M.Sc. (Nanoscience) / Supported bimetallic Fe/Ni nanoparticles have been used for years as catalysts for the dechlorination of organochlorine compounds in ground water remediation. However, their fate and potential harm to the environment is of concern, hence, ways of reducing these negative aspects are being explored. As a way to solve this problem, catalytic nanoparticles are immobilised on a variety of substrates ranging from membranes, clays, silica, etc. In the current effort, the immobilisation of Fe/Ni bimetallic nanoparticles on electospun cellulose-based nanofibers was examined with the ultimate view to apply the materials for dechlorination studies. Fe/Ni bimetallic nanoparticles were anchored on ligand-functionalised cellulose nanofibers by the successive reduction of Fe(II) and Ni(II) ions from their respective solutions using NaBH₄...

No description available.

No description available.

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2015. / In this study, comparative sorption studies of the major metal ions (Mg2+, Ca2+, K+ and Na+) in the brine wastewater were performed on hydrophilic materials (PAN nanofibre, PAN+TiO2 nanofibre, PAN+ZEOLITE nanofibre) and Purolite S950 resin to investigate their uptake performances. For this purpose, PAN nanofibre was electrospun and subsequently doped with 3 wt% each of titanium dioxide and zeolite respectively, in controlled experimental conditions in order to improve its performance. This was followed by the characterization of the respective hydrophilic materials (PAN, PAN+TiO2 and PAN+ZEOLITE nanofibres) using Fourier Transform Infrared Spectroscopy (FT-IR); Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). SEM showed that the incorporation of titanium dioxide or zeolite into the PAN structure made the surface rougher than that of the ordinary PAN nanofibre and FT-IR revealed the peaks belonging to titanium dioxide and zeolite respectively, showing the inorganic materials are within the PAN structure. The XRD analysis complemented the FT-IR of the nanofibres by revealing the peaks characteristic of titanium dioxide and zeolite are present on the PAN structure.

Co-produced water from the oil and gas industry represents a significant waste stream in the United States. Produced water is characterized by high levels of total dissolved solids (TDS), dissolved organics and oil and grease. Among the wide variety of organics present in the water, the concentration of hazardous substances such as benzene, toluene, ethylbenzene, and xylenes (BTEX) can reach 600 mg/L and the concentration of non-hazardous carboxylate can be as high as 10,000 mg/L (API, 2002). Regulations governing the disposal of produced water are tightening and the interest in reusing treated produced water is increasing in the United States particularly in regions with scarce water supplies. In order to reuse produced water, removal of both the inorganic dissolved solids and hazardous organics such as BTEX may be necessary. The main goal of this research was to investigate the feasibility of using a combined physicochemical/biological treatment system to remove the organic constituents present in saline produced water. In order to meet this objective, two separate biological treatment techniques were investigated: a vapor phase biofilter (VPB) to treat the regeneration off-gas from an upstream surfactant-modified zeolite (SMZ) adsorption system and a membrane bioreactor (MBR) to treat the carboxylate and BTEX constituents that penetrate an upstream SMZ system. Each of the biological pretreatment systems was investigated first in the laboratory treating synthetic produced water and then in the field coupled to an SMZ adsorption system treating produced water. Both of the biological treatment systems were capable of removing the BTEX constituents both in the laboratory and in the field over a range of operating conditions. For the VPB, separation of the BTEX constituents from the saline aqueous phase yielded high removal efficiencies. However, carboxylates remained in the aqueous phase and were not removed in the combined VPB/SMZ system. In contrast, the MBR was capable of directly treating the saline produced water and simultaneously removing the BTEX and carboxylate constituents. The major challenge of the MBR system was controlling membrane fouling, particularly when the system was treating produced water under field conditions.

Submitted in fulfilment of the academic requirements for the Degree of M.Tech: Chemical Engineering, M. L. Sultan Technikon, 2001. / Historically inorganic coagulants were the coagulants of choice for OAF treatment of potable water. Water treatment practitioners using OAF technology preferred ferric chloride, an inorganic coagulant. Ferric chloride formed light, floatable floes at relatively low flocculation intensities and detention times. The inorganic coagulant was also more forgiving during incidents of overdosing and raw water and pH variability / M

Monodisperse titanium dioxide (TiO2) nanoparticles were synthesized by a novel freeze-drying process herein called lyophilization. The process of lyophilization is described in detail. The materials were characterized by scanning electron microscopy SEM) including energy dispersive x-ray spectroscopy (EDXS), high resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD), Raman spectroscopy and UV-Vis-IR spectrophotometry. The TiO2 nanoparticles have narrow size distribution, mono-disperse, strained with most of the characteristics showing presence of the four phases of TiO2 thus: anatase, brookite, rutile with each lyophilization process producing its own phase mostly controlled by pH and precursor concentration and anneal/calcining temperatures. With specific reference to HRTEM, Raman spectroscopy results and XRD, it was found that the Scherrer equation, the Williamson-Hall method and others of similar nature were not enough to explain the strain and the grain sizes of these particles. Therefore the Williamson-Hall method was revised to properly explain the new results. The obtained TiO2 nanoparticles were used in three applications: (1) gas sensing (2) degradation of organic water-borne pollutants using methylene blue as an indicator (3) anti-bacterial activity. / Physics / D. Phil. Physics)

The fate of iron complexed by various organic compounds was investigated as a function of both chemical oxidative and coagulation removal methods. Dissolved organic carbon (DOC) utilized in the studies was obtained from a variety of sources and included humic and fulvic acids, tannic acid and oxalic acid. Oxidants evaluated were potassium permanganate, free chlorine, and chlorine dioxide. Both laboratory-scale and field monitoring studies were performed. The relative molecular weight distribution (MWD) of the DOC present was analyzed to evaluate how changes in this parameter affected the efficiency of soluble iron removal by oxidation. In addition, the MWD of selected coagulated samples was evaluated to determine how this parameter affected the fate of complexed iron during the coagulation of dissolved organic matter with alum. A high degree of ferrous iron complexation occurred with the DOC dominated by higher molecular weight organics. This complexation rendered the iron stable against the addition of each of the oxidants evaluated. However, soluble Fe(II) complexed by low molecular weight organics was successfully removed by chemical oxidation. Potassium permanganate was found to be the most effective oxidant of the three oxidants utilized in the study. The results indicated that soluble Fe(II) complexed by high molecular weight DOC can be efficiently removed by alum coagulation. The pH and alum dose utilized to produce effective DOC removal was also found to promote efficient complexed Fe(II) removal. / Master of Science

Orientador: Ruben Bresaola Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-11T16:16:07Z (GMT). No. of bitstreams: 1 Yano_DirceMariaEmi_M.pdf: 968062 bytes, checksum: 4a5419ce308b9a1d5ae72c0c3669355d (MD5) Previous issue date: 2007 / Resumo: A presente pesquisa teve por objetivo avaliar a formação de subprodutos da desinfecção (SPDS), gerados a partir da oxidação de soluções contendo substâncias húmicas e estas com adição de íons brometo, pelo dióxido de cloro, de forma isolada, ou associada com o cloro livre, sob diferentes concentrações e tempos de contato. A detecção dos trialometanos (THM), aldeídos e ácidos orgânicos formados foi realizada utilizando a técnica de cromatografia gasosa. Os resultados das análises cromatográficas proporcionaram a escolha da amostra que apresentou maior concentração de cada SPD para a realização de ensaios de adsorção, em diferentes concentrações de carvão ativado em pó (CAP), seguido de simulação, em condições de laboratório, de processos de tratamento físico-químico do tipo convencional de água para abastecimento. Os resultados obtidos indicaram que o uso do dióxido de cloro na oxidação de soluções contendo ácidos húmicos, com e sem a presença de brometos, gerou concentrações de THM abaixo do preconizado pela portaria 518 do MS; enquanto que a aplicação do cloro livre, após o uso do dióxido de cloro como oxidante primário, combinado com a presença de íons brometo, produziu maiores concentrações dos mesmos. Variando-se as dosagens de dióxido de cloro, houve formação de aldeídos em concentrações baixas, e a variação da dosagem de ácidos húmicos e íons brometo não acarretaram na formação significativa dos mesmos. Para as dosagens de ácidos húmicos, brometos e oxidantes estudadas não houve formação significativa de ácidos orgânicos. A utilização do CAP seguido de tratamento convencional promoveu a adequação da água nos valores máximos permitidos pelas normas vigentes para os parâmetros cor aparente e turbidez, não causando prejuízo à qualidade da água original. A variação da dosagem de CAP influenciou no tratamento da água, com remoção de THM mais efetiva para as dosagens mais altas. Já para aldeídos, dosagens mais baixas mostraram ser mais eficientes / Abstract: The objective of the present research was to analyze the formation of disinfection by products (DPB), generated by the oxidation of solutions containing humic substances with the addition of bromide ions through the use of chlorine dioxide, isolated or associated with free chlorine in different concentrations and reaction times. The technique of gaseous chromatography was applied in order to detect the formed trihalomethanes (THM), aldehydes and organic acids. The results of the chromatographic analyses allowed to choose the sample that presented the higher concentration of each DBP to carry out the assays of adsorption in different concentrations of powdered activated carbon (PAC), followed by simulation, under laboratory conditions, of conventional process of water treatment. The obtained results indicated that the use of chlorine dioxide in the oxidation of solutions containing humic acids with and without the presence of bromides resulted in THM concentrations under the ones established by the resolution n. 518 of Brazilian Health Ministry, while the use of free chlorine, after the use of chlorine dioxide as a primary oxidant, combined with the presence of bromide ions, produced higher concentrations of these. The variation of chlorine dioxide dosages resulted in the formation of aldehydes in lower concentrations, and the variation of humic acids and bromide ions dosages did not result in a significant formation of these. For the dosages of humic acids, bromides and oxidants there was no significant formation of organic acids. The use of PAC, followed by the conventional process of water treatment promoted the adequacy of the water in the maximum values allowed by the national regulations for the color and e turbity parameters, maintaining the quality of the original water, not causing loss of quality to the original water. The variation of PAC dosage influenced the treatment of the water, with more effective removal of THM for the higher dosages. On the contrary, for aldehyds, lower dosages showed to be more efficient / Mestrado / Saneamento e Ambiente / Mestre em Engenharia Civil

Manganese is a problem at the Ni River Water Treatment Plant in Spotsylvania County, Virginia. The Ni River Reservoir (the water source) is a eutrophic reservoir. In the summer, the dissolved oxygen decreases to near or zero at depths greater than two meters. As a result, soluble manganese increases to levels of nearly 6.0 mg/L at the bottom. It is released from the sediments under anaerobic conditions. Total organic carbon levels ranging from 4.0 to 7.25 mg/L were noted with increasing depth. Plant profiles were developed to indicate the performance of the sedimentation and filtration units in reducing manganese concentration. Essentially, all the particulate manganese was removed by sedimentation, and some removal of soluble manganese was evident. The filters removed additional soluble manganese. Soluble manganese removal probably was due to the adsorption of manganese on solid manganese dioxide in the sludge blanket and on the filter media with subsequent further oxidation. Ozone was effective at a dose of approximately 5 mg/L. Chlorine and chlorine dioxide were marginally effective as pretreatments at dosages of 5 and 2 rng/L, respectively. Potassium permanganate proved effective at dosages of 0.5 to 0.625 mg/L (1.5 to 1.9 times the theoretical requirement). Aeration proved effective in reducing levels of approximately 0.1 mg/L to below the secondary maximum contaminant level (0.05 mg/L) and, in addition, somewhat effective in reducing a concentration of nearly 2 mg/L by 31 percent. Aeration appears to be a viable means of reducing the anaerobic conditions in the reservoir that lead to the high soluble manganese concentrations. / M.S.