔬菜氮磷钾三元肥效模型的Monte Carlo建模法。莴苣试验结果表明,采用最小二乘法回归建模,NP、NK二元肥效模型属于非典型式,PK二元和NPK三元肥效模型属于典型式;而改用MonteCarlo建模法,NP、NK和PK二元肥效模型以及NPK三元肥效模型均属于典型式。采用最小二乘法回归建模,不同蔬菜作物建立的34个三元肥效模型的典型式出现机率为41.2%,而Monte Carlo建模法的典型式出现机率为91.2%,提高了2.2倍。Monte Carlo建模法是适当放弃数学上偏差平方和最小的最优性,使待估参数达到专业上最优而数学上较优,从而提高典型肥效模型的出现机率。对莴苣氮钾非典型肥效模型的推荐施肥表明,Monte Carlo法的结果明显优于产量频率分析法。因此,Monte Carlo建模法为建立蔬菜多元肥效模型和推荐施肥提供了一种有效方法。     

Sorption Behavior of 4-Chlorophenol from Aqueous Solutions By a Surfactant-modified Mexican Zeolitic Rock in Batch and Fixed Bed Systems

The removal of 4-chlorophenol from aqueous solutions by both a Mexican clinoptilolite-heulandite zeolitic rock and the modified zeolitic material with the surfactant hexadecyltrimethylammonium bromide (HDTMABr), using batch and packed-bed (column) configurations, was investigated. The unmodified zeolitic rock did not show any adsorption of 4-chlorophenol. The effects of pH, contact time and concentration of 4-chlorophenol on the adsorption process by the surfactant modified material were examined. The sorption of 4-chlorophenol was not affected by the pH range from 4 to 9.5. 4-chlorophenol retention reached equilibrium in about 18 h and the rate of 4-chorophenol adsorption by the modified material was faster in the first 10 h than later. The experimental data were treated with the models: pseudo-first order, pseudo-second order, fractional power and Elovich models. Although, the last three gave correlation coefficients higher than 0.96, the pseudo-second order model was the best to describe the reaction rate. The experimental data follow a linear isotherm which is characteristic for sorption of organic solutes by the partition mechanism. The Bed Depth-Service Time Model was applied to the sorption results in order to model the column operation. The results showed that the surfactant modified zeolitic rock could be considered as a potential adsorbent for 4-chlorophenol removal from aqueous solutions.     

Evaluation of Iron(III)-Coordinated Amino-Functionalized Poly(Glycidyl Methacrylate)-Grafted Cellulose for Arsenic(V) Adsorption from Aqueous Solutions

This study evaluated the effectiveness of a novel adsorbent (Fe(III)-AM-PGMACell), Iron(III)-coordinated amino-functionalized poly(glycidyl methacrylate)-grafted cellulose for the adsorption of arsenic(V) from aqueous solutions. The Fe(III)-AM-PGMACell was prepared through graft copolymerization of glycidyl methacrylate (GMA) onto cellulose (Cell) in the presence of N,N??-methylenebisacrylamide (MBA) as a cross linker using benzoyl peroxide initiator, followed by treatment with ethylenediamine and ferric chloride in the presence of HCl. Batch experiments were performed to evaluate the adsorption efficiency of Fe(III)-AM-PGMACell towards As(V) ions. The contact time to attain equilibrium and the optimum pH were 90?min and 6.0, respectively. More than 99.0% adsorption was achieved from an initial concentration of 25.0?mg/L. A two-step pseudo-first-order kinetic model agreed well with the dynamic behavior for the adsorption process. Equilibrium data fitted well with Sips isotherm model with maximum adsorption capacity of 78.8?mg/g at 30??C. The desorption of As(V) was achieved over 98.0% with 0.1?M NaCl solution.     

Applying Activated Carbon Derived from Coconut Shell Loaded by Silver Nanoparticles to Remove Methylene Blue in Aqueous Solution

This study developed a new adsorbent, specifically activated carbon-loaded silver nanoparticles (AgNPs-AC) by coating the silver nanoparticles (AgNPs) onto activated carbon (AC). The obtained AgNPs-AC were characterized by scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET). The ability of AgNPs-AC to remove methylene blue (MB) was evaluated using different experimental factors, these being pH solution, contact time, adsorbent dose, and initial MB concentration. Results indicated that the highest adsorption capacity of MB onto AgNPs-AC was obtained when the AC was loaded onto AgNPs at the impregnation ratio of 0.5% w/w for AC and AgNPs. The best conditions in which AgNPs-AC could remove MB were as follows: pH 10, contact time lasting 120 min, and adsorbent dose being 250 mg/25 mL solution. In this scenario, the maximum adsorption capacity of MB onto AgNPs-AC was 172.22 mg/g. The adsorption isothermal equilibrium was well described by the Langmuir, Freundlich and Sips models. The Sips equations had the highest correlation coefficient value (R²?=?0.935). The pseudo-first-order and pseudo-second-order kinetic models agree well with the dynamic behavior of the adsorption of dye MB on AgNPs-AC.     

Adsorptive Potential of 2-Mercaptobenzimidazole-Immobilized Organophilic Hydrotalcite for Mercury(II) Ions from Aqueous Phase and Its Kinetic and Equilibrium Profiles

An organophilic calcined hydrotalcite (OHTC) was prepared by treating calcined hydrotalcite (HTC) with sodium dodecylbenzene sulphonate (an anionic surfactant) to achieve a high loading of thiol functionality through the immobilization of 2-mercaptobenzimidazole (MBI) as a chelating agent. The adsorbent (MBI-OHTC) obtained was characterized using XRD, FTIR, SEM, TG/DTG, surface area analysis and potentiometric titration. The adsorption of MBI-OHTC to remove Hg(II) ions from aqueous solutions was studied as a function of pH, contact time, metal ion concentration, ionic strength and adsorbent dose. The optimum pH range for the maximum removal of Hg(II) was 6.0–8.0. The maximum value of Hg(II) adsorption was found to be 11.63 and 21.52 mg g^?1 for an initial concentration of 25 and 50 mg l^?1, respectively at pH 8.0. The equilibrium conditions were achieved within 3 h under the mixing conditions employed. A reversible pseudo-first-order used to test the adsorption kinetics. The adsorption mechanism consisted of external diffusion and intraparticle diffusion and the intraparticle mass transfer diffusion was predominated after 20 min of experiment. Extent of adsorption decreased with increase of ionic strength. The experimental isotherm was analyzed with two parameters (Langmuir and Freundlich) and three parameters (Redlich–Peterson) equations. The isotherm data were best modeled by the Freundlich isotherm equation. Complete removal (≈100%) of Hg(II) from 1.0 l of chlor-alkali industry wastewater containing 9.86 mg Hg(II) ions, was possible with 3 g of the adsorbent dose at pH 8.0. About 95.0% of Hg(II) can be recovered from the spent adsorbent using 0.1 M HCl.     

Adsorption Behaviour of Basic Dyes on the Humic Acid Immobilized Pillared Clay

In this work, the adsorption of three basic dyes, namely methylene blue (MB), crystal violet (CV) and rhodamine B (RB) on the humic acid (HA) immobilized pillared clay (PILC) (HA-PILC) was studied. The adsorption capacity of dyes at 30 °C using HA–PILC was foundto be 2.6, 2.0 and 2.3 times greater than that using PILC for the removal of MB, CV and RB, respectively for an initial concentrationof 250 μmol dm^-3. The adsorption process was pH dependent. The maximum dye adsorption on HA-PILC was observed at a pH of 5.0–7.0 (removal of 95.2–99.2% for MB, 92.7–97.3% for CV and 83.4–91.0% for RB) with no significant increase in removalsbeyond a pH of 7.0. The adsorption process could be best describedby the Urano and Tachikawa model showing that particle diffusion controlled adsorption. Equilibrium adsorption data were analyzed using the Langmuir, Freundlich and Redlich-Peterson isotherms. Dye adsorption was best described by the Freundlich model. The monolayer adsorption capacities of HA-PILC calculated using the Langmuir isotherm were 608.4, 484.7 and 413.1 μmol g^-1 for MB, CV and RB, respectively. The linear Sheindorf-Rebhun-Sheintuch equation (Multicomponent Freundlich-type), was applied to the isotherm data obtained for each binary-solute combination of MB, CV and RB. The study showed that HA-PILC was an excellent media for the removal of basic dyes from aqueous solutions, based on adsorption kinetics and capacity.     

基于BP神经网络模型的荔枝树叶面积测定方法

为了准确、快速地测定荔枝树叶面积，设计了一个BP神经网络模型，输入参数为叶片长度和叶片最大宽度，输出参数为叶面积。用LI-3000A型叶面积仪测量所得到的样本数据对网络进行训练，测试样本的网络输出与网络目标的相关系数达0.99609，网络模型是有效的。用训练后的网络模型对10组未参加建模的样本数据进行叶面积测定，误差平方和为1.2929，优于回归方程法的2.511。训练好的BP神经网络模型可以在不破坏叶片的情况下，简单、快速、经济地测定大量的荔枝树叶片面积。     

不同插值方法对成分数据空间预测结果的影响——以土壤连续分类模糊隶属度值为例

地球科学中成分数据(compositional data)非常普通,其在进行空间插值时必须满足4个条件:每一位置各组分之和为常数,每一组分为非负,插值结果无偏最优.本文以土壤连续分类模糊隶属度值为例,数据经对数正态变换、非对称对数比转换、对称对数比转换后进行普通克里格插值结果和成分克里格插值(compositional kriging)结果进行比较.结果表明,对原始数据和经对数正态变换后数据进行插值,每一位置预测结果隶属度之和不能满足常数1.经非对称对数比转换后,插值结果虽然满足各个位置组分之和为1,但是预测结果精度较低,且预测结果空间分布连续性不明显.数据经对称对数比转换后插值结果和成分克里格插值结果,都能满足成分数据空间插值的4个条件,但二者各有优势.相比较而言,对称对数比转换方法得到的预测结果更能体现土壤空间连续渐变特征,而成分克里格插值结果能保证隶属度本身是最优无偏估计.     

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.