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There have been few studies in Japan on the effects of the application of lime materials, especially in regard to the soil calcium-to-magnesium ratio (Ca:Mg). The aim of this study was to explore t...

Wide-area surveys have been conducted on a prefectural or regional scale in Japan for revealing soil chemical properties affecting soybean yield. However, they vary by region and thus, the common c...

The conversion between the two different systems, ISSS and FAO/USDA, of particle size distribution and soil texture classification is useful to characterize soil physical properties and usage of ea...

Redox cycle of iron (Fe) is the central process in the biogeochemistry of paddy field soil. Although Fe(II)-oxidizing process is mediated by both abiotic and biotic reactions, microorganisms involv...

Recently, forward osmosis (FO) is attracting research attention once again. In a FO process, it is important to develop a draw solution (DS) with a high osmotic pressure and low solute leakage. In this study, thermoresponsive star-shaped oligomers with a glycerol backbone were developed as new draw solutes for FO. A series of glycerol-oligo(ethylene oxide)-block-oligo(butylene oxide) (GEB) oligomers were systematically designed and synthesized. The average degrees of polymerization of ethylene oxide (EO; m) and butylene oxide (BO; n) units of GEmBn were varied to control the hydrophilic/hydrophobic balance of the molecule. Aqueous solutions of GEBs were evaluated in terms of their osmotic pressures, phase diagrams, and viscosities. Most of them showed a lower critical solution (LCST)-type phase separation at temperatures below 60 °C. The osmotic pressure of 68 wt% GE7B3 (concentration of the dense phase after phase separation at 60 °C) was 74 bar, about 2.6 times higher than that of seawater. Moreover, the leakage of GE7B3 was much lower than that of conventional draw solutes. The osmotic pressure of the dilute phase of a GE7B3 solution at 60 °C was less than 2 bar, implying reduced energy consumption during post-processing by low-pressure reverse osmosis to collect pure water.

Thermo-responsive ionic liquids (ILs) were examined as draw solutions in forward osmosis (FO) membrane process. We synthesized several ILs to understand the relationship between the hydrophilicity/hydrophobicity balance of ILs and the osmolality and phase diagram of the IL aqueous solutions. An increase in the hydrophobicity led to a decrease in the osmolality because of the formation of IL-based aggregates in water. At the critical aggregation concentration (CAC), the osmolality was drastically changed. Above the CAC, the water-rich phase appeared after liquid–liquid separation at elevated temperature. The osmolality, phase separation temperature, viscosity, and water-drawing ability of the IL-based draw solution could be controlled by controlling the chemical structure and hydrophilic/hydrophobic balance of ILs. The IL with small molecular weight and low viscosity showed the comparable water permeability as the NaCl aqueous solution and the possibility of repeated use. Prevention of the IL leakage through FO membrane is a future subject.

Chitosan, known as a most typical marine biological polymer, has a fruitful capability of biocompatible gel formation. Attempts of chitosan have been made to develop it from the multifaceted viewpoint of separation technology. The physicochemical properties of chitosan containing a lot of hydroxyl groups and reactive amino groups help to build the characteristic polymer networks. The deacetylation degree of chitosan is found as the most influential factor to regulate properties of chitosan hydrogels. The antibacterial activity of the chitosan membrane is one of its notable abilities because of its practical application. The chitosan, its derivatives, and the complex formation with other substances has been used for applications in filtration and membrane separation processes. Adsorption processes based on chitosan have been also developed widely. Moreover, complex of chitosan gel helps to immobilize adsorbent particles. The chitosan membrane immobilizing Prussian-Blue for cesium ion removal from the aqueous phase is one of the leading cases. To elaborate the adsorption behavior on the chitosan immobilizing adsorbent, the isothermal equilibrium and mass transfer characteristics can be discussed. The adsorption process using chitosan-based membranes in combination with filtration in a flow process is advantageous compared with the batch process. More advanced studies of chitosan aerogel and chitosan nanofibers have been proceeded recently, especially for adapting to water purification and air filtration.

We consider the large time behavior of the Navier-Stokes flow past a rigid body in $\mathbb{R}^n$ with $n\geq 3$. We first construct a small stationary solution possessing the optimal summability at spatial infinity, which is the same as that of the Oseen fundamental solution. When the translational velocity of the body gradually increases and is maintained after a certain finite time, we then show that the nonstationary fluid motion converges to the stationary solution corresponding to a small terminal velocity of the body as time $t\rightarrow\infty$ in $L^q$ with $q\in[n,\infty]$. This is called Finn's starting problem and the three-dimensional case was affirmatively solved by Galdi, Heywood and Shibata $(1997).$ The present paper extends their result to the case of higher dimensions. Even for the three-dimensional case, our theorem provides new convergence rate, that is determined by the summability of the stationary solution at infinity and seems to be sharp., 28 pages, Corrected typos, to appear in J. Math. Fluid Mech

This study experimentally and theoretically analyzed the performance of two types of large-scale hollow fiber (HF) forward osmosis (FO) modules for pressure retarded osmosis (PRO). The effects of operating conditions on the module performance of the 5-inch scale HF modules with a cross-wound HF configuration were investigated. A modified analytical model, based on the friction-concentration polarization (FCP) model, which combined the PRO theory with water flux and salt leakage, was proposed for PRO performance estimation. The theoretical results agreed within 9.7% deviation with the experimental results under all conditions. The energy efficiency of the HF PRO module was also theoretically derived. The power generation estimation for the 5-inch membrane module revealed that 10 to 15% of the energy could be recovered from the reverse osmosis seawater desalination process. However, some parts of the membrane could not be used efficiently inside the modules because of the non-optimal dimensions. Therefore, new types of modules, having shorter lengths and larger module diameters, were proposed and provided greater net energy output, as compared with the original module, due to the reduction of both the region where the water was not sufficiently permeated and the pressure drop inside the HF membrane.

The hydrothermal pretreatment of rice straw generates a liquid fraction that contains low concentrations of sugars, as well as fermentation inhibitors which are not favourable for efficient bioethanol production. For the development of a forward osmosis (FO) process to concentrate sugars and remove fermentation inhibitors, we fabricated polyamide-polysulfone (PA-PSf) membranes treated with NaClO solution. The NaClO treatment improved the water permeability (A value) and the permselectivity of fermentation inhibitors against sugars. Maximum separation of xylose from furfural and acetic acid was achieved when the treated membranes had A values of 5.5–7 L m−2 h−1 bar−1. Using an optimized membrane with A value of approximately 6 L m−2 h−1 bar−1, a liquid fraction from hydrothermally pretreated rice straw was concentrated in a one-step FO process to increase sugar concentrations and decrease fermentation inhibitor concentrations. The ethanol concentration and yield (ethanol/total sugar) by xylose-utilizing Saccharomyces cerevisiae reached 18.0 g/L and 0.40, respectively, which were much higher than those obtained with commercial FO membranes. These results clearly indicate the possibility of introducing a simple and low-cost FO process into bioethanol production from lignocellulosic biomass by incorporating NaClO treatment to FO membrane.

Water-soluble benzothiadiazole (BT)-based nanoparticles (NPs) with solvatochromic and thermoresponsive properties were synthesized by a one-pot procedure involving the self-assembly and selective cross-linking of a block copolymer composed of 4-bromophenyl vinyl sulfide and N-isopropylacrylamide. In situ Suzuki coupling reaction of the block copolymer with a BT-based diboronic acid afforded core cross-linked NP(BT)s having a BT-based acceptor unit between neighboring phenyl (weak donor) groups in the core. The cross-coupling polymerization of the BT-based diboronic acid and a dibromo compound in the block copolymer micelles provided NP([BT-Th]l)s or NP([BT-dTh]l)s with a π-conjugated BT-based acceptor/thiophene- or dithiophene-donor arrangement in the core, respectively. The emission of core cross-linked NPs could be tuned from blue to red by varying the solvent and the core structure. The effects of the core structure on the thermoresponsive properties were also investigated.

Membranes used for pressure-retarded osmosis (PRO) are required to be mechanically strong due to high external hydraulic pressures on the draw solution (DS) side. In this study, a series of nonwoven fabrics of varying thickness, density, and hydrophilicity were used to fabricate reinforced aliphatic polyketone (PK) membranes with excellent mechanical strength and pressure resistance. Three suitable nonwoven fabrics are selected based on the integrities of the PK layers formed on their surfaces. As a result, guidance for choosing suitable reinforcing materials for PK membranes is provided. We show that a PK-based thin-film-composite (TFC) membrane reinforced by an 11-μm-thick polyester (PET) nonwoven fabric provides a flux of 24.7 L m–2 h–1 (in “active layer facing feed solution”, AL-FS mode, 0.6 mol L–1 NaCl as the DS), while maintaining a pressure resistance of 28 bar. This membrane is shown to be capable of producing a power density of at least 6.1 W m–2 in PRO evaluation (with 0.6 mol L–1 NaCl).

This study was performed to investigate changes in available soil phosphate associated with temperature under submerged conditions and to explore the possibility for estimating those under submerge...

Effect of the supporting layer structures on antifouling properties of forward osmosis (FO) membranes in active-layer-facing-draw-solution (AL-DS) mode was investigated through a series of polyketone (PK) membranes prepared by controlling the concentration of the polymer casting solution, initial casting height, and solvent system. A double-skinned FO membrane was prepared by interfacial polymerization on the bottom surface of the PK membrane. The surface pore sizes, bulk porosities, water permeability and alginic acid sodium salt rejection properties of the prepared PK membranes were determined, and the surface roughness, membrane thickness, pure water permeability, salt permeability and FO performance of the PK-based FO membranes were characterized. The alginic acid sodium salt was used to evaluate the antifouling properties of the FO membranes in AL-DS mode. The effect of surface roughness (or surface pore size), membrane thickness, and structural parameter (S value) on the membrane fouling was investigated. The results indicate that decreasing both the surface pore size of the supporting layer and the membrane thickness effectively improves the membrane performance; that is, the membrane possesses both enhanced antifouling properties and water permeability. This work provides firm guidelines for the design of proper supporting layer structures for FO membranes with high performance in AL-DS (or pressure retarded osmosis, PRO) mode.

Water stress reduces soybean (Glycine max) yield in fields converted from clayey-soil rice (Oryza sativa) paddies to uplands (upland converted paddies [UCPs]). Subirrigation and/or allowing roots to penetrate to a deeper soil layer were expected to effectively mitigate water stress. Therefore, we examined the effects of subirrigation and slit tillage on mitigating water stress in clayey soils (52% clay) in UCPs. Four treatment experiments (subirrigation, slit tillage, subirrigation control, and slit tillage control) were conducted in each of three growing seasons, with sampling for yield analysis conducted in triplicate. Following conventional tillage, a slit tillage blade was used to cut 15-mm-wide vertical slits in the surface of the soil (cutting depth = 15–20 cm) and seeds were sown 15 mm from the cut lines. Subirrigation then occurred for approximately 21–47 days, from the end of the rainy season, when water table elevation was at 35 cm below ground. We found that subirrigation only resulted ...

Water soluble sulfur-rich nanoparticles (S-NPs) having the sulfur content of more than 80 wt% were synthesized using a self-assembled block copolymer structure comprising 4-bromophenyl vinyl sulfide (BPVS) and N-isopropyl acrylamide (NIPAM), and a site-selective cross-linking reaction in selective aqueous solution. The core cross-linking reaction of sodium polysulfide with 1,2,3-trichloropropane as a cross-linker in the presence of poly(BPVS-b-NIPAM) was conducted in water, in which the site selective reaction takes place inside the micelles. DLS analysis demonstrated the formation of stable S-NPs with uniform sizes, which could be controlled by the nature of the cross-linking agents and reaction conditions (Dh = 140–170 nm in CHCl3). UV-vis, fluorescence, and cyclic voltammetry measurements led to the optical and electrochemical properties derived from polysulfide units and incorporated cross-linked units in the resulting products, supporting the successful preparation of desired S-NPs. The S-NPs exhibited LCST behavior around 32 °C, which stems from the poly(NIPAM) shell.

A membrane process combining nanofiltraion (NF) and forward osmosis (FO) was developed for the sugar concentration with the aim of high bio-ethanol production from the liquid fraction of rice straw. The commercial NF membrane, ESNA3, was more adequate for removal of fermentation inhibitors (such as acetic acid) than the FO membrane, whereas the commercial FO membrane, TFC-ES, was more adequate for concentration of the sugars than the NF membrane. The liquid fraction was subjected to the following process: NF concentration with water addition (NF(+H2O))→enzymatic hydrolysis→FO concentration. This NF(+H2O)-FO hybrid process generated a total sugar content of 107g·L-1. Xylose-assimilating S. cerevisiae produced 24g·L-1 ethanol from the liquid fraction that was diluted 1.5-fold and then concentrated by the NF(+H2O)-FO hybrid process. The NF(+H2O)-FO hybrid process has the potential for optimized ethanol production from pretreated lignocellulosic biomass.

Forward osmosis (FO), driven by high osmotic pressure, was used for the first time for bioethanol production from lignocellulosic biomass. A commercial membrane, TFC-ES (Hydration Technology Innovation), was used and 3.6 M triethylamine (TEA) was chosen as the draw solution because the concentration ratio against a model xylose solution was similar to that achieved with 2.5 M NaCl. The liquid fraction of hot-water-pretreated rice straw was concentrated by using the FO membrane. The initial sugar concentration of 199 mM increased to 825 and 1612 mM after 48 and 72 h of FO concentration, respectively, and these values were much higher than those obtained from nanofiltration. Simultaneous saccharification and fermentation of the liquid fraction after 48 h of FO concentration by xylose-fermenting recombinant Saccharomyces cerevisiae produced 17.7 g/L of ethanol after 24 h fermentation. Thus, the FO process has tremendous potential to up-concentrate sugars obtained from lignocellulosic biomass.

In this study, we investigated the effect of the morphology of the support membrane on the forward osmosis (FO) flux and maximum hydraulic breaking pressure of thin-film composite (TFC) FO membranes for engineered osmosis applications. Eight types of porous support membranes were prepared using polyketone as a polymer material by changing the coagulation bath composition and initial casting height via the non-solvent induced phase separation method. The intrinsic membrane parameters of the prepared TFC FO membranes were determined from both reverse osmosis and FO experiments. The results revealed that there was a good correlation between the FO flux and the partial dense part morphology of the support layer, whereas the hydraulic breaking pressure strongly depended on the thickness of the entire support layer and the presence of large voids. This significant difference enabled the design of an optimal TFC FO membrane that exhibited both high FO flux as well as high pressure resistance. The prepared TFC FO membrane showed an FO flux of 24.8 L m− 2 h− 1 when tested in the active layer facing to feed solution mode using 0.6 M sodium chloride and deionized water as draw solution and feed solution, respectively, with a pressure resistance of 19 bar.

Jatropha curcas (Jatropha) is drought-resistant and produces seed oil that is suitable for biodiesel fuel production. During cultivation, Jatropha produces a large amount of non-oil biomass from fallen leaves and pruned branches; however, their utilization has been largely unexplored. In the present study, we evaluated the potential of Jatropha non-oil biomass as a feedstock for biochar that could be utilized as a soil modifier and fertilizer for sustainable farming. A total of 12 different Jatropha biochars were produced using a combination of three tissue types (leaf, trunk, and branch) and four pyrolysis temperatures (300, 400, 500, and 600 °C), and their physicochemical properties were comparatively analyzed. For each tissue type biochar, a general trend of increasing pH and electrical conductivity, and decreasing yield and cation exchange capacity was observed as the pyrolysis temperature increased. The leaf biochar had significantly lower carbon and higher nitrogen, phosphate, potassium, and magnesium contents than that of the other tissue biochars, whereas the trunk biochar had the highest calcium content among all the biochars. Except for the leaf biochar pyrolyzed at 300 °C, all biochars significantly improved the water holding capacity of silica sand applied at a 1%(w/w) concentration. Pearson’s correlation and principal component analyses highlighted a wide range of biochars with divergent physicochemical properties, which were characterized by nitrogen, phosphate, and magnesium richness in the leaf biochar; and calcium richness in the trunk biochar. Therefore, a specific combination of pyrolysis temperature and tissue type from Jatropha non-oil biomass could serve as a feedstock for tailor-made biochar products for various agronomic needs such as soil modifiers and fertilizers.

Forward osmosis (FO) has attracted attention in industry because of its low energy consumption and low fouling tendency. In this paper, the condensation of polyvinyl chloride (PVC) latex with FO as a pretreatment step prior to the final drying process was investigated. The effect of agitation speed, FO membrane type, and the NaCl concentration of the draw solution (DS) were evaluated. For the membrane performance, the water flux, NaCl flux, and total organic carbon (TOC) flux were evaluated. When the feed solution was sufficiently agitated, a PVC concentration of 75 wt% was achieved using model seawater as the DS. FO performance was experimentally compared with reverse osmosis (RO) performance using similar apparatus and the same water flux conditions. The TOC rejection in FO was higher than that in RO. Latex condensation using FO was characterized by a decrease in outlet water flux by cake-enhanced osmotic pressure, a decrease in inlet water flux by the capillary force resistance in the cake layer, and an increase in TOC rejection by the retarded forward diffusion of solutes. The control of cake-layer formation was important for the condensation of PVC latex by FO.

Temperature- and pH-sensitive nanoparticles having optoelectronic cores were synthesized by post-assembly cross-linking reaction of a block copolymer composed of poly(N-vinyl amine) and poly(N-isopropylacrylamide), which was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization. The self-assembly of the block copolymer in a selective solvent, followed by the site-selective cross-linking of poly(vinyl amine) segment with anthracene and thiophene dialdehydes, afforded stable and uniform core cross-linked nanoparticles having pH-sensitive imine linkages. As comparisons, the poly(vinyl amine) segment in the block copolymer was modified selectively with monoaldehyde derivatives to yield anthracene- and thiophene-functionalized block copolymers, which can form self-assembled micelles with optoelectronic cores in aqueous solutions. Temperature-dependent morphological changes and optical properties of the core cross-linked nanoparticles and the functionalized block copolymers were compared in selective and non-selective solvents, which were characterized by DLS, UV–vis, fluorescence, and CV measurements. The core cross-linked nanoparticles also exhibited pH-triggered disintegration. To the best of our knowledge, this is the first report on the comparison of two series of stimuli-responsive nanoparticles, in which the optoelectronic cores are formed by post-assembly cross-linking reaction with the dialdehyde derivatives and self-assembly of the functionalized block copolymers prepared with the monoaldehyde derivatives.

Previously, we presented a water treatment technology using microbubbles (MBs) in membrane filtration in order to reduce membrane fouling and to improve the filtration flux. In this study, we investigated the effect of foulants in this system. Water samples from five rivers and three model foulant solutions were used, and water quality indicators such as dissolved organic carbon (DOC), ultraviolet absorbance (E260), and specific UV absorbance (SUVA) of these solutions were analyzed. Correlations between the flux enhancement by MB and DOC, E260, and SUVA in the five river water samples indicated that MBs were effective for river water samples with fewer foulants, and that an increase in the amount of highly aromatic hydrophobic substances in the river reduced the MB effect. In the experiments using humic acid, guar gum, and bovine serum albumin (BSA) as model foulants, it was found that MBs enhanced the reduction of fouling from the initial stage in the cases of humic acid and guar gum, while in th...

The present study explores how microbubbles can improve membrane filtration by preventing membrane fouling. Microbubbles (MBs) 10–50 μm in diameter were generated by pumping the feed solution with air bubbles through a slit under high shear stress. Filtration of raw river water at pilot-plant scale confirmed that adding MBs to the feed solution does indeed reduce membrane fouling. The effect of MBs on the flux was examined under various conditions of filtration flux and experimental duration. MBs reduced fouling over both short and long (>1 month) time frames, and were also effective for cleaning the membrane. Thus, incorporating MBs into water for membrane filtration may reduce the costs and energy consumption associated with water treatment.

This study investigated the organic matter that causes fouling in the forward osmosis (FO) membrane filtration system used in wastewater concentration processes. The development of the fouling of FO membranes caused by actual municipal wastewater was compared with that of the fouling caused by solutions containing artificial foulants (i.e. Aldrich humic acid, bovine serum albumin, and sodium alginate). This comparison shows that the development of the fouling was underestimated when using the artificial foulants. The characteristics of the foulants were investigated using fluorescence excitation-emission matrix spectra and liquid chromatography-organic carbon detection analyses. The results obtained by these advanced analytical methods indicated that the so-called biopolymers (i.e. organic macromolecules mainly comprising polysaccharides and proteins) were the major components of the foulants. In contrast, hydrophobic organic matter, such as humic substances, was not a dominant component.

This study is performed in order to assess the molecular permeabilities of composite films of chondroitin sulfate C (CS) and chitosan (CHI) prepared by the hot press technique. Permeation behaviors are evaluated using horizontal diffusion cells and four substrates with different charges: methylene blue (MB), orange II (OR), l-tryptophan (Trp), and 4-methylumbelliferyl β-d-galactopyranoside (MUG). Permeability coefficients, diffusion coefficients, and partition coefficients are calculated from permeation curves. When MB and OR are used as the permeants, permeability coefficients in solutions with higher pH or ionic strength are greater than in those with lower pH or ionic strength. Permeability coefficients at pH 5.9 at which Trp carries zero net charge are as follows: Trp > MB ≈ MUG > OR. The diffusion coefficients and partition coefficients obtained indicate that CS/CHI films permeate these molecules based on a partition mechanism at lower pH and a pore model at higher pH. These characteristics appear to reflect the unique microenvironment of films consisting of polyion complexes of oppositely charged polysaccharides.