Search

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 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.

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 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.

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.

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.