Water Take-up Research Articles

Fabrication and Characterization of Baobab Pod (Adansoniadigitata) FiberReinforced Polyester Resin Composite

Baobab pod fibres were obtained from Sabo market in Zaria and sliced longitudinally, screened out from the baobab fruit, washed with water, dried under sun for fabrication and characterization. The fiber was extracted and treated with 5% NaOH solution. Important samples were fabricated with different fiber loading of 10wt%-30wt%. The samples were moulded using Hand Lay-up method followed by pressing and post cured at 60oC for 3 hours. The result showed tensile strength decreases as the loading of fiber increased from 20 wt% to 30 wt%. It was also observed that baobab composite has the highest tensile strength of 18.85 MPa at 20 wt% and least (16.45 MPa) at 15 wt%. The result also revealed the elongation at break increased from 20 wt% to 25 wt%. At 25wt% it has a maximum value (18.4%) elongation at break; at 30wt%. It was also observed that the density increased with increase in the fiber loading from 15wt% to 30wt% (1.23g/cm3 - 2g/cm3) respectively. At 15wt% shows a maximum water take-up of 6.53% while from 20 wt% to 30 wt%, Flexural strength increased from 10 wt% to 15 wt% (23.98MPa - 46.3Mpa). However, the bending stress decreases on increasing the fiber loading from 20-30 wt% (30.2 Mpa – 25.2 Mpa). The elastic nature of the composite generally increases with increased in fiber loading. This study, however recommend hybridization of baobab pod fiber with other natural fiber to investigate the mechanical and physical property of the hybrid composite for better result.

Switchable Asymmetric Water Transport in Dense Nanocomposite Membranes.

Directional water transport is technologically relevant in separation processes, functional clothing, and other applications. While asymmetric water transport characteristics are a vital feature of leaf cuticles, examples of artificial membranes that display this effect are limited. Here, we report compositionally asymmetric membranes that are based on hydrophobic poly(styrene)-block-poly(butadiene)-block-poly(styrene) (SBS) and hydrophilic poly(vinyl alcohol) (PVA) nanofibers and display directional water transport when a high relative humidity (RH) gradient is applied. This effect is caused by the asymmetric structure of the membrane and the fact that the water permeability of PVA depends on the water pressure applied and the extent of plasticization that it causes. The transport characteristics can be tuned by varying the composition of the membranes. Such materials with switchable asymmetric water transport may be useful for smart packaging applications in which the take-up or release of water is regulated as needed.

Investigating the influence of pigmentation on the electrolyte transport properties of organic coatings using ORP-EIS

In this work, the correlation between electrolyte transport properties and the variation of pigment volume concentration (PVC) in a series of organic coatings is explored. Using an odd random phase electrochemical impedance spectroscopy (ORP-EIS) approach, the diffusion of ions independent from water take-up is analysed. A higher PVC resulted in a more homogeneous coating morphology, which could be associated with a faster diffusion of ions following a Fickian regime and enhanced water uptake. In the case of lower pigment loading, the obtained heterogenous morphology of the coating introduced new challenges to the physical interpretation of the proposed electrochemical equivalent circuit.

Modification of Irind Mine Pumice Surface

In the last decade, a continuous increasing research activity is focused on the surface modification of natural porous materials for the efficient removal of oil contaminants from water. A continuous in-situ oil/water separation technique for oil spill cleanup had been designed using surface modified Irind mine pumice as a sorbent. Irind mine pumice is an aluminosilicate rock, with well-developed porosity, mechanical strength, high buoyancy, chemically inert and eco-friendly, therefore it must exhibit certain water-and oil absorption capacities. The modified pumice absorbs a broad variety of oils and organic solvents with high oil absorption capacity and negligible water take-up at both static and dynamic conditions. Irind mine pumice have been used with grain sizes ranging from 2.5 ... 5.0 mm. Oligomethylhydride siloxane is used as a modifier.

Mutual promotion between aerosol particle liquid water and particulate nitrate enhancement leads to severe nitrate-dominated particulate matter pollution and low visibility

Abstract. As has been the case in North America and western Europe, the SO2 emissions have substantially reduced in the North China Plain (NCP) in recent years. Differential rates of reduction in SO2 and NOx concentrations result in the frequent occurrence of particulate matter pollution dominated by nitrate (pNO3-) over the NCP. In this study, we observed a polluted episode with the particulate nitrate mass fraction in nonrefractory PM1 (NR-PM1) being up to 44 % during wintertime in Beijing. Based on this typical pNO3--dominated haze event, the linkage between aerosol water uptake and pNO3- enhancement, further impacting on visibility degradation, has been investigated based on field observations and theoretical calculations. During haze development, as ambient relative humidity (RH) increased from ∼10 % to 70 %, the aerosol particle liquid water increased from ∼1 µg m−3 at the beginning to ∼75 µg m−3 in the fully developed haze period. The aerosol liquid water further increased the aerosol surface area and volume, enhancing the condensational loss of N2O5 over particles. From the beginning to the fully developed haze, the condensational loss of N2O5 increased by a factor of 20 when only considering aerosol surface area and volume of dry particles, while increasing by a factor of 25 when considering extra surface area and volume due to water uptake. Furthermore, aerosol liquid water favored the thermodynamic equilibrium of HNO3 in the particle phase under the supersaturated HNO3 and NH3 in the atmosphere. All the above results demonstrated that pNO3- is enhanced by aerosol water uptake with elevated ambient RH during haze development, in turn facilitating the aerosol take-up of water due to the hygroscopicity of particulate nitrate salt. Such mutual promotion between aerosol particle liquid water and particulate nitrate enhancement can rapidly degrade air quality and halve visibility within 1 d. Reduction of nitrogen-containing gaseous precursors, e.g., by control of traffic emissions, is essential in mitigating severe haze events in the NCP.

Statistical analysis and parameterization of the hygroscopic growth of the sub-micrometer urban background aerosol in Beijing

The take-up of water of aerosol particles plays an important role in heavy haze formation over North China Plain, since it is related with particle mass concentration, visibility degradation, and particle chemistry. In the present study, we investigated the size-resolved hygroscopic growth factor (HGF) of sub-micrometer aerosol particles (smaller than 350 nm) on a basis of 9-month Hygroscopicity-Tandem Differential Mobility Analyzer measurement in the urban background atmosphere of Beijing. The mean hygroscopicity parameter (κ) values derived from averaging over the entire sampling period for particles of 50 nm, 75 nm, 100 nm, 150 nm, 250 nm, and 350 nm in diameters were 0.14 ± 0.07, 0.17 ± 0.05, 0.18 ± 0.06, 0.20 ± 0.07, 0.21 ± 0.09, and 0.23 ± 0.12, respectively, indicating the dominance of organics in the sub-micrometer urban aerosols. In the spring, summer, and autumn, the number fraction of hydrophilic particles increased with increasing particle size, resulting in an increasing trend of overall particle hygroscopicity with enhanced particle size. Differently, the overall mean κ values peaked in the range of 75–150 nm and decreased for particles larger than 150 nm in diameter during wintertime. Such size-dependency of κ in winter was related to the strong primary particle emissions from coal combustion during domestic heating period. The number fraction of hydrophobic particles such as freshly emitted soot decreased with increasing PM2.5 mass concentration, indicating aged and internal mixed particles were dominant in the severe particulate matter pollution. Parameterization schemes of the HGF as a function of relative humidity (RH) and particle size between 50 and 350 nm were determined for different seasons and pollution levels. The HGFs calculated from the parameterizations agree well with the measured HGFs at 20–90% RH. The parameterizations can be applied to determine the hygroscopic growth of aerosol particles at ambient conditions for the area of Beijing (ultrafine and fine particles) and the North China plain (fine particles).

ELECTRORESPONSIE BEHAVIOR OF POLYELECTROLYTE GELS (ACRYLIC ACID-CO-N-N' METHYLENE BISACRYLAMIDE) UNDER THE INFLUENCE OF ELECTRIC FIELD

Polymer gels which were synthesized from acrylic acid and N-N’ methylene bisacrylamide exhibited electrical sensitive behavior. Their swelling properties and electroresponsive behavior were studied. The results indicated that the water take-up ability of the hydrogel increased with the decreased N-N’ methylene bisacrylamide content within the network. The hydrogel membranes swollen in a neutral NaCl solution, bent toward the cathode under non-contact DC electric fields, and their bending speed and equilibrium strain increased with the increased of applied voltage. In addition, the effect of crosslinker concentration of N-N’ methylene bisacrylamide on bending behavior of the gels have been studied. The equilibrium strain decreased as the crosslinker concentration increased. By changing the direction of the applied potential cyclically, the hydrogel membranes exhibited good reversible bending behavior. The bending of the hydro gel membranes was initially explained by a bending theory of polyelectrolyte hydrogel based on the charge of osmotic pressure due to the ion concentration different between the inside and the outside of the network.

A short review on the effects of aerosols on visibility impairment

Ozone in the lower planetary boundary layer of the earth atmosphere is dangerous to people and vegetation, since it oxidizes natural tissue. The diminished in visibility is because of dispersing of sun based radiation by high convergences of anthropogenic aerosols. Visibility impairment is most prominent at high relative mugginess when the aerosols swell by the take-up of water to expand the cross sectional area for dispersing; this is the wonder known as haze. Haze has become a major air pollution challenge the aviation industry has to cope with in recent time. In this review, two major problems were spotted to be responsible for air disaster in any region of the world. While some developed countries had almost resolved the challenge of visibility impairment by seeking relevant solutions, most developing countries do not have a recovery plan. Therefore, the resolution of this major challenge may be the leverage for most developing nations to draw out a recovery plan.

Pore shape and sorption behaviour in mesoporous ordered silica films.

Mesoporous silica films templated by pluronic P123 were prepared using spin and dip coating. The ordered cylindrical structure within the films deforms due to shrinkage during calcination. Grazing-incidence small-angle X-ray scattering (GISAXS) measurements reveal that both the unit cell and the cross section of the pores decrease in size, mainly normal to the surface of the substrate, leading to elliptical cross sections of the pores with axis ratios of about 1:2. Water take-up by the pores upon changing the relative humidity can be monitored quantitatively by the shift in the critical angle of X-ray reflection as seen by the Yoneda peak.

Grape quality starts at the roots

Vine productivity and grape quality are closely related not only to external factor, such as climatic conditions and canopy management, but also to the relationships formed between the roots and the dynamic and variable properties of the soil. Root density and distribution are affected by rootstock genotype, soil texture, soil water and nutrient availability, soil aeration. Vineyard practices, like ploughing or manuring and composting, can partially modified soil characteristics that hinder the correct root development. In order to establish appropriate vineyard management practices that focus on the health of the root system, it is crucial to understand their rhythms of growth and absorption. It is important to remember that root development is cyclical, with annual growth peaks which are not synchronous with above-ground growth and fruit ripening. The periodic growth of new root structures is aimed both at increasing overall root exploration range and at replacing senescent structures. Absorption of minerals, however, occurs subsequent to start of vine growth, inasmuch as in its initial stages of growth, the vine depends strictly on reserves accumulated over the preceding season by the permanent organs. This seasonal development should be taken into account for appropriate fertilizer application. A desired natural distribution of a root system is characterized by an upper layer (feeder roots) primarily involved in the uptake of nutritive elements and the lower one (sinker roots) dedicated to water take-up in periods of need. This paper focuses on the soil factors that interact with vine root development and it highlights the relevance of the study of root physiology for improving vine productivity.

Continuous oil–water separation with surface modified sponge for cleanup of oil spills

A continuous in situ oil–water separation technique for cleanup of oil spills has been designed using surface modified polyurethane (PU) sponges as sorbents. By connecting PU sponges to a vacuum pump, they can continuously separate various kinds of oil and organic pollutant, including engine oil, diesel oil, peanut oil, liquid paraffin and hexane, from the surface of water with negligible water take-up. The sorbents used in the technique were prepared by dip-coating commercial PU sponges with TiO2 sol and n-octadecylthiol successively. After surface modification, the sponges change from hydrophilic to superhydrophobic and superoleophilic surface with the water contact angle measured to be 152°. The as-prepared sponges absorb a broad variety of oils and organic solvents with high oil absorption capacity (80–110 g g−1) and negligible water take-up at both static and dynamic conditions. The success of the continuous in situ oil–water separation technique is based on the excellent oil–water selectivity and oil adsorption capacity of the modified sponges.

Sulfoacetic acid modifying poly(vinyl alcohol) hydrogel and its electroresponsive behavior under DC electric field

A strong electrolyte hydrogel was prepared by modifying poly (vinyl alcohol) hydrogel with sulfoacetic acid (SA–PVA). Its swelling properties, mechanical properties, and electroresponsive behavior in Na2SO4 solutions were studied. The results indicated that the water take-up ability of the hydrogel decreased with the increasing ionic strength of Na2SO4 solution. The Young’s modulus, elongation at break and tensile strength of the hydrogel swollen in deionized water are 1.247 MPa, 187% and 2.2 MPa, respectively. The hydrogel swollen in a Na2SO4 solution bent towards the cathode under non-contact dc electric fields, and its bending speed and equilibrium strain increased with increasing applied voltage. There is a critical ionic strength of 0.03 at which the maximum equilibrium strain of the hydrogel occurs. Also the bending behavior of hydrogel was not affected by the pH changes. By altering the direction of the applied potential cyclically, the hydrogel exhibited good reversible bending behavior. On this basis, a gel-worm was designed. Under a cyclically varying electric field (the period was 8 s, and the voltage ranged from −10 to 10 V), the walking speed was up to 15 cm min−1 in Na2SO4 solution with an ionic strength of 0.03.

Electroresponsive Behavior of Sulfonated Benzal Poly(vinyl alcohol) Hydrogel Under Direct-Current Electric Field

A novel sulfonated benzal poly(vinyl alcohol) (S-B-PVA) hydrogel was prepared by sulfonating benzal poly(vinyl alcohol) hydrogel with concentrated sulfuric acid, and its swelling properties, mechanical properties, and electroresponsive behavior in Na2SO4 solutions were studied. The results indicated that the water take-up ability of the hydrogel decreased with the increasing ionic strength of Na2SO4 solution. The Young's modulus, elongation at break and tensile strength of the hydrogel swollen in deionized water is 8.38 MPa, 22.2% and 3.14 MPa, respectively. The hydrogel swollen in Na2SO4 solution bent toward the cathode under non-contact dc electric fields, and its bending speed and equilibrium strain increased with the increasing of applied voltage. The electroresponsive behavior of the hydrogel was also affected by the electrolyte concentration of external Na2SO4 solution, and there is a critical ionic strength of 0.1 at which the maximum equilibrium strain of the hydrogel occurs. Under a cyclically varying electric field, the hydrogel exhibited a good reversible bending behavior.

Characterisation of a re-cast composite Nafion ® 1100 series of proton exchange membranes incorporating inert inorganic oxide particles

A series of cation exchange membranes was produced by impregnating and coating both sides of a quartz web with a Nafion ® solution (1100 EW, 10%wt in water). Inert filler particles (SiO 2, ZrO 2 or TiO 2; 5–20%wt) were incorporated into the aqueous Nafion ® solution to produce robust, composite membranes. Ion-exchange capacity/equivalent weight, water take-up, thickness change on hydration and ionic and electrical conductivity were measured in 1 mol dm −3 sulfuric acid at 298 K. The TiO 2 filler significantly impacted on these properties, producing higher water take-up and increased conductivity. Such membranes may be beneficial for proton exchange membrane (PEM) fuel cell operation at low humidification. The PEM fuel cell performance of the composite membranes containing SiO 2 fillers was examined in a Ballard Mark 5E unit cell. While the use of composite membranes offers a cost reduction, the unit cell performance was reduced, in practice, due to drying of the ionomer at the cathode.

Chemical Contamination Sensor for Phosphate Ester Hydraulic Fluids

The paper deals with chemical contamination monitoring in phosphate-ester-based hydraulic fluids using nondispersive infrared (NDIR) optical absorption. Our results show that NDIR monitoring allows detecting the take-up of water into such fluids and their hydrolytic disintegration as these become additionally stressed by Joule heating. Observations on the O–H stretching vibration band (3200–3800 ) are used for determining the free water content (0–1.5%) and the Total Acid Number (0–1 mgKOH/g). Both quantities can be assessed by monitoring the strength and the asymmetry of the O–H vibration band with regard to the free water absorption band centred around 3500 . As such optical parameters can be assessed without taking fluid samples from a pressurised hydraulic system, fluid degradation trends can be established based on regular measurements, before irreversible damage to the fluid has occurred. Therefore maintenance actions can be planned accordingly, which is very important for the airline, as unscheduled maintenance disturbs the flights organisation and often generates money loss.

Electroresponsive Behavior of Sodium Alginate-g-Poly (acrylic acid) Hydrogel Under DC Electric Field

A novel sodium alginate-graft-poly(acrylic acid) (SA-g-PAA) hydrogel was prepared by radical graft copolymerization with ammonium persulfate (APS) as initiator and N,N′-methylene-bis-(acrylamide) (MBAA) as crosslinker, and its swelling properties and electroresponsive behavior in aqueous NaCl solutions were studied. The results indicated that the water take-up ability of the hydrogel decreased with the increasing ionic strength of aqueous NaCl solution. The hydrogel swollen in a NaCl solution bent toward the cathode under non-contact dc electric fields, and its bending speed and equilibrium strain increased with the increasing of applied voltage. With the increasing of ionic strength of aqueous NaCl solution, the equilibrium strain of the hydrogel increased first and then decreased gradually. The maximum equilibrium strain occurs when the ionic strength of aqueous NaCl solution is 0.03. By changing the direction of the applied potential cyclically, the hydrogel exhibited good reversible bending behavior.

Preparation and characterization of fibroin/hyaluronic acid composite scaffold

Hyaluronic acid (HA) was added into fibroin solution to prepare fibroin-based porous composite scaffolds. HA exhibited important effects on pore formation and hydrophilicity of fibroin-based scaffold. The aqueous-fibroin/HA scaffolds had highly homogeneous and interconnected pores with porosity of above 90% and controllable pore size ranging from 123 to 253 μm. The water take-up of fibroin/HA scaffolds increased significantly with the increase of HA content. Containing HA at a defined content range, such as 3–6%, fibroin-based scaffolds’ affinity to primary neural cells was improved. In 6%HA/fibroin scaffolds, neurosphere-forming cell migrated from their original aggregate and adhered tightly to the surface of scaffolds.

Interaction of water with bioactive glass surfaces

The bioactivity of bioactive glasses is related to their dissolution in the presence of body fluid, or water. The dissolution process involves disruption of the tetrahedral network structure through the formation of silanol groups on the take-up of water by bioactive glasses. Molecular dynamics simulations show that the dissolution energy varies considerably depending on the nature and environment of the Si–O–Si bond being broken. However, no obvious correlation with bioactivity is observed, suggesting that although the network disruption is a necessary process, it is not rate determining.

Characterization of germination with physical parameters: correlation of relative mass and density as an indicator function of the germination of European Turkey oak acorn

During germination of European Turkey oak acorn (Quercus cerris L.), a linear relationship was established between mass and density. Water take-up induced by osmotic pressure of imbibition was established to be independent of the volume of the acorn. Development of the germinating acorn can be characterized by its physical parameters of relative mass (the mass of the germinating acorn divided by its mass at the beginning of germination) and density. Linear correlation between the increment of relative mass and the decrease in density reveals an important property of the germinating acorn, namely that the slopes of the straight lines fitted to the data pairs of relative mass and density can statistically be considered as a constant. On the basis of this finding, the germinating acorns having the same values of relative mass and density can be grouped into the same developmental stage.

Cucurbits under protected cultivation

Cucurbits under protected cultivation