Sorption of Cd in Soils: Pedotransfer Functions for the Parameters of the Freundlich Sorption Isotherm

Using a data set derived from 480 soil samples, pedotransfer functions for the coefficient (K) and the exponent (m) of the Freundlich sorption isotherm were developed. The functions were validated with data from 135 independent soil samples. We found high goodness-of-fit for the approaches of the Freundlich coefficient, whereas the efficiency of the models for predicting the independent samples should be improved. For the Freundlich exponent, the mean value of the parameterisation data set (m = 0.88) served as a better predictor than any of the developed functions. These findings contribute to the interpretation stated by previous authors that variation of the Freundlich exponent is of minor importance and therefore negligible in the course of sorption modelling.     

Effect of Sediment Humic Substances on Sorption of Selected Endocrine Disruptors

Characterizing sorption processes is essential to understand the environmental distribution and toxicity potential of endocrine disruptors in terrestrial and aquatic systems. The sorption behaviors of three endocrine disruptors (bisphenol A (BPA), 17β-estradiol (E2), and 17α-ethynylestradiol (EE2)) on sediments were investigated using batch techniques. Samples were taken from some representative reaches in several major Chinese rivers. More attention has been paid to the effect of sediment organic components on the sorption of BPA, E2, and EE2. The results show that the sediment organic carbon-normalized partition coefficients (K _oc (sed)) for three endocrine disruptors are in the order of EE2 > E2 > BPA, which corresponds to the octanol-water partitioning coefficients (logK _ow) of the compounds. Moreover, the K _oc values for humic substances (K _oc (hs)) are comparable with the K _oc (sed) values and highly dependent on the physico-chemical properties of humic substances in sediments. The UV absorptivity at 272 nm (A ₂₇₂), which suggests the abundance of aromatic rings in humic substance structure, correlates well with the K _oc (hs) values. In addition, the infrared spectra of the humic substances extracted from sediments show four strong bands centered at 3,400 cm⁻¹, 1,625 cm⁻¹, 1,390 cm⁻¹, and 1,025 cm⁻¹. The K _oc (hs) values have a positive linear relation with the peak area ratio for peak at 1,025 cm⁻¹ and a negative linear relation with the peak area ratio between peaks at 1,625 cm⁻¹ and 1,025 cm⁻¹. Hence, the hydrogen bonds play a critical role to the sorption of selected endocrine disruptors.     

Estimation of critical ratio of bentonite addition to tuff sand

A design method was proposed to determine the critical ratio of bentonite addition, based on a macro void ratio that considers the swelling property of bentonite. The critical ratio of bentonite addition was defined as the ratio corresponding to a macro void ratio of zero. However, when lightweight soil such as tuff sand is mixed with bentonite, the estimated critical ratio of bentonite addition is too high. Several tests on the water absorbing property of tuff sand and its permeability were conducted to confirm the concept of a revised macro void ratio. The revised macro void ratio, which takes into account the swelling of bentonite and the particle pores of lightweight soil, is much smaller than the former macro void ratio for a given ratio of bentonite addition. The estimated critical ratio of bentonite addition to tuff sand that gives a revised macro void ratio of zero is around 18% and is in good agreement with the ratio of bentonite addition beyond which the value of hydraulic conductivity does not decrease markedly.     

The effects of apple pomace,bentonite and calcium superphosphate on swine manure aerobic composting

The effects of additives such as apple pomace, bentonite and calcium superphosphate on swine manure composting were investigated in a self-built aerated static box (90 L) by assessing their influences on the transformation of nitrogen, carbon, phosphorous and compost maturity. The results showed that additives all prolonged the thermophilic stage in composting compared to control. Nitrogen losses amounted to 34–58% of the initial nitrogen, in which ammonia volatilization accounted for 0.3–4.6%. Calcium superphosphate was helpful in facilitating composting process as it significantly reduced the ammonia volatilization during thermophilic stage and increased the contents of total nitrogen and phosphorous in compost, but bentonite increased the ammonia volatilization and reduced the total nitrogen concentration. It suggested that calcium superphosphate is an effective additive for keeping nitrogen during swine manure composting.     

Use of rubber and bentonite added fly ash as a liner material

In many countries regulations require all hazardous waste disposal facilities to be lined with suitable impermeable barriers to protect against contamination. In this study, a series of laboratory tests on rubber and bentonite added fly ash were conducted. The aim of the tests was to evaluate the feasibility of utilizing fly ash, rubber and bentonite as a low hydraulic conductivity liner material. Type C fly ash was obtained from Soma thermal power plant in Turkey; rubber in pulverized form was waste from the retreading industry. To investigate the properties of rubber and bentonite added fly ash, hydraulic conductivity, leachate analysis, unconfined compression, split tensile strength, one-dimensional consolidation, swell and freeze/thaw cycle tests were performed. The overall evaluation of results have revealed that rubber and bentonite added fly ash showed good promise and a candidate for construction of a liner.     

Moisture Sorption Characteristics of Chitosan/Polyethylene Oxide Blended Films

Studies on the moisture sorption characteristics of chitosan/polyethylene oxide (PEO) blended films have been carried out at 27 °C for water activity (a _w) from 0.1 to 0.9. The sorption data at different a _w were used to fit 12 different sorption isotherm models proposed in the literature. The model constants were determined by linear fitting of the sorption equations. The ranges of applicability of water activity for the isotherms reported in the article lie between 0.11 to 0.44 (monomolecular layer) for the BET model and between 0.11 to 0.86 (monolayer & multilayer’s) for Smith, Caurie, Bradley and Oswin. The water activity for Halsey and Chung & Pfost models lies between 0.44 to 0.86 (multilayer) and 0.33 to 0.86 for Henderson and Freundlich models and 0.11 to 0.65 for Kuhn, Linear and Iglesias & Chirife models. The high coefficient of determination R ² (ranges from 0.82 to 1) confirms the applicability of the equations employed. The study on the application of such water activity data of chitosan/PEO blended films on different model equations will be helpful in prediction of durability and functional behavior of moisture sensitive biopolymeric films     

Moisture Sorption Characteristics of Microbially Produced Polysaccharide and Polyvinyl Alcohol Blends

Moisture sorption characteristics of microbial polysaccharide (Ps.C101) from Pseudomonas caryophilli and polyvinyl alcohol (PVA) blends have been carried out at 27°C for water activity from 0.1 to 0.9. The sorption data was used to fit six different sorption isotherm models proposed in literature. The model constants were determined by linear fitting of the sorption equations. The ranges of applicability of water activity for isotherm models reported in this paper lie in between 0.1 and 0.4 for Brunaur–Emmet–Teller (BET) model (monolayer), and in between 0.2 and 0.9 for other models. The value of the coefficient of determination (R² = 0.97 ± 0.02) confirms the applicability of the equations studied.     

Effects of calcium hydroxide and calcium chloride addition to bentonite in iron ore pelletization.

Pyrite ash is created as waste from the roasting of pyrite ores during the production of sulphuric acid. These processes generate great amounts of pyrite ash waste that is generally land filled. This creates serious environmental pollution due to the release of acids and toxic substances. Pyrite ash waste can be utilized in the iron production industry as a blast furnace feed to process this waste and prevent environmental pollution. The essential parameters affecting the pelletization process of pyrite ash were studied using bentonite as a binder. Experiments were then carried out using bentonite and a mixture of bentonite with calcium hydroxide and calcium chloride in order to make the bentonite more effective. The metallurgical properties of pyrite ash, bentonite, calcium hydroxide, calcium chloride, a mixture of these and sintered pellets were studied using X-ray analysis. The crushing strength tests were carried out to investigate the strength of pyrite ash waste pellets. The results of these analyses showed that pyrite ash can be agglomerated to pellets and used in the iron production industry as a blast furnace feed. The crushing strength of the pellets containing calcium hydroxide and calcium chloride in addition to bentonite was better than the strength of pellets prepared using only bentonite binder.     

Concentration Effects on Competitive Sorption of Trichloroethylene and Tetrachloroethylene to the Roots of Typha latifolia: Implications for Phytomonitoring

Uptake of organic contaminants by plant roots consists of two consecutive steps: sorption to plant roots and entrance into root xylem tissues through epidermal and endodermic membranes. Most research pertaining to phytoremediation assumed that sorption to plant roots is linear and non-competitive. A growing body of evidence, however, is suggesting that sorption to plant roots is nonlinear and competitive. The objective of this study was to examine the concentration effects of chemical constituents on the competitive sorption of trichloroethylene (TCE) and tetrachloroethylene (PCE) to the roots of Typha latifolia. Competitive sorption was clearly demonstrated by the reduced sorption of TCE and PCE in bi-solute systems than in single-solute systems. Concentration is an important factor affecting the extent of competition. In bi-solute systems, the PCE/TCE ratio on root surface approximately reflected the contaminant footprints in solution. The result was attributed to limited high energetically favorable sorption sites on the root surface and similar sorption mechanisms of TCE and PCE. The results hold significant importance for the application of phytomonitoring of organic contaminant mixtures.     

Bisolute Equilibrium Studies for the Sorption of Basic Dyes on a GAC from Almond Shells: A Nonlinear Approach

Aqueous phase adsorption of three textile dyes onto a granular activated carbon produced from acid activation of almond shells is presented. Primarily, the sorption of three basic dyes, methylene blue, rhodamine b, and malachite green oxalate were studied. Four models, the Freundlich, the Langmuir, the Redlich-Peterson, and the Toth isotherms were compared for their quality of fit to the single-solute sorption data. Next, sorption of the three likely binary systems was examined. Four bi-solute models, the extended Langmuir with and without an interaction term, the extended Redlich-Peterson with an interaction term, and the empirical extended Freundlich model were used to predict sorption in the binary systems. Nonlinearly determined constants of the corresponding single-solute isotherms were used in the binary models to compare with experimental binary sorption data. For the single-solute system, the three-parameter models of the Redlich-Peterson and the Toth isotherms outperformed the Langmuir and Freundlich models. The empirical extended Freundlich model produced the closest comparison to the binary data in each system. In general, the nonlinear method provided a simple and computationally effective technique of producing optimal fitting parameters for the bi-solute sorption models.     

固定化海带生物吸附剂的制备及其吸附Ni2+的动力学特性

以海藻酸钠、明胶和海带粉为原料制备了固定化海带生物吸附剂。固定化海带生物吸附剂对Ni2＋的吸附过程可分为3个阶段：快速吸附阶段、缓慢吸附阶段和吸附平衡阶段。动力学过程可用Lagergren准二级反应动力学方程描述,限速步骤为化学吸附。随Ni2＋初始质量浓度的增加,固定化海带生物吸附剂的Ni2＋吸附量逐渐增大,Ni2＋去除率逐渐降低。吸附过程符合Langmuir和Freundlich吸附等温方程,说明该吸附体系既有物理吸附又有化学吸附,从吸附状态看属于多层吸附,由Langmuir吸附等温方程得出固定化海带生物吸附剂对Ni2＋的最大吸附量为39．43mg／g,说明固定化海带生物吸附剂对Ni2＋有较好的吸附性能。     

Hexavalent Chromium Sorption by Modified Cellulose Macro and Nanofibers Obtained from Eucalyptus Residues

Journal of Polymers and the Environment - Exposure to potentially toxic metallic elements (PTME) released in watercourses by industries results in irreversible damage to living beings or even...     

固定化海带生物吸附剂的制备及其吸附Ni~(2+)的动力学特性

以海藻酸钠、明胶和海带粉为原料制备了固定化海带生物吸附剂。固定化海带生物吸附剂对Ni2+的吸附过程可分为3个阶段:快速吸附阶段、缓慢吸附阶段和吸附平衡阶段。动力学过程可用Lagergren准二级反应动力学方程描述,限速步骤为化学吸附。随Ni2+初始质量浓度的增加,固定化海带生物吸附剂的Ni2+吸附量逐渐增大,Ni2+去除率逐渐降低。吸附过程符合Langmuir和Freundlich吸附等温方程,说明该吸附体系既有物理吸附又有化学吸附,从吸附状态看属于多层吸附,由Langmuir吸附等温方程得出固定化海带生物吸附剂对Ni2+的最大吸附量为39.43mg/g,说明固定化海带生物吸附剂对Ni2+有较好的吸附性能。     

Correlating pH and Swelling Degree Parameters to Understand the Sorption and Desorption Process of Diquat Herbicide from Nanocomposites Based on Polysaccharide and Clinoptilolite

Journal of Polymers and the Environment - Zeolite-based nanocomposites have become an efficient option for application in herbicide removal and controlled release systems. Our group previously...     

Effects of Compatibilizer and Thermoplastic Starch (TPS) Concentration on Morphological,Rheological, Tensile,Thermal and Moisture Sorption Properties of Plasticized Polylactic Acid/TPS Blends

The blends of polylactic acid plasticized with acetyl tributyl citrate (P-PLA) and thermoplastic wheat starch (TPS) were prepared by a co-rotating twin screw extruder and the effect of maleic anhydride grafted PLA (PLA-g-MA) content as reactive compatibilizer on blends compatibility through morphological, rheological and tensile properties of the blends was investigated. Considerable improvement in properties of P-PLA/TPS (70/30 w/w) blend with incorporating the optimum PLA-g-MA content of 4 phr was achieved as this blend exhibited better morphological and rheological properties with an increase by 158 and 276% in tensile strength and elongation at break, respectively, compared to the uncompatibilized blend. Also the thermal stability and moisture sorption properties of the blends as effected by TPS content were studied. Decreasing in thermal stability and increasing in equilibrium moisture content of the blends were observed with progressively increasing of TPS content. For prediction the moisture sorption behaviour of blends with various TPS contents at different relative humidity, the moisture sorption isotherm data were modeled by GAB (Guggenheim–Anderson–de Boer) model.     

城市变电站对电磁环境的影响探讨

对近年来南京市区投入运行的220kV和110kV变电站周围电磁场强进行了调查和测量分析.结果表明,户内型变电站(电缆进出)对周围电磁环境的影响要明显小于户外型变电站(架空进线)对周围电磁环境的影响,户内型变电站(电缆进出)对周围电磁环境基本无影响.     

脱硫粉的粒度评述

阐述了脱硫粉剂粒度组成的内涵，确定粒度配比的必要性和3种粒度配比（曲线）的比较，为正确选用脱硫粉粒度提供基础资料。     

协同学视角下的生态工业园结构研究

首先,按照协同学划分子系统的要求,将生态工业园划分成推力子系统、内部子系统及拉力子系统.然后,从各子系统对生态工业园稳定性的作用力角度,进一步研究了各子系统的组成结构.研究表明推力子系统作用力由政府支持、经济支持、资源支持及市场支持构成,内部子系统作用力由技术充足、成员多样、关键种企业、合作距离、信息平台、空间距离、领导因素及企业关联度组成,生态效率为拉力子系统作用力.     

二氧化钛光催化降解甲醛反应动力学研究

以钛酸丁酯为前驱体,应用溶胶一凝胶法制备TiO2粉体和负载TiO2薄膜,考察了不同活化温度和活化时间对TiO2光催化降解甲醛性能的影响,并对TiO2薄膜光催化降解甲醛的反应动力学进行了研究。试验结果表明,在活化温度450℃、活化时间5h条件下,所得TiO2粉体及薄膜的光催化活性较好。不同初始浓度下甲醛光催化降解率与时间关系的动力学研究表明,一级反应动力学模型与试验数据拟合较好,方差R^2大于或等于0．99。