Papers by Keyword: pH

Abstract: Supercritical carbon dioxide (SCCO₂) containing calcium propionate or magnesium bicarbonate was used to deacidify paper. In the experiment, to compare the effects of SCCO₂ technology deacidification and immersion deacidification, two kinds of paper samples were chosen to do these two kinds of deaciditication tests respectively. And pH, alkali reserve and mechanical properties of paper samples were measured before and after these treatments. The experiments showed that the pH and alkaline reserve of paper samples treated with SCCO₂ were nearly similar to that of immersion treatments. Otherwise, compared with immersion deacidification, supercritical carbon dioxide had some advantages of strengthening the mechanical properties of paper and shortening treatment time.

Abstract: The effects of pH on the advanced treatment of mid-stage pulping effluent with potassium ferrate were studied. Firstly, the effect of pH on the stability of the potassium ferrate solution was studied, which indicated that potassium ferrate was more stable in alkaline conditions than in acidic and neutral conditions, and the most stability was achieved at pH of 9-10. Then the effect of pH on the mid-stage pulping effluent treatment with potassium ferrate showed that the oxidation increased firstly and then decreased with the increase of the pH. The best treatment efficiency was at pH=4, under which COD removal efficiency reached 40%. The flocculation experiment was conducted using Fe³⁺ produced by the oxidation reaction as flocculant and PAC as extra flocculant and PAM as coagulant aid. Effect of pH on the flocculation process was studied, which showed that the flocculation effect first increased and then decreased with pH increasing. When pH was 9, COD removal efficiency reached 60%. The final effluent of COD concentration was less than 60mg/L, which met the requirements from the national first-order discharge standard.

Abstract: The size and shape of gold nanoparticles controlled by pH was studied in the reacted solutions containing peptides (NH₂-Leu-Aib-Trp-Ome) as reducing agent. The resulting gold nanostructures were characterized by transmission electron microscopy (TEM), XRD and UV-vis-NIR spectra. Different shape of gold nanoparticles such as spheres, multipod and branch were prepared by changing the pH of solution. The resulting gold nanostructures may be have potential applications in the Surface Enhanced Raman Spectroscopy (SERS) and NIR-absorbing filters and coatings.

Abstract: Anodic aluminium oxide fabricated at ambient temperature and low potential in phosphoric acid electrolyte was used as the working electrode for the electrochemical measurement of phosphate buffer saline under different pH conditions using the cyclic voltammetry tool. We investigate the reversibility of the electrochemical reaction as a redox reaction from the cyclic graphs that were obtained. We observed that the ratio of the peak current passed at both the reduction and oxidation when measured was very close to unity in all the pH but except one which produced a none reversible reaction with a non cyclic graph. The peak potential for both reduction and oxidation reactions using phosphate buffer saline as the analyte under different pH of 3, 5, 7, and 9 was also obtained.

Abstract: Deposition of Pd on the surface of zero-valent iron (Pd/Fe) further enhances the ability of the metal to reductively dechlorinate organic contaminants. This work determined the dechlorination of chlorobenzene in water by Pd/Fe and evaluated the effects of Pd loading in Fe, Pd/Fe dosage, solution pH and temperature on the reaction. Pseudo-first-order rate constants were obtained to analyze the reaction kinetics. Chlorobenzene was nearly completely dechlorinated within 60 min by Pd/Fe at room temperature. Benzene was the end product of the reaction, along with the release of chloride into water. The rate constant of chlorobenzene dechlorination increased with increasing Pd loading in Fe and Pd/Fe dosage within the tested ranges of 0.005 - 0.020% and 2.0 - 6.0 g/75 mL, respectively. The rate constant increased with decreasing solution pH over the tested pH range of 4.5 - 6.5, indicating the role of protons in dechlorination. The reaction was considered to occur primarily on the surface of Pd where protons were reduced to hydrogen species and chlorobenzene was subsequently dechlorinated by the hydrogen species. The rate of chlorobenzene dechlorination increased with increasing temperature. The estimated activation energy of the reaction was 47.94 kJ/mol within the temperature range of 15 - 40°C, indicating that the dechlorination of chlorobenzene by Pd/Fe readily occurs at room temperature. Pd/Fe may be a potential reductant for effective removal of chlorinated organic contaminants from water.

Abstract: The phosphorus removal from low concentration phosphorus wastewater in two BAFs with different artificial crystal seed meida and the influence of HRT, Ca/P and pH on the treatment performance were investigated. The results showed that the artificial crystal media BAFs was more efficient than that of the current commercial filter media for phosphorus removal and recovery, and the suitable pH range of wastewater was also enlarged. When the initial phosphorus concentration was 10 mg/L, the optimum operational condition of steel slag base composite meida filter was HRT=30 min, n (Ca)/n (P)=1 and pH=8, as well as the optimum condition of water slag base composite media filter was HRT=60 min, n (Ca)/n (P)=2.5 and pH=8. XRD analysis showed that the reaction products of phosphorus removal by the two artificial crystal seed media filters were all hydroxy calcium phosphate, but its crystallinity was not high, which might due to the production of calcium carbonate in the reaction of phosphorus removal simultaneously.

Abstract: This paper designs a multi parameter real-time water quality on-line monitoring system for aquaculture water. This system achieves the online monitoring among temperature, turbidity, DO (dissolved oxygen), pH and electrical conductivity. The crosstalk, produced by the simultaneous measurement with DO and pH sensors, will affect accuracy and stability of monitoring results. This paper analyzes the source of crosstalk, describes a circuit model of causing crosstalk, and designs an isolated circuit between powers and signals as well. The experimental results show that, the real-time monitoring of DO and pH has the characteristics of speediness, high precision, small error and low noise.

Abstract: This study describes how the control of bath pH allows different types of phase formation in the ternary Co-Ni-Fe nanocoating. The acidity of the plating bath has been known as a main factor to the properties of coatings. The Co-Ni-Fe coating was fabricated using a commercial electrodepostion process. Several pH solutions (3, 7 and 9) were employed to determine the optimum condition for Co-Ni-Fe synthesis. The bath pH was varied by using sodium hydroxide (NaOH) and sulphuric acid (H₂SO₄). Other parameters such as temperature, electrolyte composition, deposition time and current density were kept constant. The experiment was performed at 50°C. This temperature is commonly used in the industrial plating process. XRD analysis indicated the presence of both phases: body centred cubic (BCC) and face centred cubic (FCC) dependent on the pH value. Co-Ni-Fe nanocoatings obtained from the electrolyte of low pH showed the fine-grain morphology. The hardness of the Co-Ni-Fe nanocoatings was closely related to the obtained morphology.

Abstract: The effects of pH on the morphology and size distribution of Sn nanoparticles (NPs)synthesized using a modified polyol method were investigated. An ammonia solution wasused to increase the pH, and at pHvalues ranging from 10.3 to 12, the average size and size deviation of thesynthesized Sn NPs decreased with increasing pH. We believe that higherpH enhances the rate of reduction of Sn ions during the synthesis, resulting inan increase in nucleation. Therefore, theconcurrent formation of many nuclei might be the main cause for the reduction inaverage particle size and for the enhancement in size uniformity.

Abstract: To study the effect of different pH on degradation products of tinidazole pills and direct preparation of tinidazole pills, Tinidazole pills were prepared and the solution of different pH was compounded. The tinidazole content of pills and degradation products were determined by being heated at 80°C via high performance liqud chromatographic (HPLC). The number and concentration of tinidazole pills were increased with the increase of temperature and pH. Tinidazole pills in acidic conditions with the pH value within 4~5 were more stable than in neutral and alkaline conditions. It was shown that shortening the melting time and keeping pH value within 4~5 were in favor of preparation and assurance of pills quality.