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Kinetika i mehanizam uklanjanja odabranih metala iz vode adsorpcijom na aminofunkcionalizovanom ugljeničnom nanomaterijalu / The kinetics and mechanism of removal of selected metals from water by adsorption on amino functionalized carbon nanomaterialsŠućurović Aleksandra 27 September 2017 (has links)
<p>Predmet istraživanja ove doktorske disertacije bio je ispitivanje adsorpcionog ponašanja As(III) i odabranih metala (Cu(II), Cd(II), Pb(II), Cr(VI)) na amino- funkcionalizovanim višeslojnim ugljeničnim nanocevima, MWCNT-NH<sub>2 </sub>, na četiri odabrane pH vrednosti (3; 4,5; 6 i 11) i pri različitim sastavima vodenog rastvora (prisustvo hlorida, nitrata, sulfata i fosfata), a u cilju ispitivanja mogućnosti primene MWCNT-NH<sub>2</sub> za uklanjanje arsena i jona metala iz vodenih rastvora u oblasti relativno niskih koncentracija (0,01-3 mg L <sup>-1</sup> ). Fokus ove doktorske disertacije<br />je bio na utvrđivanju mehanizma procesa adsorpcije u ispitivanim uslovima. Adsorpciju arsena i metala na MWCNT-NH<sub>2</sub> najbolje je opisao reakcioni model pseudo-drugog reda što znači da adsorpcija može biti pripisana uspostavljanju hemijskih interakcija između adsorbata i vezivnih grupa na površini adsorbenta. Modelovanje brzine Weber Morris-ovim difuzionim modelom ukazalo je na to da unutarčestična difuzija, iako sporiji korak od eksterne difuzije, nije jedini ograničavajući korak u procesu adsorpcije, već su za to odgovorne i interakcije ispitivanih jona sa vezivnim mestima na površini adsorbenta. U ravnotežnim uslovima, na različitim pH vrednostima, adsorpcija se mogla opisati Langmuir-ovim i Freundlich-ovim adsorpcionim modelima. Kapacitet i afinitet adsorbenta, kao i sam mehanizam adsorpcije, značajno su bili uslovljeni pH vrednošću rastvora, kako zbog karakteristika površine ispitivanog adsorbenta uslovljenih pH vrednošću, tako i zbog uticaja pH vrednosti rastvora na pojavne hemijske oblike u kojima se arsen i metali nalaze. Ispitivanje uticaja anjona pokazalo je da je prisustvo hlorida povećalo afinitet površine MWCNT-NH<sub>2 </sub>ka jonima arsena i svih metala u oblasti niskih<br />koncentracija, dok je prisustvo hlorida, nitrata, sulfata i fosfata pozitivno uticalo na afinitet površine (od 2 do 8 puta veći u odnosu na dejonizovanu vodu) MWCNT-NH<sub>2</sub><br />ka Cu(II) u oblasti viših koncentracija. Najmanji uticaj anjona na afinitet površine ka vezivanju metala primećen je kod hroma. Pretpostavljeni mehanizmi uklanjanja arsena i odabranih metala u prisustvu anjona ukljuĉuju reakcije građenja različitih vrsta spoljašnje- i unutrašnje-sfernih kompleksa, jonske izmene, kao i elektrostatičke interakcije koje se ostvaruju između pozitivno naelektrisane površine MWCNT-NH<sub><span style="font-size: 8.33333px;">2</span></sub> i anjona, na pH vrednostima manjim od 6,4, a koje menjaju afinitet<br />površine ka jonima arsena i metala. Rezultati ove doktorske disertacije pokazuju da se ispitivani adsorbent, MWCNT-NH<sub>2 </sub>, može koristiti za uklanjanje arsena i teških metala iz vode u prisustvu različitih anjona i da, svojim adsorpcionim karakteristikama, može konkurisati komercijalnim i ekonomski pristupačnim adsorbentima.</p> / <p>The subject of this doctoral thesis was the examination of the adsorption behaviour of As(III), and selected metals (Cu(II), Cd(II), Pb(II), Cr(VI)) on the amino-functionalized multiwalled carbon nanotubes, MWCNT-NH<sub>2</sub>, at four pH values (3, 4.5, 6, and 11) with different compositions of aqueous solutions (in the presence of chlorides, nitrates, sulphates and phosphates), in order to examine the possibilities of applying MWCNT-NH<sub>2</sub> in removal of arsenic and metal ions from aqueous solutions in relatively low concentration (0,01- 3mg L<sup>-1</sup>). The focus of this doctoral thesis was to establish the mechanism of adsorption process in given conditions. Arsenic and metal adsorption on MWCNT-NH<sub>2</sub> were best described with the pseudo-second order kinetic model, which assumes that adsorption can be attributed to the establishment of chemical reactions between the adsorbate, and the binding groups at the surface of adsorbent. The Weber - Morris diffusion model indicated that intercellular diffusion, although being a slower step than external diffusion, is not the only limiting step in the adsorption process, but also that the interactions of ions with the adsorbent surface binding sites, are responsible. In equilibrium, at different pH values, the adsorption could be described by the Langmuir and Freundlich adsorption models. The capacity and affinity of the adsorbent, and adsorption mechanism, were considerably determined by the pH value of the solution, either because of the characteristics of the surface of the investigated adsorbent depending on pH value, or the effect of the solution’s pH value on the chemical forms of arsenic and other metals. Investigation of the influence of the anion showed that the presence of chloride increased affinity of the surface of MWCNT-NH<sub>2</sub> to arsenic ions and to all metals in low concentration ranges, while presence of chlorides, nitrates, sulphates and phosphates had a positive impact on the affinity of the surface (2 or 8 times greater than for deionized water) MWCNT-NH<sub>2</sub> for Cu(II) in high concentration ranges. The smallest impact of anions to affinity of the surface to bond metals was noticed for chromium. The assumed mechanisms of removing arsenic and selected metals in the presence of anions include reactions of forming various kinds of outer- and inner-spheric complexes, ionic exchange, as well as electrostatic interaction which occur between positively charged surface of MWCNT-NH<sub>2</sub> and anions, for pH < 6.4, and which change affinity of the surface towards arsenic and metal ions. Results of this doctoral thesis show that the investigated adsorbent, MWCNT-NH<sub>2</sub>, can be used for the removal of arsenic and heavy metals from water, in the presence of different anions, and that with its adsorbent characteristic it can compete with commercially, and economically more affordable adsorbents.</p>
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Biosorpcija jona teških metala iz vode izluženim rezancima šećerne repe / Biosorption of heavy metal ions from water by sugar beet shredsKukić Dragana 18 November 2016 (has links)
<p>Cilj ove doktorske disertacije je bio da se ispita mogućnost primene izluţenih rezanaca šećerne repe i njihovih tretiranih oblika, nastalih u procesu proizvodnje bioetanola, kao biosorbenata za uklanjanje jona teških metala iz vode. U okviru eksperimenata, u laboratorijskim uslovima izvedeni su predtretman i hidroliza izluženih rezanaca kako bi se dobili tretirani oblici, a zatim je izvršena karakterizacija adsorbenata, ispitane njihove adsorpcione sposobnosti, utvrđeni najbolji uslovi za njihovu primenu i ispitana mogućnost njihove višestruke primene u obradi vode.<br />U okviru karakterizacije materijala određen je njihov sastav, specifiĉna površina i poroznost, ispitana površina primenom FTIR i EDS metode i kvantifikovana količina pojedinih funkcionalnih grupa prisutnih na površini primenom Boehm-ove titracije. Na osnovu FTIR metode pre i posle adsoprcije utvrđeno je koje grupe učestvuju u vezivanju jona metala.<br />Ispitan je i uticaj razliĉitih parametara na adsorpciju (vreme kontakta adsorbenta i adsorbata, veličina čestice, pH, temperatura, primenjena doza adsorbenta, jonska jačina, sušenje) radi utvrđivanja najboljih uslova za maksimalnu efikasnost.<br />Kako bi se stekao bolji uvid u sam proces adsorpcije jona na površinu adsorbenata, na eksperimentalne podatke primenjeni su različiti modeli adsorpcionih izotermi, a mehanizam vezivanja je detaljnije razmotren primenom kinetiĉkih modela. Primenom termodinamičkih modela utvrđena je priroda procesa.<br />Radi višestruke primene ovih ekoloških biosorbenata ispitana je i mogućnost regeneracije materijala razliĉitim kiselinama kao desorbensima i utvrđeno optimalno vreme desorpcije. Ispitana je primena kroz više uzastopnih ciklusa adsorpcija – desropcija. Rezultati su pokazali da ispitani materijali imaju zadovoljavajući adsorpcioni kapacitet, ali da se mogu primenjivati i vlažni, odmah nakon procesa ekstrakcije šećera, depektinacije i hidrolize, bez utroška energije za sušenje. Pored toga, utvrđeno je da se mogu regenerisati i koristiti uspešno više puta, što otvara mogućnost za njihovu primenu u praksi.</p> / <p>The aim of this PhD thesis was to investigate the possibility of usage of sugar beet shreds and their treated forms from the bioethanol production for removal of heavy metal ions from water. In the context of experiments, pretreatment and hydrolysis of sugar beet shreds were performed in order to obtain treated forms. The characterization of biosorbents was conducted and their adsorption capacity was investigated. Also, the optimal conditions for their implementation and the possibility of their multiple applications for water treatment were determined.<br />Within the characterization of materials their composition, specific surface area and porosity were determined. The surface of biosorbents was investigated by using FTIR and EDS methods. The amount of the functional groups present on the surface was quantified by Boehm's titration. On the basis of the FTIR method before and after adsorption it was determined which functional groups participate in the binding process.<br />The influence of various parameters on the adsorption (contact time of the adsorbent and adsorbate, particle size, pH, temperature, adsorbent dose, ionic strength, drying process) were examined in order to determine the best conditions for maximum efficiency.<br />For better insight into the process of adsorption of ions on the surface of the adsorbents, different models of adsorption isotherms were applied to experimental data. Mechanism of adsorption was determined by applying different kinetic models. The nature of the process was investigated by determining thermodynamic parameters.<br />The multiple applications of these eco-friendly biosorbents was examined by regeneration investigation. The optimal time of desorption was determined and different acids were used for regeneration study. The multiple cycles adsorption – desorption was also conducted.<br />The results showed that the investigated materials have a satisfactory adsorption capacity. They can also be applied wet, immediately after the process of sugar extraction, depectination and hydrolysis, without the energy consumption for drying. In addition, it was found that they can be regenerated and successfully used several times. This opens up the possibility for their practical application.</p>
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Transport kovových iontů v huminových hydrogelech / Transport of metal ions in humic hydrogelsHegr, Martin January 2017 (has links)
This diploma thesis is focused on the study of diffusion of metal ions in hydrogel of humic acid. The objective of this thesis was to investigate the effect of the concentration of metal ions supply source and duration of diffusion on transport through the gel using method of diffusion couple. Cupric, nickel and cobalt ions were esed like the diffusion medium. All these ions were selected thanks to their high affinity for the humic acids and because they are ideal to investigate the diffusion through the humic gel. Chloride salts of these metals, namely CuCl2, NiCl2 and CoCl2, were used like supply sources. Three different concentrations of each solution were compared, specifically 0,05M, 0,1M and 1M, and also were three different durations of diffusion, specifically 10 hours, 1 day and 3 days. Metal ions were compared with each other in order to determine which one has the best transport properties through the humic hydrogel. The data, necessary for calculation, were obtained by UV-VIS spectrophotometry. Diffusion coefficients and duffusive flux of individual metal ions were determined from measured data.
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Carbon nanotube sensor design and fabrication for determining lead in drinking water and ammonia gas in the airRahm, Connor 23 August 2022 (has links)
No description available.
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Enzymy kvasinky Candida tropicalis biodegradující fenol / Enzymes of Candida tropicalis yeast biodegrading phenolKoubková, Zuzana January 2011 (has links)
Effluents of industrial wastewaters from oil refineries, paper mills, dyes, ceramic factories, resins, textiles and plastic contain high concentrations of aromatic compounds, which are toxic to organisms. Degradation of these compounds to tolerant limits before releasing them into the environment is an urgent requirement. Candida tropicalis yeast is an important representative of eucaryotic microorganisms that are able to utilize phenol. During the first phase of phenol biodegradation, cytoplasmatic NADPH-dependent phenol hydroxylase of C. tropicatis oxidizes phenol to catechol. Catechol is in the second phase of biodegradative process oxidized to cis,cis-muconic acid by the reaction catalyzed with catechol-1,2-dioxygenase. In this diploma thesis we investigated the effect of the heavy metal ions on NADPH-dependent phenol hydroxylase and catechol-1,2-dioxygenase of C. tropicalis. Phenol hydroxylase was inhibited by Cu2+ and Pb2+ ions. Catechol dioxygenase was inhibited by all substances containing heavy metal ions (Fe2+ , Mn2+ , Cd2+ , Cu2+ and Pb2+ ), which were tested in this work. The most effective inhibition was produced by Pb2+ followed by Mn2+ , Cd2+ Fe2+ and Cu2+ ions. The higher sensitivity of catechol-1,2-dioxygenase to heavy metal ions might follow from the presence of histidine residue...
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Production of adsorptive material from modified nanocrystals cellulose for industrial applicationBanza, Musamba Jean Claude 05 1900 (has links)
PhD. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / Water is the essence of life, yet it is progressively polluted by dyes, heavy metal ions, food
additives, medicines, detergents, agrochemicals, and other toxins from industrial,
municipal, and agricultural sources. Among the different wastewater treatment
technologies, adsorption is a technique that, when used in conjunction with a welldesigned
system, produces high-quality treated water at a reasonable cost. For water
treatment, activated carbon is the most often employed adsorbent. Its manufacture, on the
other hand, is energy demanding, costly, and creates greenhouse emissions. As a result,
finding low-cost alternative adsorbents from industrial and agricultural waste and
biomass has attracted a lot of interest. In this context, developing sustainable platforms
for wastewater treatment using sustainable nanomaterials such as cellulose nanocrystals
(CNCs) is a unique technique with a low carbon footprint. CNCs, which are made by
hydrolyzing pulp fibers in sulfuric acid, are rod-like nanomaterials with a lot of
remarkable qualities including high specific surface area, high specific strength,
hydrophilicity, biodegradability, and surface functionalization.
These characteristics, as well as their accessibility, make them suitable candidates for
water treatment applications. However, because of their great colloidal stability and
nano-dimensions, extracting these CNCs after usage in water treatment is difficult. To
overcome this problem, including these CNCs into nanocomposite systems that can be
readily separated after usage in batch and continuous water treatment processes is a great
concept. Furthermore, pure CNCs have low selectivity towards a wide range of water
pollutants, necessitating surface functionalization to provide this selectivity. As a result,
this thesis investigates the extraction of CNCs from millet husk waste and waste papers,
the development of CNC-incorporated nanocomposites and evaluation of their
adsorption characteristics using batch and fixed bed column adsorption studies, and (ii)
the evaluation of the selective adsorption characteristics of surface functionalized CNCs
and their ability to tailor the nanocomposites' characteristics for use in water treatment
applications. The response surface methodology, artificial neural network, and adaptive
neuro-fuzzy inference systems were also applied to model the removal of heavy metal
ions.
The first part of the research ( cellulose nanocrystals extraction and optimization)
The cellulose nanocrystals were extracted from millet husk residue waste using a
homogenized acid hydrolysis method. The effects of the process variables
homogenization speed (A), acid concentration (B), and acid to cellulose ratio (C) on the
yield and swelling capacity were investigated and optimized using the Box Behnken
design (BBD) method in response surface methodology. The numerical optimization
analysis results showed that the maximum yield of CNCs and swelling capacity from
cellulose was 93.12 % and 2.81 % obtained at homogenization speed, acid concentration,
and acid to cellulose ratio of 7464.0 rpm, 63.40 wt %, and 18.83 wt %, respectively. ANOVA
revealed that the most influential parameter in the model was homogenization speed for
Yield and acid concentration for swelling capacity. The TGA revealed that cellulose had
greater heat stability than CNCs. The functional groups of CNCs and cellulose were
identical according to the FTIR data. When compared to cellulose, the SEM picture of
CNCs is porous and shows narrow particle size with needle-like shape. The XRD pattern
revealed an increase in CNC intensity.
The second part of the research ( CNCs modification for selective removal)
A novel type of recyclable adsorbents with outstanding adsorption capability was
produced using CNCs with succinic anhydride and EDTA. and their adsorption
properties were studied in detail utilizing batch adsorption experiments of Chromium
(VI) in aqueous solution. The effects of several factors on Cr (VI) adsorption were
examined, including contact duration, adsorbent dose, starting concentration, pH, and
temperature. The cellulose nanocrystals treated with succinic anhydride and EDTA
possessed a needle-like form, high porosity, and a narrow particle size distribution. The
carboxylate transition of the carboxyl group of cellulose was verified by FTIR. XRD
analysis of particles after modification revealed the presence of additional phases, which
were attributed to succinic anhydride and EDTA modification. A spontaneous exothermic
adsorption process was validated by the observed thermodynamic characteristics. The
best model for describing adsorption kinetics and mechanism was a pseudo-second order
kinetic and intra-particle diffusion model. The Langmuir adsorption isotherm was seen in
equilibrium adsorption data, with a maximum adsorption capacity (qmax) of 387.25± 0.88
mgL-1. We showed that the removal effectiveness of Cr (VI) maintained at 220± 0.78 mg.g-1after 6 adsorption-desorption cycles, and that the CNC-ALG hydrogel beads are excellent adsorbents for the selective removal of Cr (VI) from wastewaters.
The third part of the research ( modeling of removal of heavy metal ions using RSM,
ANN and quantum mechanism studies )
The effects of contact time , pH, nanoparticle dose, and beginning Cd2+ concentration on
Cd2+ removal were examined using the central composite design (CCD) technique. The
performance and prediction capabilities of Response Surface Methodology (RSM) and
Artificial Neural Network (ANN) modelling methodologies were explored, as well as their
performance and prediction capacities of the response (adsorption capacity). The
process was also described using the adsorption isotherm and kinetic models. Statistical
data, on the other hand, revealed that the RSM-CCD model beat the ANN model technique. The optimum conditions were determined to be a pH of 5.73, a contact time of 310 minutes, an initial Cd2+ concentration of 323.04 mg/L, a sorbent dosage of 16.36 mg, and an adsorption capacity of 440.01 mg/g. The spontaneous adsorption process was well
characterized by the Langmuir model, and chemisorption was the dominant regulator.
The binding energy gaps HOMO-LUMO were used to find the preferred adsorption sites.
The fourth part of research ( optimization of removal using ANN and ANFIS)
An artificial neural network and an adaptive neuro-fuzzy inference system were utilized
to predict the adsorption capability of mix hydrogels in the removal of nickel (II) from
aqueous solution. Four operational variables were evaluated in the ANFIS model to
determine their influence on the adsorption study, including starting Ni (II) concentration
(mg/L), pH, contact time (min), and adsorbent dosage (mg/L) as inputs and removal
percentage (percent) as the single output. In contrast, 70% of the data was employed to
develop the ANN model, while 15% of the data was used in testing and validation. To train
the network, feedforward propagation with the Levenberg-Marquardt algorithm was
used. To optimise, design, and develop prediction models for Ni (II) adsorption using
blend hydrogels, (ANN) and (ANFIS) models were employed for trials. The results
demonstrate that the ANN and ANFIS models are viable prediction techniques for metal
ion adsorption.
The fourth part of research ( mechanistic modeling and optimization of removal using
ANN, RSM and ANFIS)
An artificial neural network, response surface methodology and an adaptive neuro-fuzzy
inference system were utilized to predict the adsorption capability of modified cellulose
nanocrystals and sodium alginate for the removal of Cr (VI) from aqueous solution. Four
variables such as time, pH, concentration, and adsorbent dose were evaluated to
determine their influence on the adsorption study. To examine the viability of the models,
five statistical functions ( RMSE, ARE, SSE, MSE, and MPSD) were applied. absorption
mechanism was described via four mechanistic models (Film diffusion, Weber and
Morris, Bangham, and Dummwald-Wagner models. Further statistical indices supported
ANFIS as the best prediction model for adsorption compared to ANN and RSM. Film
diffusion was identified as the rate-limiting process via mechanistic modelling.
The sixth part of research (continuous fixed-bed column study)
The hydrogel's technical feasibility for adsorption of Cu2+, Ni2+, +Cd2+, and Zn2+ ions
from the packed bed column's produced AMD was assessed. The hydrogel was considered
to have a high potential for significant interactions with dangerous metal ions. This
characteristic, together with the adsorbent's availability, low cost, and efficient
regeneration of the spent adsorbent, distinguishes it from the many other adsorbents
described in the literature by other researchers. With a bed height of 25 cm, an influent
metal ion concentration of 10 mg/l, and a flow velocity of 10 ml/min, the bed performed
better. As a consequence, the breakthrough curve for the packed bed experiment shows
that the breakthrough points were approached sooner by increasing the flow rate and
influent concentration, and later by increasing the bed height. The experimental results
were satisfactorily described by the BDST, Yoon–Nelson, and Thomas models. The
hydrogels had a net-work structure and more homogeneous porosity, according to the
SEM, TGA, XRD, and FTIR results for CNCs. The hydrogels revealed varied degrees of
opacity and heavy metal ions absorption capacity depending on the temperature of the
analysis. Diffraction confirmed the existence of crystalline structures and the presence of
carboxyl and amide groups.
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Vario (II) ir chromo (VI) jonų pašalinimas metaline geležimi iš vandeninių tirpalų / "Copper(II) and chromium(VI) ions removal from aqueous solutions by metallic iron"Baronaitė, Sandra 29 June 2009 (has links)
Šiame eksperimente buvo nagrinėjama pH įtaka Cr (VI) ir Cu (II) jonų pašalinimui iš vandeninių tirpalų, naudojant metalinę geležį Fe (0), kai tirpalų pH vertės buvo nuo 2 iki 6, purtymo procese, uždaruose ir atviruose induose. Kadangi Cr (VI) ir Cu (II) jonų koncentracijų sumažėjimas tirpale priklauso nuo geležies paviršiaus, tai labai svarbu ją tinkamai paruošti: išvalyti ir aktyvuoti. Maksimalus Cr (VI) jonų pašalinimo efektyvumas buvo esant pH vertei 2, o Cu (II) jonų atveju, kai pH vertė 4 uždaruose induose ir atviruose induose – chromo atveju pH 6, vario atveju, kai pH 4. Pašalinimo įvertinimui naudojamos kalibraciniės kreivės pagal kurias apskaičiuojamos likusiųjų jonų koncentracijos, matuojant tirpalų optinius tankius. Metodas yra pigus ir patikimas, nes pašalinima didelė dalis sunkiųjų metalų jonų. / The effects of pH on Cr (VI) and Cu (II) ions removal from solutions by Fe (0) was investigated by batch shaking process. Since the presence of ferrous iron in the solution is mainly responsible for Cr (VI) and Cu (II) reduction the surface of iron must be purified and activated. The maximum Cr (VI) removal efficiency was found at pH 2 and in Cu (II) case it was pH 4 without oxygen and in case with open jar it was for Cr (vi) removal pH 6 and for Cu (II) removal pH 4. Remained concentrations of Cu (II) and Cr (VI) ions were investigated using calibrated graphs and analysis of optical density. This study confirmed that this method is cheap because we can use wasted iron and effective of removing most of heavy metal ions from solutions.
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Development of new types of composite electrodes based on natural clays and their analytical applications / Développement de nouveaux types d'électrodes composites à base d'argiles naturelles et leurs applications analytiquesMaghear, Adela 12 November 2013 (has links)
Le travail de thèse est consacré au développement d'électrodes composites à base d'argiles naturelles et à leur caractérisation électrochimique à des fins analytiques, notamment pour le dosage de cations métalliques (Cu2+) et de quelques substances à visée thérapeutique. Le premier chapitre expérimental est consacré à une étude comparée des caractéristiques chimiques, structurales et physico-chimiques de deux argiles naturelles extraites sur deux sites en Roumanie. Il apparaît que l'argile de Valea Chioarului, de type montmorillonite, présente les propriétés les plus intéressantes avec une surface spécifique importante (190 m2/g). Le deuxième chapitre fait état d'une analyse prospective des deux argiles comme matériaux d'électrodes en utilisant un film composite argile/poly-électrolyte. Trois molécules d'intérêt pharmaceutique ont été choisies pour cible, l'acide ascorbique, la riboflavine et l'acétaminophène. Cette dernière molécule peut être détectée soit par oxydation directe, soit via une réaction électro-enzymatique avec la peroxydase de raifort. Les troisième et quatrième chapitres sont consacrés à l'utilisation d'argiles échangées par des cations ammonium pour la détection du cuivre. Ainsi, l'argile de Valea Chioarului a été échangée partiellement avec du tétrabutylammumium. La perméabilité des films d'organo-argile recouverts d'un film de cellulose a été étudiée en utilisant différentes sondes électro-actives de charge différentes, Ru(NH3)63+, [Fe(CN)6]3-, Fc(MeOH)2. Les conditions expérimentales ont été ensuite optimisées pour la détection du Cu(II) et Cd(II) avec ces électrodes modifiées en voltammétrie à vague carrée. Dans le dernier chapitre, une configuration originale d'électrode modifiée a été mise au point. Il s'agit d'électrodes composites argile-silice mésoporeuse préparée par électrodéposition en présence ou non d'un tensioactif, le cétyltriméthylammonium. La perméabilité des films a également été étudiée avec les mêmes molécules que précédemment. Il apparait que l'extraction du tensio-actif conduit à des films homogènes très poreux et stables qui présentent des propriétés d'accumulation du Cu(II) / The thesis is devoted to the development of composite electrodes based on natural clays and their electrochemical characterization for analytical purposes, in particular for the determination of metal cations (Cu2+) and some therapeutic substances. The first experimental chapter is devoted to a comparative study of the chemical, structural and physico-chemical properties of two natural clays extracted from two sites in Romania. It appears that Valea Chioarului clay, of montmorillonite type, has the most interesting properties with a high specific surface area (190 m2/g). The second chapter presents a prospective analysis of the two clays as electrode materials using a clay/polyelectrolyte composite film. Three target molecules of pharmaceutical interest have been selected: ascorbic acid, riboflavin, and acetaminophen. This last molecule can be detected either by direct oxidation or through an electro-enzymatic reaction with horseradish peroxidase. The third and fourth chapters are devoted to the use of clays exchanged by ammonium cations for copper detection. Thus, Valea Chioarului clay was partially exchanged with tétrabutylammumium. The permeability of the organoclay films coated with a cellulose membrane was studied by using different electroactive probes of different charging, Ru(NH3)63+, [Fe(CN)6]3-, Fc(MeOH)2. The experimental conditions were then optimized for the detection of Cu (II) and Cd (II) with the modified electrodes by square wave voltammetry. In the last chapter, an original modified electrode configuration was developed. This implies composite mesoporous silica-clay electrodes prepared by electrodeposition in the presence or absence of a surfactant, like cetyltrimethylammonium. The permeability of the films was also investigated with the above mentioned molecules. It appears that the extraction of the surfactant leads to very stable and homogeneous porous films that show Cu (II) accumulation properties
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[pt] DETECÇÃO ÓPTICA DE ÍONS DE METAIS PESADOS ATRAVÉS DA ESPECTROMETRIA SPR COM INTERFACES OURO-GRAFENO / [en] OPTICAL DETECTION OF HEAVY METAL IONS THROUGH SPR SPECTROMETRY WITH GOLD-GRAPHENE INTERFACESLUIS GONZALO BALDEON HUANQUI 04 July 2023 (has links)
[pt] A espectroscopia de ressonância de plásmon superficial (SPR) é uma técnica
óptica baseada na excitação coletiva dos elétrons livres de metais nobres,
tradicionalmente utilizada em sensoriamento de analitos de diferente natureza.
Neste trabalho foi otimizado o processo de fabricação de sensores plasmônicos
baseados em filmes finos de ouro e interfaces ouro-grafeno. As plataformas de
sensoriamento SPR foram usadas para a detecção de íons de metais tóxicos pesados
de Pb(2+), Hg(2+) e Cd(2+) em concentrações de 0.1ppm até 1ppm. Os sensores
baseados em interfaces ouro-grafeno, onde o grafeno foi crescido mediante o
método CVD, demonstraram uma sensitividade entre 3 até 6 vezes maior que os
sensores constituídos por filmes finos de ouro, apontando para uma absorção
química devida à transferência de elétrons do grafeno para os íons. / [en] Surface plásmon resonance (SPR) spectroscopy is an optical technique
based on the collective excitation of free electrons of noble metals, traditionally
used in sensing different types of analytes. In this work the fabrication process of
plásmonic sensors based on thin gold films and gold-graphene interfaces was
optimized. SPR sensing platforms were used for the detection of toxic heavy metals
ions Pb(2+), Hg(2+) and Cd(2+) in concentrations ranging from 0.1ppm to 1ppm. The
sensors based on gold-graphene interfaces, where graphene was grown using the
CVD method, demonstrated a sensitivity between 3 and 6 times greater than the
sensor made of thin films of gold, pointing to a chemical absorption due to the
transfer of electrons from the graphene to the ions.
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STUDY OF THE TRANSPORT OF HEAVY METAL IONS THROUGH CATION-EXCHANGE MEMBRANES APPLIED TO THE TREATMENT OF INDUSTRIAL EFFLUENTSMartí Calatayud, Manuel César 12 January 2015 (has links)
La presente Tesis Doctoral consiste en la determinación de las propiedades de transporte de diferentes especies catiónicas a través de membranas de intercambio catiónico. Las membranas de intercambio iónico son un componente clave de los reactores electroquímicos y de los sistemas de electrodiálisis, puesto que determinan el consumo energético y la eficiencia del proceso. La utilización de este tipo de membranas para el tratamiento de efluentes industriales no es muy extendida debido a los requisitos de elevada resistencia química y durabilidad que deben cumplir las membranas. Otro asunto importante radica en la eficiencia en el transporte de los iones que se quieren eliminar a través de la membrana. Normalmente, existe una competencia por el paso a través de las membranas entre diferentes especies debido al carácter multicomponente de los efluentes a tratar. Sin embargo, una mejora en las propiedades de las membranas de intercambio iónico permitiría la implantación del tratamiento mediante reactores electroquímicos de efluentes industriales con un contenido importante en compuestos metálicos, tales como los baños agotados de las industrias de cromado. La utilización de una tecnología limpia como la electrodiálisis conllevaría diferentes ventajas, entre las cuales destacan la recuperación de los efluentes para su reutilización en el proceso industrial, el ahorro en el consumo de agua y la disminución de la descarga de contaminantes al medio ambiente.
La determinación de las condiciones de operación óptimas así como la mejora de las propiedades de transporte de las membranas constituye el principal tema de la presente investigación. Para ello, se emplearán diferentes tipos de membrana. En primer lugar, se estudiará el comportamiento de las membranas poliméricas comerciales que poseen unas propiedades de resistencia química elevadas, las cuales se tomarán como referencia. De forma paralela, se producirán membranas conductoras de iones a partir de materiales cerámicos económicos, ya que la resistencia de los materiales cerámicos a sustancias oxidantes y muy ácidas es mayor que la de los materiales poliméricos. Este punto constituye la parte más innovadora de la investigación, puesto que la mayoría de las membranas de intercambio iónico comerciales están basadas en materiales poliméricos que no pueden resistir las condiciones específicas de los efluentes industriales. Una vez determinadas las condiciones de operación óptimas, se realizarán ensayos en plantas piloto con el fin de confirmar los resultados obtenidos mediante las técnicas de caracterización y determinar el grado de recuperación y coste energético asociado a los procesos electrodialíticos de tratamiento de efluentes industriales. / Martí Calatayud, MC. (2014). STUDY OF THE TRANSPORT OF HEAVY METAL IONS THROUGH CATION-EXCHANGE MEMBRANES APPLIED TO THE TREATMENT OF INDUSTRIAL EFFLUENTS [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/46004 / TESIS / Premios Extraordinarios de tesis doctorales
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