Ritchie Equation Research Articles

High‐resolution reference evapotranspiration for arid Egypt: Comparative analysis and evaluation of empirical and artificial intelligence models

AbstractAccurate estimation of evapotranspiration has crucial importance in arid regions like Egypt, which suffers from the scarcity of precipitation and water shortages. This study provides an investigation of the performance of 31 widely used empirical equations and 20 models developed using five artificial intelligence (AI) algorithms to estimate reference evapotranspiration (ET0) to generate gridded high‐resolution daily ET0 estimates over Egypt. The AI algorithms include support vector machine‐radial basis function (SVM‐RBF), random forest (RF), group method of data handling neural network (GMDH‐NN), multivariate adaptive regression splines (MARS), and dynamic evolving neural fuzzy interference system (DENFIS). Daily observations records of 41 stations distributed over Egypt were used to calculate ET0 using FAO56 Penman–Monteith equation as a reference estimate. The multiparameter Kling‐Gupta efficiency (KGE) metric was used as an evaluation metric for its robustness in representing different statistical error/agreement characteristics in a single value. By category, the empirical equations based on radiation performed better in replicating FAO56‐PM followed by temperature‐ and mass‐transfer‐based ones. Ritchie equation was found to be the best overall in Egypt (median KGE 0.76) followed by Caprio (median KGE 0.64), and Penman (median KGE 0.52) equations based on station‐wise ranking. On the other hand, the RF model, having maximum and minimum temperatures, wind speed, and relative humidity as predictors, outperformed other AI algorithms. Overall, the RF model performed the best among all the AI models and empirical equations. The generated 0.10° × 0.10° daily estimates of ET0 enabled the detection of a significant increase of 0.12–0.16 mm·decade−1 in the agricultural‐dependent Nile Delta using the modified Mann–Kendall test and Sen's slope estimator.

Noble metal sensitized SnO2/RGO nanohybrids as chemiresistive E-nose for H2, H2S and NO2 detection

Hydrothermally synthesised noble metal (Pt, Pd) doped SnO2/RGO nanohybrids has been demonstrated first time for chemiresistive e-nose application towards the detection of H2, H2S and NO2 below their threshold limit values. More specifically, the multivariate statistical tools namely Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA), and Hierarchical Cluster Analysis (HCA) have been employed effectively to achieve fruitful discrimination of H2, H2S, and NO2. The two-dimensional PCA studies reveals the discrimination between the three test-gases under observation with the variance of 59.16% and 40.84% for first and second principal components, respectively. Importantly, LDA has been demonstrated to be useful to classify the data with 76.39% accuracy. HCA dendrograms depicted into three different clusters indicates a significant discrimination of gases with 95.55% classification confidence. The adsorption studies along with the validity of the kinematical models indicated that SnO2/RGO and SnO2/RGO: Pt follows the pseudo second order equations for H2S and H2 adsorption respectively. On the contrary, SnO2/RGO: Pd obeys Ritchie equation for NO2 adsorption. In addition, the work function values for SnO2/RGO and SnO2/RGO: Pd were found decrease and increase by 153 and 135 meV, respectively upon exposure to H2S and NO2 gases. This clearly indicates the n-type nature of the synthesised nanohybrids.

Gamma ray irradiation dose dependent methanol sensing with ZnO nanoparticles

This study reports the influence of gamma ray irradiation of various doses in the range of 1–150 kGy on methanol sensing performance and adsorption kinetics of ZnO nanoparticles based sensors. ZnO nanoparticles were synthesized via sol-gel method and characterized with X-ray diffraction (XRD), transmission electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) techniques. The results revealed that the methanol sensing performance of ZnO nanoparticles based sensor including sensitivity, response and recovery times improved by the gamma ray irradiation. Additionally, Elovich equation, Ritchie's equation and pseudo first-order model were selected to follow the methanol adsorption process. The preliminary result of the methanol adsorption kinetic studies revealed that the adsorption kinetics strongly depends on the gamma irradiation dose. Among other kinetic models investigated, the pseudo first-order equation was the best to describe the adsorption kinetics of methanol on ZnO nanoparticles up to 50 kG dose of gamma ray, as evidenced by the highest correlation coefficients. On the other hand, for higher doses than of 50 kGy of gamma irradiation, our analysis showed that Elovich equation generates a straight line that best fit to methanol adsorption data on ZnO nanoparticles.

Electrospun CuO nanofibers for room temperature volatile organic compound sensing applications

Volatile organic compound (VOC) sensing performance and kinetics of adsorption onto electrospun CuO nanofibers have been studied. The effect of the relative humidity (between 5% and 50%) on VOC sensing behavior and adsorption kinetics have also been investigated. The formation of single phase monoclinic CuO nanofibers with preferentional orientation of (002) were confirmed by X-ray diffraction and scanning electron microscopy studies. Three different kinetic models, Elovich model, pseudo first-order equation, and the Ritchie's equation were selected to follow the adsorption process. Sensing studies revealed that electrospun CuO nanofibers have a great potential for room temperature VOC sensing applications with high sensitivity, short response and recovery times. From the analysis of kinetic studies, it was observed that the kinetics of VOC vapors onto the electrospun CuO nanofibers strongly depends on level of the relative humidity and the concentration of VOC vapors.

Upgrading waste tires by chemical activation for the capture of SO2

Waste tires have been upgraded as activated carbon by chemical activation with KOH at different KOH:tire ratios, 0:1, 0.5:1, 1:1 and 4:1, namely AC-0, AC-0.5, AC-1 and AC-4 and characterized in terms of elemental and proximate analyses, nitrogen adsorption/desorption, acid/base and Boehm titrations. An increase in activating agent:tire ratio resulted in an increase in the fixed carbon content, surface area and pore volume, and a decrease in surface basicity and sulfur content. The so-prepared materials were tested in the adsorption of SO2, as an important pollutant from fuel combustion, using a thermogravimetric analyzer. The final adsorption capacity followed the trend AC-0<AC-0.5<AC-1<AC-4, matching that of increasing surface area and pore volume, while adsorption affinity was impacted by both textural and acid/base properties. A kinetic model with statistical validation based on Ritchie's equation successfully matched the transient uptake data, where larger rate constant values were obtained for those carbons presenting higher surface basicity.

Kinetics of CO2 adsorption on ball-type dicopper phthalocyanine thin film

Adsorption kinetics of CO2 on ball-type dicopper phthalocyanine thin film had been studied. The experimental data were analysed using four adsorption kinetic models; the pseudo first- and second-order equations, Ritchie's equation and the Elovich equation to determine the best fit equation for the adsorption of CO2 gas onto dicopper phthalocyanine thin film. The rate constants, equilibrium capacities and related correlation coefficients for each kinetic model were calculated and discussed. Results show that the linear regression analysis with respect to Ho's pseudo second order rate equation generates a straight line that best fit to the data of adsorption of CO2 on Pc film. It, unexpectedly, does not fit Elovich's or Ritchie's equation which are widely used in describing the adsorption of gaseous particles on solid systems. The variation of current in ball-type CuPc thin film as a function of temperature at constant bias voltage were also studied in the presence of CO2, SO2 and CO gases. While exposure to SO2 and CO have no considerable influence on the electrical conductivity of compound 4, the conductivity of the film strongly depend on the presence of the CO2 gas. The results indicated that the film of compound 4 has potential as a sensitive coating for the monitoring of CO2 gas even at room temperature.

Ethanol sensing property of novel phthalocyanines substituted with 3,4-dihydroxy-3-cyclobuten-1,2-dione

The novel mono metallo [Zn(II) 2a and Co(II) 2b] phthalocyanines have been synthesized from compound 1, which can be obtained by the reaction of 4-nitrophthalonitrile with 3,4-dihydroxy-3-cyclobuten-1,2-dione. The novel mono phthalocyanines with cyclobuten unit have been characterized by elemental analysis, UV–vis, FT-IR, 1H NMR, and mass spectroscopy. The effect of humidity on the ethanol sensing capability of the spin coated lilms 2a and 2b has been studied. The results showed that the presence of humidity, acting as interference gas, reduces both sensitivity and response time of the sensors. In addition, studies on response time and repeatability of the sensors have also been carried out. Applications of Elovich and Ritchie kinetic models to adsorption systems were reviewed. Results show that while the Ritchie equation may be applied for low temperature adsorption processes, while Elovich equation generates a straight line that best fit to the data of adsorption of ethanol vapors on Pc films at higher temperature.

Biosorptive distillations to purify isopropanol: improvements over the current process in terms of energy consumption and exergy

ABSTRACTThe removal of water from certain organic solvents via ordinary distillation requires several equilibrium stages if the organics are sufficiently concentrated, because the equilibrium curve for isopropanol–water is near the operating line, whereas acetone–water mixtures form a tangent pinch. In contrast, biosorption is only competitive when small quantities of adsorbate are removed. To overcome the drawbacks of both ordinary distillation and biosorption, a biosorptive distillation process was suggested for purifying 99.7 wt% isopropanol from a feed containing small amounts of water. Adsorption/regeneration experiments were conducted to investigate the breakthrough time and reusability of the adsorbent. The Ritchie equation, which fits the adsorption experimental data well, was embedded into the modified process simulation. Most of the water was removed via the adsorption part, which reduced its influence on the distillation. Compared to current commercial process, biosorptive distillation leads to a 25.4% reduction in the total energy and an overall exergy loss of 28.9% relative to absorbent regeneration. Furthermore, less than 1 year is required to recover the additional investment of the modified process. The proposed process can be both environmentally friendly and energy efficient. © 2013 Curtin University of Technology and John Wiley &amp; Sons, Ltd.

Modeling of Adsorption of Chromium(VI) on Activated Carbons Derived from Corn (Zea mays) Cob

Chromium in its trivalent and hexavalent form in the environment is toxic above certain concentrations. Cr(VI), which is more toxic than Cr(III), was chosen in this work and removed from aqueous solutions of potassium dichromate by adsorption onto physically and chemically activated carbons derived from Zea mays(corn or maize) cob, an agricultural waste product. Adsorption studies were done at the optimum pH of 2 and at the room temperature of 30°C. The aim of the work was to study the adsorption equilibrium and kinetic data with various isotherm and kinetic models. The best fit to the equilibrium data was provided by the 3-parameter Fritz-Schluender model followed by the 2-parameter Langmuir model. The adsorption isotherms were favorable and the adsorption on chemically activated carbons improved as the impregnation ratio was increased. Kinetic modeling showed that the fractional power model provided the best fit followed by the second-order Ritchie's equation. The adsorption of Cr(VI) on the activated carbons was film-diffusion controlled.

Evaluation of Marine BrownLaminaria JaponicaAlgae as a Low-cost Adsorbent for the Removal of Malachite Green Dye from Aqueous Solution

Batch adsorption experiments were carried out using marine brown Laminaria japonica algae for the removal of the Basic dye Malachite Green from aqueous solution. The influence of process parameters such as the initial solution pH, the contact time, the adsorbent concentration, the particle size, the interaction temperature and the ionic strength were investigated. The adsorbent was characterized by FT-IR spectroscopy. The adsorption of Malachite Green was pH-dependent and attained equilibrium within 60 min for two particle size fractions.The kinetic data were tested using the pseudo-first-order equation and the second-order Ritchie equation. The results showed that the adsorption of Malachite Green onto Laminaria japonica followed the second-order Ritchie equation very well. The Langmuir and Freundlich equations were applied to the data relating to the adsorption isotherms and the observed maximum adsorption capacity (qmax) for the particle size fraction < 150 μm was 89.44 mg/g at 20 °C. The effects of ad...

Do general nucleophilicity scales exist?

AbstractComprehensive nucleophilicity scales including π‐, n‐ and σ‐nucleophiles have been constructed using benzhydrylium ions and structurally related quinone methides as reference electrophiles. It is shown how the correlation (Eqn (1)) log k20°C = s(E + N), where s and N are nucleophile‐specific parameters and E is an electrophile‐specific parameter, has recently been employed to characterize further classes of nucleophiles (phosphines, amines, isonitriles, trifluoromethanesulfonyl‐substituted carbanions) and electrophiles (2‐benzylideneindan‐1,3‐diones and benzylidenebarbituric acids). Practical applications of the reactivity parameters E, N and s for developing Friedel–Crafts alkylations in neutral alcoholic or aqueous solution and for characterizing nucleophilic organocatalysts will be discussed. Eventually, a new correlation equation will be presented, which includes Eqn (1), the Ritchie equation (nucleophilic additions to stabilized carbocations), and the Swain–Scott equation (nucleophilic substitutions of methyl halides) as special cases. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Copper Ions Binding in Cu‐Alginate Gelation

Alginate polysaccharide forms viscous aqueous dispersions and has the ability to form gels in the presence of divalent cations such as calcium and copper. In this work, we have studied cooper ions binding during Cu‐alginate gelation, obtaining quantitative information about the amount and kinetics of cation binding. Our results indicate that copper binding during gelation occurs until a Langmuir‐type equilibrium is reached between bound and free ions in the gel‐contacting solution. The kinetics of metal ions binding can be modeled using Ritchie equation–derived models, allowing the prediction of ionic binding and gel formation temporal evolution. The ratio between cationic and polysaccharide quantities in the gelation system determines the kinetics of gelation and the characteristics of the gel formed. The experimental results and models applied in the work give more insights on alginate gelation and contribute to a reliable design and control of production methods for alginate gel structures.

Nucleophilic reactivities of carbanions in water: the unique behavior of the malodinitrile anion.

The kinetics of the reactions of nine carbanions 1a-i, each stabilized by two acyl, ester, or cyano groups, with benzhydrylium ions in water were investigated photometrically at 20 degrees C. Because the competing reactions of the benzhydrylium ions with water and hydroxide ions are generally slower, the second-order rate constants of the reactions of the benzhydrylium ions with the carbanions can be determined with high precision. The rate constants thus obtained can be described by the Ritchie equation, log(k/k(0)) = N(+) (eq 1), which allows us to calculate Ritchie N(+) parameters for a series of stabilized carbanions, for example, malonate, acetoacetate, malodinitrile, etc., and compare them with those of other n-nucleophiles in water (hydroxide, amines, azide, thiolates, etc.). Because the Ritchie relationship (eq 1) is a special case of the more general relationship log k = s(N + E) (eq 4), the reactivity parameters N and s for the carbanions 1a-i can also be calculated and compared with the nucleophilic reactivities of a large variety of n-, pi-, and sigma-nucleophiles, including reactivities of carbanions in dimethyl sulfoxide. While the acyl and ester substituted carbanions are approximately 3 orders of magnitude less reactive in water than in dimethyl sulfoxide, the malodinitrile anion (1i) shows almost the same reactivity in both solvents. Correlations between the nucleophilic reactivities of carbanions with the pK(a) values of the corresponding CH acids reveal that the malodinitrile anion (1i) is considerably more nucleophilic than was expected on the basis of its pK(a) value. This deviation is assigned to the exceptionally low Marcus intrinsic barriers of the reactions of the malodinitrile anion (1i).

How constant are Ritchie's "constant selectivity relationships"? A general reactivity scale for n-, pi-, and sigma-nucleophiles.

The kinetics of 82 reactions of benzhydrylium ions (Ar(2)CH(+)) with n-nucleophiles has been determined at 20 degrees C. Evaluation by the equation log k = s(N + E) delivered the reactivity parameters N and s for 15 n-nucleophiles (water, hydroxide, amines, etc.). All nucleophiles except water (s = 0.89) and (-)SCH(2)CO(2)(-) (s = 0.43) have closely similar slope parameters (0.52 < s < 0.71), indicating that the reactions of most n-nucleophiles approximately follow Ritchie's constant selectivity relationship (s = constant). The different slope parameter for water is recognized as the main reason for the deviations from the Ritchie relationship reported in 1986. Correlation analysis of the rate constants for the reactions of benzhydrylium ions with the n-nucleophiles (except H(2)O) on the basis of Ritchie's equation log k = N(+) + log k(0) yields a statistically validated set of N(+) parameters for Ritchie-type nucleophiles and log k(0) parameters for benzhydrylium ions. The N and s parameters of the n-nucleophiles derived from their reactions with benzhydrylium ions were combined with literature data for the reactions of these nucleophiles with other carbocations to yield electrophilicity parameters E for tritylium, tropylium, and xanthylium ions. While the E parameters for tropylium and xanthylium ions appear to be generally applicable, it is demonstrated that the E parameters of tritylium ions can be used to predict reactivities toward n-nucleophiles as well as hydride transfer rate constants but not rates for the reactions of tritylium ions with pi-nucleophiles. It is now possible to merge the large data sets determined by Ritchie and others with our kinetic data and present a nucleophilicity scale comprising n- (e.g., amines), pi- (e.g., alkenes and arenes), and sigma-nucleophiles (e.g., hydrides).

Selectivity and the Ritchie equation

The rates of addition of six primary amines to various electrophiles in aqueous solution have been analysed using a log k–log k type LFER treatment. Observed behaviour is in accord with the reactivity–selectivity principle and in quantitative agreement with previous work, questioning the validity of the Ritchie equation over large ranges of Lewis acidity. It is suggested that it is the range of electrophile stability considered, and not the intrinsic reactivity of the electrophiles themselves, which determines the degree of conformity to Ritchie type constant selectivity relationships.

Nucleophilic attacks on activated 9-methylenefluorenes. Application of the Ritchie equation to low-lying LUMO substrates

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNucleophilic attacks on activated 9-methylenefluorenes. Application of the Ritchie equation to low-lying LUMO substratesShmaryahu Hoz and Dov SpeizmanCite this: J. Org. Chem. 1983, 48, 17, 2904–2910Publication Date (Print):August 1, 1983Publication History Published online1 May 2002Published inissue 1 August 1983https://doi.org/10.1021/jo00165a023RIGHTS & PERMISSIONSArticle Views170Altmetric-Citations32LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (926 KB) Get e-Alerts Get e-Alerts

Application of Soil Water Flow Theory in Field Simulation

A numerical model based on a finite difference approximation of the basic differential equation for soil water flow is described. The equation includes a sink term representing moisture extraction by root systems, and allowance for evaporation from the soil surface is made too. Estimation of these terms is based on a potential transpiration calculated from Penman-Monteith's equation, on a potential evaporation calculated from Ritchie's equation and in both cases on relations to soil moisture status over various soil depths. The model simulations are compared with field observations of moisture content and soil moisture tension. Further, the model has been applied in evaluating how irrigation treatment effects the increases in evapotranspiration and deep percolation.

On Ritchie's equation for the analysis of kinetics of adsorption of gases on solids

On Ritchie's equation for the analysis of kinetics of adsorption of gases on solids

On Ritchie's equation for adsorption kinetics of gases on solids

Ritchie's equation for the kinetic adsorption isotherm has been derived on the basis of the theory describing the kinetics of adsorption of gases on energetically heterogeneous solid surfaces. This eqation has also been generalized to the kinetics of adsorption of multicomponent gas mixtures.

Studies in solvolysis. Part IX. Some commente on anion–cation combination reactions

The general validity of the Ritchie equation log (kn/k0) = N+ is evaluated on the basis of the bimolecular rate constants for various nucleophiles attacking crystal violet, malachite green, and the tris-p-anisylmethyl carbonium ion. A more general form of the Ritchie equation is required to accommodate the data viz. log (kn/k0) = S+N+(S+ = constant) for the most reactive carbonium ion. The latter modified form of the Ritchie equation is analogous to the Swain–Scott equation log (k0/kn) = sn and the new form follows the usual relationship between reactivity and selectivity, i.e. the value of S+ for the tris-p-anisylmethyl carbonium ion is less than unity.