Isotherm and Kinetic Studies on Adsorption of Pb, Zn and Cu by Kaolinite

The feasibility of kaolinite used as a low-cost adsorbent for the removal of Pb(II), Zn(II) and Cu(II) from aqueous solutions was investigated. During the removal process, batch technique was used, and the effects of heavy metal concentration and contact time on adsorption efficiency at pH of 4.5, under a constant temperature of 20±1 °C were studied. The experimental results were analyzed using four adsorption isotherm models; Freundlich, Langmuir, Temkin and Redlich-Peterson. Evaluating the correlation coefficients showed that the Redlich-Peterson isotherm described the data appropriable than others. The adsorption capacities (qm) from the Langmuir isotherm for Pb(II), Zn(II) and Cu(II) are found as 7.75 mg/g, 4.95 mg/g and 4.42 mg/g respectively. The effectiveness of kaolinite in the sorption of the three metals from aqueous system was Pb(II) > Zn(II) > Cu(II). Kinetic studies showed that a pseudosecond order model was more suitable than the pseudo first order model. It is concluded that kaolinite can be used as an effective adsorbent for removing Pb(II), Zn(II) and Cu(II) from aqueous solutions

Evaluation of NPP1 as a novel biomarker of coronary artery disease: A pilot study in human beings

Purpose: Coronary artery calcification (CAC) is utilized as an important tool for global risk assessment of cardiovascular events in individuals with intermediate risk. Ecto phosphodiesterase/nucleotide phosphohydrolase-1(ENPP1) converts extracellular nucleotides into inorganic pyrophosphate and it is a key regulator of tissue calcification that adjusts calcification in tissues like vascular smooth muscle cells. The main purpose of this clinical study was to find out the correlation between ENPP1 serum concentration and CAC in human for the first time. Methods: In this study 83 patients (16 diabetic patients and 67 non-diabetic patients) with coronary artery disease who fulfilled inclusion and exclusion criteria, entered the study. For all patients a questionnaire consisting demographic data and traditional cardiovascular risk factors were completed. Computed tomography (CT)-Angiography was carried out to determine coronary artery calcium score and enzyme-linked immunosorbent assay (ELISA) method was used for measuring ENPP1 serum concentrations. Results: There was a reverse significant correlation between ENPP1 serum concentration and total CAC score and also CAC of right coronary artery (RCA) (P < 0.05) in non-diabetic patients. Conclusion: On the basis of our results, ENPP1 serum concentration may be a suitable biomarker for coronary artery disease at least in non-diabetic patients. However, more studies with higher sample size are necessary for its confirmation. © 2018 The Authors

Moment analysis for modeling soil water distribution in furrow irrigation: Variable vs. constant ponding depths

Despite increasing use of pressurized irrigation methods, most irrigation projects world-wide still involve surface systems. Accurate estimation of the amount of infiltrating water and its spatial distribution in the soil is of great importance in the design and management of furrow irrigation systems. Moment analysis has previously been applied to describe the subsurface water distribution using input data from numerical simulations rather than field measured data, and as-suming a constant ponding depth in the furrow. A field experiment was conducted in a blocked-end level furrow at Maricopa Agricultural Center, Arizona, USA, to study the effect of time-variable ponding depths on soil water distribution and the resulting wetting bulb under real conditions in the field using moment analysis. The simulated volumetric soil water contents run with variable and constant (average) ponding depths using HYDRUS 2D/3D were almost identical, and both compared favorably with the field data. Hence, only the simulated soil water contents with variable ponding depths were used to calculate the moments. It was concluded that the fluctuating flow depth had no significant influence on the resulting time-evolving ellipses. This was related to the negligible 10-cm variation in ponding depths compared to the high negative matric potential of the unsaturated soil. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Laboratory investigation of water extraction effects on saltwater wedge displacement

There is a close connection between saltwater intrusion into aquifers and groundwater extraction. Freshwater extraction in coastal aquifers is one of the most important reasons for the saltwater intrusion into these aquifers. Condition of extraction system such as well depth, discharge rate, saltwater concentration and etc. could affect this process widely. Thus, investigating different extraction conditions comprises many management advantages.  In the present study, the effects of freshwater extraction on saltwater interface displacement have been investigated in a laboratory box. Three different well depths (H) were considered with combinations of 3 different extraction rates (Q) and 3 saltwater concentrations (C) for detailed investigation of the effects of these factors variations on saltwater displacement. SEAWAT model has been used to simulate all the scenarios to numerically study of the process. The experimental and numerical results showed that when the C and Q rates were small and the well depth was shallow, the saltwater interface wouldn’t reach the extraction well, so the extracted water remained uncontaminated. When the C and Q rates were increased and the well was deepened, the salinity of the extracted water became higher. When the Q and C rates were high enough, in the shallow well depth, the final concentration of the extracted water was low but a huge part of the porous media was contaminated by the saltwater, furthermore when the well was deepened enough, the final concentration of the extracted water was increased but a small part of the porous media was contaminated by the saltwater. Finally, the results showed that when the Q and H rates were high enough, the extraction well behaved like a barrier and didn’t allow the advancing saltwater wedge toe to be intruded beyond the wells

Daily reference evapotranspiration modeling by using genetic programming approach in the Basque Country (Northern Spain)

Evapotranspiration, as a major component of the hydrological cycle, is of importance for water resources management and development, as well as for estimating the water budget of irrigation schemes. This study presents a Gene Expression Programming (GEP) approach, for estimating daily reference evapotranspiration (ET0) in four weather stations in Basque Country (Northern Spain), for a 5-year period (1999-2003). The data set comprising air temperature, relative humidity, wind speed and solar radiation was employed for modeling ET0 using FAO-56 Penman Monteith equation as the reference. The GEP results were compared with the Adaptive Neuro-Fuzzy Inference System (ANFIS), Priestley-Taylor and Hargreaves-Samani models. Based on the comparisons, the GEP was found to perform better than the ANFIS, Priestley-Taylor and Hargreaves-Samani models. The ANFIS model is ranked as the second best model