scholarly journals Modeling and Simulation of Fabricated Graphene Nanoplates/Polystyrene Nanofibrous Membrane for DCMD

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2987 ◽  
Author(s):  
Ahmad Abdullah ◽  
Abdulaziz Al-Qahatani ◽  
Mohammed Alquraish ◽  
Colin Bailey ◽  
Ahmed El-Shazly ◽  
...  
Keyword(s):  
Contact Angle ◽  
Composite Membrane ◽  
Pure Water ◽  
Weight Percent ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Hot Water ◽  
Hydrophobic Nature ◽  
Porosity Characterization ◽  
Graphene Nanoplates

Membrane distillation is an active technique that provides pure water with very good rejection and could be applied to water of extremely high salinity. The low productivity of membrane distillation needs intensive efforts to be competitive with other desalination techniques. In this current study, a composite (PS/GNP) membrane, which is composed of polystyrene (PS) based and 0.25% weight percent graphene nanoplates (GNP) has been fabricated via electrospinning and compared with the blank PS membrane. SEM, FTIR, contact angle and porosity characterization have been performed, and the results show that the validity of the predefined conditions, and the contact angle of the composite membrane, which is found to be 91.68°, proved the hydrophobic nature of the composite membrane. A numerical simulation using Ansys 2020 software has been introduced to study the performance of the fabricated composite membrane when used in direct contact membrane distillation (DCMD). The numerical model has been validated with experimental work from the literature and showed an excellent match. The blank PS and composite PS/GNP membranes have been investigated and compared at different operating conditions, i.e., hot water supply temperature and system flow rate. The results show that the composite PS/GNP membrane outperforms the blank PS membrane at all studied operating conditions.

Morphological Study of Fabricated PVDF Based Hydrophobic Membrane for Different Additives and Coagulation Bath Temperature

2021 ◽  
Vol 18 (3) ◽  
pp. 39-47
Author(s):  
Meenakshi Yadav ◽  
Sushant Upadhyaya ◽  
Kailash Singh ◽  
Manish Vashishtha
Keyword(s):  
Contact Angle ◽  
Water Content ◽  
Temperature Difference ◽  
Synergistic Effects ◽  
Weight Percent ◽  
Membrane Distillation ◽  
Coagulation Bath ◽  
Hydrophobic Membrane ◽  
Sem Micrograph ◽  
Dope Solution

The demand of membrane distillation (MD) has increased since last few decades for numerous applications. The membrane used in MD is hydrophobic; therefore, the focus has been emphasised on the development of a suitable membrane with desired microstructure. In this study, the flat sheet hydrophobic membrane of suitable properties has been casted with various additives such as water, ethane-di-ol, and propan-2-ol in dope solution using a non-solvent induced phase separation (NIPS) technique. The effect of water content in dope solution has been studied on casted membrane porosity and contact angle. The maximum contact angle and porosity were found to be 96° and 53.23% at 4 weight percent of water content in dope solution of PVDF polymer and di.methyl.acetamide as solvent. It was found that SEM micrograph when ethane-di-ol and propan-2-ol are used as an additive shows more finger-like pores and nodules, respectively, in the microstructure of the casted membrane. Furthermore, synergistic effects using water with other additives were also identified using SEM micrograph of casted membrane and it was observed that water with ethane-di-ol and propan-2-ol form contact angle of 98° and 105°, respectively, for 2 weight percent each additive in dope. In this study, the membrane was also cast by dissolving PVDF powder in di.methyl.acetamide solvent with lithium chloride and the effect of the temperature difference between coagulation bath and film temperature was investigated using an SEM micrograph. Overall, it was found that water content and temperature difference aid in developing hydrophobic porous membrane of desired properties for MD applications.

scholarly journals Experimental Investigation of Fabricated Graphene Nanoplates/Polystyrene Nanofibrous Membrane for DCMD

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3499
Author(s):  
Ahmad Abdullah ◽  
Abdulaziz Al-Qahatani ◽  
Mohammed Alquraish ◽  
Colin Baily ◽  
Salah El-Mofty ◽  
...  
Keyword(s):  
Composite Membrane ◽  
Positive Impact ◽  
Composite Membranes ◽  
Weight Percent ◽  
Membrane Distillation ◽  
Vital Role ◽  
Base Polymer ◽  
Stable Performance ◽  
Average Flux ◽  
Overall Performance

In recent decades, the fabrication of composite membranes using nanoparticles has played a vital role in membrane distillation (MD) technique. It could make available membranes with superior characteristics as excellent candidates for MD technique. The most well-known obstacles regarding the MD method are the low productivity and high cost. Thus, fabricating membranes with superior properties is a significant challenge. In the current study, a composite membrane has been fabricated using 0.25, 0.5, and 0.75 weight percent (wt.%) of graphene nanoparticles (GNPs) with polystyrene (PS) as a base polymer and characterized using SEM, FTIR, and contact angle. The characterization results prove the successful fabrication using electrospinning and the validity of the fabricated membranes to be applied to direct contact membrane distillation (DCMD). In addition, a DCMD experimental setup has been designed to examine the performance of the fabricated membranes and compare the performance of blank PS with composite PS/GNPs membranes. The results show that all fabricated membranes produced an approximately similar average flux of about 10 kg/m2 h, while the highest GNPs wt.% showed the highest salt rejection. Accordingly, this composite membrane has been examined at different operating parameters and showed stable performance. Moreover, feed temperature and the rate of flow have a positive impact on the overall performance of the DCMD.

scholarly journals A contact angle study of different greywater sources with hydrophobic membranes

2020 ◽  
Vol 55 (3) ◽  
pp. 310-326
Author(s):  
Mohammad Ramezanianpour ◽  
Muttucumaru Sivakumar ◽  
Natalie Osborn ◽  
Ying Zhang ◽  
Hakim Kawa
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Pure Water ◽  
Membrane Distillation ◽  
Hydrophobic Membrane ◽  
Flat Sheet ◽  
Hydrophobic Membranes ◽  
Different Types ◽  
The Impact ◽  
Surface Tension Forces

Abstract The wetting phenomenon is a major problem in the membrane distillation (MD) process, and it is the main reason that limits MD being used in wastewater reclamation. Active surfactant in the detergents reduces the contact angle between the liquid and the hydrophobic membrane surface, which could result in wetting. Extensive laboratory research was conducted using commercial hydrophobic flat-sheet membranes to identify the impact of anionic surfactants and surface tension forces on these membranes. The aim of this paper is to find a suitable membrane for pure water production from greywater using MD, as well as to provide a relationship between surfactant concentration and the contact angle for different types of membrane. The absorbance of each sample was measured by a spectrophotometer prior to the contact angle test on four different types of hydrophobic membranes. It was concluded that the polypropylene membrane would be unsuitable for the treatment of greywater directly due to the loss of surface tension forces upon the addition of an anionic surfactant. However, the polytetrafluoroethylene membrane could be effective in this process while the concentration of surfactant in the feed source is kept constant. The results from the experimental tests proposed a relationship between the contact angle of a water droplet on the surface of a flat-sheet membrane and the concentration of surfactant in the solution.

scholarly journals Powdered activated carbon (PAC) – vacuum-assisted air gap membrane distillation (V-AGMD) hybrid system to treat wastewater containing surfactants: Effect of operating conditions

2020 ◽  
Vol 26 (5) ◽  
pp. 200377-0
Author(s):  
Yusik Kim ◽  
Yongjun Choi ◽  
Jihyeok Choi ◽  
Sangho Lee
Keyword(s):  
Activated Carbon ◽  
Pure Water ◽  
Membrane Distillation ◽  
Air Gap ◽  
Powdered Activated Carbon ◽  
Operating Conditions ◽  
Synthetic Wastewater ◽  
Air Gap Membrane Distillation ◽  
Short Period ◽  
Membrane Wetting

Membrane distillation (MD), which uses hydrophobic porous membranes with a temperature gradient to produce pure water, has the potential to treat high-salinity wastewater. However, it cannot directly treat wastewater containing surfactants, which lower the surface tension and thus result in membrane wetting. To overcome this limitation, this study proposed a hybrid process consisting of powdered activated carbon (PAC) adsorption and MD, where PAC removes the surfactants in the wastewater to alleviate the wetting of the MD membranes. A bench-scale vacuum-assisted air gap MD (V-AGMD) equipment was adopted for the treatment of synthetic wastewater containing inorganic salts and surfactants. The conductivity of the permeate from V-AGMD was continuously monitored to detect membrane wetting. Without the use of PAC, the MD membrane was wetted within a short period, which decreased as the surfactant concentration increased. On the other hand, the addition of PAC retards the onset of wetting even at higher surfactant concentrations. The effectiveness of the PAC addition to the MD system on wetting control was examined under various conditions to elucidate its mechanism.

Application of the Buckingham ∏ theorem to model multiple effect vacuum membrane distillation

2021 ◽  
pp. 1-40
Author(s):  
Abdullah Mohammed ◽  
Jamel Orfi ◽  
Hany Al-Ansary ◽  
Emadadeen Ali
Keyword(s):  
Performance Indicators ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Hot Water ◽  
Vaporization Enthalpy ◽  
Design Parameters ◽  
Recovery Ratio ◽  
Actual Behavior ◽  
Dimensionless Parameters ◽  
Output Ratio

Abstract This study aims to develop a dimensionless model of the V-MEMD performance indicator through which a preliminary prediction of the most critical performance indicators can be attained. Buckingham ∏ theorem was utilized to define dimensionless parameters that allow the predicted relationships associating independent input parameters to describe the essential performance indicators of the V-MEMD system. The obtained compact model reduces the design parameters from ten to two effective dimensionless parameters to realize the realistic and actual behavior of the designated system. The self-sustained model stands as a short-cut tool for design and performance analysis avoiding time consuming experimentations and/or complicated theoretical models. The compatibility of the generated model is assessed by matching the expected response of output dimensionless parameters (e.g., recovery ratio, R, and gain output ratio, GOR) to variation in pressure ratio and cooling process. The model is validated with other works, and discrepancies are remarked to be within ±10% and ±25% for recovery ratio and gain output ratio, respectively. Furthermore, the specific thermal energy consumption, STEC is correlated to GOR assuming constant vaporization enthalpy and density of the distillate water. The correlation can predict STEC within 5% accuracy over different operating conditions for the supplied hot water.

scholarly journals Numerical Investigation of Fabricated MWCNTs/Polystyrene Nanofibrous Membrane for DCMD

Polymers ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 160
Author(s):  
Asmaa Elrasheedy ◽  
Mohammed Rabie ◽  
Ahmed El-Shazly ◽  
Mohamed Bassyouni ◽  
S.M.S. Abdel-Hamid ◽  
...  
Keyword(s):  
Contact Angle ◽  
Water Contact Angle ◽  
Composite Membrane ◽  
Composite Membranes ◽  
Membrane Distillation ◽  
Nanofibrous Membrane ◽  
Permeate Flux ◽  
Water Contact ◽  
Static Water Contact Angle ◽  
Static Water

The effect of compositing multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) to fabricate nanofibrous membrane by electrospinning technique and comparing the direct contact membrane distillation (DCMD) performance of the blank and composite membranes is evaluated numerically. Surface morphology of both the pristine and the composite membrane was studied by SEM imaging while the average fiber diameter and average pore size were measured using ImageJ software. Static water contact angle and porosities were also determined for both membranes. Results showed significant enhancement in both the hydrophobicity and porosity of the composite membrane by increasing the static water contact angle from 145.4° for the pristine PS membrane to 155° for the PS/MWCNTs composite membrane while the porosity was increased by 28%. Simulation results showed that at any given feed inlet temperature, the PS/MWCNTs membrane have higher permeate flux and better overall system performance.

Wetting of glass surface using natural surfactants

2020 ◽  
Vol 12 ◽  
Author(s):  
Nihar Ranjan Biswal
Keyword(s):  
Contact Angle ◽  
Glass Surface ◽  
Pure Water ◽  
Amyl Alcohol ◽  
Synthetic Surfactant ◽  
Wide Range ◽  
Different Types ◽  
Natural Surfactants ◽  
Triton X ◽  
Solid Liquid

Background: Surfactant adsorption at the interfaces (solid–liquid, liquid–air, or liquid–liquid) is receiving considerable attention from a long time due to its wide range of practical applications. Objective: Specifically wettability of solid surface by liquids is mainly measured by contact angle and has many practical importances where solid–liquid systems are used. Adsorption of surfactants plays an important role in the wetting process. The wetting behaviours of three plant-based natural surfactants (Reetha, Shikakai, and Acacia) on the glass surface are compared with one widely used nonionic synthetic surfactant (Triton X-100) and reported in this study. Methods: The dynamic contact angle study of three different types of plant surfactants (Reetha, Shikakai and Acacia) and one synthetic surfactant (Triton X 100) on the glass surface has been carried out. The effect of two different types of alcohols such as Methanol and amyl alcohol on wettability of shikakai, as it shows little higher value of contact angle on glass surface has been measured. Results: The contact angle measurements show that there is an increase in contact angle from 47° (pure water) to 67.72°, 65.57°, 68.84°, and 68.79° for Reetha, Acacia, Shikakai, and Triton X-100 respectively with the increase in surfactant concentration and remain constant at CMC. The change in contact angle of Shikakai-Amyl alcohol mixtures are slightly different than that of methanol-Shikakai mixture, mostly there is a gradual increase in contact angle with the increasing in alcohol concentration. Conclusion: There is no linear relationship between cos θ and inverse of surface tension. There was a linear increase in surface free energy results with increase in concentration as more surfactant molecules were adsorbing at the interface enhancing an increase in contact angle.

scholarly journals The Soil Organic Matter in Connection with Soil Properties and Soil Inputs

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 779
Author(s):  
Václav Voltr ◽  
Ladislav Menšík ◽  
Lukáš Hlisnikovský ◽  
Martin Hruška ◽  
Eduard Pokorný ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Texture ◽  
Management Practices ◽  
Soil Depth ◽  
Operating Conditions ◽  
Hot Water ◽  
Natural Soil ◽  
Soil Productivity ◽  
Linear Regression Models

The content of organic matter in the soil, its labile (hot water extractable carbon–HWEC) and stable (soil organic carbon–SOC) form is a fundamental factor affecting soil productivity and health. The current research in soil organic matter (SOM) is focused on individual fragmented approaches and comprehensive evaluation of HWEC and SOC changes. The present state of the soil together with soil’s management practices are usually monitoring today but there has not been any common model for both that has been published. Our approach should help to assess the changes in HWEC and SOC content depending on the physico-chemical properties and soil´s management practices (e.g., digestate application, livestock and mineral fertilisers, post-harvest residues, etc.). The one- and multidimensional linear regressions were used. Data were obtained from the various soil´s climatic conditions (68 localities) of the Czech Republic. The Czech farms in operating conditions were observed during the period 2008–2018. The obtained results of ll monitored experimental sites showed increasing in the SOC content, while the HWEC content has decreased. Furthermore, a decline in pH and soil´s saturation was documented by regression modelling. Mainly digestate application was responsible for this negative consequence across all soils in studied climatic regions. The multivariate linear regression models (MLR) also showed that HWEC content is significantly affected by natural soil fertility (soil type), phosphorus content (−30%), digestate application (+29%), saturation of the soil sorption complex (SEBCT, 21%) and the dose of total nitrogen (N) applied into the soil (−20%). Here we report that the labile forms (HWEC) are affected by the application of digestate (15%), the soil saturation (37%), the application of mineral potassium (−7%), soil pH (−14%) and the overall condition of the soil (−27%). The stable components (SOM) are affected by the content of HWEC (17%), soil texture 0.01–0.001mm (10%), and input of organic matter and nutrients from animal production (10%). Results also showed that the mineral fertilization has a negative effect (−14%), together with the soil depth (−11%), and the soil texture 0.25–2 mm (−21%) on SOM. Using modern statistical procedures (MRLs) it was confirmed that SOM plays an important role in maintaining resp. improving soil physical, biochemical and biological properties, which is particularly important to ensure the productivity of agroecosystems (soil quality and health) and to future food security.

scholarly journals Experimental Comparison of Innovative Composite Sorbents for Space Heating and Domestic Hot Water Storage

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 476
Author(s):  
Vincenza Brancato ◽  
Larisa G. Gordeeva ◽  
Angela Caprì ◽  
Alexandra D. Grekova ◽  
Andrea Frazzica
Keyword(s):  
Silica Gel ◽  
Xrd Analysis ◽  
Complete Characterization ◽  
Operating Conditions ◽  
Hot Water ◽  
Experimental Comparison ◽  
Space Heating ◽  
Calorimetric Analysis ◽  
Domestic Hot Water ◽  
Composite Sorbents

In this study, the development and comparative characterization of different composite sorbents for thermal energy storage applications is reported. Two different applications were targeted, namely, low-temperature space heating (SH) and domestic hot water (DHW) provision. From a literature analysis, the most promising hygroscopic salts were selected for these conditions, being LiCl for SH and LiBr for DHW. Furthermore, two mesoporous silica gel matrixes and a macroporous vermiculite were acquired to prepare the composites. A complete characterization was performed by investigating the porous structure of the composites before and after impregnation, through N2 physisorption, as well as checking the phase composition of the composites at different temperatures through X-ray powder diffraction (XRD) analysis. Furthermore, sorption equilibrium curves were measured in water vapor atmosphere to evaluate the adsorption capacity of the samples and a detailed calorimetric analysis was carried out to evaluate the reaction evolution under real operating conditions as well as the sorption heat of each sample. The results demonstrated a slower reaction kinetic in the vermiculite-based composites, due to the larger size of salt grains embedded in the pores, while promising volumetric storage densities of 0.7 GJ/m3 and 0.4 GJ/m3 in silica gel-based composites were achieved for SH and DHW applications, respectively.

scholarly journals Evaluation of a High-Performance Solar Home in Loveland, Colorado

2006 ◽  
Vol 129 (2) ◽  
pp. 226-234
Author(s):  
Robert Hendron ◽  
Mark Eastment ◽  
Ed Hancock ◽  
Greg Barker ◽  
Paul Reeves
Keyword(s):  
High Performance ◽  
Energy Savings ◽  
High Efficiency ◽  
Building Envelope ◽  
Operating Conditions ◽  
Hot Water ◽  
Space Heating ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water

Building America (BA) partner McStain Neighborhoods built the Discovery House in Loveland, CO, with an extensive package of energy-efficient features, including a high-performance envelope, efficient mechanical systems, a solar water heater integrated with the space-heating system, a heat-recovery ventilator (HRV), and ENERGY STAR appliances. The National Renewable Energy Laboratory (NREL) and Building Science Consortium conducted short-term field-testing and building energy simulations to evaluate the performance of the house. These evaluations are utilized by BA to improve future prototype designs and to identify critical research needs. The Discovery House building envelope and ducts were very tight under normal operating conditions. The HRV provided fresh air at a rate of about 35L∕s(75cfm), consistent with the recommendations of ASHRAE Standard 62.2. The solar hot water system is expected to meet the bulk of the domestic hot water (DHW) load (>83%), but only about 12% of the space-heating load. DOE-2.2 simulations predict whole-house source energy savings of 54% compared to the BA Benchmark (Hendron, R., 2005 NREL Report No. 37529, NREL, Golden, CO). The largest contributors to energy savings beyond McStain’s standard practice are the solar water heater, HRV, improved air distribution, high-efficiency boiler, and compact fluorescent lighting package.

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