Application of silver nitrate colorimetric method to non-steady-state diffusion test

NT build 443, or profile fitting method, is often used to measure the diffusion coefficient of chloride in concrete. However, this method is quite laborious and needs special equipment. Colorimetric method is a quick and simple method to measure the penetration depth of chloride by spraying 0.1 mol/L silver nitrate solution. The objective of this work is to study the possibility of the use of colorimetric method in the calculation of non-steady-state diffusion coefficient. Twelve concrete mixtures with different supplementary cementitious materials and water-to-cement ratios of 0.35, 0.48 and 0.6 were used for study. According to NT build 443, the concrete specimens were immersed in 165 g/L NaC1 （2.8 mol/L） solution for 42 d. Both water-soluble （convert to free chloride） chloride and acid-soluble chloride at different layers of specimens were measured. The results show that the mean value of free chloride concentration at the color change boundary Cd was 0.306 mol/L. The surface free chloride concentration cs was obtained by profile fitting method, which was 40% lower than the chloride concentration of exposure solution after an immersion period of 42 d. Chloride diffusion coefficients obtained by the colorimetric method was not well correlated with those obtained by profile fitting method.

A novel colorimetric method for field arsenic speciation analysis

Accurate on-site determination of arsenic （As） concentration as well as its speciation presents a great environmental challenge especially to developing countries. To meet the need of routine field monitoring, we developed a rapid colorimetric method with a wide dynamic detection range and high precision. The novel application of KMnO4 and CHaN2S as effective As（III） oxidant and As（V） reductant, respectively, in the formation of molybdenum blue complexes enabled the differentiation of As（III） and As（V）. The detection limit of the method was 8 ~tg/L with a linear range （R2 = 0.998） of four orders of magnitude in total As concentrations. The As speciation in groundwater samples determined with the colorimetric method in the field were consistent with the results using the high performance liquid chromatography atomic fluorescence spectrometry, as evidenced by a linear correlation in paired analysis with a slope of 0.9990- 0.9997 （p 〈 0.0001, n = 28）. The recovery of 96%-116% for total As, 85%-122% for As（III）, and 88%-127% for As（V） were achieved for groundwater samples with a total As concentration range 100-800 μg/L. The colorimetric result showed that 3.61 g/L As（III） existed as the only As species in a real industrial wastewater, which was in good agreement with the HPLC-AFS result of 3.56 g/L As（Ⅲ）. No interference with the color development was observed in the presence of sulfate, phosphate, silicate, humic acid, and heavy metals from complex water matrix. This accurate, sensitive, and easy-to-use method is especially suitable for field As determination.

Modification of colorimetric method based digital soil test kit for determination of macronutrients in oil palm plantation

It is the need of time that oil palm farmers must perform the spatially planned soil analysis to know about the fertilizer sufficient and deficient zones of land.Colorimetric method is a suitable and fast solution of soil analysis for NPK determination using the digital soil test kit.NPK determination procedure with a digital soil test kit was undefined for oil palm.Furthermore,the digital soil test kit determines the passage of light through an opaque medium of soil solution with a specified reagent.Therefore,environmental light may interfere leading to wrong results of NPK measurement.Likewise,this equipment was non-incorporable with the controller of any VRT fertilizer applicator.In this research,these issues were addressed and the NPK measurement procedure was defined for oil palm plantation by modifying the‘soil to water’ratio in sample soil solution with an optimum environmental light range of 18-23 W/m^(2).‘Soil to water’ratios were found for nitrogen,phosphorus and potassium as 0.31 to 5.00,1.00 to 5.00 and 4.50 to 5.00,respectively to fit the requirement of NPK for oil palm in the prescribed range of the equipment.Validation study of modified digital soil test kit showed that 91.7%N,89.6%P and 93.8%K results of modified digital soil test kit were matched with analytical laboratory method.Thus,the reliability of NPK results using digital soil test kit was enhanced,making the kit incorporable with the controller of variable rate fertilizer applicator through remote monitoring based data acquisition system.The outcome of this research can be used in the development of an IoT network data fusion for dynamic assessment of the NPK variation in the soil and nutrient management in oil palm plantations.

Assessment of the Presence of Chlorides in Mortar through the Silver Nitrate Colorimetric Spraying Method

This study aims to evaluate the presence of free chlorides by the silver nitrate colorimetric spraying method in mortars made with Portland cement CP II Z-32. In order to make an assessment beyond the qualitative analysis, a calculation of the contaminated areas by free chlorides was performed by measuring the regions using a computer image analysis software （IMAGEJ）. The experimental part of the research involved samples of 5 cm x 10 cm of mortar and 0.1 M solution of silver nitrate in distilled water. The mortar samples were made with cement CP II Z-32 with the following concentrations of chloride incorporated into the mixing water： 0%0, 0.4%, 0.6%, 0.8%, 1.0% and 2.0%, in relation to the mass of cement, totaling 108 samples. The average of percentage results from the contaminated area of the series of samples was respectively 0%, 14.9694%, 19.7444%, 46.0239%, 62.3311% and 96.0083% in relation to the total area, concluding that the method of silver nitrate spraying is applicable and that the white color indicates the presence of chloride ions and other possible aggressive salts to the structure or the concrete.

Species analysis methods for hydrolysis polymerization of aluminum

Al Ferron timed complex colorimetric method (AFM) and 27 Al NMR spectroscopy method(ANM) were discussed. For the former, the different colorimetric reagent preparation methods' results indicate that there are some differences beteween them, and the combined method can be used as a simplified procedure. For the latter, the small tube method is more accurate. Eventually, the Al 13 (ANM) was compared to the Al b (AFM).

Enzymatic Method for Rapid Determination of Oxalic Acid in Bleaching Filtrates from the Pulp and Paper Industry

Bleaching with oxygen-containing agents and recirculation of process streams in the pulp and paper industry has increased the accumulation of oxalic acid and danger for precipitation of calcium oxalate encrusts, scaling. Analysis and control of oxalic acid in bleaching filtrates is therefore becoming increasingly important in the pulp and paper industry. Chromatographic methods, such as IC and HPLC, are generally more time-consuming but are valuable as standard methods for determination of oxalic acid. However, the instrumentation needed is expensive and stationary. In this study, an enzymatic method based on oxalate oxidase and peroxidase was developed to determine oxalic acid in authentic bleaching filtrates using a spectrophotometer. The results showed that bleaching filtrates contain some compounds interfering with the enzymatic method. Pretreatment of the samples with activated charcoal was a successful approach for decreasing problems with interference. By using dilution followed by charcoal treatment, the results obtained from five bleaching filtrates with the colorimetric method correlated very well with those obtained using IC. This study offers a selective, fast and mobile analysis method to determine oxalic acid in bleaching fiRrates from the pulp and paper industry, The convenient enzyme-based method improves the possibilities for control of critical oxalic acid concentrations in closed-loop bleaching streams.

Purification of Jinggangmycin and Its Content Determination

[ Objective ] In order to get the standard substance of Jinggangmycin used in quality control, Jinggangmycin was purified from its original pesticide and its content was determined, t Method] Mixed solvents were selected to recrystallize Jinggangmycin （content 62% ）. Phenol-sulfuric acid colofirnetric method was adopted to determine its content, and the effects of different determination conditions on the content results were also studied. E Result~ The purity of the samples after re-eryatallization was increased to 97.7%. The optimal conditions for phenol-sulfuric acid colorimetric method to determine the content of Jinggan^nyein were as follows： anhydrous glucose as control sample, 5% phenol, 1.0 ml phenol solution, 5.0 nfl sulfuric acid, stilly placed for20 min after reaction, 490 nm as detec- tion wavelength; the correlation coefficient of glucose standard curve （ R2 ） was 0. 993 9; the average recovery of standard addition was 99.72%, RSD was 0. 362 8%. ~ Conclusion] Re-cryatallization is a good way to refine Jinggan^nycin. Phenol-sulfuric acid colorimetric method can be used to determine the content of Jinggangmycin with simple operation, high accuracy and strong reliability, which can be widely applied in industrial production.

Distribution of aluminum species and the characteristics of structure of poly-aluminum-chloride-sulfate(PACS)

A series of poly-aluminum-chloride-sulfate (PACS), which has different basicities (gamma) and Al3+/SO42- molar ratio, has been prepared and dried at 105degreesC and 65degreesC, respectively. The distribution of aluminum species of PACS was examined, and the effect of 7 value, Al3+/SO42- molar ratio, dilution on the distribution of aluminum species of PACS was also investigated by using Al-ferron timed complex colorimetric method. The IR spectroscopy and X-ray diffraction were used to study the effect of gamma value, Al3+ / SO42- molar ratio and the drying temperature on the structure of PACS. The experimental results show that Al3+/SO42- molar ratio has a great effect on the distribution of aluminum species, but the dilution has a little effect on the distribution of aluminum species. The lower the Al3+/SO42- molar ratio, the higher the proportions of the polymer and colloidal species in PACS, The polymeric degree of PACS was related to gamma value and Al3+/SO(4)(2-)molar ratio. Drying temperature has an influence on the structure and the solubility of solid PACS products.

Gas-liquid-liquid slug flow and mass transfer in hydrophilic and hydrophobic microreactors

Gas-liquid-liquid three-phase slug flow was generated in both hydrophilic and hydrophobic microreactors with double T-junctions.The bubble-droplet relative movement and the local mass transfer within the continuous slug and the dispersed droplet were investigated.It was found that bubbles moved faster than droplets under low capillary number(Ca),while droplets moved faster upon the increase of Ca due to the increased inertia.For the first time,we observed that the increased viscosity of droplets fastened the droplet movement.The mass transfer in the continuous slug was dominated by convection,leading to nearly constant global mass transfer coefficient(k_(L)a);while that in the dispersed droplet was dominated by diffusion,resulting in k_(L) decreasing along the channel.Such features are analogical to the corresponding gas-liquid or liquid-liquid two-phase slug flow,but the formation of bubble-droplet clusters caused by relative movement lowered the absolute mass transfer coefficient.These results provide insights for the precise manipulation of gas-liquid-liquid slug flow in microreactors towards process optimization.

Real-time measurement of welding temperature field and closed loop control of penetration

Colormetric method of images by using two different wavelength images is a new measuring method for welding temperature field on the basis of ordinary colorimetric method, which depends little on the measuring distance, emissivity of body etc. In this paper the real time measuring system and measuring principle of welding temperature field are described, the whole welding temperature field is real time measured, so the temperature distribution at the welding direction and its cross section is obtained, then parameters of thermal cycle. With data from the temperature closed loop control system of the parameters of temperature field is developed and tested. Experimental results prove that it has high measurement speed (time of a field within 0.5 s ) and good dynamic response quality. Weld penetration can be controlled satisfactorily under the variation of welding condition such as welding thickness, welding speed and weldment gap etc.

Research on synchronous measurement technique of temperature and deformation fields using multispectral camera with bilateral telecentric lens

The hot-section parts easily occur the creep-fatigued interaction under the condition of mechanicalthermal coupled load during the period of service, which may lead to the damage of the parts, and therefore, the measurement and characterization of thermal-deformed fields of the parts are important to understand its damage process. Aiming at relevant demand, the bilateral telecentric-multispectral imaging system was established, the research of synchronous measurement technique of the temperature and deformation fields was developed. On the one hand, the measurement technology for surface temperature of the object was developed using the two-color images captured by the multispectral camera with bilateral telecentric lens and combined with colorimetric method. On the other hand, the 2 D-DIC measurement technique of the multispectral camera was developed by conducting digital image correlation analysis using the blue light images before and after deformation, which can measure the high temperature deformation field of the object(the blue light images were filtered by multispectral camera).Results showed that the bilateral telecentric lens is used to replace the ordinary optical lens for imaging,which can effectively eliminate the distortion of the multispectral imaging system. Since the temperature measurement process of this measurement system is little affected by the emissivity of the object, therefore, it has excellent robustness. The thermal expansion coefficients of the nickel alloys are evaluated at the temperature ranges of 700–1000℃, indicating this system can achieve the synchronous and precise measurement of the temperature and deformation fields of the object.

Multiphysics coupling in situ measurement method for laser repair of the Inconel 718 alloy structure

As an additive manufacturing technique,the laser-aided direct energy deposition(L-DED)method has been widely used for component repair(also called laser repair).With significant differences from traditional manufacturing techniques,the laser repair process has the characteristics of point-by-point deposition and has a high-temperature gradient in the repair area,resulting in the formation of heterogeneous thermal deformation and residual stress after cooling.High stress may lead to the appearance of cracks in the repair area and may seriously influence the bearing capacity of the repaired parts.Therefore,the characterization of the temperature and deformation fields of the components during laser repair is important for the analysis of the mechanism of damage evolution in the repair area,optimization of the process parameters,and improvement of the mechanical properties of the repaired components.Because of the demand for the simultaneous measurement of the temperature and deformation fields,using a multispectral camera and a self-designed three-peak filter,a temperature-deformation field measurement technique was developed and applied to in situ monitoring during the L-DED manufacturing process.In the actual measurement process,the synchronous measurement of the temperature field of the laser molten pool and the deformation field of the side surface of the repaired component were realized using the images of multiple channels in the multispectral camera.The experimental results verify that a three-peak filter can effectively eliminate the influences of glare and overexposure on the recorded multispectral images.Moreover,the amplitude of the displacement field and the temperature gradient of the repaired component will increase with the increase in laser power,which may affect the final molding of the repaired component.This work extends the function of the multispectral camera to measure the temperature and deformation fields and provides a new measurement method for further optimizing the process parameters of laser repair.

Saponin Accumulation in Flower Buds of Panax notoginseng

Objective Panax notoginseng is an important Chinese medicinal plant. Saponin accumulation is higher in the flower buds than in the other parts of P. notoginseng. However, the flower bud compositions have not yet been quantified. The aim of this study is to investigate the formation and accumulation of saponins in the flower buds of P. notoginseng from different populations and at different growth years. Methods Fourteen types of P. notoginseng with different growing durations and from different areas of Wenshan County, Yunnan Province were collected. We separated P. notoginseng individually into the flower buds, stems, leaves, and roots at the places where it has the highest saponin content. An efficient high-performance liquid chromatography（HPLC） method was developed for simultaneously quantifying two active saponins, ginsenoside Rb1 and ginsenoside Rb3, in the flower buds of P. notoginseng. The total saponin content was determined by using a quantitative vanillin-sulfuric acid colorimetric method. HPLC method was used to establish the fingerprints of 13 saponins and then quantify the composition in the whole plant of P. notoginseng. Results The saponin contents of different parts differ significantly, and the total saponin content and those of Rb1 and Rb3 do not entirely correlated. The flower buds of P. notoginseng contain 27.79% of total saponins, which is the highest saponin content in the whole plant. Fingerprint result showed that different saponins were appeared in different parts of the plant, i.e. flower buds, stems, leaves, and roots.Conclusion The saponin contents from the flower buds of P. notoginseng vary depending on the growth area and duration. The fingerprints show that the saponin contents and compositions vary depending on the part of P. notoginseng. These results are useful for the pharmacological evaluation and quality control of P. notoginseng.