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Synthesis, characterisation and application of organoclaysXi, Yunfei January 2006 (has links)
This thesis focuses on the synthesis and characterisation of organoclays. X-ray diffraction has been used to study the changes in the basal spacings of montmorillonite clay and surfactant-intercalated organoclays. Variation in the d-spacing was found to be a step function of the surfactant concentration. Three different molecular environments for surfactant octadecyltrimethylammonium bromide (ODTMA) within the surface-modified montmorillonite are proposed upon the basis of their different decomposition temperatures. High-resolution thermogravimetric analysis (HRTG) shows that the thermal decomposition of montmorillonite modified with ODTMA takes place in four steps attributing to dehydration of adsorbed water, dehydration of water hydrating metal cations, loss of surfactant and the loss of OH units respectively. In addition, it has shown that the decomposition procedure of DODMA and TOMA modified clays are very different from that of ODTMA modified ones. The surfactant decomposition takes place in several steps in the DODMA and TOMA modified clays while for ODTMA modified clays, it shows only one step for the decomposition of surfactant. Also TG was proved to be a useful tool to estimate the amount of surfactant within the organoclays. A model is proposed in which, up to 0.4 CEC, a surfactant monolayer is formed between the montmorillonite clay layers; up to 0.8 CEC, a lateral-bilayer arrangement is formed; and above 1.5 CEC, a pseudotrimolecular layer is formed, with excess surfactant adsorbed on the clay surface. While for dimethyldioctadecylammonium bromide (DODMA) and trioctadecylmethylammonium bromide (TOMA) modified clays, since the larger sizes of the surfactants, some layers of montmorillonite are kept unaltered because of steric effects. The configurations of surfactant within these organoclays usually take paraffin type layers. Thermal analysis also provides an indication of the thermal stability of the organoclay as shown by different starting decomposition temperatures. FTIR was used as a guide to determine the phase state of the organoclay interlayers as determined from the CH asymmetric stretching vibration of the surfactants to provide more information on surfactant configurations. It was used to study the changes in the spectra of the surfactant ODTMA upon intercalation into a sodium montmorillonite. Surfaces of montmorillonites were modified using ultrasonic and hydrothermal methods through the intercalation and adsorption of the cationic surfactant ODTMA. Changes in the surfaces and structure were characterized using electron microscopy. The ultrasonic preparation method results in a higher surfactant concentration within the montmorillonite interlayer when compared with that from the hydrothermal method. Both XRD patterns and TEM images demonstrate that SWy-2-Namontmorillonite contains superlayers. TEM images of organoclays prepared at high surfactant concentrations show alternate basal spacings between neighboring layers. SEM images show that modification with surfactant will reduce the clay particle aggregation. Organoclays prepared at low surfactant concentration display curved flakes, whereas they become flat with increasing intercalated surfactant. Fundamentally this thesis has increased the knowledge base of the structural and morphological properties of organo-montmorillonite clays. The configurations of surfactant in the organoclays have been further investigated and three different molecular environments for surfactant ODTMA within the surface-modified montmorillonite are proposed upon the basis of their different decomposition temperatures. Changes in the spectra of the surfactant upon intercalation into clay have been investigated in details. Novel surfactant-modified montmorillonite results in the formation of new nanophases with the potential for the removal of organic contaminants from aqueous media and for the removal of hydrocarbon spills on roads.
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Laponite-supported titania photocatalystsDaniel, Lisa Maree January 2007 (has links)
This thesis describes the synthesis and characterisation of titania photocatalysts for incorporation into a polyethylene film. Monodisperse, anatase-phase titania nanoparticles are prepared and the synthesis conditions necessary for attraction to a laponite clay support are determined. Methods of preventing agglomeration of the laponite system such as the use of a polyethylene oxide surfactant or chemical modification of the laponite plate edges with a dimethyloctyl methoxysilane are also explored. Finally, photocatalytic studies on the laponite-supported titania nanoparticles are performed, and the compatibility and photoactivity of these materials in the polyethylene film are examined.
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Μελέτη αποδέσμευσης ιόντων δισθενούς χαλκού από συμπολυμερή τύπου κτέναςΙατρίδη, Ζαχαρούλα 22 December 2009 (has links)
Διερευνήθηκε η δέσμευση/αποδέσμευση ιόντων Cu(II) ή/και αντίθετα φορτισμένων επιφανειοδραστικών ενώσεων από συμπολυμερή τύπου κτένας. Ο κεντρικός σκελετός ήταν το πολυ(ακρυλικό νάτριο), PANa, ενώ οι πλευρικές αλυσίδες ήταν το Πολυ(Ν,Ν-διμεθυλακρυλαμίδιο) και το πολυ(Ν-Ισοπροπυλακρυλαμίδιο). Η συμπλοκοποίηση των συμπολυμερών με τα ιόντα Cu(II)σε υδατικό περιβάλλον διερευνήθηκε με θολομετρία, ιξωδομετρία, φασματοφωτομετρία UV-Vis, δυναμική σκέδαση φωτός, ιχνηθέτηση με φθορίζοντες ιχνηθέτες και προσδιορισμό του ζ-δυναμικού. Σε επόμενο στάδιο διερευνήθηκε η δυνατότητα σχηματισμού τριμερών συμπλόκων ΡAΝa/Cu(II)/επιφανειοδραστικής ένωσης σε υδατικό περιβάλλον. Από τη φυσικοχημική μελέτη των συστημάτων σε συνάρτηση του pΗ, ελήφθησαν σημαντικές πληροφορίες σχετικά με τον ανταγωνισμό των δύο ειδών (ιόντα Cu(II)ή ιόντα επιφανειοδραστικής ένωσης) να σχηματίσουν σύμπλοκα με το PANa. Ως τελικό στάδιο, παρασκευάστηκαν αδιάλυτα στο νερό υβριδικά υλικά πολυμερούς/Cu(II)ή πολυμερούς/Cu(II)/επιφανειοδραστικής ένωσης. Έπειτα από διερεύνηση της συμβατότητας/αναμιξιμότητάς τους με εμπορικές μήτρες που χρησιμοποιούνται συνήθως στη βιομηχανία χρωμάτων, ορισμένα από αυτά ενσωματώθηκαν σε πραγματικά χρώματα. / The binding/release of Cu(II) ions or/and surfactants from comb-type copolymers was studied. The backbone was poly(sodium acrylate), PANa, whereas the side chains were poly(N, N-Dimethylacrylamide) and Poly9N-Isopropylacrylamide). The complexation of these copolymers with Cu(II) ions in water, was studied by turbidimetry, viscometry, UV-Vis fasmatophotometry, dynamic light scattering, fluorescense probing and ζ-potential. As a next step, the possible formation of ternary PANa/Cu(II)/surfactant complexes in water was studied. From the physiocochemical studies with pH, important information was taken as far as the competition of the two species (Cu(II) ions and surfactant) to form complexes with PANa is concerned. As a next step, water-insoluble hybrid polymer/Cu(II) or polymer/Cu(II)/surfactant materials were produced. After studies upon the compatibility/mischibility of the hybrid materials with matrices that are usually used in paints, some of the materials were incorporated to paints.
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Ação da fosfolipase B extracelular de Paracoccidioides brasiliensis na interação ex vivo com macrófagos alveolares / Action of extracellular phospholipase B of Paracoccidioides brasiliensis interaction with alveolar macrophage ex vivoSOARES, Deyze Alencar 26 March 2010 (has links)
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Previous issue date: 2010-03-26 / Paracoccidioides brasiliensis, a thermodimorphic fungus, is the causative agent of the most
prevalent systemic mycosis in Latin America, paracoccidioidomycosis. The phospholipase B
(PLB) enzyme is considered an important virulence factor in this dimorphic fungus, involved
in the immune response of the host-pathogen interaction. Our objective was to determine
whether a P. brasiliensis (Pb18) PLB is involved in adhesion / internalization of yeast and
evasion of host immune responses. The effect of PLB was analysed using specific inhibition
of PLB (alexidine dihydrochloride) and pulmonary surfactant in an ex vivo model (Pb18) of
alveolar macrophage (MHS cells) infection. PLB enzyme assays and real time RT-PCR (qRTPCR)
analysis of genes differentially expressed in the process of evasion: plb1 (phospholipase
B1), icl1 (isocitrate lyase) and sod3 (Cu, Zn dismutase) and immune responses: clec2 (C-type
lectin domain 2), cd14 (cluster of differentiation 14), tlr2 (toll-like receptor 2), nfkb (nuclear
factor kappa B), nkrf (NF-kappaB repressing factor), il1β (inteleukin-1β) and tnfα (tumor
necrosis factor alpha) were carried out using selective inhibition of PLB activity and
pulmonary surfactant. The levels of cytokines inteleukin 10 (IL-10), IL-12 and TNF-α) were
also determined by ELISA. PLB activity under adhesion conditions of P. brasiliensis (Pb18)
to alveolar macrophage cells was found at high levels up to 6 hours post-infection. In the
conditions of exposure to pulmonary surfactant and alexidine dihydrochloride, PLB activity
and the level of transcripts of genes related to phagocytosis and inflammatory response were
measured. We found that PLB activity had an influence on the phagocytic activity of alveolar
macrophages. Alexidine dihydrochloride (0,25 μM) selectively inhibited PLB activity by 66%
and decreased significantly the adhesion and internalization of yeast on MHS cells. Genes
involved in phagocytosis (trl2 and cd14) and inflammatory response (nrkf, tnfα and il1β) were
down-regulated in the presence of the PLB inhibitor. In contrast, the PLB activity and
internalization of fungal yeast cells increased significantly in the presence of pulmonary
surfactant (100 μg/mL) and genes such as clec2, important for effective phagocytosis by MHS
cells, and the pro-inflammatory inhibitor (nkrf) were up-regulated. Also, the pulmonary
surfactant did not alter cytokine production, while alexidine dihydrochloride decreased the
levels of IL-10 and increased the levels of IL-12 and TNF-α. In addition, through
simultaneous analyses of gene expression for the pathogen, P. brasiliensis, we found upregulation
of the genes sod3, icl1 and plb1, required for the evasion of alveolar macrophages.
P. brasiliensis PLB is important for the binding and internalization of yeast at macrophage
surfaces. The specific effect of inhibiting PLB enzyme activity indicates that adhesion may be
facilitated indirectly via fatty acid release from phospholipids of the membrane of host cells.
This is the first study to show that PLB activity may modulate immune responses to P.
brasiliensis infection. / Paracoccidioides brasiliensis, fungo dimórfico, é o agente etiológico principal micose
sistêmica da América Latina, paracoccidioidomicose. A enzima fosfolipase B (PLB) é
considerada um importante fator de virulência nesse fungo dimórfico e está envolvida na
resposta imune da interação patógeno-hospedeiro. Nosso objetivo foi determinar se a PLB de
P. brasiliensis (Pb18) está envolvida na adesão e internalização de leveduras e na evasão da
resposta imune hospedeira. O efeito da PLB foi analisado usando o inibidor seletivo de PLB
(alexidine dihydrochloride) e o surfactante pulmonar (Survanta) em um modelo ex vivo de
infecção de macrófagos alveolares (MHS) com Pb18. Ensaio enzimático de PLB e análise de
genes diferencialmente expressos por RT-PCR em tempo real (qRT-PCR) no processo de
evasão: plb1 (fosfolipase B1), icl1 (isocitrato liase) e sod3 (Cu, Zn dismutase); e na resposta
imune: clec2 (lecitina tipo-C 2), cd14 (cluster de diferenciação 14), tlr2 (receptor toll-like 2),
nfkb (fator nuclear kappaB), nkrf (repressor fator nuclear kappaB), il1β (interleucina- 1 beta) e
tnfα (fator de necrose tumoral alfa) foram realizados usando o inibidor seletivo da atividade
de PLB e surfactante pulmonar. Os níveis de citocinas interleucina 10 (IL-10), IL-12 e TNF-
α) foram determinados por ELISA. A atividade de PLB usadas em baixas condições para a
adesão de P. brasiliensis (Pb18) obteve altos níveis em 6 horas pós-infecção. Na presença do
surfactante pulmonar e alexidine dihydrochloride, a atividade da PLB e os níveis de
transcritos dos genes relacionados à fagocitose e à resposta inflamatória foram quantificados.
A PLB teve influência na atividade fagocítica dos macrófagos. Alexidine dihydrochloride
(0,25 μM) inibiu seletivamente a atividade PLB em 66% e diminuiu significativamente a
adesão e internalização de leveduras por macrófagos alveolares (MHS). Genes envolvidos na
fagocitose (trl2 e cd14) e resposta inflamatória (nrkf, tnfα e il1β) foram reprimidos na
presença do inibidor de PLB. Em contraste, a atividade PLB e internalização de leveduras
aumentou significativamente na presença do surfactante pulmonar (100 μg/mL) e genes assim
como clec2, importante para uma fagocitose efetiva pelos macrófagos alveolares (MHS), e o
inibidor pró-inflamatório (nkrf) foram induzidos. Entretanto, o surfactante pulmonar não
alterou a produção de citocinas, enquanto que alexidine dihydrochloride diminuiu os níveis de
IL-10 e aumentou os níveis de IL-12 e TNF-α. Em adição, nas análises simultâneas de
expressão de genes, P. brasiliensis, houve indução dos genes sod3, icl1 e plb1, requeridos
para a evasão dos macrófagos alveolares. A PLB de P. brasiliensis é importante na adesão e
internalização de leveduras pelos macrófagos alveolares. O efeito específico da inibição da
atividade da PLB indica que a adesão pode ser facilitada indiretamente via liberação de ácidos
graxos dos fosfolipídeos de membrana das células hospedeiras. Esse é o primeiro estudo
mostrando que a atividade da PLB pode modular a resposta imune à infecção pelo P.
brasiliensis.
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Genetic predisposition to spontaneous preterm birth:approaches to identify susceptibility genesKarjalainen, M. (Minna) 06 December 2011 (has links)
Abstract
Approximately 5.5% of all infants are born preterm (before 37 completed weeks of gestation) in Finland. Preterm birth is the cause of several life-threatening neonatal diseases and long-term morbidity. The most important risk factor for preterm birth is intrauterine infection and inflammation. Approximately 70% of preterm births have a spontaneous onset. Evidence suggests that genetic factors are involved in spontaneous preterm birth (SPTB), but knowledge about the actual genes conferring genetic predisposition is limited.
The major aim of this work was to identify genetic factors that predispose to SPTB. Genome-wide linkage analysis was performed to identify genomic regions associating with SPTB in large northern Finnish families recurrently affected by SPTB. Genes near regions with linkage signals were subsequently analyzed in a Finnish case-control population of mothers and infants. Due to their roles in innate immunity, the genes encoding surfactant protein A (SP-A), SP-C, SP-D and mannose-binding lectin (MBL) were also investigated as candidates for SPTB in this population. In addition, expression of SP-C in human and mouse gestational tissues was examined.
Linkage signals were detected on chromosome loci 15q26.3, Xq13.1 and Xq21.1 with the phenotype of being born preterm. In subsequent association analyses, the genes encoding the insulin-like growth factor 1 receptor (IGF1R) located within locus 15q26.3 and the androgen receptor (AR) located near locus Xq13.1 were identified as potential novel fetal SPTB susceptibility genes. These genes did not associate with SPTB in the mothers.
An association was found between the Met31Thr polymorphism of the SFTPD gene encoding SP-D and SPTB in the infants. There was no association in the mothers. Polymorphisms of the genes encoding SP-A or MBL did not associate with SPTB.
The Thr138Asn polymorphism of the SFTPC gene encoding SP-C did not associate with SPTB. However, this polymorphism associated strongly with the interval between preterm premature rupture of membranes and SPTB in the fetuses. Expression of SP-C was detected in human and mouse fetal membranes and placenta, and in mouse pregnant uterus.
Currently, there is no effective method to prevent SPTB. The results of this study may help to clarify some of the biological mechanisms underlying SPTB and finally allow the development of specific treatment strategies for its prevention. / Tiivistelmä
Suomessa syntyy noin 5,5 % lapsista ennenaikaisina eli raskauden kestettyä vähemmän kuin 37 täyttä viikkoa. Näillä lapsilla on alttius hengenvaarallisiin sairauksiin, ja osalle heistä jää pysyvä kehitysvamma. Noin 70 % ennenaikaisista syntymistä käynnistyy spontaanisti. Tärkein ennenaikaisen syntymän riskitekijä on kohdunsisäinen tulehdusreaktio. Myös perinnöllisten tekijöiden tiedetään vaikuttavan spontaanin ennenaikaisen syntymän (SEAS) käynnistymiseen, mutta alttiusgeenejä tunnetaan huonosti.
Työssä pyrittiin tunnistamaan SEAS:lle altistavia perinnöllisiä tekijöitä. Perimänlaajuista kytkentäanalyysiä käyttäen etsittiin SEAS:ään liittyviä perimän kohtia tutkimalla toistuvasti ennenaikaisia syntymiä kokeneita isoja pohjoissuomalaisia perheitä. Kytkentäsignaalien lähellä olevia geenejä tutkittiin tutkimusaineistossa, joka koostui suomalaisista äideistä ja lapsista. Surfaktanttiproteiini A:ta (SP-A), SP-C:tä, SP-D:tä ja mannoosia sitovaa lektiiniä (MBL) koodaavia geenejä tutkittiin ehdokasgeeneinä SEAS:lle tässä populaatiossa, koska nämä proteiinit osallistuvat elimistön puolustukseen ja voivat siten vaikuttaa SEAS:ään liittyvään tulehdusreaktioon. Lisäksi tutkittiin SP-C:n ilmentymistä ihmisen ja hiiren sikiökalvoilla, istukassa ja kohdussa.
Kytkentäsignaaleja havaittiin kromosomikohdissa 15q26.3, Xq13.1 ja Xq21.1, kun tutkittavana ilmiasuna oli ennenaikaisena syntyminen. Lisätutkimukset osoittivat, että sikiön insuliininkaltaisen kasvutekijän 1 reseptoria koodaava IGF1R-geeni (kohta 15q26.3) ja androgeenireseptorigeeni AR (lähellä kohtaa Xq13.1) ovat mahdollisia uusia SEAS:n alttiusgeenejä. Nämä geenit eivät selittäneet SEAS:ää äideissä.
Sikiön SP-D:tä koodaavan geenin Met31Thr-polymorfismi tunnistettiin mahdolliseksi riskitekijäksi, mutta tämä polymorfismi ei selittänyt SEAS:ää äideissä. SP-A:ta ja MBL:ää koodaavat geenit eivät liittyneet SEAS:ään.
SP-C:tä koodaavan geenin Thr138Asn-polymorfismi ei ollut yhteydessä SEAS:ään. Sikiön Thr138Asn-polymorfismi liittyi kuitenkin vahvasti sikiökalvojen puhkeamisen ja SEAS:n väliseen kestoon. SP-C:n havaittiin ilmentyvän ihmisen ja hiiren sikiökalvoilla ja istukassa sekä raskaana olevan hiiren kohdussa.
Tulokset antavat uutta tietoa SEAS:n perinnöllisestä taustasta. Tämä tieto voi auttaa selvittämään sen käynnistymiseen johtavia biologisia mekanismeja ja johtaa lopulta uusiin hoitokeinoihin, joilla pystytään estämään spontaaneja ennenaikaisia syntymiä.
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Synthesis and potential application of Fe3+/Mn2+ bimetal and hexadecyltrimethylammonium bromide (HDTMA-Br) modified clayey soils for arsenic removal in groundwaterMudzielwana, Rabelani 16 May 2019 (has links)
PhD (Environmental Sciences) / Department of Ecology and Resource Management / The presence of arsenic in groundwater has drawn worldwide attention from researchers and public
health officials due to its effects on human health such as, cancer, skin thickening, neurological
disorders, muscular weakness, loss of appetite and nausea. World Health Organisation (WHO) has
set the limit of 10 μg/L for arsenic in drinking water in trying to reduce the effects of arsenic. This
was further adopted by South African National Standard (SANS). The present study aims at
evaluating arsenic concentration in selected groundwater sources around Greater Giyani
Municipality in Limpopo Province and further synthesize clay based adsorbents for arsenic
removal using Fe3+ and Mn2+ oxides and hexadecylammonium bromide (HDTMA-Br) cationic
surfactant as modifying agents.
The first section of the work presented the hydrogeochemical characteristics of groundwater in the
Greater Giyani Municipality. The results showed that the pH of the samples ranges from neutral
to weakly alkaline. The dominance of major anionic and cationic species was found to be in the
order: HCO3
->Cl->SO4
2->NO3
- and Na+>Mg2+>Ca2+>K+>Si4+, respectively. Hydrogeochemical
facies identified in the study area include CaHCO3 (90%) and mixed CaNaHCO3 (10%) which
shows the dominance of water-rock interaction. About 60% of the tested samples contains arsenic
concentration above 10 μg/L as recommended by SANS and WHO. Concentration of arsenic was
found to be ranging between 0.1 to 172.53 μg/L with the average of 32.21 μg/L.
In the second part of this work, arsenic removal efficiency of locally available smectite rich and
kaolin clay was evaluated. Results showed that the percentage As(V) removal by kaolin clay was
optimum at pH 2 while the percentage As(III) removal was greater than 60% at pH 2 to 12. For
smectite rich clay soils, the percentage of As(III) and As(V) removal was found to be optimum at
pH between 6 and 8. The adsorption isotherm data for As(III) and As(V) removal by both clays
fitted better to Freundlich isotherm. Adsorption of both species of arsenic onto the clay mineral
occurred via electrostatic attraction and ion exchange mechanisms. Both clay soils could be
regenerated twice using Na2CO3 as a regenerant. Kaolin clay showed a better performance and was
selected for further modification.
In the third section of this work, Fe-Mn bimetal oxide modified kaolin clay was successfully
synthesized by precipitating Fe3+ and Mn2+ metal oxides to the interlayer surface of kaolin clay.
Modification of kaolin clay increased the surface area from 19.2 m2/g to 29.8 m2/g and further
v
decreased the pore diameter from 9.54 to 8.5 nm. The adsorption data fitted to the pseudo second
order of reaction kinetics indicating that adsorption of As(III) and As(V) occurred via
chemisorption. The adsorption isotherm data was described by Langmuir isotherm models
showing a maximum As(III) and As(V) adsorption capacities of 2.16 and 1.56 mg/g, respectively
at a temperature of 289 K. Synthesized adsorbent was successfully reused for 6 adsorptiondesorption
cycles using K2SO4 as a regenerant. Column experiments showed that maximum
breakthrough volume of ≈2 L could be treated after 6 hours using 5 g adsorbent dosage.
Furthermore, the concentration of Fe and Mn were within the WHO permissible limit.
In the fourth part of the work kaolin clay was functionalized with hexadecyltrimethylamonium
bromide (HDTMA-Br) cationic surfactant and its application in arsenic removal from groundwater
was investigated. The results revealed that adsorption of As(III) and As(V) is optimum at pH range
4-8. The maximum As(III) and As(V) adsorption capacities were found 2.33 and 2.88 mg/g,
respectively after 60 min contact time. Pseudo first order model of reaction kinetics described the
adsorption data for As(V) better while pseudo second order model described As(III) adsorption
data. The adsorption isotherm data for As(III) and As(V) fitted well to Langmuir model indicating
that adsorption of both species occurred on a mono-layered surface. Adsorption thermodynamics
model revealed that adsorption of As(III) and As(V) was spontaneous and exothermic. The
As(III)/As(V) adsorption mechanism was ascribed to electrostatic attraction and ion exchange.
The regeneration study showed that synthesized adsorbent can be used for up to 5 times.
In the firth part of the work inorgano-organo modified kaolin clay was successfully synthesized
through intercalation of Fe3+ and Mn2+ metal oxides and HDTMA-Br surfactant onto the
interlayers of the clay mineral. The batch experiments showed that As(III) removal was optimum
at pH range of 4-6, while the As(V) removal was optimum at pH range 4-8. The adsorption data
for both species of arsenic showed a better fit to pseudo second order of reaction kinetics which
suggest that the dominant mechanism of adsorption was chemisorption. The isotherm studies
showed better fit to Langmuir isotherm model as compared to Freundlich model. The maximum
adsorption capacity As(III) and As(V) at room temperature as determined by Langmuir model
were found to be 7.99 mg/g and 7.32 mg/g, respectively. The thermodynamic studies for sorption
of As(III) and As(V) showed negative value of ΔGᴼ and ΔHᴼ indicating that adsorption process
occurred spontaneously and is exothermic in nature. The regeneration study showed that the
vi
inorgano-organo modified kaolin clay can be reused for up 7 adsorption-regeneration cycles using
0.01 M HCl as a regenerant. Thomas kinetic model and Yoon-Nelson model showed that the rate
of adsorption increases with increasing flow rate and initial concentration and decreases with
increasing of the bed mass.
In conclusions, adsorbents synthesized from this work showed a better performance as compared
to other adsorbents available in the literature. Among the synthesized adsorbents, inorgano-organo
modified clay showed highest adsorption capacity as compared to surfactant functionalized and
Fe-Mn bimetal oxides modified kaolin clay. However, all adsorbents were recommended for use
in arsenic remediation from groundwater. The following recommendations were made following
the findings from this study: 1) routine monitoring of arsenic in groundwater of Greater Giyani
Municipality, 2) evaluating the possible link between arsenic exposure and arsenic related diseases
within Giyani in order to find the extent of the problem in order to establish the population at risk,
3) The toxicity assessment for HDTMA-Br modified kaolin clay should be carried out, 4) Materials
developed in the present study should be modeled and tested at the point of use for arsenic removal,
and lastly, 5) this study further encourage the development of other arsenic removal materials that
can be used at household level. / NRF
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Untersuchungen zur Tensidverteilung in Reinigungsbädern in der Metall verarbeitenden IndustrieSteiner-Ander, Andrea 02 April 2001 (has links)
In dieser Arbeit wird ein industriell genutzter Metallreiniger auf Basis nichtionischer Tenside untersucht. Dabei werden ausschließlich Messmethoden verwendet, die sich auch für eine industrielle Fertigung eignen.
Zu Anfang enthält die Arbeit kurze Abrisse zum gegenwärtigen Kenntnisstand bezüglich der Inhaltstoffe industriell genutzten Reiniger, der Analytik von Tensiden in Reinigern und der Adsorption der Tenside auf Feststoffoberflächen. Im Mittelpunkt der Arbeit steht neben der Charakterisierung und Analyse des Reinigers die quantitative Bestimmung der im Reiniger enthaltenen Tenside in industriellen Reinigungsbädern. Mit Hilfe der Hochleistungsflüssigkeitschromatografie mit einem Verdampfungs - Lichtstreudetektor wird die quantitative Verteilung der Tenside in Reinigungsbädern unter verschiedenen der industriellen Fertigung entsprechenden Bedingungen untersucht. Die Adsorption der im Reiniger enthaltenen Tenside auf der Metalloberfläche unter Fertigungsbedingungen wird mit Fluoreszenzspektroskopie und IR-Spektroskopie quantitativ bestimmt. Im letzten Kapitel wird auf die Umsetzung der gefundenen Ergebnisse in die industrielle Praxis eingegangen.
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Wetting Optimized Solutions for Plasma Etch Residue Removal for Application in Interconnect Systems of Integrated Circuits: Benetzungsoptimierte Reinigungslösungen für die Entfernung von Plasmaätzresiduen für die Anwendung im Verdrahtungssystem integrierter SchaltungenAhner, Nicole 04 April 2012 (has links)
In multi-level Co/low-k based interconnect systems of ultralarge-scale integrated electronic devices the removal of plasma etch residues by common plasma cleaning processes has been shown to alter material properties like k-value and leakage current of the low-k dielectric. Besides the development of less damaging plasma processes their substitution by wet cleaning steps is in the focus of research and development. With further decreasing feature dimensions the development of wet cleaning processes has to include wetting issues like the non-wetting of small features due to the surface energy of the liquid or pattern collapse effects of low-k dielectric trenches due to high capillary forces This work at first focuses on the determination of the surface energetic character of common cleaning solutions for PERR and differently etched or ashed low-k dielectric surfaces by contact angle analysis, to outline which combinations of solid and liquid will be critical regarding their wetting behavior. Besides the determination of the wetting behavior the contact angle analysis turned out to be a fast and sensible analytic tool to understand the surface modifications introduced by different plasma processes and can help to understand the mechanisms of plasma damage of low-k dielectric surfaces. The analysis showed that especially polymerizing plasma etch processes produce a low-energetic low-k dielectric surface with a negligible polar energy contributions, which inhibits their wetting by high energetic water based cleaning solutions, which actually are favored by semiconductor manufacturers. The strategy to overcome these wetting issues followed in the present work is the reduction of the surface energy of the cleaning liquids by the application of surfactants. Several types of surfactants have been applied to the cleaning liquids and the compatibility of the surfactant solutions to BEOL materials like low-k dielectrics, copper and diffusion barriers as well as their dynamic behavior has been studied. The analysis showed that choosing the appropriate rinsing solution after the cleaning process is essential to ensure its compatibility to porous low-k dielectrics. Optical, electrical and structural data indicated that DIW rinse in most of the cases was not able to remove residual surfactant species within the material, while for an IPA rinse most of the residual surfactants have been removed. Considering the data received for compatibility to low-k materials, copper and barriers, the dynamic behavior of the surfactant solutions as well as influences of increased bath temperature and long term stability a general advice about surfactant selection and processing of surfactant aided solutions within BEOL is given. / In mehrlagigen Kupfer/low-k basierten Metallisierungssystemen hochintegrierter elektronischer Bauelemente kann die Entfernung von Residuen nach der Plasmastrukturierung des Dielektrikums mittels herkömmlicher Plasmareinigungsprozesse zur Schädigung der Isolatorschicht und damit zum Ansteigen der relativen Dielektrizitätszahl sowie der Leckströme führen. Neben der Entwicklung schädigungsarmer Plasmaprozesse stellt der Ersatz dieser Prozesse durch Nassreinigungsschritte zur Ätzresiduenentfernung eine vielversprechende Alternative dar. Mit stetig abnehmenden Strukturabmaßen ist bei der Entwicklung dieser Nassreinigungsprozesse neben der Materialkompatibilität auch das Benetzungsverhalten der Reinigungsflüssigkeit von entscheidender Bedeutung, da die Oberflächenenergie der Reinigungslösung das Eindringen dieser in kleinste Strukturen verhindern und es durch hohe Kapillarkräfte zum Kollaps von Grabenstrukturen im Dielektrikum kommen kann. In der vorliegenden Arbeit wurde zunächst mittels Kontaktwinkelanalyse die Oberflächenenergie verschieden prozessierter low-k Dielektrikaschichten sowie herkömmlicher Lösungen zur Entfernung von Ätzresiduen untersucht, um hinsichtlich ihres Benetzungsverhaltens besonders kritische Materialkombinationen aufzuzeigen. Neben der Bestimmung des Benetzungsverhaltens hat sich die Kontaktwinkelanalyse zur Oberflächenenergieberechnung als schnelle und empfindliche Methode zur Analyse der Auswirkung von Plasmaprozessen auf die Oberfläche von low-k Dielektrika erwiesen. Die Untersuchungen haben gezeigt, dass besonders polymerisierende Plasmaprozesse eine niederenergetische Oberfläche erzeugen, welche von den derzeit in der Halbleiterfertigung bevorzugten hochenergetischen wasserbasierten Reinigungslösungen nur schlecht benetzt wird. Um diesem Effekt entgegenzuwirken wurde in der vorliegenden Arbeit die Senkung der Oberflächenenergie der Reinigungslösungen durch Zugabe von Tensiden untersucht. Es wurden mehrere Tenside unterschiedlichen Typs den Reinigungsflüssigkeiten zugemischt und die Kompatibilität dieser Lösungen mit low-k Dielektrika, Kupferschichten und Diffusionsbarrieren untersucht sowie ihr dynamisches Verhalten analysiert. Dabei hat sich gezeigt, dass die Auswahl der geeigneten Spüllösung nach dem eigentlichen Reinigungsprozess von entscheidender Bedeutung ist. Optische, elektrische sowie strukturelle Daten deuten darauf hin, dass bei Verwendung einer Spülung mit deionisiertem Wasser in den meisten Fällen Tensidrückstände im porösen Dielektrikum verbleiben. Eine Spülung mit Isopropanol war hingegen in der Lage, einen Großteil dieser Tensidrückstände zu entfernen. Unter Einbeziehung der Daten zur Materialkompatibilität und dem dynamischen Verhalten der Tensidlösungen bei Raumtemperatur und erhöhter Badtemperatur sowie ihrer Langzeitstabilität konnte schließlich eine Prozessempfehlung für die Verwendung der benetzungsoptimierten Reinigungslösungen in der BEOL-Prozessierung gefunden werden.
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Asociace polymerů s amfifilními sloučeninami (surfaktanty) ve vodných roztocích / Self-assembly of polymers with amphiphilic compounds (surfactants) in aqueous solutionsDelisavva, Foteini January 2017 (has links)
Title: Self-assembly of polymers with amphiphilic compounds (surfactants) in aqueous solutions Abstract: This PhD Thesis is devoted to the co-assembly in systems containing electrically charged polymers (polyelectrolytes and block copolymers containing polyelectrolyte sequences). I studied the interactions between block copolymers and oppositely charged surfactants in aqueous solutions, and the structure and properties of co-assembled nanoparticles by a combination of several experimental methods. I found that the spontaneous formation, solubility and stability of complex nanoparticles depend not only on the electrostatic attractive forces but also on the hydrophobic effects. In a major part of my Thesis, I studied the interaction of polyelectrolytes with oppositely charged gemini surfactants (containing two charged head-groups interconnected by a short linker and two hydrophobic tails) which is a relatively new topic - much less studied than the co-assembly with conventional single tail surfactants. Better understanding of the formation and properties of complexes containing gemini surfactants and polymers provides knowledge that should lead to novel tailor-made nanoparticles with desired properties for applications in medicine and new technologies (including nano-technologies). We have shown that the...
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Untersuchungen zu Eigenschaften und Funktionen ausgewählter (Bio-)Tenside beim mikrobiellen Schadstoffabbau mittels kalorimetrischer und oberflächenanalytischer MethodenFrank, Nicole 22 February 2013 (has links)
Im Rahmen der vorliegenden Arbeit wurden die Wechselwirkungen im System Bakterium –Tensid – Schadstoff mittels kalorimetrischer Untersuchungen (ITC, DSC) sowie mit XPS-Analysen und durch Zeta-Potential-Messungen an Bakterienoberflächen charakterisiert. Für die Untersuchungen wurden zwei Gram-positive Rhodococcus-Stämme und ein Gram-negativer Pseudomonas putida-Stamm verwendet. Als Biotenside wurden das Rhamnolipid JBR 425 und der von Rhodococcus erythropolis B7g produzierte Trehalosetetraester (THL-4) ausgewählt. Das synthetische Tensid SDS diente als Referenzsubstanz. Aus den kalorimetrischen Experimenten konnte eine starke Wechselwirkung zwischen den Tensiden und den aktiven Bakterienkulturen abgeleitet werden. THL-4 führte beim Wachstum der Rhodococcen auf n-Hexadecan zur Verkürzung der lag-Phase. SDS wies hingegen eine toxische Wirkung für die Bakterienstämme auf. Thermodynamische Betrachtungen ergaben, dass Wechselwirkungen des SDS mit den Bakterienzellen gegenüber der Mizellbildung bevorzugt werden.
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