No description available.

A maior parte dos insetos possui uma estrutura anatômica em forma de filme (membrana peritrófica, MP) composta de quitina e proteínas (peritrofinas), que separa o alimento do epitélio do intestino médio. A MP protege o epitélio de microorganismos e da abrasão, e possui outras funções baseadas no fato de que a MP promove a compartimentalização de enzimas, que incluem: aumento da eficiência digestiva através da diminuição da taxa de excreção das enzimas e de outros mecanismos postulados que são testados nesta tese. A síntese das peritrofinas é mais conhecida do que a da quitina componente da MP, tornando desejável um esforço no detalhamento dessa última. Foram realizadas a caracterização e expressão de genes de S. frugiperda que codificam uma peritrofina e enzimas responsáveis pela síntese e degradação de quitina (quitina sintases 1 (SfCHS1) e 2 (SfCHS2), e quitinase (SfCHI), respectivamente). As sequências dos cDNAs correspondentes foram determinadas através da amplificação de fragmentos de PCR que se sobrepõem. Os padrões de expressão dos genes envolvidos no metabolismo da quitina da MP foram analisados durante o desenvolvimento do inseto por RT-PCR. SfCHS2 é expresso no intestino médio durante os estágios de alimentação da larva, enquanto que SfCHI é expresso durante as fases de pós-alimentação, pré-pupa, e pupa. Ambos os genes são predominantemente expressos na região anterior no intestino médio com um gradiente decrescente de expressão ao longo do tubo digestivo. A citolocalização da quitina revelou que o polissacarídeo está presente somente quando SfCHS2 é expresso e não há quitina no intestino médio quando SfCHI é expresso. Esses resultados levaram a formulação da hipótese de que SfCHS2 é responsável pela síntese da quitina da MP durante o estágio larval e SfCHI degrada a quitina da MP durante a muda larva-pupa, sugerindo padrões inversos de expressão desses genes. Em Spodoptera frugiperda, Tenebrio molitor e Musca domestica é possível prever o sítio de secreção das enzimas digestivas (ventrículo anterior, médio ou posterior) a partir da distribuição antero-posterior das enzimas no espaço endoperitrófico. Também foi possível mostrar, usando vários modelos experimentais, que a separação de compartimentos luminais pela MP: a) impede a inibição de despolimerazes por remover oligômeros do espaço endoperitrófico; b) evita a inibição de oligômero hidrolases restringindo-as ao espaço ectoperitrófico e impedindo que entrem em contato com o alimento e c) anula a inibição de enzimas envolvidas na digestão terminal presentes na superfície do epitélio, impedindo que o alimento entre em contato com elas. / Most insects have a film-like anatomical structure (peritrophic membrane, PM) composed of chitin and proteins (peritrophins), which separates food from midgut tissue. It protects the epithelium against food abrasion and microrganisms and has other functions based on compartmentalization of enzymes, which include: increasing digestive efficiency by decreasing enzyme excretion and by other mechanisms that were tested in this thesis. The peritrophin synthesis is less known than PM chitin synthesis, which needs to be better understood. The characterization and expression of S. frugiperda genes encoding a peritrophin and enzymes responsible for the synthesis and degradation of chitin, chitin synthases 1(SfCHS1) and 2 (SfCHS2), and chitinase (SfCHI), respectively, were analysed. Sequences of corresponding cDNAs were determined by amplification of overlapping PCR fragments and the expression patterns of chitin metabolism genes were analyzed during insect development by RT-PCR. SfCHS2 is expressed in the midgut during the feeding stages, whereas SfCHI is expressed during the wandering and pupal stages. Both genes are predominantly expressed in the anterior portion of the midgut with a decreasing gradient of transcript levels in the medial and posterior portions. Chitin staining revealed that the polysaccharide is present in the PM only when SfCHS2 is expressed. There is little or no chitin in the midgut when SfCHI is expressed. These results support the hypothesis that SfCHS2 is responsible for PM chitin synthesis during the larval stage and SfCHI for PM chitin degradation during larval-pupal molting, suggesting inverse patterns of expression of these genes. The secretion site (anterior, middle or posterior midgut) of digestive enzymes can be predicted in Spodoptera frugiperda, Tenebrio molitor and Musca domestica based on enzyme activity distribution along the endoperitrophic space. We also have shown, using several experimental models, that the luminal compartment separation by PM: a) avoid the polimer hidrolases inhibition by removing oligomer from endoperitrophic space; b) decrease the oligomer hidrolases inhibition by restricting them to the ectoperitrophic space (by avoiding their contact with food); and c) block the inhibition of enzymes located at the cell surface involved in terminal digestion by avoiding their contact with food.

A maior parte dos insetos possui uma estrutura anatômica em forma de filme (membrana peritrófica, MP) composta de quitina e proteínas (peritrofinas), que separa o alimento do epitélio do intestino médio. A MP protege o epitélio de microorganismos e da abrasão, e possui outras funções baseadas no fato de que a MP promove a compartimentalização de enzimas, que incluem: aumento da eficiência digestiva através da diminuição da taxa de excreção das enzimas e de outros mecanismos postulados que são testados nesta tese. A síntese das peritrofinas é mais conhecida do que a da quitina componente da MP, tornando desejável um esforço no detalhamento dessa última. Foram realizadas a caracterização e expressão de genes de S. frugiperda que codificam uma peritrofina e enzimas responsáveis pela síntese e degradação de quitina (quitina sintases 1 (SfCHS1) e 2 (SfCHS2), e quitinase (SfCHI), respectivamente). As sequências dos cDNAs correspondentes foram determinadas através da amplificação de fragmentos de PCR que se sobrepõem. Os padrões de expressão dos genes envolvidos no metabolismo da quitina da MP foram analisados durante o desenvolvimento do inseto por RT-PCR. SfCHS2 é expresso no intestino médio durante os estágios de alimentação da larva, enquanto que SfCHI é expresso durante as fases de pós-alimentação, pré-pupa, e pupa. Ambos os genes são predominantemente expressos na região anterior no intestino médio com um gradiente decrescente de expressão ao longo do tubo digestivo. A citolocalização da quitina revelou que o polissacarídeo está presente somente quando SfCHS2 é expresso e não há quitina no intestino médio quando SfCHI é expresso. Esses resultados levaram a formulação da hipótese de que SfCHS2 é responsável pela síntese da quitina da MP durante o estágio larval e SfCHI degrada a quitina da MP durante a muda larva-pupa, sugerindo padrões inversos de expressão desses genes. Em Spodoptera frugiperda, Tenebrio molitor e Musca domestica é possível prever o sítio de secreção das enzimas digestivas (ventrículo anterior, médio ou posterior) a partir da distribuição antero-posterior das enzimas no espaço endoperitrófico. Também foi possível mostrar, usando vários modelos experimentais, que a separação de compartimentos luminais pela MP: a) impede a inibição de despolimerazes por remover oligômeros do espaço endoperitrófico; b) evita a inibição de oligômero hidrolases restringindo-as ao espaço ectoperitrófico e impedindo que entrem em contato com o alimento e c) anula a inibição de enzimas envolvidas na digestão terminal presentes na superfície do epitélio, impedindo que o alimento entre em contato com elas. / Most insects have a film-like anatomical structure (peritrophic membrane, PM) composed of chitin and proteins (peritrophins), which separates food from midgut tissue. It protects the epithelium against food abrasion and microrganisms and has other functions based on compartmentalization of enzymes, which include: increasing digestive efficiency by decreasing enzyme excretion and by other mechanisms that were tested in this thesis. The peritrophin synthesis is less known than PM chitin synthesis, which needs to be better understood. The characterization and expression of S. frugiperda genes encoding a peritrophin and enzymes responsible for the synthesis and degradation of chitin, chitin synthases 1(SfCHS1) and 2 (SfCHS2), and chitinase (SfCHI), respectively, were analysed. Sequences of corresponding cDNAs were determined by amplification of overlapping PCR fragments and the expression patterns of chitin metabolism genes were analyzed during insect development by RT-PCR. SfCHS2 is expressed in the midgut during the feeding stages, whereas SfCHI is expressed during the wandering and pupal stages. Both genes are predominantly expressed in the anterior portion of the midgut with a decreasing gradient of transcript levels in the medial and posterior portions. Chitin staining revealed that the polysaccharide is present in the PM only when SfCHS2 is expressed. There is little or no chitin in the midgut when SfCHI is expressed. These results support the hypothesis that SfCHS2 is responsible for PM chitin synthesis during the larval stage and SfCHI for PM chitin degradation during larval-pupal molting, suggesting inverse patterns of expression of these genes. The secretion site (anterior, middle or posterior midgut) of digestive enzymes can be predicted in Spodoptera frugiperda, Tenebrio molitor and Musca domestica based on enzyme activity distribution along the endoperitrophic space. We also have shown, using several experimental models, that the luminal compartment separation by PM: a) avoid the polimer hidrolases inhibition by removing oligomer from endoperitrophic space; b) decrease the oligomer hidrolases inhibition by restricting them to the ectoperitrophic space (by avoiding their contact with food); and c) block the inhibition of enzymes located at the cell surface involved in terminal digestion by avoiding their contact with food.

Composites, in which the matrix and the reinforcing fillers are respectively, poly(acrylic acid) (PAA) with two different molecular weights, and chitin whiskers (CHW) were successfully prepared using an evaporation method. The weight fraction of CHW was varied from 0.03 to 0.73. Mechanical and thermal properties and crystallinity of the composites were characterised using tensile testing, differential scanning calorimetry, thermogravimetric analysis and X-ray diffraction. The tensile strength of the composite increased up to 11 wt % CHW after which it decreased. XRD characterisation showed a decrease in crystalline index, crystalline size, chitin crystalline peak and intensity as the content of PAA and its molecular weight increased. Raman spectroscopy was used for the first time to monitor the deformation of chitin film and CHW reinforced PAA composites. The Raman band located at 1622 cm^(-1) was monitored for deformation. On application of tensile deformation the Raman band initially located at 1622 cm^(-1) shifted toward a lower wavenumber. Raman band shift rates of -1.85 cm^(-1)/% for chitin film and -0.59 and -0.25 cm^(-1)/% for 73 and 23 wt % CHW content, respectively, were measured. The modulus of a single chitin whisker and composites were found to be 115, 37 and 16 GPa respectively, for a two dimensional (2D) in-plane distribution of CHW. CHW within a PAA matrix did not show any preferential alignment in a polarised Raman. The Raman intensity ratio〖 I〗_1698 /I_1622 showed that the strongest interaction of the carboxylic group in the composites occured at 3 wt % CHW content. The interaction gradually reduced as the CHW content increased. 〖 CaCO〗_3 crystals were grown in CHW, PAA and CHW/PAA composites by a solution and evaporation casting method. In the absence of PAA and CHW, rhombohedral calcites were observed while rod-like aragonite polymorphs were seen when only PAA was used as a template. In the presence of only CHW, a morphological mixture of ellipsoidal and disc shape with traces of rhombohedral aggregate calcite were the features. In the presence of both PAA and CHW, the rhombohedral shape showed roughness with irregular faces while the vaterite polymorph continued to agglomerate with the observation of porosity at higher CHW content. The vaterite particles gradually decreased as the CHW content was decreased. At lower CHW content aragonite polymorph growth was favoured to the detriment of calcite. The results showed that the vaterite polymorph can be grown even at higher filler loading. The effect of 〖 CaCO〗_3 growth on the mechanical properties of CHW reinforced PAA indicated that better mechanical properties can be achieved at a CHW content of 3 wt % when compared with neat PAA and when 〖 CaCO〗_3 was not incorporated into the CHW/25PAA composites.

No description available.

Thesis: M.S., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 1978 / Includes bibliographical references. / M.S. / M.S. Massachusetts Institute of Technology, Department of Materials Science and Engineering

The present thesis presents new renewable, antimicrobial and biodegradable superabsorbent polymers (SAPs), produced from the cell wall of zygomycetes fungi. The cell wall was characterized and chitosan, being one of the most important ingredients, was extracted, purified, and converted to SAP for use in disposable personal care products designed for absorption of different body fluids. The cell wall of zygomycetes fungi was characterized by subsequent hydrolysis with sulfuric and nitrous acids and analyses of the products. The main ingredients of the cell wall were found to be polyphosphates (4-20%) and copolymers of glucosamine and N-acetyl glucosamine, i.e. chitin and chitosan (45-85%). The proportion of each of these components was significantly affected by the fungal strain and also the cultivation conditions. Moreover, dual functions of dilute sulfuric acid in relation to chitosan, i.e. dissolution at high temperatures and precipitation at lowered temperatures, were discovered and thus used as a basis for development of a new method for extraction and purification of the fungal chitosan. Treatment of the cell wall with dilute sulfuric acid at room temperature resulted in considerable dissolution of the cell wall polyphosphates, while chitosan and chitin remained intact in the cell wall residue. Further treatment of this cell wall residue, with fresh acid at 120°C, resulted in dissolution of chitosan and its separation from the remaining chitin/chitosan of the cell wall skeleton which was not soluble in hot acid. Finally, the purified fungal chitosan (0.34 g/g cell wall) was recovered by precipitation at lowered temperatures and pH 8-10. The purity and the yield of fungal chitosan in the new method were significantly higher than that were obtained in the traditional acetic acid extraction method. As a reference to pure chitosan, SAP from shellfish chitosan, was produced by conversion of this biopolymer into water soluble carboxymethyl chitosan (CMCS), gelation of CMCS with glutaraldehyde in aqueous solutions (1-2%), and drying the resultant gel. Effects of carboxymethylation, gelation and drying conditions on the water binding capacity (WBC) of the final products, were investigated. Finally, choosing the best condition, a biological superabsorbent was produced from zygomycetes chitosan. The CMCS-based SAPs were able to absorb up to 200 g water/g SAP. The WBC of the best SAP in urine and saline solutions was 40 and 32 g/g respectively, which is comparable to the WBC of commercially acceptable SAPs under identical conditions (34-57 and 30-37 g/g respectively). / <p>Disputationen sker fredagen den 1 oktober kl. 10.00 i KA-salen, Kemigården 4, Chalmers, Göteborg</p>

Submitted in fulfillment of the requirements of the degree of Doctor of Philosophy: Chemistry, Durban University of Technology, 2015. / Chitin, the second most abundant natural biopolymer, is composed of repeating units of N-acetyl-β-D-glucosamine and primarily forms the structural component of protective biological matrices such as fungal cell walls and exoskeletons of insects. Chitinases are a ubiquitous class of extracellular enzymes that have gained attention in the past few years due to their wide range of biotechnological applications, especially in the field of agriculture for bio-control of fungal phytopathogens. They play an important role in the defense of organisms against chitin-containing parasites by hydrolyzing the β-1,4-linkages in chitin and hence act as anti-fungal as well as anti-biofouling agents. Moreover, the effectiveness of conventional insecticides is increasingly compromised by the occurrence of resistance and thus, chitinases offer a potential alternative to the use of chemical fungicides. In recent years, thermostable enzymes isolated from thermophilic microorganisms have gained widespread attention in industrial, medical, environmental and biotechnological applications due to their inherent stability at high temperatures and a wide range of pH optima. Determination of the three- dimensional structure of a protein can provide important details about its biological functions and its mode of action. However, despite their significance, the precise three-dimensional structures of most of the chitinases, including those isolated from Thermomyces lanuginosus is not fully characterized so far. Hence, the main focus of the present study was to gain a better understanding of the structural features of chitinases obtained from this thermostable fungus using both experimental and computational techniques, and their relationship with their activity profiles. The genes encoding thermostable chitinase II from T. lanuginosus were isolated and cloned in both E. coli as well as the Pichia pastoris expression system. Analysis of the nucleotide sequences revealed that the chitinase II gene (1196 bp) encodes a 343 amino acid protein of molecular weight 36.65 kDa whereas the chitinase I gene (1538 bp) encodes a 400 amino acid protein of molecular weight 44.14 kDa. In silico protein modeling was helpful in predicting the 3D models of the novel chitinase II enzyme, followed by the prediction of its active sites. The presence of Glu176 was found to be essential for the activity of chitinase II. Similarly, analysis of chitinase I revealed several active sites in its structural framework. A 10 ns Molecular dynamics (MD) simulations was implemented to assess the conformational preferences of chitinases. The MD trajectories at different temperatures clearly revealed that the stability of the enzymes were maintained at higher temperatures. Additionally, a constant pH molecular dynamics simulations at a pH range 2-6 was performed to establish the optimum activity and stability profiles of chitinase I and chitinase II. For this purpose, the Molecular Dynamics simulations were carried out at fixed protonation states in an explicit water environment to evaluate the effect of the physiological pH on chitinase I and II enzymes obtained from T. lanuginosus. The results suggest a strong conformational pH dependence of chitinases. These enzymes retained their characteristic TIM Barrel fold at the respective protonated conditions, thus validated the experimental outcomes. Further, the different stability and flexibility predictions were used to assess the relation of point mutations and enzyme stabilities. Our results pave the way to engineer new and better thermostable enzymes.

Modificações químicas são executadas com o objetivo de preparar derivados de quitosana com melhores propriedades, inclusive a solubilidade, ampliando as suas possibilidades de aplicação. Neste projeto, gládios de lulas foram utilizados para a extração de beta-quitina, a qual foi submetida ao processo de desacetilação assistida por irradiação de ultrassom de alta intensidade visando à produção de quitosana extensivamente desacetilada. A quitosana extensivamente desacetilada foi então submetida à reação de carboximetilação, visando à preparação de O-carboximetilquitosana. Foram estudados os efeitos da razão molar quitosana/ácido monocloroacético e do tempo sobre a reação de carboximetilação de quitosana e as características do produto obtido. As características estruturais e morfológicas das amostras geradas neste projeto, a saber, beta-quitina, quitosana e os produtos de carboximetilação de quitosana, foram determinadas pelo emprego de espectroscopias de ressonância magnética nuclear e no infravermelho, análise elementar, difração de raios X e microscopia eletrônica de varredura. Medidas de viscosidade foram empregadas para a determinação de massas molares médias viscosimétricas de quitina, quitosana e O-carboximetilquitosana. A solubilidade de O-carboximetilquitosana em meios aquosos em função do pH e do grau médio de carboximetilação foi investigada por espectroscopia UV/visível e a estabilidade térmica foi estudada por análise termogravimétrica.A partir dos espectros de ressonância magnética nuclear de hidrogênio das amostras de carboximetilquitosana foi constatado que a carboximetilação da quitosana ocorreu em extensões diferentes em função das condições reacionais. Também foi constatada a ocorrência de N-carboximetilação, evidenciada pelos sinais observados no intervalo de 3,0-3,4 ppm, atribuídos à mono e dissubstituição dos grupos amino. Porém, dada a baixa intensidade dos sinais, foi concluído que a carboximetilação dos grupos aminos ocorreu em baixa extensão. No intervalo 4,05-4,55 ppm foram observados os sinais correspondentes à ressonância dos hidrogênios dos grupos carboximetil (-CH2-COOD) introduzidos nas posições 3 e 6 das unidades de carboximetilquitosana. A espectroscopia no infravermelho também permitiu a distinção das características estruturais de beta-quitina, quitosana, carboximetilquitosana e a determinação dos graus médios de substituição das amostras carboximetiladas, que variaram no intervalo 0,21&lt;GS&lt;0,43. As análises de difração de raios X e as análises termogravimétricas mostraram que a carboximetilação de quitosana gerou derivados menos cristalinos, mais hidrofílicos e termicamente menos estáveis do que o polímero de partida. As amostras de carboximetilquitosana apresentaram solubilidade em meios ácido (pH&lt;3,0), neutro (pH&asymp;7,5) e alcalino (pH&gt;8,0) devido à ocorrência de cargas ao longo de suas cadeias nesses meios, mas foram insolúveis no intervalo 3,5&lt;pH&lt;7,5. Foi observada a ocorrência de despolimerização simultaneamente à carboximetilação, visto que as amostras de carboximetilquitosana apresentaram valores de massas molares viscosimétricas médias inferiores ao da quitosana de partida. Os resultados deste estudo mostram que o grau médio de substituição das amostras de carboximetilquitosana é fortemente afetado pelo excesso de ácido monocloroacético empregado na reação de derivatização de quitosana, porém o prolongamento da reação não gera derivados mais substituídos. / Chemical modifications are carried out to prepare chitosan derivatives with improved properties, including solubility, extending their application possibilities. In this project, beta-chitin extracted from squid pens was subjected to the ultrasound assisted deacetylation process (USAD Process) aiming the production of extensively deacetylated chitosan. The extensively deacetylated chitosan was submitted to the carboxymethylation reaction to result in O-carboxymethylchiotosan (O-CMC). The effects of the molar ratio of chitosan / monochloroacetic acid and of the reaction time on the carboxymethylation reaction and on the characteristics of the O-CMC samples were studied. The structural and morphological characteristics of the samples generated in this project, beta-chitin, chitosan and carboximethylchitosan, were determined by nuclear magnetic resonance and infrared spectroscopy, elemental analysis, X-rays diffraction and scanning electron microscopy. Viscosity measurements were employed to determine the viscosity average molecular weight of chitin, chitosan and O-CMC. The solubility of O-CMC samples in aqueous solution of different pHs was investigated by UV / visible spectroscopy while the thermal stability was studied by thermogravimetric analysis. The 1H-NMR spectra of the O-CMC samples revealed that the carboxymethylation of chitosan occurred in different extents depending on the reaction conditions. It was also revealed the occurrence of N-carboxymethylation, evidenced by the signals observed in the range of 3.0 ppm - 3.4 ppm, assigned to the mono and disubstitution of amino groups. However, as the signal intensity was low, it was concluded that the N-carboxymethylation occurred in low extension. In the interval 4.05 ppm - 4.55 ppm it were observed the signals corresponding to the resonance of the hydrogens of the carboxymethyl groups (-CH2-COOD) introduced in positions 3 and 6 of the repeating units of O-CMC. The infrared spectroscopy also allowed the distinction of the structural features of beta-chitin, chitosan, carboxymethylchitosan and the determination of the average degree of substitution of carboxymethylated samples, which varied in the range 0,21 &lt;GS &lt;0,43. The X-ray diffraction and thermogravimetric analysis showed that the carboximethylation of chitosan produced derivatives less crystalline, more hydrophilic and thermally less stable than the parent polymer. The O-CMC samples showed solubility in acid (pH &lt;3.0), neutral (pH &asymp; 7.5) and alkaline (pH&gt; 8.0) media due to the occurrence of charges along its chains, but the polymer was insoluble in the range 3.5 &lt;pH &lt;7.5. The occurrence of depolymerization simultaneously to the carboxymethylation reaction was observed since the O-CMC samples showed lower viscosity average molecular weight values as compared to the parent chitosan. The results of this study show that the average degree of substitution of the O-CMC samples is strongly affected by the excess of monochloroacetic acid used in the derivatization reaction of chitosan, but the extension of the reaction for longer times doesn\'t generate more substituted derivatives.

by Chan Shuk Mei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 138-149). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstracts --- p.ii / Contents --- p.vi / List of figures --- p.xi / List of plates --- p.xiv / List of tables --- p.xv / Abbreviations --- p.xvi / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Pentachlorophenol --- p.1 / Chapter 1.1.1 --- Characteristics of pentachlorophenol --- p.1 / Chapter 1.1.2 --- Application of pentachlorophenol --- p.4 / Chapter 1.1.3 --- The fate of pentachlorophenol in environment --- p.5 / Chapter 1.1.4 --- The toxicity of pentachlorophenol --- p.9 / Chapter 1.1.5 --- Remediation of pentachlorophenol --- p.13 / Chapter 1.1.5.1 --- Physical treatment / Chapter 1.1.5.2 --- Chemical treatment / Chapter 1.1.5.3 --- Biological treatment / Chapter 1.1.5.4 --- Alternative for combining two treatments / Chapter 1.2 --- Biosorbents --- p.18 / Chapter 1.2.1 --- Chitin and chitosan --- p.21 / Chapter 1.2.1.1 --- History of chitin and chitosan --- p.21 / Chapter 1.2.1.2 --- Structures of chitin and chitosan --- p.21 / Chapter 1.2.1.3 --- Sources of chitin and chitosan --- p.23 / Chapter 1.2.1.4 --- Application of chitin and chitosan --- p.26 / Chapter 1.2.1.5 --- Study on PCP removal by chitinous material --- p.28 / Chapter 1.2.2 --- Factors affecting biosorption --- p.29 / Chapter 1.2.2.1 --- Solution pH --- p.29 / Chapter 1.2.2.2 --- Concentration of biosorbent --- p.30 / Chapter 1.2.2.3 --- Retention time --- p.31 / Chapter 1.2.2.4 --- Temperature --- p.32 / Chapter 1.2.2.5 --- Agitation rate --- p.32 / Chapter 1.2.2.6 --- Initial sorbate concentration --- p.33 / Chapter 1.2.3 --- Modeling of biosorption --- p.33 / Chapter 1.2.3.1 --- Langmuir adsorption model --- p.34 / Chapter 1.2.3.2 --- Freundlich adsorption model --- p.34 / Chapter 1.3 --- Photocatalytic degradation --- p.35 / Chapter 1.3.1 --- Titanium dioxide --- p.36 / Chapter 1.3.2 --- Mechanism of photocatalytic oxidation using photocatalyst TiO2 --- p.36 / Chapter 1.3.3 --- Advantages of photocatalytic oxidation with Ti02 and H2O2 --- p.41 / Chapter 1.3.4 --- Degradation of PCP by photocatalytic oxidation --- p.41 / Chapter 2. --- Objectives --- p.45 / Chapter 3. --- Materials and methods --- p.46 / Chapter 3.1 --- Biosorbents --- p.46 / Chapter 3.1.1 --- Production of biosorbents --- p.46 / Chapter 3.1.2 --- Scanning electron microscope of biosorbents --- p.48 / Chapter 3.1.3 --- Pretreatment of biosorbents --- p.48 / Chapter 3.2 --- Pentachlorophenol preparation --- p.48 / Chapter 3.3 --- Batch biosorption experiment --- p.48 / Chapter 3.3.1 --- Quantification of pentachlorophenol by HPLC --- p.51 / Chapter 3.3.2 --- Data analysis for biosorption --- p.51 / Chapter 3.3.3 --- Selection of optimal conditions for batch PCP adsorption --- p.52 / Chapter 3.3.3.1 --- Effect of initial pH and biosorbent concentration --- p.52 / Chapter 3.3.3.2 --- Improvement on pH effect and biosorbent concentration --- p.52 / Chapter 3.3.3.3 --- Effect of temperature --- p.53 / Chapter 3.3.3.4 --- Effect of agitation rate --- p.53 / Chapter 3.3.4 --- Effect of initial PCP concentration and biosorbent concentration --- p.53 / Chapter 3.3.4.1 --- Adsorption isotherm --- p.54 / Chapter 3.4 --- Photocatalytic oxidation --- p.54 / Chapter 3.4.1 --- Reaction mixture solution --- p.54 / Chapter 3.4.2 --- Photocatalytic reactor --- p.55 / Chapter 3.4.3 --- Batch photocatalytic oxidation system --- p.55 / Chapter 3.4.4 --- Selection of extraction solvent --- p.59 / Chapter 3.4.5 --- Extraction efficiency --- p.59 / Chapter 3.4.6 --- Data analysis for PCO --- p.60 / Chapter 3.4.7 --- Irradiation time --- p.60 / Chapter 3.4.8 --- Determination of hydrogen peroxide concentration --- p.61 / Chapter 3.4.9 --- Effect of biosorbent concentration in PCO --- p.61 / Chapter 3.4.10 --- Effect of PCP amount on biosorbent in PCO --- p.61 / Chapter 3.4.11 --- Determination of chloride ion concentration and total organic carbon during PCO --- p.62 / Chapter 3.4.12 --- Identification the intermediates of PCP degradation by PCO --- p.62 / Chapter 3.4.13 --- Evaluation of the change of PCO treated biosorbents --- p.63 / Chapter 3.4.13.1 --- Chitin assay --- p.64 / Chapter 3.4.13.2 --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.64 / Chapter 3.4.13.3 --- Protein assay --- p.66 / Chapter 3.4.13.4 --- Biosorption efficiency --- p.66 / Chapter 3.4.14 --- Multiple biosorption and PCO cycles of PCP --- p.66 / Chapter 3.4.15 --- Evaluation for the toxicity change of PCP adsorbed biosorbents during PCO --- p.67 / Chapter 4. --- Results --- p.68 / Chapter 4.1 --- Batch biosorption experiment --- p.68 / Chapter 4.1.1 --- Selection of optimal conditions for batch PCP adsorption --- p.68 / Chapter 4.1.1.1 --- Effect of initial pH and biosorbent concentration --- p.68 / Chapter 4.1.1.2 --- Effect of Tris buffer and biosorbent concentrations --- p.73 / Chapter 4.1.1.3 --- Effect of temperature --- p.73 / Chapter 4.1.1.4 --- Effect of agitation rate --- p.73 / Chapter 4.1.2 --- Effect of initial PCP concentration and biosorbent concentration --- p.81 / Chapter 4.1.2.1 --- Adsorption isotherm --- p.82 / Chapter 4.2 --- Photocatalytic oxidation --- p.88 / Chapter 4.2.1 --- Selection of extraction solvent --- p.88 / Chapter 4.2.2 --- Determination of hydrogen peroxide concentration --- p.88 / Chapter 4.2.3 --- Effect of biosorbent concentration in PCO --- p.88 / Chapter 4.2.4 --- Effect of PCP amount on biosorbent in PCO --- p.94 / Chapter 4.2.5 --- Determination of chloride ion concentration and total organic carbon during PCO --- p.98 / Chapter 4.2.6 --- Identification the intermediates of PCP degradation by PCO --- p.102 / Chapter 4.2.7 --- Evaluation of the change of PCO treated biosorbents --- p.102 / Chapter 4.2.7.1 --- Chitin assay --- p.102 / Chapter 4.2.7.2 --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.102 / Chapter 4.2.7.3 --- Protein assay --- p.102 / Chapter 4.2.7.4 --- Biosorption efficiency --- p.109 / Chapter 4.2.8 --- Multiple biosorption and PCO cycles of PCP --- p.109 / Chapter 4.2.9 --- Evaluation for the toxicity change of PCP adsorbed biosorbents during PCO --- p.109 / Chapter 5. --- Discussion --- p.115 / Chapter 5.1 --- Batch biosorption experiment --- p.115 / Chapter 5.1.1 --- Selection of optimal conditions for batch PCP adsorption --- p.115 / Chapter 5.1.1.1 --- Effect of initial pH --- p.115 / Chapter 5.1.1.2 --- Effect of Tris buffer and biosorbent concentrations --- p.118 / Chapter 5.1.1.3 --- Retention time --- p.119 / Chapter 5.1.1.4 --- Effect of temperature --- p.120 / Chapter 5.1.1.5 --- Effect of agitation rate --- p.121 / Chapter 5.1.2 --- Effect of initial PCP concentration and biosorbent concentration --- p.121 / Chapter 5.1.2.1 --- Modeling of biosorption --- p.122 / Chapter 5.2 --- Photocatalytic oxidation --- p.123 / Chapter 5.2.1 --- Selection of extraction solvent --- p.124 / Chapter 5.2.2 --- Determination of hydrogen peroxide concentration --- p.124 / Chapter 5.2.3 --- Effect of biosorbent concentration in PCO --- p.125 / Chapter 5.2.4 --- Effect of PCP amount on biosorbent in PCO --- p.127 / Chapter 5.2.5 --- Determination of chloride ion concentration and total organic carbon during PCO --- p.127 / Chapter 5.2.6 --- Identification the intermediates of PCP degradation by PCO --- p.128 / Chapter 5.2.7 --- Evaluation of the change of PCO treated biosorbents --- p.128 / Chapter 5.2.7.1 --- Chitin assay --- p.129 / Chapter 5.2.7.2 --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.129 / Chapter 5.2.7.3 --- Protein assay --- p.131 / Chapter 5.2.7.4 --- Biosorption efficiency --- p.131 / Chapter 5.2.8 --- Multiple biosorption and PCO cycles of PCP --- p.132 / Chapter 5.2.9 --- Evaluation for the toxicity change of PCP adsorbed biosorbents during PCO --- p.132 / Chapter 6. --- Conclusion --- p.134 / Chapter 7. --- Recommendation --- p.137 / Chapter 8. --- References --- p.138