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This research was undertaken to evaluate the usability of ferric(III) hydroxide for phosphate removal from sewage. Batch adsorption experiments, partly fixed bed column experiments, were conducted to study the influence of various factors, competing anions and contact time on the adsorption of phosphate on ferric(III) hydroxide. Processing ferric iron in the form of akaganeite (β-FeOOH) greatly increased the adsorption capacity for phosphate. The optimum phosphate removal was observed in the pHeq ≤ 6.0. All results from this study demonstrate the potential usability of β-FeOOH as a good phosphate-selective adsorbent for the phosphate removal system for a sewage treatment plant. HIGHLIGHTS Recovery of phosphate from sewage and wastewater to control eutrophication.; To develop phosphate-selective absorbents.; The potential usability of β-FeOOH as phosphate-selective adsorbent.; β-FeOOH can be applied for the phosphate removal system.; The phosphate adsorption capacity was increased to β-FeOOH>PA rein>Fe(OH)3.

The surface of polypropylene (PP) fiber was modified by UV-induced graft polymerization of 1-vinylimidazole (Vim), followed by quaternization with iodomethane, sulfonation with chlorosulfonic acid, or loading of silver (Ag) nanoparticles to endow the surface with antibacterial properties. The modified PP fibers were characterized by FT-IR, SEM, and surface charge analyses. The antibacterial activity of the modified PP fibers was assessed against the Gram-negative and Gram-positive bacteria, Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus), respectively. The PP-g-Vim was greatly improved by loading of Ag nanoparticles (≥99.9%), quaternization (98.9–99.2%), or sulfonation (≥99.9%).

The objective of this study is to evaluate the applicability of adsorption models for predicting the properties of adsorbents. The kinetics of the adsorption of NO3− ions on a PP-g-AA-Am non-woven fabric have been investigated under equilibrium conditions in both batch and fixed bed column processes. The adsorption equilibrium experiments in the batch process were carried out under different adsorbate concentration and adsorbent dosage conditions and the results were analyzed using adsorption isotherm models, energy models, and kinetic models. The results of the analysis indicate that the adsorption occurring at a fixed adsorbate concentration with a varying adsorbent dosage occur more easily compared to those under a fixed adsorbent dosage with a varying adsorbate concentration. In the second part of the study, the experimental data obtained using fixed bed columns were fit to Bed Depth Service Time, Bohart–Adams, Clark, and Wolborska models, to predict the breakthrough curves and determine the column kinetic parameters. The adsorption properties of the NO3− ions on the PP-g-AA-Am non-woven fabric were differently described by different models for both the batch and fixed bed column process. Therefore, it appears reasonable to assume that the adsorption properties were dominated by multiple mechanisms, depending on the experimental conditions.

During solar salt production, large quantities of bittern, a liquid by-product containing high inorganic substance concentrations, are produced. The purpose of this research was to examine the utilization of waste bittern generated from salterns as a source for Mg production and as an absorbent for carbon dioxide (CO2) capture. The study was conducted in a sequential two-step process. At NaOH/Mg molar ratios of 2.70–2.75 and pH 9.5–10.0, > 99% Mg precipitation from the bittern was achieved. After washing with water, 100–120 g/L of precipitate containing 94% Mg(OH)2 was recovered from the bittern. At the optimum NH4OH concentration of 5%, 120 g of sodium bicarbonate precipitate per liter of bittern were recovered, which was equivalent to 63 g CO2 captured per liter of bittern. These results can be used to support the use of bittern as a resource and reduce economic losses during solar salt production.

The authors present the fabrication of electrospun nanofibers with antimicrobial properties by the UV-initiated grafting (photo-grafting) of 2-substituted vinylimidazoles onto nylon 6 nanofibers. The characterization was performed using IR spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM-EDX). The antimicrobial properties of the grafted electrospun nylon 6 nanofibers were evaluated against Escherichia coli and Staphylococcus aureus as model challenge microorganisms, using the dynamic shake flask method. All the grafted electrospun nylon 6 nanofibers exhibited excellent growth reduction of E. coli (99.94–99.99%) and S. aureus (99.55–99.99%). The electrospun nylon 6 nanofiber composites could be used twice before a decrease in antibacterial activity was observed. The study showed that electrospun nylon 6 nanofiber composites possess a potential for use to control pathogens in water.

The efficiency of microwave-assisted acid hydrolysis of seaweeds for the production of ethanol was investigated and its effect on hydrolysis into reducing sugar and fermentation into ethanol evaluated as compared with those by conventional heating. A brown seaweed, Laminaria japonica (10-100g/L) was hydrolysed under dilute acidic condition (0.5N , ) with two sorts of heating: microwave irradiation for and conventional heating for 10-60min. Microwave-assisted hydrolysis was shown to be more efficient. A similar range of reducing sugar and ethanol yields as with the conventional autoclave heating procedure() was observed, but it was obvious that production of ethanol from microwave-assisted hydrolysis had a 3 times faster reaction rate leading to very short production times, lower energy consumption/loss than from the conventional heating mode, and higher biomass loading without significant reducing ethanol yield, thus microwave-assisted acid hydrolysis is a potential alternative method for more effective hydrolysis of Laminaria japonica.

The aim of this study is to evaluate the applicability of adsorption models for understanding adsorption properties of adsorbents. For this study, the adsorption charateristics of NO3 by commercial anion exchange resin, PA-308, were investigated in bach process. The adsorption kinetic data for NO3 by anion exchange resin showed two stage process comprising a fast initial adsorption process and a slower second adsorption process. Both the pseudo-first-order kinetic model and the pseudo-second-order kinetic model could not be used to predict the adsorption kinetics of NO3 onto anion exchange resin for the entire sorption period. Only the fast initial portion (t≤ 20 min) of adsorption kinetics was found to follow pseudo-first-order kinetic model and controlled mainly by external diffusion that is very fast and high, whereas, the slower second portion (t > 20 min) of adsorption kinetics seems to be controlled by a second-order chemical reaction and by intraparticle diffusion.

In order to study the utilization of brown seaweed Laminaria japonica as an alternative renewable feedstock for bioethanol production, the properties of acid hydrolysis and ethanol fermentation were investigated. The acid hydrolysis enhanced the final yield of fermentable sugars, which led great increase of ethanol productivity. The maximum yield of reducing sugars reached 135 mg/g-dry Laminaria japonica after 1.0N sulfuric acid-hydrolysis at for 6 h. The Saccharomyces cerevisiae (ATCC 24858) could ferment -sugars like glucose, galactose and mannose into ethanol, but not -sugars like arabinose and xylose. Optimal fermentation time varied with sugars; 48 h for glucose, 72 h for galactose, and 96 h for mannose. Nevertheless, the ethanol yield from the hydrolysate reached 242 mg/g-dry Laminaria japonica after fermentation by the S. cerevisiae at for 96 h, which corresponds to approximately 4 times more than the theoretical yield from total reducing sugars in the hydrolysates. It indicates that the non-reducing sugars or oligosaccharides dissolved in the hydrolysate played an important role in producing bioethanol. The ethanol concentration linearly increased from 2.4 to 9.2 g/L, while the ethanol yield per dry weight of biomass decreased from 242 to 185 mg/g, with increasing the ratio of biomass to acid solution from 1 to 5% (w/v). The bioethanol yield estimated was approximately 7,400~9,600 kg/ha/year, and indicated that Laminaria japonica is a promissing feedstock for bioethanol production.

To prepare amidoxime (AO) adsorbents for uranium recovery from seawater, the optimum conditions for graft polymerization and amidoximation of acrylonitrile (AN) group and alkaline treatment of the AO group have been investigated in terms of the uranium adsorption capacity. AN has been grafted onto polypropylene (PP) fabric by photoirradiation-induced graft polymerization with benzophenone as the photoinitiator. A concentration of AN ≤1.0M, a photoirradiation time of 2 h, and a reaction temperature of 60°C proved to be optimal for the grafting of AN onto PP. The grafted AN groups were effectively converted into AO groups upon reaction with ≥5.0% (w/v) hydroxylamine solution at pH 7.0−9.0 for ≥16 h at 60−80°C. Although widely used for this purpose, we have shown that methanol is not an essential solvent for the amidoximation reaction. Conditioning of the AO group with KOH solution (alkaline treatment) proved to be effective for enhancing the uranium adsorption capacity of amidoximated PP-g-AN-AO fabric, which increased logarithmically with the conditioning time. The AO group density in the PP-g-AN-AO fabric increased linearly with the degree of AN grafting, whereas the uranium adsorption capacity of PP-g-AN-AO fabric conditioned with KOH reached a maximum at a degree of AN grafting of approximately 60%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

In order to study the utilization of seaweeds as an alternative renewable feedstock for bioethanol production, their properties of hydrolysis and fermentation were investigated. The seaweeds were well hydrolyzed with diluted sulfuric acid. The weight loss of seaweeds reached 75-90%, but only 12-51% of them was converted into reducing sugars after the acid-hydrolysis at 130℃ for 4-6h. The yield of reducing sugars increased with increasing the hydrolysis time up to 4h and then decreased thereafter. In contrast, the ethanol yield from the hydrolysates increased with hydrolysis time except for green seaweeds maximizing at 4h. Optimal fermentation time by Saccharomyces cerevisiae (ATCC 24858) varied with seaweeds; 48h for green seaweeds, 96h for brown and red seaweeds. The ethanol yield from the hydrolysate reached 138±37mg/g-dry for green seaweeds, 258±29mg/g-dry for brown seaweeds, and 343±53mg/g-dry for red seaweeds, which correspond to approximately 1.5-4.0 times more than the theoretical yield from total reducing sugars in the hydrolysates. The results obtained indicate clearly that the non-reducing sugars or oligosaccharides dissolved in the hydrolysate played an important role in producing bioethanol. Considering the productivity and production cost of each seaweed, brown seaweeds such as Laminaria japonica and Undaria pinnatifida seem to be a promissing feedstock for bioethanol production.

We improved photoinduced graft polymerization by absorbing the monomer solution onto the substrate (Ab-type) instead of immersing the substrate in the monomer solution (Im-type) before photoirradiation to yield a more practical and effective grafting system. With this system, acrylic acid (AA) was effectively grafted onto polypropylene (PP) nonwoven fabric. The maximum degree of grafting obtainable was restricted by the amount of monomer preabsorbed onto the PP fabric. However, we effectively enhanced the degree of grafting by increasing the monomer concentration, adding trimethylolpropane triacrylate (TMPTA) to the monomer solution, and repeating the photoirradiation with supplementation of the monomer solution. The net availability of the monomer for graft polymerization was 50% or greater; this increased to 90% or greater with the addition of TMPTA and was much higher than for conventional Im-type photografting (≤13%). Fourier transform infrared spectra, scanning electron microscopy morphology observations, and the adsorption–regeneration properties confirmed that the PP-g-AA fabric prepared by the improved Ab-type photografting method had comparable qualities to those of fabric prepared by conventional Im-type photografting. Thus, the improved Ab-type photografting system provides potential for the preparation of graft adsorbents on a large scale at a competitive cost with a continuous reactor, such as a conveyer belt system, instead of a batch reactor. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

The efficiency of PP-g-AA and PP-g-St nonwoven fabric synthesized by photoinduced polymerization as an adsorbent for removal from waste water was evaluated. The results evidently indicate that the adsorption capacities of onto PP-g-AA nonwoven fabric were extremely superior to those onto sulfonated PP-g-St nonwoven fabric, PK and zeolite. PP-g-AA nonwoven fabric showed the maximum adsorption capacity of at the degree of grafting of 80 wt.%. The adsorption behaviour of onto PP-g-AA and sulfonated PP-g-St nonwoven fabric was controlled by an ion exchange reaction, and tended to be similar to both trends of Langmiur and Freundlish isotherm. Futhermore, PP-g-AA non-woven fabric could be regenerated more than 5 times by a simple washing with 0.1N HCl with no decrease of adsorption capacity and no degradation of physical properties. Also sulfonated PP-g-St nonwoven fabric could be regenerated by washing with 0.1N . However, their regeneration efficiency was significantly low because grafting layer acted as functional radical for adsorption was continuously desquamated in the adsorption or regeneration processes, which resulted in decrease of adsorption capacity and weight of adsorbent. All results obtained from this study indicate that the removal capacity of PP-g-AA non-woven fabric was extremely superior to those of PP-g-St non-woven fabric, PK and zeolite.

The purpose of this study was to clarify the effects of the environmental education system focusing on the knowledge, attitude and practice in relation to environmental education to the students in Mokpo middle school. The study is accomplished by the survey which includes a total of 268 inquiry lists sampled from four groups of the middle school, one of which composing of two middle schools having the environmental curriculum, hereafter referred as 'the case group' and the other group of two middle schools without the curriculum, hereafter referred as the 'the control group'. From the results of the average scores on the environmental knowledge, attitude and practice between the two groups, the case group showed better knowledge scores than the control group (p), economic status, academic achievement and the necessity of environment conservations in order. The factor most affecting to environmental attitude and practice were the interest in environmental problems of the parents.

In this study, we focused on the synthesis, characterization, and adsorption capacity testing of aminated glycidyl methacrylate grafted rice husk (RH-g-GMA–Am). Our goal was to obtain a high-performance surface for the adsorption of various anions. Glycidyl methacrylate grafted rice husk (RH-g-GMA) was prepared by the graft copolymerization of glycidyl methacrylate with rice husk; the product was further subjected to an amination reaction. The surface properties, sorption characteristic functional groups, isotherm and kinetic studies, pore diffusion models, and effects of the temperature and pH on the material properties were studied under batch conditions. The IR spectroscopy results show additional surface functional groups for RH-g-GMA–Am. The adsorptions of and on RH-g-GMA–Am were found to follow pseudo-second-order kinetics; this indicated a possible dominant role played by chemisorption. The rate-limiting step for mass transfer was found to be boundary layer diffusion. Furthermore, the sorption isotherms for and fit the Langmuir model. The amination of RH-g-GMA drastically increased the removal efficiency from 3 to 82% and from 6 to 93% for and , respectively. Moreover, RH-g-GMA–Am exhibited a better removal efficiency in the pH range of 4–6.5. Regeneration studies revealed that the surface of RH-g-GMA–Am could be regenerated repetitively by simple acid washing with an insignificant decrease in the active surface for consecutive adsorptions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43002.

To develop the polymeric adsorbent that possess anionic exchangeable function, PP-g-AA-Am fibers were prepared by photoinduced grafting of acrylic acid (AA) onto polypropylene (PP) nonwoven fibers and subsequent conversion of carboxyl group in grafted AA to an amine (Am) group by reaction with diethylene triamine (DETA). The amination of grafted AA increased with increase in the degree of grafting, the reaction time and temperature of the chemical modification process. Catalytic effect of metal chlorides such as AlCl(3) and FeCl(3) on the amination of grafted AA was significant but not essential to lead the amination. FT-IR and solid (13)C NMR data indicate that amine group was introduced into PP-g-AA fiber through amide linkage between grafted AA and DETA. The anion exchange capacity of PP-g-AA-Am fiber increased with increase in the degree of amination, but reached maximum value at about 60% amination of 150% grafted AA. PP-g-AA-Am fiber showed much higher maximum capacity for PO(4)-P and a similar capacity for NO(3)-N compared to commercial anion resins. Furthermore, the PP-g-AA-Am fiber also has adsorption ability for cations because of unaminated residual carboxyl group.

For the ZnSO4–Na2SO4–H2SO4–NaOH–H2O system, a chemical model was developed to predict the hydrogen ion activity at 25 °C. This chemical model consisted of chemical equilibria, and mass and charge balance equations. The activity coefficients of solutes and the activity of water were calculated by using the Pitzer equation. The distribution of sulfate species as a function of the electrolyte concentration was obtained from the model. In the range of 0.5–4.3 m ionic strength of the solution, the experimental pH values were in good agreement with the predicted pH values. The mean activity coefficients of NaOH calculated by the Pitzer equation agreed well with the experimental values obtained from the literature.

Vinyl benzyl trimethyl ammonium chloride (VBTAC) could be efficiently and stably grafted onto polyester fiber coated with a surfactant polyester (PET) by a photoirradiation-induced graft polymerization with benzophenone as the photoinitiator without any cografting monomer required. The degree of VBTAC grafting could be controlled simply by the irradiation time and concentration of VBTAC in the monomer solution. The anion-exchange capacity (AEC) of the PET-g-VBTAC fabrics increased with increasing degree of grafting up to 80 ± 5% and then leveled off. The maximum AEC of PET-g-VBTAC was 2.2 mequiv/g; this was similar to that of a commercial anion-exchange resin (2.16 ± 0.04 mequiv/g) and much higher than those of nylon-g-VBTAC–2-hydroxyethyl methacrylate fabrics (≤1.0 mequiv/g) prepared with a conventional cografting system. The grafted fabric was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy studies, and the sorption selectivity for anions and regeneration efficiency were estimated. The results suggest that the grafting system, in which VBTAC alone was grafted onto PET fiber coated with surfactant, was more practical and effective for the preparation of the VBTAC-containing anion exchanger, and the resulting PET-g-VBTAC fabrics could be used as an effective anion exchanger. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41674.

A systematic and practical method for the determination of the concentration of the isotopic composition of Sr and Nd and rare-earth elements (REE) from a single sample solution has been developed by combining and improving classical cation-exchange chromatography (CCEC) and modern high-performance liquid chromatography (HPLC). The first step was used to separate Sr and the REE group from a dissolved rock solution by CCEC with a column of large volume and a combination of HClHNO3 as an eluent. The second step was used to separate individual REE components present within the REE group by HPLC, simultaneously quantify them with a post-column reaction detector, and collect Nd with a programmable fraction collector. Separated Sr and Nd fractions were then purified by another CCEC with a column of small volume and HCl as an eluent prior to the mass spectrometric analysis. The analytical results obtained for a series of standard rocks showed a good agreement with recommended values to within ± 10% for REE quantification at the 95% confidence level and ±0.004% (1σ) for the 87 Sr 86 Sr and 143 Nd 144 Nd isotopic ratios.

Vinyl benzyl trimethylammonium chloride (VBTAC) and 2-hydroxyethyl methacrylate (HEMA) were cografted onto nylon fiber by photoirradiation-induced graft polymerization with benzophenone (BP) as the photoinitiator and methanol (MeOH) as the solvent. The cografted VBTAC afforded an anion-exchange functionality to the nylon-g-HEMA–VBTAC fabric without any further modification. The concentration of each and the ratio of the HEMA and VBTAC monomers in solution were the most important factors determining the degree of grafting and anion-exchange capacity (AEC) of nylon-g-HEMA–VBTAC. With regard to the AEC of the grafted fabric, the optimal HEMA/VBTAC ratio was 10 : 7 (v/w), which gave a molar fraction of VBTAC of 0.286. The photoirradiation time, temperature of the reaction, and concentrations of BP and MeOH were optimized for the cografting of VBTAC and HEMA onto the nylon fabric. The molar ratio of VBTAC units in the grafted polymer was dependent on the photoirradiation time but not on the other parameters. The results showed that the AEC of nylon-g-HEMA–VBTAC was governed directly by its VBTAC density rather than by its degree of grafting. The grafted fabric was characterized in terms of its surface area, porosity, and surface charge density by Fourier transform infrared, 13C-NMR, and scanning electron microscopy studies, and the regeneration efficiency was estimated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

PP-g-AA-Am non-woven fabric, which possesses anionic exchangeable function, was prepared by chemical modification of carboxyl group in PP-g-AA non-woven fabric to amine group using diethylene triamine. Its sorption characteristics for anionic nutrients including isotherm, kinetics, effects of pH and co-anions, and regeneration efficiency were studied by batch sorption experiments. Sorption equilibriums of PO(4)-P on PP-g-AA-Am fabric were well described by the Langmuir isotherm model, and their sorption energies were ranged between 9.94 and 15.96 kJ/mol indicating an ion exchange process as primary sorption mechanism. Sorption kinetic data fitted with pseudo-second-order kinetic model and indicated that both external and intraparticle diffusion took part in sorption processes. The uptake of PO(4)-P by PP-g-AA-Am fabric increased with increasing pH of solution and its optimum pH region was in pH >or=4, whereas the uptake of NO(3)-N and NO(2)-N was higher in weak and strong acidic pH region, respectively. The sorption selectivity for anions by PP-g-AA-Am fabric was increased in the order: SO(4)>or=PO(4)>NO(3)>Cl. The PP-g-AA-Am fabric could be regenerated by a simple acid washing process without lowering the sorption capacity or physical durability.