Multi-component adsorption of copper,nickel and zinc from aqueous solutions onto activated carbon prepared from date stones

The removal of Cu²⁺, Ni²⁺, and Zn²⁺ ions from their multi-component aqueous mixture by sorption on activated carbon prepared from date stones was investigated. In the batch tests, experimental parameters were studied, including solution pH, contact time, initial metal ions concentration, and temperature. Adsorption efficiency of the heavy metals was pH-dependent and the maximum adsorption was found to occur at around 5.5 for Cu, Zn, and Ni. The maximum sorption capacities calculated by applying the Langmuir isotherm were 18.68 mg/g for Cu, 16.12 mg/g for Ni, and 12.19 mg/g for Zn. The competitive adsorption studies showed that the adsorption affinity order of the three heavy metals was Cu²⁺?>?Ni²⁺?>?Zn²⁺. The test results using real wastewater indicated that the prepared activated carbon could be used as a cheap adsorbent for the removal of heavy metals in aqueous solutions.     

Simultaneous adsorption and degradation of Zn2+ and Cu2+ from wastewaters using nanoscale zero-valent iron impregnated with clays

Clays such as kaolin, bentonite and zeolite were evaluated as support material for nanoscale zero-valent iron (nZVI) to simultaneously remove Cu²⁺ and Zn²⁺ from aqueous solution. Of the three supported nZVIs, bentonite-supported nZVI (B-nZVI) was most effective in the simultaneous removal of Cu²⁺ and Zn²⁺ from a aqueous solution containing a 100 mg/l of Cu²⁺ and Zn²⁺, where 92.9 % Cu²⁺ and 58.3 % Zn²⁺ were removed. Scanning electronic microscope (SEM) revealed that the aggregation of nZVI decreased as the proportion of bentonite increased due to the good dispersion of nZVI, while energy dispersive spectroscopy (EDS) demonstrated the deposition of copper and zinc on B-nZVI after B-nZVI reacted with Cu²⁺ and Zn²⁺. A kinetics study indicated that removing Cu²⁺ and Zn²⁺ with B-nZVI accorded with the pseudo first-order model. These suggest that simultaneous adsorption of Cu²⁺and Zn²⁺ on bentonite and the degradation of Cu²⁺and Zn²⁺ by nZVI on the bentonite. However, Cu²⁺ removal by B-nZVI was reduced rather than adsorption, while Zn²⁺ removal was main adsorption. Finally, Cu²⁺, Zn²⁺, Ni²⁺, Pb²⁺ and total Cr from various wastewaters were removed by B-nZVI, and reusability of B-nZVI with different treatment was tested, which demonstrates that B-nZVI is a potential material for the removal of heavy metals from wastewaters.     

Removal mechanisms and kinetics of trace tetracycline by two types of activated sludge treating freshwater sewage and saline sewage

Understanding the removal mechanisms and kinetics of trace tetracycline by activated sludge is critical to both evaluation of tetracycline elimination in sewage treatment plants and risk assessment/management of tetracycline released to soil environment due to the application of biosolids as fertilizer. Adsorption is found to be the primary removal mechanism while biodegradation, volatilization, and hydrolysis can be ignored in this study. Adsorption kinetics was well described by pseudo-second-order model. Faster adsorption rate (k ₂?=?2.04?×?10^?2?g?min^?1?μg^?1) and greater adsorption capacity (q _e?=?38.8 μg?g^?1) were found in activated sludge treating freshwater sewage. Different adsorption rate and adsorption capacity resulted from chemical properties of sewage matrix rather than activated sludge surface characteristics. The decrease of tetracycline adsorption in saline sewage was mainly due to Mg²⁺ which significantly reduced adsorption distribution coefficient (K _d) from 12,990?±?260 to 4,690?±?180 L?kg^?1. Species-specific adsorption distribution coefficients followed the order of $ K_{\mathrm{d}}^{{ + 00}} \gg K_{\mathrm{d}}^{{ + - 0}} > K_{\mathrm{d}}^{{ + - - }} $ . Contribution of zwitterionic tetracycline to the overall adsorption was >90 % in the actual pH range in aeration tank. Adsorption of tetracycline in a wide range of temperature (10 to 35 °C) followed the Freundlich adsorption isotherm well.     

Competitive biosorption of lead, cadmium, copper, and arsenic ions using algae

The present study aims to evaluate the competitive biosorption of lead, cadmium, copper, and arsenic ions by using native algae. A series of experiments were carried out in a batch reactor to obtain equilibrium data for adsorption of single, binary, ternary, and quaternary metal solutions. The biosorption of these metals is based on ion exchange mechanism accompanied by the release of light metals such as calcium, magnesium, and sodium. Experimental parameters such as pH, initial metal concentrations, and temperature were studied. The optimum pH found for removal were 5 for Cd²⁺ and As³⁺ and 3 and 4 for Pb²⁺ and Cu²⁺, respectively. Fourier transformation infrared spectroscopy analysis was used to find the effects of functional groups of algae in biosorption process. The results showed that Pb²⁺ made a greater change in the functional groups of algal biomass due to high affinity to this metal. An ion exchange model was found suitable for describing the biosorption process. The affinity constants sequence calculated for single system was K _Pb > K _Cu > K _Cd > K _As; these values reduced in binary, ternary, and quaternary systems. In addition, the experimental data showed that the biosorption of the four metals fitted well the pseudo-second-order kinetics model.     

Synthesis and optimization of spherical nZVI (20–60 nm) immobilized in bio-apatite-based material for efficient removal of phosphate: Box-Behnken design in a fixed-bed column

In the present study, bio-apatite/nZVI composite was synthesized through Fe(III) reduction with sodium borohydride and was fully characterized by FTIR, XRD, SEM–EDX, TEM, BET, BJH, and pH_PZC. Column experiments were carried out for the removal of phosphate as a function of four operational parameters including initial phosphate concentration (100–200 mg L^?1), initial solution pH (2–9), bed height (2–6 cm), and influent flow rate (2.5–7.5 mL min^?1) using a response surface methodology (RSM) coupled with Box-Behnken design (BBD). 2D contour and 3D surface plots were employed to analyze the interactive effects of the four operating parameters on the column performance (e.g., uptake capacity and saturation time). According to ANOVA analysis, the influent flow rate and bed height are the most important factor on phosphate uptake capacity and saturation time, respectively. A quadratic polynomial model was excellently fitted to experimental data with a high coefficient of determination (>?0.96). The RSM-BBD model predicted maximum phosphate adsorption capacity of 85.71 mg g^?1 with the desirability of 0.995 under the optimal conditions of 135.35 mg L^?1, 2, 2 cm, and 7.5 mL min^?1 for initial phosphate concentration, initial solution pH, bed height, and influent flow rate, respectively. The XRD analysis demonstrated that the reaction product between bio-apatite/nZVI composite and phosphate anions was Fe₃ (PO₄)₂. 8H₂O (vivianite). The suggested adsorbent can be effectively employed up to five fixed-bed adsorption–desorption cycles and was also implemented to adsorb phosphate from real samples.

     

Enhancement of phenanthrene adsorption on a clayey soil and clay minerals by coexisting lead or cadmium

Phenanthrene is commonly present together with heavy metals at many contaminated sites. This study investigated the influence of coexisting lead (Pb²⁺) or cadmium (Cd²⁺) on phenanthrene adsorption on soils. Batch experiments were conducted under different geochemical conditions including pH, mineral structure, organic matter content, and varying amounts of heavy metals. The results showed that the presence of heavy metals in solution at a fixed pH of 5.8 ± 0.1 enhanced phenanthrene adsorption, the extent of which was closely related to the concentrations and the electro-negativity of the metals. The enhancement on phenanthrene adsorption was positively correlated to the amount of adsorbed metals. Although Cd²⁺ is a softer Lewis acid, Pb²⁺ displayed a more significant effect as it was adsorbed to a greater extent on the soil surfaces. Thus, density of cation accumulation appears to be more influential than metal softness in enhancing phenanthrene adsorption. Moreover, with a portion of organic matter removed by heating at 550 °C, there was a stronger enhancement of phenanthrene adsorption by coexisting Pb²⁺, indicating an increasingly dominant mechanisms associated with Pb²⁺ at a lower organic matter content. Similar enhancement phenomenon was observed on bentonite and kaolinite, probably resulting from the cation-π bonding between the adsorbed soft metal cations and the aromatic ring of phenanthrene in solution. The desorption experiments further suggested that the bonding of phenanthrene adsorption was strengthened in the presence of Pb²⁺ and that a larger proportion of adsorbed phenanthrene remained on the soils (residual fraction) even after sequential methanol extractions. Further spectroscopic analyses and surface characterization are required to provide direct evidence of the formation and relative significance of cation-π bond for phenanthrene adsorption.     

Remediation of organic and inorganic arsenic contaminated groundwater using a nanocrystalline TiO2-based adsorbent

A nanocrystalline TiO₂-based adsorbent was evaluated for the simultaneous removal of As(V), As(III), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) in contaminated groundwater. Batch experimental results show that As adsorption followed pseudo-second order rate kinetics. The competitive adsorption was described with the charge distribution multi-site surface complexation model (CD-MUSIC). The groundwater containing an average of 329 μg L^?1 As(III), 246 μg L^?1 As(V), 151 μg L^?1 MMA, and 202 μg L^?1 DMA was continuously passed through a TiO₂ filter at an empty bed contact time of 6 min for 4 months. Approximately 11 000, 14 000, and 9900 bed volumes of water had been treated before the As(III), As(V), and MMA concentration in the effluent increased to 10 μg L^?1. However, very little DMA was removed. The EXAFS results demonstrate the existence of a bidentate binuclear As(V) surface complex on spent adsorbent, indicating the oxidation of adsorbed As(III).     

Removal of heavy metal ions from wastewater by a novel HEA/AMPS copolymer hydrogel: preparation, characterization, and mechanism

This study aims to synthesize 2-hydroxyethyl acrylate (HEA) and 2-acrylamido-2-methylpropane sulfonic (AMPS) acid-based hydrogels by gamma radiation and to investigate their swelling behavior and heavy metal ion adsorption capabilities. The copolymer hydrogels prepared were characterized via scanning electron microscopy, Fourier transformed infrared spectra, thermal gravimetric analysis, and X-ray photoelectron spectroscopy. The research showed that the copolymer hydrogel was beneficial for permeation due to its porous structure. In addition, the experimental group A-2-d [70 % water volume ratio and (n (AMPS)/n (HEA))?=?1:1] was an optimal adsorbent. The optimal pH was 6.0 and the optimal temperature was 15 °C. Pb²⁺, Cd²⁺, Cu²⁺, and Fe³+ achieved adsorption equilibriums within 24 h, whereas Cr³⁺ reached equilibrium in 5 h. Pb²+, Cd²⁺, Cr³⁺, and Fe³⁺ maximum load capacity was 1,000 mg L^?1, whereas the Cu²⁺ maximum capacity was 500 mg L^?1. The priority order in the multicomponent adsorption was Cr³⁺>Fe³⁺>Cu²⁺>Cd²⁺>Pb²⁺. The adsorption process of the HEA/AMPS copolymer hydrogel for the heavy metal ions was mainly due to chemisorption, and was only partly due to physisorption, according to the pseudo-second-order equation and Langmuir adsorption isotherm analyses. The HEA/AMPS copolymer hydrogel was confirmed to be an effective adsorbent for heavy metal ion adsorption.     

Purification of industrial phosphoric acid (54 %) using Fe-pillared bentonite

The current problem of excess impurities in industrial phosphoric acid (IPA) 54 % P₂O₅ makes phosphates industries look toward low-cost but efficient adsorbents. In the present study, iron-oxide-modified bentonite (Fe-PILB) was prepared and investigated as a possible adsorbent for the removal of organic matter (OM) like humic acid (HA), chromium (Cr(III)), and zinc (Zn(II)) from IPA aqueous solutions. These adsorbents were characterized using XRD, TEM, and BET. The adsorption of impurities is well described by the pseudo-second-order model. The results indicate that Fe-PILB has a good ability to resist co-existing anions and the low-pH condition of IPA and owns a relatively high-removal capacity of 80.42 and 25 % for OM, Cr(III), and Zn(II). The mechanism of adsorption may be described by the ligand and ion exchange that happened on the active sites. The selected order of adsorption OM?>?Cr³⁺?>?Zn²⁺ showed the importance of the competitive phenomenon onto bentonite materials’ pore adsorption. For the adsorption of OM at the low pH of IPA, H-bond complexation was the dominant mechanism. From the adsorption of heavy metals and OM complex compounds contained in IPA 54 % on Fe-PILB, the bridging of humic acid between bentonite and heavy metals (Zn(II) or Cr(III)) is proposed as the dominant adsorption mechanism (bentonite-HA-Me). Overall, the results obtained in this study indicate Fe-pillared bentonite possesses a potential for the practical application of impurity (OM, Zn(II), and Cr(III)) removal from IPA aqueous solutions.     

Effective adsorbent for arsenic removal: core/shell structural nano zero-valent iron/manganese oxide

Recently, nano zero-valent iron (nZVI) has emerged as an effective adsorbent for the removal of arsenic from aqueous solutions. However, its use in various applications has suffered from reactivity loss resulting in a decreased efficiency. Thus, the aim of this study was to develop an effective arsenic adsorbent as a core/shell structural nZVI/manganese oxide (or nZVI/Mn oxide) to minimize the reactivity loss of the nZVI. As the major result, the arsenic adsorption capacities of the nZVI/Mn oxide for As(V) and As(III) were approximately two and three times higher than that of the nZVI, respectively. In addition, the As(V) removal efficiency of the nZVI/Mn oxide was maintained through 4 cycles of regeneration whereas that of the nZVI was decreased significantly. The enhanced reactivity and reusability of the nZVI/Mn oxide can be successfully explained by the synergistic interaction of the nZVI core and manganese oxide shell, in which the manganese oxides participate in oxidation reactions with corroded Fe²⁺ and subsequently retard the release of aqueous iron providing additional surface sites for arsenic adsorption. In summary, this study reports the successful fabrication of a core/shell nZVI/Mn oxide as an effective adsorbent for the removal of arsenic from aqueous solutions.     

胺基树脂的合成及对水中重金属离子的吸附特征

研究了使用氯甲基化聚苯乙烯交联微球为前驱体与二乙烯三胺经回流反应合成胺基树脂及其对水中Cd2+和Ni2+的吸附特征。结果表明,胺基官能团成功地嫁接到树脂表面,胺基含量为5.6 mmol/g。胺基树脂对Cd2+和Ni2+的吸附等温线表明,温度的升高有利于吸附,且吸附等温线都符合Langmuir模型。pH值对吸附的影响较大,最佳吸附pH值范围为4~6。2种金属离子在胺基树脂上的吸附都符合准二级动力学方程。     

改性花生壳对Cd(Ⅱ)和Pb(Ⅱ)的吸附机理

以前期制得改性块状花生壳为对象,测定改性花生壳等电点,考察离子强度对改性花生壳吸附Cd2+和Pb2+的影响、吸附前后吸附质溶液pH变化情况及蒸馏水、NaCl、HNO3、柠檬酸和EDTA 5种解吸液对Cd2+和Pb2+的解吸效果,并通过X-射线光电子能谱仪和傅里叶变换红外光谱仪对吸附前后的改性花生壳进行表征,推测并证实了改性花生壳对Cd2+和Pb2+可能的吸附机理。结果表明,改性花生壳对Cd2+和Pb2+可能的吸附机理是:Cd2+是通过外层络合、离子交换和内层络合的联合作用被吸附的;Pb2+主要是与改性花生壳上的O、N等活性基团发生内层络合;此外,改性花生壳表面生成的二氧化锰对Cd2+和Pb2+的吸附也起到一定的作用。     

巯基化改性膨润土对重金属的吸附性能

以钙基膨润土为基本材料,制备了巯基化改性膨润土,并对比研究了此材料与其他17种改性膨润土和原材料对重金属的吸附性能.结果表明,巯基化膨润土对镉的吸附能力显著优于其他材料,在本实验条件下,其对镉的吸附率高于其他材料30％以上,对镉的吸附量可达52.1 mg/g.巯基化膨润土对铅的吸附能力在重金属竞争吸附条件下优于其他材料,而其对镍的吸附能力在所有材料中处于中等水平;另外,巯基化膨润土对3种重金属的吸附受重金属竞争吸附影响较小.因此,在所研究的材料中,巯基化膨润土材料是一种最理想的重金属吸附材料.     

Enhanced removal of tetracycline via advanced oxidation of sodium persulfate and biochar adsorption

Advanced oxidation of antibiotic tetracycline (TC) is becoming an accessible and efficient technology. The removal of TC from the complex wastewater needs to be lucubrated. In this study, a TC removal system involving degradation and adsorption was established. TC degradation was accomplished by enhanced advanced oxidation via the addition of sodium persulfate (SP) and biochar into simulated wastewater containing Mn²⁺ and TC wastewater. The adsorption of TC and its derivatives was removed by biochar. The results indicate that the optimized reaction parameters were 3.0 g/L of biochar prepared at 600 °C (B600) and 400 mg/L of SP under acidic condition, and the removal percentage of TC was 87.48%, including 74.23% of degradation and 13.28% of adsorption; the anions Cl^?, NO₃^?, and H₂PO₄^? had negligible effects on the removal of TC in this Mn²⁺/B600/SP system. The system also functioned well with an aqueous solution with a high chemical oxygen demand (COD) concentration. Electron paramagnetic resonance (EPR) analysis indicated that ·OH and SO₄^? free radicals were present in the Mn²⁺/B600/SP system. Based on the testing and analysis results, a removal mechanism and potential TC degradation pathway for this system were proposed. TC can be degraded by ·OH and SO₄^? via three degradation pathways. Mn²⁺ can be precipitated as MnO₂, and a part of the TC and its derivatives can be adsorbed on the biochar surface. The Mn²⁺/B600/SP system also performed satisfactorily for a complex aqueous solution with various cations and antibiotics.

     

矸石基X型分子筛对水中Co2+、Cu2+、Cd2+和Cr3+的去除

以煤矸石为原料,采用碱熔后水热合成法制备X型分子筛并进行XRD、SEM、BET和Zeta电位分析。研究其对水中Co2+、Cu2+、Cd2+和Cr3+4种离子的吸附性能,包括吸附等温线、吸附动力学以及初始金属离子浓度、pH值对吸附性能的影响。所合成的矸石基X型分子筛的BET比表面积为676.02 m2/g,微孔孔容为0.263 cm3/g。吸附实验表明,矸石基X型分子筛能有效去除上述4种离子,同时实现煤矸石的资源化和金属离子的去除。4种离子的平衡吸附量均随初始浓度的增大而增大,相同条件下平衡吸附量的大小顺序为Cd2+>Cr3+>Cu2+>Co2+。准二级动力学模型能很好地描述4种离子的吸附动力行为。Langmuir模型对Co2+、Cu2+和Cd2+吸附的拟合较Freundlich模型高,说明其主要表现为物理吸附过程。4种离子的吸附速率均由液膜扩散和颗粒内扩散共同控制。     

共存物质对重金属絮凝剂 MCC 除镉性能的影响简

为进一步拓展天然高分子絮凝剂壳聚糖的应用范围，以壳聚糖、L-半胱氨酸为原料，通过酰胺化反应制备一种具有重金属捕集功能的高分子重金属絮凝剂-2-氨基-3-巯基丙酰壳聚糖（MCC），研究了水体中常见的阴阳离子、有机配位剂及浊度对MCC除镉性能的影响，探讨了絮体形貌与絮体分形维数及絮凝除镉效果间的关系。结果表明，Na⁺、Cl^-、NO₃^-、F^-、SO₄^2-的存在对MCC除Cd²⁺均有促进作用，Ca²⁺表现为明显的抑制作用；低浓度的EDTA对除镉有促进作用，随着EDTA浓度的增大，逐渐转为抑制作用；低浓度的腐殖酸对MCC去除Cd²⁺有显著的促进作用；在一定范围内，浊度可促进 MCC对Cd²⁺的去除；絮体间空隙越多，絮体分形维数越小，除镉效果越好。     

Development of an in vitro toxicological test system based on zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>) sperm analysis

The effect of seven heavy metals on the motility parameter of zebrafish sperm was tested in order to develop an in vitro toxicological test system as an alternative to live animal testing. In vitro test systems are currently preferred in ecotoxicology due to their practical and ethical advantages and fish sperm can be a suitable model. A number of studies had been carried out previously on this topic, but the described methods had not been standardized in numerous aspects (donor species, measured endpoint, etc.). In this study, heavy metals (mercury, arsenic, chromium, zinc, nickel, copper, cadmium) were used as reference toxicants with known toxicity to develop a standardized fish sperm in vitro assay. The tested concentrations were determined based on preliminary range finding tests. The endpoints were progressive motility (PMOT, %), curvilinear velocity (VCL, μm/s), and linearity (LIN, %) measured by a computer-assisted sperm analysis (CASA) system. According to our results, PMOT was the most sensitive of the three investigated parameters: dose-response curves were observed for each metal at relatively low concentrations. VCL values were less sensitive: higher concentrations were needed to observe changes. Of the three parameters, LIN was the least affected: dose-response relationship was observed only in the case of mercury (e.g., lowest observed effect concentration (LOEC) of Hg at 120 min: 1 mg/L for PMOT, 2.5 mg/L for VCL, 5 mg/L for LIN; LOEC of Cu at 120 min: 1 mg/L for PMOT, 5 mg/L for VCL, any for LIN). The order of toxicity as determined by PMOT was as follows: Hg²⁺?>?As³⁺?>?Cd²⁺?>?Cu²⁺?>?Zn²⁺?>?Cr³⁺?>?Ni²⁺. In conclusion, we found that PMOT of zebrafish sperm was an accurate and fast bioindicator of heavy metal load. Sperm analysis can be adopted to estimate the possible toxic effects of various chemicals in vitro. Future investigations should concentrate on the applicability of this assay to other contaminants (e.g., organic pollutants).     

微波辐射回用活性炭对水中亚甲基蓝和Cd~(2+)去除效果的研究

考察了微波-活性炭联合处理技术对模拟染料废水中亚甲基蓝和Cd2+的去除效果。对于100 mL浓度为1 000 mg/L的亚甲基蓝溶液、活性炭用量为10 g时,新活性炭对亚甲基蓝的去除率为99.99%;采用700 W微波对吸附亚甲基蓝的活性炭辐射10 min进行再生并回用,经微波辐射再生10次后活性炭对亚甲基蓝的去除率为99.68%,未经微波作用反复使用10次的活性炭对亚甲基蓝的去除率为85.41%。结果表明:微波处理有效地减缓了活性炭吸附能力的下降速率,实现了活性炭再生和反复使用。在吸附过程中,Cd2+使活性炭对亚甲基蓝的吸附能力略有下降,而共存的亚甲基蓝则促进了活性炭对Cd2+的吸附,对新炭和再生后活性炭物理化学特性的表征证明了活性炭对亚甲基蓝的吸附为物理吸附,对Cd2+的吸附为化学吸附。     

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.     

镉溶液污染黏土微观结构演化规律

镉溶液在压实黏土中迁移会引起黏土微观结构的变化。通过一系列扫描电子显微镜与低温氮吸附实验,观察了镉溶液污染黏土的表面微观形貌与孔隙结构的演化规律。扫描电子显微镜观察结果显示,受镉溶液污染严重的土柱上表面孔隙明显,土颗粒之间主要以点-点排列方式为主;而受镉溶液污染较弱的下表面,土颗粒之间主要以片-片状排列为主。低温氮吸附实验结果表明,Z=0 cm、Z=10 cm、Z=20 cm、Z=30 cm处,污染黏土吸附量分别为682.65、631.72、583.25和523.36 cm3/g。随土柱中土层深度的增大,黏土颗粒间微孔增多,二次孔减少,孔隙体积与比表面积减小。镉溶液污染黏土孔隙主要集中在10 nm以下。