Many grades of paper have shifted from acid to alkaline production conditions. This change excludes the usage of traditional alum-rosin sizing chemistry. In some cases however, rosin sizing could prove beneficial if it could be used under neutral to alkaline paper making conditions. One effort toward this goal has been the use of epi-halohydrin modified polyamine/polyaminoamide in place of alum. The optimum sizing conditions, as well as the mechanism that modified polyamines/polyaminoamides use to size rosin, is investigated. Polyethyleneimine modified with epi-chlorohydrin was used in these studies. Rosin dosage was found to be the main variable that controlled the degree of sizing achieved. As the only hydrophobic material added, this was expected. In addition to rosin dosage, the polymer and pH had significant impacts on this sizing chemistry. Laboratory data shows that the synthesis procedure for and structure of polyethyleneimine-epi-cholohydrin (PEI-epi) impacts the degree of sizing achieved. Use of different modification techniques and degrees of modification illustrated several key factory regarding the polymer as a rosin sizing mordant. Prevention or removal of by-products from epi-chlorohydrin imporves the sizing efficiency of PEI-epi with rosin. A critical molecular weight of the PEI-epi was found to be important to sizing. Higher charge density on PEI-epi provides better the sizing efficiency. In addition to the polymer, other important factors where examined. The pH of the stock impacted the degree of sizing and permanency of the sizing achieved. Varying stock pH showed changes in sizing that are consistent with effects seen for rosin retention and of PAE as a wet strength agent. Low and high pH levels also caused reversion of the sizing effect. A pilot trial of the PEI-epi-rosin sizing chemistry was conducted at the Herty Foundation. The pilot trial shows that PEI-epi-rosin can reach the required level of sizing for linerboard. Trial results showed that calcium carbonate filled sheets could be sized by this chemistry. No significant impact on strength is seen from the sizing chemistry at the required dosage levels. As would be expected, addition of filler diminishes sheet strength. No sizing reversion was seen from any samples of this trial. Size reversion at low stock pH indicated that acid catalytic cleavage of an ester bond could have been occurring. Addition of acid or base to permanently sized sheets showed significant levels of reversion, similar to that seen for low stock pH sheets. This provides further supporting eviden ce for the formation and importance of an ester bond between rosin and PEI-epi. FTIR spectra were collected for model compounds to further examine the presence and importance of ester bonds. An ester bond was found to form at room temperature with aging or immediately with drying. Further, the ester bonds were found to decrease when the sample was subjected to acidic or basic environments. Solid state NMR was run to demonstrate the presence and importance of ester bonds to sizing in handsheets. Use of a [superscript 13]C labeled fatty acid showed that the ester bond peak dominated when sizing was present. After treatment with sodium hydroxide, the sizing disappeared and much of the ester bond signal shifted to a carboxylic acid or salt. Further solid state NMR of a non-reactive cationic polymer or a fully pre-reacted PEI-epi polymer shows retention of the fatty acid, but no ester bond and no sizing. The sizing mechanism of PEI-epi-rosin sizing appears to be connected to an ester bond formed during drying or with aging. While the amount of rosin retained controls the degree of sizing, retention alone is not enough to give sizing. The most effective pH for this sizing chemistry is near neutral, pH 6-8. FTIR and solid state NMR shows that an epichlorohydrin modified polyamine can form ester bonds with fatty acids in handsheets under conditions comparable to papermaking. The presence of residual acid or base in handsheets destroys the sizing effect achieved. Destruction of the sizing by addition of sodium hydroxide parallels the cleavage of many of the ester bonds present. PEI-epi appears to function as a mordant for rosin by creating an ester bond to anchor and help orient the hydrophobic portion of rosin.

No description available.

The Walnut Creek Wastewater Treatment Plant in Austin, Texas, has recently experienced increasing influent ammonia concentrations. Nitrification, the biological process used to treat ammonia, consumes alkalinity, which makes it difficult to properly treat ammonia while still maintaining the pH above the required discharge level of pH 6. Operators have looked to the addition of chemicals to supplement alkalinity; one creative alkalinity source was CaCO₃ solids, which are generated by the lime-softening process at Davis Water Treatment Plant. In 2011, the utility began transferring solids to Walnut Creek and immediately noticed improvements in both the nitrification efficiency and the effluent pH. However, undissolved solids accumulated at Walnut Creek and had a detrimental effect on the biosolids treatment efficiency at Hornsby Bend Biosolids Management Plant. Ultimately the costs of the poor biosolids treatment forced the utility to examine an alternative alkalinity source. The objective of this thesis is to help Walnut Creek optimize the use of various alkalinity sources to find a long-term solution that will improve the alkalinity and ammonia balance for adequate nitrification. Analysis of the plant’s influent characteristics suggested that industrial users, especially the semiconductor industry, are major contributors of ammonia and sulfate to the wastewater. A theoretical modeling based on chemical equilibrium predicted that using the CaCO₃ solids would provide a maximum alkalinity benefit of 47 mg/L as CaCO₃. Experimental dissolution jar tests were conducted to verify the model predictions and estimate the kinetics of dissolution. Results from these tests showed no significant dissolution of CaCO₃, and that the solids remained unchanged throughout the test. These results indicate that CaCO₃ solids are not recommended to provide alkalinity at Walnut Creek. Finally, the use of Mg(OH)₂ for alkalinity was employed at Walnut Creek and allowed operators to reduce the blowers that provide aeration. To quantify this observation, bubbling column tests were conducted to measure differences in the oxygen transfer rate at various Mg(OH)₂ concentrations. However experimental results did not match the expectations, so future work is required. / text

No description available.

There is strong evidence that variations in seawater chemistry occurred during the Phanerozoic Eon. Of particular importance are the changes in the Mg2+/Ca2+ ratio because they have been attributed to the oscillations between “calcite” and “aragonite seas” over time. In addition to the Mg2+/Ca2+ ratio variations, there were also major changes in pCO2 levels and alkalinity that could also affect the calcium carbonate (CaCO3) polymorph that precipitates from seawater. Experiments were conducted in seawater where the initial alkalinity and pCO2 levels were varied and then slow degassing of CO2 resulted in a gradual increase of saturation state with respect to CaCO3 and eventually nucleation. The pH was continually monitored throughout the experiments and it was used in combination with the initial alkalinity to calculate the pCO2 and saturation state of aragonite (sigmarag) at the time of nucleation. The morphology and mineralogy of the precipitates were determined using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, respectively. It was observed that the initial alkalinity greatly affected the nucleation pCO2 value and the CaCO3 polymorph that was precipitated. In seawater with Mg2+/Ca2+=1.2 and ~10 mM alkalinity and a pCO2 below 2,500 μatm, calcite that was overgrown with aragonite was the dominate polymorph nucleated, while pure aragonite precipitated when the pCO2 was above 2,500 μatm. Seawater with Mg2+/Ca2+=1.2 and a wide range of initial alkalinities (5-50 mM) produced variable results. Seawater with Mg2+/Ca2+=1.7 produced only aragonite at lower alkalinities, but calcite was nucleated when the alkalinity and pCO2 values were exceptionally high, typically above 11 mM. These results point to the need to also consider the effects of the carbonic acid system in the “critical” Mg2+/Ca2+ region of about 1 to 2 for “calcite seas” and “aragonite seas” at various times throughout the Phanerozoic Eon.

As stagnant water contacts copper pipe and lead solder (simulated soldered joints), a corrosion cell is formed between the metals in solder (Pb, Sn) and copper. If the resulting galvanic current exceeds about 2 µA/cm², a highly corrosive microenvironment can form at the solder surface, with pH <2.5 and chloride concentrations 11 times higher than bulk water levels. Waters with relatively high chloride tend to sustain high galvanic currents, preventing passivation of the solder surface and contributing to lead contamination of potable water. If the concentration of sulfate increased relative to chloride, galvanic currents and associated lead contamination could be greatly reduced, and solder surfaces were readily passivated. Mechanistically, at the relatively high concentrations of lead and low pH values that might be present at lead surfaces, sulfate forms precipitates while chloride forms soluble complexes with lead. Considering net transport of anions in water, a chloride-to-sulfate mass ratio (CSMR) above 0.77 results in more chloride than sulfate transported to the lead anode surface, whereas the converse occurs below this CSMR. Bicarbonate can compete with chloride transport and buffer the pH, providing benefits to lead corrosion. Although orthophosphate is often an effective corrosion inhibitor, tests revealed cases in which orthophosphate increased lead and tin release from simulated soldered joints in potable water. Phosphate tended to increase the current between lead-tin and copper when the water contained less than 10 mg/L SO₄²⁻ or the percentage of the anodic current carried by SO₄²- ions was less than 30%. Additionally, nitrate in the potable water range of 0-10 mg/L N dramatically increased lead leaching from simulated soldered pipe joints. Chloramine decay and the associated conversion of ammonia to nitrate during nitrification could create much higher lead contamination of potable water from solder in some cases. In practical bench-scale studies with water utilities, the CSMR was affected by the coagulant chemical, blending of desalinated seawater, anion exchange, and sodium chloride brine leaks from on-site hypochlorite generators. Consistent with prior experiences, increasing the CSMR in the range of 0.1 to 1.0 produced dramatic increases in lead leaching from lead-tin solder connected to copper. / Ph. D.

Empirical algorithms are developed using high-quality GO-SHIP hydrographic measurements of commonly measured parameters (temperature, salinity, pressure, nitrate, and oxygen) that estimate pH in the Pacific sector of the Southern Ocean. The coefficients of determination, R-2, are 0.98 for pH from nitrate (pH(N)) and 0.97 for pH from oxygen (pH(Ox)) with RMS errors of 0.010 and 0.008, respectively. These algorithms are applied to Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) biogeochemical profiling floats, which include novel sensors (pH, nitrate, oxygen, fluorescence, and backscatter). These algorithms are used to estimate pH on floats with no pH sensors and to validate and adjust pH sensor data from floats with pH sensors. The adjusted float data provide, for the first time, seasonal cycles in surface pH on weekly resolution that range from 0.05 to 0.08 on weekly resolution for the Pacific sector of the Southern Ocean.

Dissertação(mestrado)-Universidade Federal do Rio Grande, Programa de Pós–Graduação em Aqüicultura, Instituto de Oceanografia, 2011. / Submitted by Cristiane Silva (cristiane_gomides@hotmail.com) on 2012-08-17T12:47:58Z No. of bitstreams: 1 dissertao plinio em pdf.pdf: 641234 bytes, checksum: d4bb74480675f59d2f0875e7836a76e1 (MD5) / Approved for entry into archive by Bruna Vieira(bruninha_vieira@ibest.com.br) on 2012-08-21T17:46:11Z (GMT) No. of bitstreams: 1 dissertao plinio em pdf.pdf: 641234 bytes, checksum: d4bb74480675f59d2f0875e7836a76e1 (MD5) / Made available in DSpace on 2012-08-21T17:46:11Z (GMT). No. of bitstreams: 1 dissertao plinio em pdf.pdf: 641234 bytes, checksum: d4bb74480675f59d2f0875e7836a76e1 (MD5) Previous issue date: 2011 / O camarão Litopenaeus vannamei é o mais cultivado em sistemas super-intensivos em meio a flocos microbianos (BFT) e sem renovação de água. Nestes sistemas de bioflocos a tendência natural é que ocorra a diminuição do material carbonático ao longo do cultivo, devido aos processos de nitrificação que reduzem a alcalinidade na forma de carbonatos e bicarbonatos. Além disso, o pH pode diminuir devido a redução da alcalinidade e ao acúmulo de dióxido de carbono dissolvido, proveniente da respiração. O objetivo do estudo foi avaliar o efeito da aplicação de hidróxido de cálcio, carbonato e bicarbonato de sódio na qualidade de água do cultivo do L. vannamei em sistema BFT. Para tal, 600 juvenis (6g) foram estocados em 12 tanques com 150L de volume útil (ρ=333/m³). Os camarões foram alimentados duas vezes por dia, com ração comercial (Guabi®) seguindo tabela de alimentação por 60 dias de experimento. Foram avaliados quatro tratamentos com três repetições cada: T1- Na2CO3 (correção do pH acima de 7,5); T2- Ca(OH)2 (correção da alcalinidade acima de 100mg/L de CaCO3 e pH acima de 7,5); T3- NaHCO3 (correção da alcalinidade acima de 100 mg/L de CaCO3 ); e T4- Controle (sem correção do pH e alcalinidade). Para correção de pH, alcalinidade e ambos, foi utilizado carbonato de sódio 0,06 g/L, bicarbonato de sódio 0,20 g/L e cal hidratada 0,15 g/L, respectivamente. Os resultados dos parâmetros físicos, químicos, biológicos apresentaram diferença significativa (p<0,05) entre os tratamentos. Os animais do controle mostraram desempenho zootécnico inferior (p<0,05) aos demais tratamentos. As aplicações de carbonato de sódio (Na2CO3) e bicarbonato de sódio (NaHCO3) resultaram em condições favoráveis de qualidade de água para o crescimento dos bioflocos e dos camarões cultivados, no entanto os custos destes compostos os tornam pouco atrativos para aplicação em escala comercial. Já a cal hidratada apresentou a melhor relação custo-benefício. Por fim, este estudo torna claro que os níveis de alcalinidade e pH decrescem ao longo do cultivo e que os níveis de CO2 dissolvido se incrementam em sistemas super-intensivos, com bioflocos, sem renovação de água. Além disso, a qualidade da água de cultivo e o desempenho zootécnico dos camarões são afetados negativamente quando os níveis de alcalinidade permanecem por longos períodos abaixo de 100 mg CaCO3/L e o pH abaixo de 7. Portanto, é necessária a correção da alcalinidade e do pH através da aplicação de materiais carbonáticos ou hidróxido de cálcio. / The white shrimp Litopenaeus vannamei is the most reared in super-intensive biofloc systems (BFT) and without water renewal. In BFT systems there is a natural tendency to decrease of carbonate material (carbonates and bicarbonates) along the rearing due to nitrification that consumes alkalinity. In addition, the pH may be decreased due to reduction of alkalinity and increase of dissolved carbon dioxide. This study was to evaluated the influence of pH and alkalinity in the rearing of L. vannamei without water renewal. The experiment was carried out using 600 juveniles (6 g) stocked in 12 tanks of 150L, for a final stocking density of 333 m-³). Shrimp were fed twice daily with commercial feed (Guabi ®) following feeding table for 60 days of experiment. There were four treatments with three replicates each: T1 – Na2CO3 (pH correction above 7.5), T2 – Ca(OH)2 (pH correction above 7.5 and alkalinity above 100 mg / L CaCO3), T3- NaHCO3 (correction of the alkalinity above 100 mg / L CaCO3) and T4 - Control (without correction of pH and alkalinity). For pH correction, alkalinity and both, it was used sodium carbonate 0.06 g / L, sodium bicarbonate 0.20 g / L hydrated lime and 0.15 g / L, respectively. It were detected significant differences (p <0.05) of the physical, chemical, biological among treatments. In the Control shrimps showed lower growth performance (p <0.05) than shrimps of other treatments. The applications of sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3) improve water quality for development of bioflocs and performance shrimps. However, costs of these compounds make them unattractive for commercial scale application. Since hydrated lime (Ca(OH)2) showed the most cost-effective. Finally, this study clarify that the results obtained in the treatment control levels of alkalinity and pH decrease during the rearing, and that CO2 levels would be increased in super-intensive systems, with bioflocs without water renewal. In addition, water quality and growth performance of shrimp are adversely affected when the levels of alkalinity remain for long periods under 100 mg CaCO3/L and pH below 7. Therefore, it is necessary to correct the alkalinity and pH through the application of carbonate materials or calcium hydroxide.

As argamassas e concretos de cimento Portland são materiais de construção duráveis, relativamente baratos que, embora apresentem boa rigidez e adequada resistência à compressão, têm outras propriedades deficientes, tais como: resistência à tração, ao impacto, à fadiga, além de baixa tenacidade e ductilidade. Uma considerável melhora destas propriedades pode ser obtida com adição de fibras, em quantidades adequadas, na composição destes materiais. A utilização de fibra de vidro convencional (tipo E) no reforço das argamassas de cimento Portland, pode ser viável uma vez contornado o ataque do meio alcalino à fibra, principalmente o hidróxido de cálcio Ca(OH)2, produzido na hidratação do cimento. No presente trabalho foi obtida uma menor intensidade de ataque alcalino às fibras de vidro E, por meio da modificação com látex Estireno Butadieno, da adição de sílica ativa em substituição ao cimento Portland e da utilização de ambos concomitantemente. Outro procedimento utilizado, visando uma maior durabilidade das fibras de vidro, foi a proteção da superfície desta fibra com uma película de látex Estireno Butadieno e de uma mistura deste látex e sílica ativa. A eficiência de um e outro procedimento foi verificada por meio da comparação dos resultados de ensaio à tração e flexão, em amostras submetidas a processo de hidratação convencional e acelerado e observações pro meio de microscopia óptica. / Portland cement mortar and concrete are durable building materials, relatively cheap and, despite they display a good rigidity and an adequate compressive strength, they have other deficient properties such as tensile strength, impact, fatigue, beyond low toughness and ductility. A considerable improvement of these properties can be obtained adding fibers, in adequate quantities, in the composition of the materials. The use of conventional glass fiber (E-glass) in the reinforcement of Portland cement mortar can be possible if the attack of the alkaline environment, produced by cement hydration (chiefly by calcium hydroxide), to the fiber is controlled. In this work, a lesser intensity of alkaline attack on the E-glass fibers was succeded through the modification of the Portland cement matrix by styrene butadiene latex, the addition of silica fume or through the utilization of both additives at the same time. Another proceeding, aiming at a greater durability of the E-glass, has been the protection of the fiber surface with a styrene butadiene latex coating or with a mixture of this same latex and silica fume. The efficiency of each proceeding was verified by the comparison of tensile strength and flexural strength in samples submitted to accelerate and conventional hydration processes and by the observation of the interface glass/matrix with optical microscopy.

As argamassas e concretos de cimento Portland são materiais de construção duráveis, relativamente baratos que, embora apresentem boa rigidez e adequada resistência à compressão, têm outras propriedades deficientes, tais como: resistência à tração, ao impacto, à fadiga, além de baixa tenacidade e ductilidade. Uma considerável melhora destas propriedades pode ser obtida com adição de fibras, em quantidades adequadas, na composição destes materiais. A utilização de fibra de vidro convencional (tipo E) no reforço das argamassas de cimento Portland, pode ser viável uma vez contornado o ataque do meio alcalino à fibra, principalmente o hidróxido de cálcio Ca(OH)2, produzido na hidratação do cimento. No presente trabalho foi obtida uma menor intensidade de ataque alcalino às fibras de vidro E, por meio da modificação com látex Estireno Butadieno, da adição de sílica ativa em substituição ao cimento Portland e da utilização de ambos concomitantemente. Outro procedimento utilizado, visando uma maior durabilidade das fibras de vidro, foi a proteção da superfície desta fibra com uma película de látex Estireno Butadieno e de uma mistura deste látex e sílica ativa. A eficiência de um e outro procedimento foi verificada por meio da comparação dos resultados de ensaio à tração e flexão, em amostras submetidas a processo de hidratação convencional e acelerado e observações pro meio de microscopia óptica. / Portland cement mortar and concrete are durable building materials, relatively cheap and, despite they display a good rigidity and an adequate compressive strength, they have other deficient properties such as tensile strength, impact, fatigue, beyond low toughness and ductility. A considerable improvement of these properties can be obtained adding fibers, in adequate quantities, in the composition of the materials. The use of conventional glass fiber (E-glass) in the reinforcement of Portland cement mortar can be possible if the attack of the alkaline environment, produced by cement hydration (chiefly by calcium hydroxide), to the fiber is controlled. In this work, a lesser intensity of alkaline attack on the E-glass fibers was succeded through the modification of the Portland cement matrix by styrene butadiene latex, the addition of silica fume or through the utilization of both additives at the same time. Another proceeding, aiming at a greater durability of the E-glass, has been the protection of the fiber surface with a styrene butadiene latex coating or with a mixture of this same latex and silica fume. The efficiency of each proceeding was verified by the comparison of tensile strength and flexural strength in samples submitted to accelerate and conventional hydration processes and by the observation of the interface glass/matrix with optical microscopy.