Relations between sorption behavior and electrokinetic remediation effect in soils contaminated with heavy metals

Soil Research ◽  
2008 ◽  
Vol 46 (5) ◽  
pp. 485 ◽  
Author(s):  
Zhemin Shen ◽  
Bingxin Ju ◽  
Xuejun Chen ◽  
Wen-hua Wang
Keyword(s):  
Exchange Capacity ◽  
Metal Mobility ◽  
Purple Soil ◽  
Sorption Behavior ◽  
Sorption Behaviour ◽  
Fast Reactions ◽  
Exchange Processes ◽  
Heavy Metal Sorption ◽  
Remediation Efficiency ◽  
Adsorption Desorption

Adsorption–desorption is an important mechanism for controlling metal mobility in soil and has a large effect on remediation efficiency. Very little research has examined the relations between heavy metal sorption behaviour and electrokinetic (EK) remediation effect. Four typical soil samples in China (Chernozem, Fluvisol, Yellow brown earth, and Purple soil) were studied. Adsorption isotherms were fit to Freundlich equations. EK removal ratios in the 4 soils were: Purple soil > Yellow brown earth > Fluvisol > Chernozem. Results show that the influencing characteristics significant to Cd EK removal order as follows: total organic carbon (TOC) > 1/n (Freundlich constant) > clay ratio > K (Freundlich constant) > cation exchange capacity > background pH. When 1/n (Freundlich constant) increases by 0.124 or TOC increases by 0.858 g/kg in soils, EK removal ratio (%) of Cd decreases by 1.0%. A ‘2-reactions’ mechanism during EK remediation is speculated, including rapid and slow reactions. Fast reactions are attributed to H+–M2+ exchange processes occurring on the surfaces of different inorganic phases and to the dissolution of the water-insoluble precipitates. Slow irreversible reactions refer to H+ ions exchanging with metal ions bound in the internal lattice sites and organic matter being oxidised by oxidants produced by electrochemical reactions. Slow reactions limit the EK remediation effect.

scholarly journals Sorption performances of TiO(OH)(H2PO4)·H2O in synthetic and mine waters

RSC Advances ◽  
2017 ◽  
Vol 7 (4) ◽  
pp. 1989-2001 ◽  
Author(s):  
Mylène Trublet ◽  
Marina V. Maslova ◽  
Daniela Rusanova ◽  
Oleg N. Antzutkin
Keyword(s):  
Exchange Capacity ◽  
Titanium Phosphate ◽  
Mine Waters ◽  
Sorption Behaviour ◽  
Fast Kinetics ◽  
First Report

The first report on sorption behaviour of a titanium phosphate sorbent containing entirely –H2PO4 groups reveals a high exchange capacity and fast kinetics.

scholarly journals Ball-milling effect on Indonesian natural bentonite for manganese removal from acid mine drainage

2018 ◽  
Vol 156 ◽  
pp. 03046 ◽  
Author(s):  
Widyawanto Prastistho ◽  
Winarto Kurniawan ◽  
Hirofumi Hinode
Keyword(s):  
Particle Size ◽  
Acid Mine Drainage ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Mine Drainage ◽  
Nitrogen Adsorption ◽  
Exchange Capacity ◽  
Manganese Removal ◽  
Acid Mine ◽  
Adsorption Desorption

The influences of mechanical milling on Indonesian Natural Bentonite (INB) characteristics and manganese (Mn) removal from acid mine drainage (AMD) were investigated. The INB characteristics were observed by scanning electron microscope (SEM), X-ray diffraction (XRD), nitrogen adsorption-desorption for specific surface area (SSA) and microporosity measurement, cation exchange capacity (CEC) and particle size distribution (PSD) analyzer. Four minutes milling with frequency 20 Hz on INB caused morphological change which showed more crumbled and destructed particle, lost the (001) peak but still retained the (100) peak that indicated delamination of montmorillonite mineral without breaking the tetrahedral-octahedral-tetrahedral (T-O-T) structure, rose the CEC from 28.49 meq/100g to 35.51 meq/100g, increase in the SSA from 60.63 m2/g to 104.88 m2/g, significant increase in microporosity which described in the t plots and decrease in the mean particle size distribution peak from 49.28 μm to 38.84 μm. The effect of contact time and effect of adsorbent dosage on Mn sorption was studied. Both unmilled and milled samples reached equilibrium at 24 hours and the pH rose from 4 to 7 in first 30 minutes. The Mn removal percentage increased significantly after milling. Using Langmuir isotherm, the maximum adsorbed metals (qmax) also increased from 0.570 to 4.219 mg/g.

scholarly journals Mineralogical and physico-chemical characterizations of clay from Keur Saër (Senegal)

Clay Minerals ◽  
2012 ◽  
Vol 47 (4) ◽  
pp. 499-511 ◽  
Author(s):  
A. Mbaye ◽  
C. A. K. Diop ◽  
B. Rhouta ◽  
J. M. Brendle ◽  
F. Senocq ◽  
...  
Keyword(s):  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Clay Fraction ◽  
Exchange Capacity ◽  
Raw Material ◽  
Basic Knowledge ◽  
Mineral Mixture ◽  
Fine Clay ◽  
Main Component ◽  
Adsorption Desorption

AbstractThere is interest in exploiting and developing natural resources, particularly deposits of natural clays. Senegal has several clay mineral deposits for which chemical and mineralogical compositions have been little studied. Some of these natural materials are nowadays used in pottery and ceramics. To extend applications, a better basic knowledge is required and, for this objective, the raw clay and separated <2 μm clay fraction from Keur Saër (Senegal) were subjected to chemical and mineralogical studies. Several techniques including X-ray diffraction (XRD), thermal analysis (TG-DTA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), N2 adsorption-desorption isotherms, cation exchange capacity (CEC) measurements and solid state nuclear magnetic resonance (NMR) have been used to characterize the material. It was found that the raw clay and the separated clay fraction consist of a mineral mixture in which kaolinite is the main component. 29Si and 27Al MAS-NMR spectra show the presence of silicon atoms linked to three other silicon atoms via an oxygen atom and six coordinated Al atoms. Significant increases in the specific surface area and cation exchange capacity were observed on purification, reaching a maximum of about 73.2 m2g–1 and 9.5 meq/100 g for the separated fine clay fraction while the values for the raw material were around 28.9 m2g–1 and 7.3 meq/100 g.

Effect of Paper Mill Sludge on Adsorption and Desorption of Cd(II) and Pb(II) in Paddy Soils

2014 ◽  
Vol 955-959 ◽  
pp. 2539-2545
Author(s):  
Yan Liu ◽  
Pei Qin Peng ◽  
Xiao Long Zhu ◽  
Xian Qing Ding
Keyword(s):  
Paper Mill ◽  
Sorption Process ◽  
Exchange Capacity ◽  
Red Soil ◽  
Purple Soil ◽  
Paper Sludge ◽  
Paper Mill Sludge ◽  
Adsorption And Desorption ◽  
Freundlich Equation ◽  
Amend Soil

There are high organic matter and cation exchange capacity (CEC) in paper mill sludge, which can be used efficiently to amend soil properties and promote the growth of crops. The batch method was used to investigate effects of paper sludge on adsorption and desorption of Cd (II) and Pb (II) in two types paddy soil (red soil, purple soil), through adding paper sludge to red soil and purple soil. The results showed that isothermal sorption process of Cd (II) and Pb (II) by soils and paper sludge could be well described by Langmuir equation and Freundlich equation, and all coefficients (r) were higher than 0.9. The purple soil had a higher sorption capacity of Cd (II) and Pb (II) than red soil. The sorption capacities of Cd (II) and Pb (II) in soils increased after added paper sludge, and they reached adsorption equilibrium as the percentages of paper sludge were 10%, 1% in red soil and purple soil, respectively. The desorption capacities of Cd (II) and Pb (II) in soils decreased after added paper sludge, and they reached minimum as the percentages of paper sludge were 5%, 2% in red soil and purple soil, respectively. It was better to immobilize Cd (II) and Pb (II) after added paper sludge, thus paper mill sludge can relieve the migration of heavy metals in soil-crop systems. It can provide a new way for safe using of heavy metal contaminated soil and resource utilization of paper sludge.

A Mathematical Model Forecasting HF Adsorption onto Cu-Coated Wafers as a Function of the Airborne Concentration and Moisture

2016 ◽  
Vol 255 ◽  
pp. 323-328
Author(s):  
Fernando Herrán ◽  
Hervé Fontaine ◽  
Paola González-Aguirre ◽  
Carlos Beitia ◽  
Jim Ohlsen ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Surface Concentration ◽  
Threshold Concentration ◽  
Sorption Behavior ◽  
Yield Losses ◽  
Airborne Concentration ◽  
Adsorption Desorption

In order to better understand and model the whole sorption behavior of the HF when in contact with a Cu surface inside a FOUP and thus control the related yield losses, Cu-coated wafers have been exposed to varying HF (ppbv) and H2O (% RH) airborne concentrations. These experiments have yielded a HF-Cu sorption empirical-mathematical model that may be used as an industrial tool for queue-time or fluoride surface concentration predictions. Besides, the formation of CuF2 only in case of corrosion is evidenced by the XPS measurements whereas the key role of the H2O is further confirmed by the desorption experiments. The H2O retained by the surface is actually responsible for promoting the HF adsorption/desorption onto/from Cu and enables a HF threshold concentration that separates the two well differenced uptake regimes; adsorption and corrosion.

scholarly journals Synthesis and CO2 sorption of silica particles, kinetics and thermodynamics

2014 ◽  
Vol 10 (5) ◽  
pp. 2711-2719
Author(s):  
Hasna BOUHALI ◽  
Nabila CHALAL ◽  
Hadj HAMAIZI ◽  
Abdelkader BENGUEDDACH
Keyword(s):  
Mesoporous Silica ◽  
Silica Particles ◽  
Sorption Behavior ◽  
Porous Texture ◽  
Co2 Sorption ◽  
Ordered Mesoporous ◽  
Adsorption Of Co2 ◽  
Adsorption Desorption ◽  
Langmuir And Freundlich Equations ◽  
Good Agreement

Spherical ordered mesoporous silica particles with radially oriented mesopores were successfully prepared by using non-ionic amphiphilic di-block co-polymers CnH2n+1-(EO)x-OH as template and tetraorthosilicate (TEOS) as silica precursor. The synthesized mesoporous silica materials were characterized by XRD, N2 adsorption-desorption and SEM techniques. CO2 adsorption at 0 °C was evaluated by a volumetric method, and the CO2 sorption behavior was described by applying both Langmuir and Freundlich equations. Results indicate a high adsorption capacity of CO2 (5-9 mmol/g), depending essentially on the porous texture of the materials. An adsorption kinetic model was proposed to describe the adsorption of CO2 over template-free mesoporous siliceous materials. A good agreement with experimental data was found.

Sorption of Eu(III) on Fe–montmorillonite relevant to geological disposal of HLW

2018 ◽  
Vol 106 (12) ◽  
pp. 971-983 ◽  
Author(s):  
Santosh Chikkamath ◽  
Madhuri A. Patel ◽  
Aishwarya S. Kar ◽  
Vaibhavi Raut ◽  
Bhupendra Singh Tomar ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Cation Exchange ◽  
Exchange Capacity ◽  
High Level Waste ◽  
Sudden Increase ◽  
Exchange Method ◽  
Sorption Data ◽  
Sorption Behaviour ◽  
Geological Disposal ◽  
Buffer Material

Abstract Montmorillonite (Mt) is the major clay mineral of bentonite, which is the candidate buffer material in the engineered barrier system for geological disposal of high level waste (HLW). The alteration of Mt due to its interaction with carbon steel (overpack) can produce Fe–Mt. In order to understand the basic properties of Fe–Mt, the sorption studies using Eu(III) are reported here. For this, Fe(III)–Mt was prepared by conventional cation exchange method using FeCl3 with Na–Mt. The obtained Fe(III)–Mt was then reduced to Fe(II)–Mt using ascorbic acid. Both the samples were characterized based on their X-ray diffraction, Fourier transform infrared spectra, cation exchange capacity and specific surface area. The batch sorption studies of Eu(III) were conducted for both Fe(III)–Mt and Fe(II)–Mt as a function of pH (3–10), ionic strength (0.001 M–1 M) and Eu(III) concentration (10−8–10−3 M). The distribution coefficient (Kd) was found to be higher for Fe(III)–Mt compared to Fe(II)–Mt and Na–Mt. The sudden increase in sorption in the pH range 4.5–6 and remaining constant beyond it indicates ion exchange mechanism at pH<4.5, with surface complexation mechanism dominating the sorption at pH>4.5. This is further corroborated by ionic strength dependent sorption data which shows decrease in sorption capacity of Fe–Mt with increasing ionic strength at low pH, but remaining more or less unchanged at higher pH. Eu(III) adsorption isotherm on Fe–Mt increased linearly with [Eu(III)] reaching saturation at 10−5 M and 10−4 M for Fe(III)–Mt and Fe(II)–Mt, respectively. The amount of iron released from Fe–Mt and Fe(II)/Fetotal during sorption were estimated to understand the effect on Eu(III) sorption behaviour by release of interlayer iron in Fe–Mt.

scholarly journals Solid desiccants from natural and modified bentonites

Cerâmica ◽  
2018 ◽  
Vol 64 (372) ◽  
pp. 526-537
Author(s):  
N. Castrillo ◽  
A. Mercado ◽  
C. Volzone
Keyword(s):  
Water Adsorption ◽  
Exchange Capacity ◽  
X Ray Diffraction ◽  
Hydration Degree ◽  
X Ray ◽  
Textural Characterization ◽  
Close Relationship ◽  
Natural Clays ◽  
Bentonite Clays ◽  
Adsorption Desorption

Abstract The aim of the present work was to study Argentinean natural clays with different modifications and their use as desiccants. To this end, bentonite clays collected from different regions were characterized and modified by heat treatment and calcium addition, and the desiccant capacity, in the form of powder and pellets, was studied. In addition, the hydration degree reversibility of these materials was estimated. The mineralogical and structural characterization was performed by X-ray diffraction, Fourier-transform infrared spectroscopy, differential thermal analysis, and thermogravimetric analysis. The textural characterization was performed by adsorption-desorption of N2, chemical composition by X-ray fluorescence and cation exchange capacity. The water adsorption was determined at 25 °C between 11-98% relative humidity. The results indicated that the desiccant power has a close relationship with the degree of clay purity, drying of the sample and the method of calcium incorporation.

Pulmonary and cutaneous O2 gas exchange: a student laboratory exercise in the frog

2013 ◽  
Vol 37 (1) ◽  
pp. 97-105 ◽  
Author(s):  
Glenn J. Tattersall ◽  
Suzanne Currie ◽  
Danielle M. LeBlanc
Keyword(s):  
Gas Exchange ◽  
Physical Properties ◽  
Exchange Capacity ◽  
Gas Flux ◽  
Diving Reflex ◽  
Laboratory Exercise ◽  
Exchange Processes ◽  
Undergraduate Laboratory ◽  
Student Laboratory ◽  
Cutaneous Respiration

Gas exchange in animals is ultimately diffusion based, generally occurring across dedicated respiratory organs. In many aquatic amphibians, however, multiple modes of gas exchange exist, allowing for the partitioning of O2 uptake and CO2 excretion between respiratory organs with different efficiencies. For example, due to the physical properties of O2 being vastly different between air and water phases, the lung and skin play disproportionately important roles in O2 uptake. Many aquatic frogs are renowned for their cutaneous gas exchange capacity, where often the majority of CO2 is excreted across the skin. Furthermore, the roles of these gas exchange organs change with the animal's behavior. Under diving conditions, most of the frog's gas exchange needs must be met by the skin. In this article, we describe an interactive undergraduate laboratory that allows a class of students to share equipment while assessing pulmonary and cutaneous respiration in frogs provided with an air/water choice and under enforced dive conditions. Concepts explored in this laboratory exercise include animal energetics, diving reflex, pulmonary and cutaneous gas exchange processes, diffusion-based gas flux, and O2 debt.

Soil-mediated effects of atmospherically deposited sulphur and nitrogen

1984 ◽  
Vol 305 (1124) ◽  
pp. 383-392 ◽  
Keyword(s):  
N Deposition ◽  
Exchange Capacity ◽  
Negative Effects ◽  
Cation Leaching ◽  
Mediated Effects ◽  
Exchange Processes ◽  
Site Characteristics ◽  
Aquatic Effects ◽  
Highly Weathered Soils ◽  
Atmospheric Inputs

The soil mediates both terrestrial and aquatic effects of sulphur (S) and nitrogen (N) deposition in a number of ways. Atmospherically deposited S in excess of biological requirements often accumulates by SO 2- 4 adsorption onto Fe and Al oxides in highly weathered soils, causing the release of OH - , which can neutralize incoming H + , or an increase in cation exchange capacity. Atmospherically deposited N seldom exceeds biological requirements; when it does, NO - 3 is rapidly leached since no adsorption reactions analogous to those for sulphate exist. When the biological and adsorption capacities are exceeded, cation leaching is accelerated by the mobile SO 2- 4 or NO - 3 anions. The effects of this increased cation leaching must be assessed within the context of natural processes of cation removal such as leaching by internally produced carbonic, organic or (occasionally) nitric acid; natural atmospheric S inputs; and cation export by vegetation harvest. The proportion of individual cations available for leaching is regulated by soil exchange processes and biological demand, both of which tend to minimize the losses of those particular cations most tightly bound and, or, in shortest supply. The ultimate effects of atmospheric S and N deposition will be highly site-specific in nature, depending on both inherent site characteristics and amounts and duration of atmospheric inputs. Thus, benefits of S or N deposition may outweigh negative effects in some sites, whereas the reverse may be true for other sites, making broad, global generalizations hazardous.

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