جستجوی مقالات مرتبط با کلیدواژه "هضم اسیدی" در نشریات گروه "پزشکی"

 Given the high amounts of metals in the paint sludge, the recovery of metals can be seen as an effective and economic method for reducing its pollution. The combination of mechanochemical process and acid digestion may enhance the recovery yield of metals. In this process, milling parameters play a pivotal role in determining the chemical structure of the final products.

 Paint sludge samples were milled at three speeds of 150, 250, and 350 rpm for 2, 4 and 6 hours. Two weight ratios of ball-to-sample, i.e., 10 and 20 also was worked out. The milled samples were then subjected to acid digestion under the same conditions, and the amount of titanium was measured. The data were analyzed using the Taguchi method with Minitab software. Ethical considerations were taken into account at all stages of the study implementation.

 Among the milling parameters, ball milling speed showed the greatest impact on increasing titanium recovery, with a contribution of 49%, followed by time and ball-to-sample ratio, with contributions of 34% and 17%, respectively. The optimal milling conditions for achieving the highest recovery were determined to be a speed of 350 rpm, a time of 4 hours, and a ball-to-sample ratio of 20.

 Generally, the recovery yield of metals built up by increasing the amount and intensity of milling parameters. However, excessive increases in these parameters may result in the opposite effect and lead to the loss of cost, time, and energy. Therefore, the operating parameters of milling should be optimized, so that the optimal values of speed, time, and the weight ratio of ball-to-sample were obtained here.

 Both the number of water treatment plants and their sludge volume increases by population. Considering the presence of high amounts of valuable coagulants in water treatment plant sludge, it’s recovery and reuse is sought to be one of the practical and cost effective solutions for sludge management in water treatment plants.

 Iron sludge was collected from the sludge dryer bed of Jalaliyeh water treatment plant in Tehran. A planetary mill device was used to prepare samples and to investigate the effect of mechanochemical process on sludge recovery as an Iron based coagulant. XRD, XRF, TEM، MP-AES tests were performed on the sludge sample before and after the mechanochemical process. Ethical considerations were observed in all stages of the study.

 The results of this study showed that the use of a planetary mill leads to more recovery of iron, so that at 1 N acid concentration, iron recovery increases from 23.5% in the unmilled sludge sample to 60.5% in the milled sludge. Phase and chemical structure changes of sludge after planetary mill were clearly visible in XRD analysis.

 The results showed that by combining mechanochemical and acid digestion, it is possible to significantly improve ferric chloride recovery in terms of acid consumption and final product quality; so that the iron based final product could be used for industrial wastewater treatment.

The consequence of using coagulant materials such as aluminum sulfate and ferric chloride in the coagulation unit of conventional water treatment plants can generate plenty of sludge that contains large amounts of coagulant, which in addition to environmental risks, will also possess disposal costs. Today, intending to preserve the environment and reduce treatment costs, researchers emphasize the recovery and reuse of coagulants from sludge. In this regard, the present study was proposed and implemented to recover and reuse water treatment plant sludge as a low-cost coagulant in wastewater treatment.

This research is an experimental-laboratory study. In order to recover the coagulant from the collected sludge, acid hydrolysis method was used. The physicochemical characteristics of the recovered sludge were also determined using FTIR, FE-SEM, and BET analysis. Moreover, the efficiency of recovered sludge in different doses (50 to 300 mg/L) on wastewater treatability in terms of COD, TSS, VSS, turbidity, phosphorus, and coliform indices was compared with aluminum sulfate, ferric chloride coagulants, also the results of the study were analyzed and presented using Excel software (version, 2016).

According to the results, the prepared sludge had no crystalline structure with amorphous morphology. In addition, recovered coagulant from water treatment sludge has demonstrated high efficiency for wastewater treatment, so 66.6%, 82.49%, 79.66%, 80%, 65 %, 99.18% of COD, turbidity, TSS, VSS, phosphorus, total coliform were removed at the highest dosage of recovered coagulant (300 mg/L), respectively. Furthermore, the recovered coagulant dosage had a significant effect on the performance of the coagulation and flocculation process in wastewater treatment.

The results showed that recovered coagulant from the sludge of the water treatment plant can be considered an acceptable option with appropriate effectiveness in the wastewater treatment processes.

Digestion is an important step in urine iodine determination methods. High temperatures and long heating durations can be considered as weaknesses of the present methods. The aim of the study was assessment of microwave use for digestion of urine and decompostion of interfering substances, aimed at shortening the time and increasing safety in the procedure. Random urine samples were processed by conventional acid digestion and also by new microwave optimized digestion methods. After digestion, iodine levels of samples, digested by the two mentioned methods, were also determined using chemical colorimetric kinetic reaction Ce+4 and Ce+3 according to the well known Sandell-Kolthoff reaction. Microplate reading format by ELISA reader was used to increase speed and precision of reading. Sensitivity, precision and comparison results were assayed in both the methods as well. Optimized microwave digestion showed that merely a 10 min duration is adequate for complete digestion of urine samples. Intra- and inter- assay coefficients of variation were 6.7- 9.3% and 9.8-12.3% respectively. The final results of the comparison of iodine contents of samples, were obtained through the two microwave and conventional methods, showed acceptable correlation (r=0.928). The assay recovery was 91-113% and the sensitivity 5 µg/dL. The results of this study showed that the microwave procedure for urine digestion is acceptable. The digestion method obtained comparable results with conventional digestion methods, and can hence replace conventional electrical heat digestion methods.

Main shortcomings in existing methods for iodine determination in milk samples are non safe alkaline solution, harsh thermal conditions, and their being time consuming. In this study, for determination of total iodine content in milk, a simple and rapid kinetic catalytic colorimetric, acid digestion and rapid microplate reading format method, was investigated. Sample digestion was done on 50L milk in metavanadate/perchloric acid, at 230◦C for 10 min. After digestion, iodine determination was based on famous Sandell – Kolthoff reaction. The reaction results were read in 96 wells microplate by ELISA reader. Work range of the assay was between 2-40µg/dl. The within-run coefficient of variation percent ranged from 6. 7 to 9. 3 and between-run coefficients of variation ranged from 8.6 to 12.3%. The results obtained (n=70) by the optimized method had good correlation with the results of alkaline incineration as the reference method (p<0.000, n=70 r2=0.907 y=0. 952x-0.084). Recovery tests for accuracy assessment were between 91.3 to 113%. This method enabled us to achieve 0.1 µg/dl sensitivity. This study showed that, fast acid digestion, mild thermal, fast results reading and low sample volume, were the main advantages of the acid digestion and microplate reading format investigated.