scholarly journals Valorisation des coques de noyaux de Balanites aegyptiaca (L.) Del. et Hyphaene thébaica (L.) Mart. pour l’élaboration et caractérisation de Charbons Actifs; application pour l’élimination du chrome

2018 ◽  
Vol 14 (21) ◽  
pp. 195
Author(s):  
Sanda Mamane Ousmaila ◽  
Siragi Dounounou Boukari Maâzou ◽  
Malam Alma Maman Mousbahou ◽  
Natatou Ibrahim
Keyword(s):  
Specific Surface ◽  
Adsorption Process ◽  
Activated Carbons ◽  
Correlation Coefficients ◽  
Balanites Aegyptiaca ◽  
Adsorption Capacities ◽  
Calculated Parameter ◽  
Parameter Values

This paper focuses on the development and characterization of activated carbons to agro-food waste by activation with ortho phosphoric acid, and its application in the elimination of chromium in solution. The functions were determined by Bohem's method. The thermal analysis was carried out on the hulls of waste. The specific surface area and the pore volume are determined according to the method of Brunauer, Emmet and Teller and the method of Barret, Joyner and Halenda respectively. The Lagergren and Ho and McKay models were used for the kinetic study of chromium removal. Those of Langmuir and Freundlich have to do with the study of isotherms and the law of Van't Hoff and Gibbs in relation to the determination of thermodynamic parameters. The results obtained show that the surface functions are acidic in nature. Activated carbon from balanites aegyptiaca has developed a specific surface (1560.7401 m2 g -1 ) that exceeds that of Hyphaene thebaica (722.1510 m2 g -1 ). The pseudo-order 2 kinetics (Ho and McKay) better describe the adsorption with correlation coefficients close to unity. Adsorption capacities and rate constants prove rapid adsorption at the early stages. For the isotherms, the calculated parameter values are much more consistent with those of the Langmuir isotherm. ∆Gads 0 < 0 ; the adsorption process is spontaneous. Moreover, the values are in the range of a physisorption.

scholarly journals Measuring specific surface area of snow by near-infrared photography

2006 ◽  
Vol 52 (179) ◽  
pp. 558-564 ◽  
Author(s):  
Margret Matzl ◽  
Martin Schneebeli
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Near Infrared ◽  
Two Dimensions ◽  
Chemical Models ◽  
Snow Stratigraphy ◽  
Physical And Chemical

AbstractThe specific surface area (SSA) is considered an essential microstructural parameter for the characterization of snow. Photography in the near-infrared (NIR) spectrum is sensitive to the SSA. We calculated the snow reflectance from calibrated NIR images of snow-pit walls and measured the SSA of samples obtained at the same locations. This new method is used to map the snow stratigraphy. The correlation between reflectance and SSA was found to be 90%. Calibrated NIR photography allows quantitative determination of SSA and its spatial variation in a snow profile in two dimensions within an uncertainty of 15%. In an image covering 0.5–1.0 m2, even layers of 1mm thickness can be documented and measured. Spatial maps of SSA are an important tool in initializing and validating physical and chemical models of the snowpack.

Design Shell for Parametric Design at Embodiment Stage

2003 ◽  
Author(s):  
Adwait Vaidya ◽  
Jami Shah
Keyword(s):  
Parametric Design ◽  
Problem Definition ◽  
Design Stage ◽  
Embodiment Design ◽  
System Requirements ◽  
Parameter Values ◽  
Domain Independent

The embodiment design stage involves determination of geometric sizes, key parameter values, and matching of component variables to system requirements. This embodiment design stage can be parametrically represented as an iterative design-redesign problem. This paper presents a domain independent characterization of such problems; the characterization includes problem definition, design relations/procedures, and measures of goodness. The paper also discusses representation issues and solution techniques for design-redesign problems. Design tasks are differentiated as domain independent or problem specific and the scope of each design task with respect to the characterization is delineated. A Design Shell implemented on the basis of this characterization is described. This shell can be configured for evaluating designs in any domain. A case study illustrates the use of this Design Shell in characterizing a specific design problem and exploring its design space.

Characterization of Phthalate Plasticizer from Bottled Beverages by GC-MS

2013 ◽  
Vol 401-403 ◽  
pp. 590-593 ◽  
Author(s):  
Qiu Ju Sun ◽  
Lin Li ◽  
Zhong Li Jiang ◽  
Shi Gang Xin ◽  
Shi Wei Wu ◽  
...  
Keyword(s):  
Correlation Coefficients ◽  
The Other ◽  
Calibration Curves ◽  
Phthalate Plasticizer ◽  
Testing Data

A GC/MS method was established for the determination of phthalates plasticizers in bottled beverages. The calibration curves are all linear in the range of 0.01 to 5μg/L with correlation coefficients greater than 0.997. The recoveries are in the range between 97.27% and 105.05% under two levels. The testing data of the samples showed that the five bottled beverages all contained DBP, DIBP and DEHP plasticizers, and DIBP content was obviously higher than the other two.

scholarly journals The Efficiency of the Removal of Naphthalene from Aqueous Solutions by Different Adsorbents

2020 ◽  
Vol 17 (16) ◽  
pp. 5969
Author(s):  
Alicja Puszkarewicz ◽  
Jadwiga Kaleta
Keyword(s):  
Adsorption Process ◽  
Activated Carbons ◽  
Water Solution ◽  
Breakthrough Curves ◽  
Maximum Adsorption Capacity ◽  
Flow Conditions ◽  
Filtration Method ◽  
Adsorption Capacities ◽  
Effects Of Ph ◽  
Static Conditions

The paper presents the results of laboratory tests on possibilities to utilize active carbons produced in Poland (AG-5 and DTO) and clinoptilolite for removing naphthalene from a water solution in the adsorption process. The concentration of naphthalene in the model solution was 20 mg/dm3. The effects of pH, dose and adsorption time were determined under static conditions. Adsorption kinetics were consistent with the pseudo-second-order model (PSO). Among the applied models, the best fit was obtained using the Langmuir isotherms. The maximum adsorption capacity for the activated carbons (AG-5 and DTO) equaled 24.57 and 30.28 mg/g, respectively. For clinoptilolite, all the analyzed models of adsorption poorly described the adsorption process. The flow conditions were realized by filtration method. On the basis of the obtained results, the breakthrough curves, so-called isoplanes, were prepared and served in turn to determine the adsorption capacities in flow conditions. The total adsorption capacities determined under dynamic conditions of the AG-5 and DTO activated carbons were 85.63 and 94.54 mg/g, respectively, and only 2.72 mg/g for clinoptilolite. The exit curves (isoplanes) were also utilized to determine the mass penetration zone (the adsorption front height), as well as to calculate the rate of mass-exchange zone advance.

scholarly journals Characterization of Activated carbons Prepared from a Locally Available Material by Iodine Number

2018 ◽  
Vol 13 (1) ◽  
pp. 139-144
Author(s):  
Rajeshwar Man Shrestha
Keyword(s):  
Phosphoric Acid ◽  
Iodine Number ◽  
Activated Carbons ◽  
Carbonization Temperature ◽  
Preparation Conditions ◽  
Time Determination ◽  
Phosphoric Acid Concentration ◽  
Acid Percentage

 The adsorption of Iodine by the activated carbons prepared from a locally available material Lapsi Seed Stone has been studied. Various activated carbons were prepared by varying the parameters such as ratio of Lapsi Seed Stone particles to Phosphoric acid, percentage of phosphoric acid concentration, carbonization temperature and carbonization time. Determination of Iodine numbers of the activated carbons was done by the standard method. The effect of various preparation conditions on Iodine number of different activated carbons is also investigated. The optimum conditions for the preparation of activated carbon are found to be 400 ° C -the carbonization temperature, 4 hours - the carbonization time, 1:1- the ratio of Lapsi Seed Stone particles and Phosphoric acid and 50 %- the percentage of phosphoric acid concentration.Journal of the Institute of Engineering, 2017, 13(1): 139-144

Performance of poly(styrene-co-divinylbenzene) functionalized with different aminophosphonate pendant groups, in the removal of phenolic compounds from aqueous solutions

2016 ◽  
Vol 88 (10-11) ◽  
pp. 993-1004 ◽  
Author(s):  
Corneliu-Mircea Davidescu ◽  
Radu Ardelean ◽  
Popa Adriana
Keyword(s):  
Phenolic Compounds ◽  
Aqueous Solutions ◽  
Functional Groups ◽  
Adsorption Process ◽  
Active Centers ◽  
One Pot ◽  
Batch System ◽  
Adsorption Capacities ◽  
The Difference

AbstractIn the present work, we describe the synthesis and characterization of styrene-6.7%-divinylbenzene copolymers functionalized with aminophosphonate groups by “one-pot” reactions. Different aminophosphonate groups were grafted on the copolymer with the aim of obtaining adsorbents for removal of phenolic compounds from aqueous solutions. Adsorption experiments were carried out in batch system. The phenolic compounds studied were phenol and 2,4,6-trimethyl-phenol. The best adsorption capacity was observed in the case of polymeric adsorbents functionalized with aminophosphonate groups in para- position of the aromatic nucleus for both phenol and 2,4,6-trimethyl-phenol. In comparison, the copolymers with the functional groups in ortho- position and respectively in meta- position were slightly less efficient. The differences in adsorption efficiency may be explained taking into account the structure of the adsorption active centers. The possible explanation is that the active functional groups responsible for the adsorption process, grafted in ortho- or meta- position could be affected by possible steric hindrance effects. The difference between the adsorption capacities of the polymers of the same series, are rather small and depending on the nature of the radical found in the structure of the aminophosphonate: isopropylamine or isobuthylamine.

scholarly journals Application of Sludge-Based Activated Carbons for the Effective Adsorption of Neonicotinoid Pesticides

2021 ◽  
Vol 11 (7) ◽  
pp. 3087
Author(s):  
Eva Sanz-Santos ◽  
Silvia Álvarez-Torrellas ◽  
Lucía Ceballos ◽  
Marcos Larriba ◽  
V. Ismael Águeda ◽  
...  
Keyword(s):  
Adsorption Process ◽  
Wastewater Treatment Plants ◽  
Activated Carbons ◽  
Low Cost ◽  
High Adsorption ◽  
Secondary Pollution ◽  
Adsorption Capacities ◽  
Agricultural Use ◽  
Neonicotinoid Pesticides ◽  
Watch List

The amount of sludge produced in wastewater treatment plants (WWTPs) has increased over the years, and the methods used to reduce this waste, such as incineration, agricultural use, or disposal in landfills, cause problems of secondary pollution. For this reason, it is necessary to find sustainable and low-cost solutions to manage this waste. Additionally, emerging and priority pollutants are attracting attention from the scientific community as they can generate health problems due to inadequate removal in conventional WWTPs. In this work, a pharmaceutical industry sludge was used as a precursor in the synthesis of four activated carbons (ACs) using different activating agents (ZnCl2, FeCl3∙6H2O, Fe(NO3)3∙9H2O, and Fe(SO4)3∙H2O), to be used for the removal by adsorption of three neonicotinoid pesticides included in latest EU Watch List (Decision 2018/840): acetamiprid (ACT), thiamethoxam (THM), and imidacloprid (IMD). The prepared ACs showed micro–mesoporous properties, obtaining relatively slow adsorption kinetics to reach equilibrium, but despite this, high values of adsorption capacity (qe) were obtained. For example, for AC-ZnCl2 (SBET = 558 m2/g), high adsorption capacities of qe = 128.9, 126.8, and 166.1 mg/g for ACT, THM, and IMD, respectively, were found. In most cases, the adsorption isotherms showed a multilayer profile, indicating an important contribution of the mesoporosity of the activated carbons in the adsorption process.

scholarly journals CHARACTERIZATION OF HEAT CONDUCTIVITY OF ECCENTRICALLY ROTATING HEAT PIPES USED FOR COOLING OF MOTOR SPINDLES

2021 ◽  
Vol 2021 (3) ◽  
pp. 4698-4705
Author(s):  
B. Denkena ◽  
◽  
B. Bergmann ◽  
K. Kono ◽  
R. Ishiguro ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Pipe ◽  
Heat Exchangers ◽  
Thermal Characteristics ◽  
Heat Pipes ◽  
Simulation Based ◽  
Wick Structure ◽  
Parameter Values

Heat losses within motor spindles lead to undesired effects such as machining inaccuracies and de-creasing lifetime of the motor and bearings. To reduce thermal loads, complex shaft cooling concepts with costly sealing techniques exist. For this reason, a novel, less costly cooling concept has been de-veloped based on heat pipes with high thermal conductivity and fin-shaped heat exchangers. The de-sign and integration of these heat exchanger elements into a motor spindle is carried out using the fi-nite element method. The aim is to optimize the efficiency of the heat pipes and heat exchangers for optimal shaft cooling performance. For a simulation-based development of a prototype spindle, un-known thermal characteristics of the heat transfer elements must be determined. In this paper, the de-termination of the thermal conductivity of the heat pipes is described. The determination of conductivi-ty is done experimentally. First, the developed test rig and the applied procedure for the determination of the conductivity are shown. Subsequently, the experimental results are presented and discussed. Two types of heat pipes were analyzed: Copper heat pipes with sintered wick structure and nickel-plated copper heat pipes with axial grooves. The influences of rotational speed, heat flow rates and the angle between the heat pipe and main axis of rotation were investigated. The results indicate a distinct dependency of the conductivity on the varied parameters. However, changes of parameter values have very different quantitative and qualitative effects on the determined conductivities de-pending on the type of heat pipe.

scholarly journals Gain Error end DNL for Testing ADCs: Optimization in Time Domain

2020 ◽  
Vol 9 (3) ◽  
pp. 891-894
Keyword(s):  
Digital Form ◽  
Analog To Digital ◽  
Test Conditions ◽  
Gain Error ◽  
Transition Level ◽  
Determination Of Parameters ◽  
Parameter Values ◽  
Estimation Of Variance

Optimization in ADC is an important component which predicts overall accuracy of a system using it. Signals are in real time nature and it is necessary to convert these signals in digital form to interpret with digital form of signals and microcomputer based systems. ADC is used to carry out these conversions process from analog to digital. Determination of parameters of an ADC such as DNL, INL, SNR and ENOB are necessary for complete dynamic analysis and characterization of ADC. In frequently, application prerequisite input to an Analog to digital converter is time varying which requires determination of its parameters at corresponding frequency and different test conditions In order to test an ADC, it is necessary to first determine its code transition levels. Further Gain error, DNL are estimated using code transition level based on histogram technique. If there is an code transition level error introduced then effect of this error leads to error in estimate of gain, offset, DNL and ENOB. Further estimation of variance in different parameter values is analyzed in the proposed work.

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