Allowable concentration of soluble silicate (S. SiO2) in treated waste water containing water glass in rainbow trouts (Salmo gairdneri) rearing was examined with acute toxicity tests and ...histopathological examinations. The polymerization rate of soluble silicate or water glass at pH 7.27.8 in a rearing water and the time course change of electric charge of colloidal silica were measured. These measurements make clear the states of silicate, the mechanism of acute toxicity occurrence and the histopathological phenomena. The results of this research are summerized as follows. (1) LC50 (48h) value of rainbow trout (four to five month old) was estimated to be 302±27 mg E l-1 with initial S. SiO2 concentration. (2) Samples which have heigher concentration than 300 mg·l-1 decreased to 160 mg ± l-1 through polymerization at pH 7.27.8. (3) At heigher S. SiO2 concentration as 350 mg·l-1, the negative charge of colloidal silica increased with aging time at neutral zone. (4) The death of rainbow trout were considered to be caused by necrosis of the gill filaments with the colloidal silica. (5) The allowable S. SiO2 concentration of a treated waste water containing water glass would be 150 mg·l-1 in order to avoid sol formation. Thence, 100 mg·l-1 of S. SiO2 concentration could practically be set as an allowable concentration of the treated effluent.
The kaolinite suspension containing water glass is the one of the most popular waste water from chemical grouting tunnel constructions. In this study treatability of kaolinite suspension containing ...water glass in the coagulation process has been investigated. To make clear the effects of soluble or polymerized silicate on the coagulation process, various experiments were carried out. The polymerization rate and the value of electric charge of colloidal silica were measured under various pH and initial soluble silicate concentrations to characterize the nature of silicate. The results obtained by the study can be summarized as follows. (1) The highest polymerization rate of silicate is observed at pH 8.5 under the concentration of 300-1500 mg/l. (2) Polymerized silica colloids show the largest negative charge at pH 9.2-9.5. (3) The optimum pH range for the coagulation of kaolinite coexisting with water glass is between 4.5 and 7.0. The optimum pH value, however, changes depending upon the concentration of the soluble silicate and alum (aluminium sulfate) dosage. (4) In the above mentioned optimum coagulation pH region, silicate exists mainly as the monomer. Therefore, polymerized silica dose not play an important roll for coagulation. (5) Removal of soluble silica is very difficult by the both reasons that it requires high alum dosage and generates high sediment volume.
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For refractory application, amongst others, inorganic chemical binders are used to shape and process loose, unpacked materials. The binder influences the chemical composition within the ceramic body ...during setting, aging and firing and thus the finally reached properties of the refractory material. For an effective design of tailored materials with required properties, the mode of action of the binder systems should carefully be investigated. A combination of both structure analysis techniques and macroscopic property investigations proved to be a powerful tool for a detailed description of structure–property correlations. This is shown on the basis of X-ray powder diffraction and nuclear magnetic resonance spectroscopy analyses combined with observation of (thermo)mechanical and chemical investigations.
Cotton fabrics have been treated with two different finishing compositions based on urea (U) and ammonium dihydrogen phosphate (AP) in order to enhance their flame retardancy properties, particularly ...referring to the resistance to a flame application (namely, Limiting Oxygen Index tests) and to an irradiative heat flux of 35 kW/m² (by cone calorimetry). The collected results have proven a remarkable increase of cotton flame resistance: indeed, the fabrics treated with the high concentrated bath showed a LOI increase of 121 % (from 19 for neat cotton, to 42 %) and did not ignite under 35 kW/m² heat flux. Thermogravimetry coupled with pyrolysis-combustion flow calorimetry has demonstrated efficient features of the proposed flame retardant system as char-promoter for cotton. In order to reduce the amounts of U and AP employed in the selected formulations, the use of water glasses (WG) has been explored. A very low WG amount has proven to be effective in halving U and AP contents, maintaining the same fire performances already provided by the high concentrated finishing bath. Furthermore, WG have turned out to act as synergistic species as demonstrated by evaluating the synergistic effectiveness parameter.
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