scholarly journals Fixed-bed Adsorption of Congo red dye and Bisphenol A from solution onto surfactant modified walnut shell

2021 ◽  
Author(s):  
Evans Dovi ◽  
Aaron Albert Aryee ◽  
Alexander Nti Kani ◽  
Farid Mzee Mpatani ◽  
Jianjun Li ◽  
...  
Keyword(s):  
Flow Rate ◽  
Endocrine Disrupting Chemicals ◽  
Fixed Bed ◽  
Industrial Effluents ◽  
Environmental Safety ◽  
Low Flow ◽  
Walnut Shell ◽  
Synthetic Dyes ◽  
Living Organisms ◽  
Agricultural Byproduct

Abstract Wastewater stemming from industries may contain pollutants such as synthetic dyes and endocrine-disrupting chemicals which are known to be harmful to living organisms. Therefore, to safeguard the wellbeing of humankind and environmental safety, it is imperative for industrial effluents to be sanitized before their discharged into water bodies. Furthermore, to explore the utilization of agricultural byproduct is valuable to study. To achieve this, a Cetyltrimethylammonium bromide functionalized Walnut shells (WNS-CTAB) were prepared to remove pollutants in column approach. The column work was carried out for diverse working conditions. There is in favor of adsorption at low influent pollutant concentration, low flow rate or high bed depth. As the highest breakthrough time of 113 and 23 min at flow rate 6 mL min −1 was recorded for both CR and BPA, respectively, the Yan’s kinetic model best described the breakthrough curve. The adsorbent showed better regeneration capabilities; accordingly can offer practical use for adsorption of CR and BPA from wastewaters.

scholarly journals Amine-grafted Walnut Shell for Efficient Removal Phosphate and Nitrate from Aqueous Solution

2021 ◽  
Author(s):  
Evans Dovi ◽  
Aaron Albert Aryee ◽  
Jianjun Li ◽  
Zhaohui Li ◽  
Lingbo Qu ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Industrial Effluents ◽  
Environmental Safety ◽  
Water Bodies ◽  
Walnut Shell ◽  
Uptake Capacity ◽  
Effective Removal ◽  
Characterization Studies ◽  
Lower Temperature ◽  
The Individual

Abstract The presence of emerging pollutants such as PO43− and NO3− in water bodies has attracted worldwide concern about their severe effects on water bodies and the health of humankind in general. Therefore, to preserve the health of humankind and environmental safety, it is of the essence that industrial effluents are treated before they are discharged into water bodies. To accomplish this, the walnut shell was functionalized (ACWNS) with amine for effective removal of PO43− and NO3−. Characterization studies of ACWNS were conducted using FTIR, XRD, XPS and BET techniques. Removal of both ions was enhanced at lower temperature (293 K). The maximum uptake capacity of phosphate and nitrate, at 293 K, was 82.2 and 35.7 mg g− 1, respectively. The primary mechanism by which these ions were uptaken onto ACWNS could be electrostatic interactions and hydrogen bonding.Pseudo-second-order kinetics fitted the PO43̶ and NO3− adsorption, while Freundlich and Langmuir models best fitted the PO43̶ and NO3̶ adsorption, respectively. Furthermore, in the binary system, the uptake capacity of phosphate decreased by 14.4% while nitrate witnessed a reduction in its uptake capacity by 10.4 %. So ACWNS has a higher attraction towards both ions and this could be attributed to the existence of a variety of active areas on ACWNS that exhibit a degree of specificity for the individual anions. Results obtained from real water samples analysis confirmed ACWNS as highly efficient to be utilized for practical remediation processes.

Resistance of Binding Systems of Various Compositions to the Action of Molds

2020 ◽  
Vol 786 (11) ◽  
pp. 41-46
Author(s):  
V.V. STROKOVA ◽  
◽  
V.V. NELUBOVA ◽  
M.N. SIVALNEVA ◽  
M.D. RYKUNOVA ◽  
...  
Keyword(s):  
Aging Process ◽  
Building Materials ◽  
Environmental Safety ◽  
Fungal Resistance ◽  
Building Structures ◽  
Vital Activity ◽  
Regulatory Documents ◽  
Living Organisms ◽  
Biological Corrosion ◽  
Test Objects

The dynamic development of urbanization contributes to an increase in emissions of industrial waste, which is the cause dysfunction of the ecosystem balance and leads to the development of biological corrosion on building materials associated with the products of the vital activity of microorganisms. In this regard, it is necessary to assess the resistance of composites to predict the durability of building structures under conditions of biological influence of microorganisms. Binder systems of various compositions were studied: cementless nanostructured binders (NB) based on quartz sand and granodiorite, gypsum, Portland cement and alumina cement. The toxicity of binders was assessed by biotesting on living organisms – cladocerans Daphnia Magna – according to the criteria of the intensity of their growth and viability. As a result, the high environmental safety of NB is substantiated, and the ranking of the studied binders according to the degree of increase in their toxicity to test objects is presented. Fungal resistance was assessed by the ability of molds for growing and reproduction on the studied samples. It was found that the most active in terms of the development of binders were representatives of the genus Aspergillus, the intensity of growing of which in all variants did not decrease below 3 points. Gypsum and NB were especially vulnerable, where the degree of fouling repeatedly reached 5 points. Even the initially biostable cement, after the aging process, lost its stability at different extent. The obtained results indicate the need to increase the resistance of composites for various purposes under conditions of biocorrosion at the stage of design and updating of regulatory documents, including tests for fungal resistance in the list of mandatory.

scholarly journals Backflow effects on mass flow gain factor in a centrifugal pump

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042199886
Author(s):  
Wenzhe Kang ◽  
Lingjiu Zhou ◽  
Dianhai Liu ◽  
Zhengwei Wang
Keyword(s):  
Centrifugal Pump ◽  
Mass Flow ◽  
Flow Rate ◽  
Low Frequency ◽  
Gain Factor ◽  
Low Flow ◽  
Cavity Volume ◽  
Cavitating Flows ◽  
Inlet Tube ◽  
Low Flow Rate

Previous researches has shown that inlet backflow may occur in a centrifugal pump when running at low-flow-rate conditions and have nonnegligible effects on cavitation behaviors (e.g. mass flow gain factor) and cavitation stability (e.g. cavitation surge). To analyze the influences of backflow in impeller inlet, comparative studies of cavitating flows are carried out for two typical centrifugal pumps. A series of computational fluid dynamics (CFD) simulations were carried out for the cavitating flows in two pumps, based on the RANS (Reynolds-Averaged Naiver-Stokes) solver with the turbulence model of k- ω shear stress transport and homogeneous multiphase model. The cavity volume in Pump A (with less reversed flow in impeller inlet) decreases with the decreasing of flow rate, while the cavity volume in Pump B (with obvious inlet backflow) reach the minimum values at δ = 0.1285 and then increase as the flow rate decreases. For Pump A, the mass flow gain factors are negative and the absolute values increase with the decrease of cavitation number for all calculation conditions. For Pump B, the mass flow gain factors are negative for most conditions but positive for some conditions with low flow rate coefficients and low cavitation numbers, reaching the minimum value at condition of σ = 0.151 for most cases. The development of backflow in impeller inlet is found to be the essential reason for the great differences. For Pump B, the strong shearing between backflow and main flow lead to the cavitation in inlet tube. The cavity volume in the impeller decreases while that in the inlet tube increases with the decreasing of flow rate, which make the total cavity volume reaches the minimum value at δ = 0.1285 and then the mass flow gain factor become positive. Through the transient calculations for cavitating flows in two pumps, low-frequency fluctuations of pressure and flow rate are found in Pump B at some off-designed conditions (e.g. δ = 0.107, σ = 0.195). The relations among inlet pressure, inlet flow rate, cavity volume, and backflow are analyzed in detail to understand the periodic evolution of low-frequency fluctuations. Backflow is found to be the main reason which cause the positive value of mass flow gain factor at low-flow-rate conditions. Through the transient simulations of cavitating flow, backflow is considered as an important aspect closely related to the hydraulic stability of cavitating pumping system.

Assessment of the Use of Humidified Nasal Cannulas for Oxygen Therapy in Patients with Epistaxis

ORL ◽  
2021 ◽  
pp. 1-5
Author(s):  
Jingjing Liu ◽  
Tengfang Chen ◽  
Zhenggang Lv ◽  
Dezhong Wu
Keyword(s):  
Flow Rate ◽  
Oxygen Therapy ◽  
Preliminary Investigation ◽  
Nasal Cannula ◽  
Low Flow ◽  
Antiplatelet Drugs ◽  
Flow Rates ◽  
The Past ◽  
Oxygen Inhalation ◽  
Significant Difference

<b><i>Introduction:</i></b> In China, nasal cannula oxygen therapy is typically humidified. However, it is difficult to decide whether to suspend nasal cannula oxygen inhalation after the nosebleed has temporarily stopped. Therefore, we conducted a preliminary investigation on whether the use of humidified nasal cannulas in our hospital increases the incidence of epistaxis. <b><i>Methods:</i></b> We conducted a survey of 176,058 inpatients in our hospital and other city branches of our hospital over the past 3 years and obtained information concerning their use of humidified nasal cannulas for oxygen inhalation, nonhumidified nasal cannulas, anticoagulant and antiplatelet drugs, and oxygen inhalation flow rates. This information was compared with the data collected at consultation for epistaxis during these 3 years. <b><i>Results:</i></b> No significant difference was found between inpatients with humidified nasal cannulas and those without nasal cannula oxygen therapy in the incidence of consultations due to epistaxis (χ<sup>2</sup> = 1.007, <i>p</i> &#x3e; 0.05). The same trend was observed among hospitalized patients using anticoagulant and antiplatelet drugs (χ<sup>2</sup> = 2.082, <i>p</i> &#x3e; 0.05). Among the patients with an inhaled oxygen flow rate ≥5 L/min, the incidence of ear-nose-throat (ENT) consultations due to epistaxis was 0. No statistically significant difference was found between inpatients with a humidified oxygen inhalation flow rate &#x3c;5 L/min and those without nasal cannula oxygen therapy in the incidence of ENT consultations due to epistaxis (χ<sup>2</sup> = 0.838, <i>p</i> &#x3e; 0.05). A statistically significant difference was observed in the incidence of ENT consultations due to epistaxis between the low-flow nonhumidified nasal cannula and nonnasal cannula oxygen inhalation groups (χ<sup>2</sup> = 18.428, <i>p</i> &#x3c; 0.001). The same trend was observed between the 2 groups of low-flow humidified and low-flow nonhumidified nasal cannula oxygen inhalation (χ<sup>2</sup> = 26.194, <i>p</i> &#x3c; 0.001). <b><i>Discussion/Conclusion:</i></b> Neither high-flow humidified nasal cannula oxygen inhalation nor low-flow humidified nasal cannula oxygen inhalation will increase the incidence of recurrent or serious epistaxis complications; the same trend was observed for patients who use anticoagulant and antiplatelet drugs. Humidification during low-flow nasal cannula oxygen inhalation can prevent severe and repeated epistaxis to a certain extent.

scholarly journals Effect of Air Injection on the Internal Flow Characteristics in the Draft Tube of a Francis Turbine Model

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1182
Author(s):  
Seung-Jun Kim ◽  
Yong Cho ◽  
Jin-Hyuk Kim
Keyword(s):  
Flow Rate ◽  
Draft Tube ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Air Injection ◽  
Low Flow ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Vortex Rope

Under low flow-rate conditions, a Francis turbine exhibits precession of a vortex rope with pressure fluctuations in the draft tube. These undesirable flow phenomena can lead to deterioration of the turbine performance as manifested by torque and power output fluctuations. In order to suppress the rope with precession and a swirl component in the tube, the use of anti-swirl fins was investigated in a previous study. However, vortex rope generation still occurred near the cone of the tube. In this study, unsteady-state Reynolds-averaged Navier–Stokes analyses were conducted with a scale-adaptive simulation shear stress transport turbulence model. This model was used to observe the effects of the injection in the draft tube on the unsteady internal flow and pressure phenomena considering both active and passive suppression methods. The air injection affected the generation and suppression of the vortex rope and swirl component depending on the flow rate of the air. In addition, an injection level of 0.5%Q led to a reduction in the maximum unsteady pressure characteristics.

scholarly journals Investigating the performance of agricultural wastes and their ashes in removing phenol from leachate in a fixed-bed column

2020 ◽  
Vol 81 (10) ◽  
pp. 2109-2126 ◽  
Author(s):  
Seyed Omid Ahmadinejad ◽  
Seyed Taghi Omid Naeeni ◽  
Zahra Akbari ◽  
Sara Nazif
Keyword(s):  
Activated Carbon ◽  
Large Scale ◽  
Fixed Bed ◽  
Walnut Shell ◽  
Continuous Systems ◽  
Phenol Removal ◽  
Adsorption Method ◽  
Fixed Bed Column ◽  
Saturation Time ◽  
Coconut Shell Activated Carbon

Abstract One of the major pollutants in leachate is phenol. Due to safety and environmental problems, removal of phenol from leachate is essential. Most of the adsorption studies have been conducted in batch systems. Practically, large-scale adsorption is carried out in continuous systems. In this research, the adsorption method has been used for phenol removal from leachate by using walnut shell activated carbon (WSA) and coconut shell activated carbon (CSA) as adsorbents in a fixed-bed column. The effect of adsorbent bed depth, influent phenol concentration and type of adsorbent on adsorption was explored. By increasing the depth of the adsorbent bed in the column, phenol removal efficiency and saturation time increase significantly. Also, by increasing the influent concentration, saturation time of the column decreases. To predict the column performance and describe the breakthrough curve, three kinetic models of Yon-Nelson, Adams-Bohart and Thomas were applied. The results of the experiments indicate that there is a good match between the results of the experiment and the predicted results of the models.

Measurement and Modeling of Condensation Heat Transfer Coefficients in Circular Microchannels

2006 ◽  
Vol 128 (10) ◽  
pp. 1050-1059 ◽  
Author(s):  
Todd M. Bandhauer ◽  
Akhil Agarwal ◽  
Srinivas Garimella
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Heat Transfer Model ◽  
Condensation Heat Transfer ◽  
Low Flow ◽  
Transfer Model ◽  
Shear Stresses ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Circular Microchannels

A model for predicting heat transfer during condensation of refrigerant R134a in horizontal microchannels is presented. The thermal amplification technique is used to measure condensation heat transfer coefficients accurately over small increments of refrigerant quality across the vapor-liquid dome (0<x<1). A combination of a high flow rate closed loop primary coolant and a low flow rate open loop secondary coolant ensures the accurate measurement of the small heat duties in these microchannels and the deduction of condensation heat transfer coefficients from measured UA values. Measurements were conducted for three circular microchannels (0.506<Dh<1.524mm) over the mass flux range 150<G<750kg∕m2s. Results from previous work by the authors on condensation flow mechanisms in microchannel geometries were used to interpret the results based on the applicable flow regimes. The heat transfer model is based on the approach originally developed by Traviss, D. P., Rohsenow, W. M., and Baron, A. B., 1973, “Forced-Convection Condensation Inside Tubes: A Heat Transfer Equation For Condenser Design,” ASHRAE Trans., 79(1), pp. 157–165 and Moser, K. W., Webb, R. L., and Na, B., 1998, “A New Equivalent Reynolds Number Model for Condensation in Smooth Tubes,” ASME, J. Heat Transfer, 120(2), pp. 410–417. The multiple-flow-regime model of Garimella, S., Agarwal, A., and Killion, J. D., 2005, “Condensation Pressure Drop in Circular Microchannels,” Heat Transfer Eng., 26(3), pp. 1–8 for predicting condensation pressure drops in microchannels is used to predict the pertinent interfacial shear stresses required in this heat transfer model. The resulting heat transfer model predicts 86% of the data within ±20%.

Simulation on Linear-Motor-Driven Water Hydraulic Reciprocating Plunger Pump

2013 ◽  
Vol 842 ◽  
pp. 530-535 ◽  
Author(s):  
Zeng Meng Zhang ◽  
Yong Jun Gong ◽  
Jiao Yi Hou ◽  
Han Peng Wu
Keyword(s):  
Flow Rate ◽  
Deep Sea ◽  
High Efficiency ◽  
Control Method ◽  
Sea Water ◽  
Linear Motor ◽  
Low Flow ◽  
Flow Pulsation ◽  
Plunger Pump ◽  
Water Hydraulic

The water hydraulic reciprocating plunger pump driven by linear motor is suitable to deep sea application with high efficiency and variable control. Aiming to study the principle structure and working characteristics of the pump, two patterns of valve and piston distribution were designed. And the control method and the performance were analyzed by simulation based on the AMESim model. The results show that the pressure and flow pulsation of piston type pump are much smaller than the valve type, even though the piston type is large in scale and works at low flow rate. Compared with a valve distribution tri-linear-motor reciprocating plunger pump (VDTLMP), as the flow rate of the piston distribution double linear motor reciprocating plunger pump (PDDLMP) is decreased from 36.7 L/min to 21.2 L/min theoretically, the pressure pulsation amplitude is decreased from 46% to 2%, and the flow pulsation rate is also decreased from 0.266 to 0.007. These results contribute to the research on deep-sea water hydraulic power pack and direct drive pump with high efficiency and energy conservation.

A Meanline Model for Impeller Flow Recirculation

2008 ◽  
Author(s):  
Xuwen Qiu ◽  
David Japikse ◽  
Mark Anderson
Keyword(s):  
Flow Rate ◽  
Recirculation Zone ◽  
Reverse Flow ◽  
Low Flow ◽  
Suction Surface ◽  
Blade Loading ◽  
Flow Recirculation ◽  
Impeller Outlet ◽  
Active Flow ◽  
Low Flow Rate

Flow recirculation at the impeller inlet and outlet is an important feature that affects impeller performance, especially the power consumption at a very low flow rate. Although the mechanisms for this flow phenomenon have been studied, a practical model is needed for meanline modeling of impeller off-design performance. In this paper, a meanline recirculation model is proposed. At the inlet, the recirculation zone acts as area blockage to relieve the large incidence of the active flow at a low flow rate. The size of the blockage is estimated through a critical area ratio of an artificial “inlet diffuser” from the inlet to throat. The intensity of the reverse flow can then be calculated by assuming a linear velocity profile of meridional velocity in the recirculation zone. At the impeller outlet, a recirculation zone near the suction surface is established to balance the velocity difference on the pressure and suction sides of the blade. The size and the intensity of the outlet recirculation zone is assumed related to blade loading, which can be evaluated based on flow turning and Coriolis force. A few validation cases are presented showing a good comparison between test data and prediction by the model.

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