scholarly journals In situ lead stabilization using natural and synthetic apatite

2008 ◽  
Vol 14 (4) ◽  
pp. 269-271 ◽  
Author(s):  
T. Kaludjerovic-Radoicic ◽  
S. Raicevic
Keyword(s):  
Computer Simulation ◽  
Computer Program ◽  
Sorption Capacity ◽  
Water Solution ◽  
Lead Contamination ◽  
Lead Removal ◽  
Visual Minteq ◽  
Experimental Values ◽  
Natural Apatite

In this work, mineral apatite was investigated for the remediation of lead contamination. Two different apatite minerals were used: synthetic apatite, Ca10(PO4)6(OH)2 (hereafter denoted as HAP) and natural apatite from Lisina, near Bosilegrad, Serbia (hereafter denoted as LA). Phosphate ore from Lisina deposit consists of 43.3 % apatite in the form of fluorapatite, Ca10(PO4)6(F)2. Sorption properties of HAP and LA were investigated. The results show that both of these minerals are effective in lead removal from the water solution. Sorption capacity of HAP obtained in this experiment is 0.216 mmol Pb/g HAP, while the value for LA is 0.162 mmol Pb/g LA. Modeling of these systems was conducted using Visual Minteq computer program. The values obtained from the computer simulation were compared to experimental values.

scholarly journals Remediation of the Serbian soils contaminated by radionuclides in the function of the sustainable development

2008 ◽  
Vol 14 (4) ◽  
pp. 265-267 ◽  
Author(s):  
M. Stojanovic ◽  
M. Grubisic ◽  
D. Stevanovic ◽  
J. Milojkovic ◽  
D. Iles
Keyword(s):  
Contaminated Soils ◽  
Water Solution ◽  
Solution Concentration ◽  
Large Area ◽  
The Sustainable Development ◽  
Geological Conditions ◽  
Wide Range ◽  
Uranium Phosphate ◽  
Natural Apatite

Phosphate-induced metal stabilization (PIMS) using apatite stabilizes uranium in situ, by chemically binding it into the new low-solubility (Ksp=10-49) phase. Uranium-phosphate-autunite is stable across a wide range of geological conditions for millions of years. A large area of contaminated soil is suitable for in situ remediation that involves minimizing the mobility of the uranium. Laboratory study was conducted to quantify different forms of apatite sequestration of uranium contaminant. The experiment was done with natural phosphate from Lisina deposit (14.43 % P2O5), with non-treated samples, phosphate concentrate samples with 34.95 % P2O5 and mechanochemically activated of natural apatite. Different concentration of P2O5 in apatite, pH, reaction time, solid/liquid ratio was investigated. The concentrate at pH 5.5 for 7 days sorbed around 93,64 % and nature apatite, with 14,43 % P2O5, for 30 days sorbed 94.54 % of the uranium from the water solution, concentration 100 ?g U/ml. The results show that mineral apatite 'Lisina' is very effective for the treatment of contaminated soils in situ immobilization of U. Mechanochemical activation of natural apatite in vibration mill immobilized 85.37 % of uranium in the 7-day period of acting. This research on natural apatite from the deposit 'Lisina' for immobilization of uranium was the first one of this type in our country.

Природные материалы для сорбционной очистки хром- и кадмийсодержащих инфильтратов полигонов ТБО

2019 ◽  
pp. 13-19
Author(s):  
A. Safonov ◽  
N. Andriushchenko ◽  
N. Popova ◽  
K. Boldyrev
Keyword(s):  
Sorption Capacity ◽  
Electron Acceptors ◽  
Bacterial Cells ◽  
Maximum Sorption Capacity ◽  
Sorption Material ◽  
Maximum Sorption ◽  
Properties Of Materials ◽  
Solid Waste Landfills ◽  
Sorption Characteristics

Проведен анализ сорбционных характеристик природных материалов (вермикулит, керамзит, перлит, цеолит Трейд ) при очистке кадмий- и хромсодержащих сточных вод с высокой нагрузкой по ХПК. Установлено, что цеолит обладает максимальными сорбционными характеристиками для Cd и Cr и наименьшим биологическим обрастанием. При использовании вермикулита и керамзита или смесей на их основе можно ожидать увеличения сорбционной емкости для Cd и Сr при микробном обрастании, неизбежно происходящем в условиях контакта с водами, загрязненными органическими соединениями и биогенами. При этом биообрастание может повысить иммобилизационную способность материалов для редоксзависимых металлов за счет ферментативных ресурсов бактериальных клеток, использующих их в качестве акцепторов электронов. Эффект микробного обрастания разнонаправленно изменял параметры материалов: для Cr в большинстве случаев уменьшение и для Cd значительное увеличение. При этом дополнительным эффектом иммобилизации Cr является его биологическое восстановление биопленками. Варьируя состав сорбционного материала, можно подбирать смеси, оптимально подходящие для очистки вод инфильтратов с полигонов твердых бытовых отходов с высокой нагрузкой по ХПК и биогенным элементам как при использовании in situ, так и в системах на поверхности.The analysis of the sorption characteristics of natural materials (vermiculite, expanded clay, perlite, Trade zeolite) during the purification of cadmium and chromium-containing leachate with a high COD load was carried out. It was determined that zeolite had the maximum sorption capacity for Cd and Cr and the lowest biological fouling. When using vermiculite and expanded clay or mixtures on their basis, one can expect an increase in the sorption capacity for Cd and Cr during microbial fouling that inevitably occurs during contacting with water polluted with organic compounds and nutrients. In this case biofouling can increase the immobilization properties of materials for redox-dependent metals due to the enzymatic resources of bacterial cells that use them as electron acceptors. The effect of microbial fouling changed the parameters of materials in different directions: for Cr, in most cases, downward, and for Cd, significantly upward. Moreover, chromium biological recovery by biofilms is an additional effect of immobilization. Varying the composition of the sorption material provides for selecting mixtures that are optimally suitable for the purification of leachates from solid waste landfills with high COD and nutrients load, both when used in situ and in surface systems.

Clay liner materials for land disposal of hazardous non-metal wastes

1996 ◽  
Vol 33 (8) ◽  
pp. 71-77
Author(s):  
I. M.-C. Lo ◽  
H. M. Liljestrand ◽  
J. Khim ◽  
Y. Shimizu
Keyword(s):  
Sorption Capacity ◽  
Organic Anion ◽  
Surface Exchange ◽  
Clay Liner ◽  
Effective Removal ◽  
Exchange Constants ◽  
Anionic Species ◽  
Surface Ligand ◽  
Land Disposal

Simple land disposal systems for hazardous and mixed wastes contain heavy metal cationic species through precipitation and ion exchange mechanisms but typically fail by releasing soluble organic and inorganic anionic species. To enhance the removal of anions from leachate, clays are modified with coatings of iron or aluminium cations to bridge between the anionic surface and the anionic pollutants. A competitive surface ligand exchange model indicates that surface coatings of 10 meq cation/gm montmorillonite under typical leachate conditions increase the inorganic anion sorption capacity by at least a factor of 6 and increase the intrinsic surface exchange constants by more than a factor of 100. Similarly, metal hydroxide coatings on montmorillonite increase the organic anion sorption capacity by a factor of 9 and increase the intrinsic surface exchange constants by a factor of 20. For historical concentrations of non-metal anions in US hazardous and mixed waste leachate, sorption onto natural clay liner materials is dominated by arsenate sorption. With cation coatings, anion exchange provides an effective removal for arsenate, selenate, phenols, cresols, and phthalates. Engineering applications are presented for the use of modified clays as in situ barriers to leachate transport of anionic pollutants as well as for above ground treatment of recovered leachate.

Computer simulation to evaluate the economics of landfill gas recovery

1998 ◽  
Vol 38 (2) ◽  
pp. 201-208
Author(s):  
M. W. Milke
Keyword(s):  
Computer Simulation ◽  
Computer Program ◽  
Landfill Gas ◽  
Base Case ◽  
Simulation Tool ◽  
Hypothetical Case ◽  
Gas Recovery ◽  
Fixed Set ◽  
Key Variables ◽  
Simulation Results

A need exists for tools to improve evaluations of the economics of landfill gas recovery. A computer simulation tool is presented. It uses a spreadsheet computer program to calculate the economics for a fixed set of inputs, and a simulation program to consider variations in the inputs. The method calculates the methane generated each year, and estimates the costs and incomes associated with the recovery and sale of the gas. Base case results are presented for a city of 500,000. An uncertainty analysis for a hypothetical case is presented. The simulation results can help an analyst see the key variables affecting the economics of a project.

An efficient ZnS-UV photocatalysts generated in situ from ZnS(en)0.5 hybrid during the H2 production in methanol–water solution

2012 ◽  
Vol 37 (22) ◽  
pp. 17002-17008 ◽  
Author(s):  
Agileo Hernández-Gordillo ◽  
Francisco Tzompantzi ◽  
Ricardo Gómez
Keyword(s):  
Water Solution ◽  
H2 Production

Ruthenium catalyzed hydrogen production from formaldehyde–water solution

2021 ◽  
Author(s):  
Mahendra Kumar Awasthi ◽  
Sanjay Kumar Singh
Keyword(s):  
Hydrogen Production ◽  
Water Solution ◽  
Ruthenium Catalyst ◽  
Aqueous Formaldehyde

Efficient hydrogen production from aqueous formaldehyde with appreciably high TOF and TON achieved over an in situ generated ruthenium catalyst in water at 95 °C.

Numerical Analysis of the Acoustical Quality of a Multi-Purpose Hall

1995 ◽  
Vol 2 (3) ◽  
pp. 487-500 ◽  
Author(s):  
X.W. Meng ◽  
G. De Borger ◽  
M. Van Overmeire
Keyword(s):  
Computer Simulation ◽  
Sound Pressure Level ◽  
Decay Time ◽  
Sound Pressure ◽  
Field Measurements ◽  
Pressure Level ◽  
Energy Fraction ◽  
Experimental Values ◽  
Simulation Package

In this paper, the acoustical features are described of a multi-purpose auditorium of the Free University of Brussels which were investigated both with field measurements and computer simulation. The convergence of the algorithm of the simulation package RAYNOISE was investigated as a function of the influence on the calculated results of the choice of the number of rays and the reflection order. By comparing the numerical and experimental values of the sound pressure level and early decay time, it is demonstrated that sufficiently accurate acoustical models can be developed. Based on these models, acoustical quantities such as the early energy fraction, sound pressure level, early decay time and early lateral energy fraction were calculated and employed to evaluate the acoustical quality of this multi-purpose hall.

Computersimulation der Rückstreuung schneller schwerer Ionen an einkristallinen (001)-und (111̅)-Goldoberflächen / Computer Simulation of the Backscattering of High Energy Ions from (001)- and (111̅)-surfaces of Au-Single Crystals

1976 ◽  
Vol 31 (3-4) ◽  
pp. 316-326 ◽  
Author(s):  
H. Schmidt ◽  
K. Güttner
Keyword(s):  
Computer Simulation ◽  
Computer Program ◽  
Single Crystals ◽  
Grazing Incidence ◽  
High Energy ◽  
Rapid Decrease ◽  
Fcc Lattice ◽  
High Energy Ions

A computer program for following the trajectories of high energy ions in an fcc-lattice has been written to evaluate the reflection rate of high energy ions with grazing incidence to (001)- and (111̅)-Au-surfaces. The calculation yields a rapid decrease of the reflection rate for penetration directions close to low-index atomic planes. It can be shown that this result is caused by channeling of the ions between the atomic planes.

Investigation of 137Cs and plutonium isotope sorption–desorption in bio- and synthetic materials

2016 ◽  
Vol 56 (2) ◽  
Author(s):  
Benedikta Lukšienė ◽  
Zita Žukauskaitė ◽  
Nikolaj Tarasiuk ◽  
Evaldas Maceika ◽  
Vitold Filistovič ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Lake Water ◽  
Water Solution ◽  
Plutonium Isotope ◽  
Dynamic Flow ◽  
Batch Type ◽  
Environmental Friendly ◽  
Synthetic Materials ◽  
Physico Chemical

Investigations on the pre-concentration of radionuclides (137Cs and plutonium isotopes) from fresh water on solid matrices are presented in this study. A particular focus was given to an innovative physico-chemical removal process such as adsorption of radionuclides from an aqueous medium on new type adsorbents, environmental-friendly materials. Sorption of the tested radionuclides from the lake water solution by environmental assays and synthetic sorbents was compared. Lake water was analyzed for main anions, micro- and macroelements, using ion and atomic absorption chromatography methods, respectively. Batch type and dynamic flow column laboratory experiments were performed. The sorption–desorption capacity of radionuclides by the tested sorbents was estimated based on the results of α- and γ-spectrometric measurements. According to the removal efficiency results, moss can be considered as the best sorbent for plutonium of the tested environmental-friendly sorbents, whereas the moss sorption capacity exceeded even that of the tested synthetic ones. The highest 137Cs removal efficiency from the lake water solution was obtained for granular activated carbon. Application of the dynamic flow method carried out in situ confirmed the reversibility of sorbed background 137Cs activity in the moss observed during the batch type experiments, and the method of the moss bed column turned to be unfit for the pre-concentration of 137Cs from the lake water. Application of a single moss bed column for the 137Cs and plutonium isotope pre-concentration for the first time carried out in situ allowed us to determine the activity concentration of 239,240Pu and 238Pu in the lake water – 4.87±0.98 and 0.67±0.21 mBq/m3, respectively. The reversible 137Cs and different plutonium sorption in the moss apparently indicates different binding properties of these radionuclides to the moss, therefore further investigations on this issue are foreseen.

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