Takahiro Hirotsu

An exploratory research of PVC-Chlorella composite material (PCCM) as effective utilization of Chlorella biologically fixing CO2

A new PVC-Chlorella composite material (PCCM) was investigated aiming at the effective utilization of biological CO2 fixing Chlorella. The microalga Chlorella, after fixing CO2, was molded with PVC. Molding conditions of PCCM, and physical properties of Chlorella were studied using tensile strength as an index for estimating the properties of PCCM. The optimum parameters for molding of PCCM were as follows: temperature = 180°C, pressure = 4.4 MPa and time = 5 min. The following physical parameters of Chlorella best enhance high tensile strength: water content of 2%, average particle size of 30–80 μm and a relatively homogeneous distribution of particle size. Chlorella, maintaining its original shape, exists in PCCM as an empty ball inlaid in the matrix of PVC. The PCCM shows a lower elongation and is more brittle than PVC, possibly as a result of gas and residual PVC primary particles around Chlorella grains. A comparison between theoretical and experimental results show that there is an effective combination between the PVC matrix and the Chlorella surface in PCCM. PCCM has a tensile strength higher than 30 MPa which meets the requirements for rigid PVC products, if Chlorella content is less than 20%. Chlorella can thus be effectively utilized as a practical filler.

Synthesis and characterization of a novel blendof polypropylene with Chlorella

A novel blend of polypropylene (PP) with Chlorella, a natural microalga, was synthesized successfully by a melt-mixing method with maleic anhydride-modified polypropylene (MPP) as a compatibilizer. The adhesion of hydrophobic PP to hydrophilic Chlorella is based on the formation of chemical bonds between the maleic anhydride groups of MPP and hydroxy groups of Chlorella through solid-phase esterification. The single maleic anhydride groups have the highest reactivity with Chlorella. From the comparison with PP–Chlorella blends without MPP, the ester bonds between MPP and Chlorella cause a decrease in crystallinity of the MPP matrix which is a primary origin of the decrease in melting and solidification enthalpies of the MPP–Chlorella blend, and induce intensive expansion of the MPP matrix around the Chlorella particles which decreases the glass transition temperature. Consequently, the PP–Chlorella blend with MPP exhibits a marked increase in tensile strength and Youngs modulus compared with the blend without MPP because of the stronger interactions between MPP and Chlorella than those between Chlorella cells.

Binding Properties of a Polymer Having Amidoxime Groups with Proton and Metal Ions

Abstract The proton-binding behavior of a polymer having amidoxime groups was examined by the potentiometric titration method. Adsorptive properties of the polymer for UO2(VI), Mg(II), Fe(II), Ni(III), Co(II), Ni(II), Cu(II), and Zn(II) were also examined at very low concentrations in the 1–9 pH range. The amidoxime polymer possesses adsorptive affinities of the following order: (Mg(II), Ca(II)) < Zn(II) < Co(II) < Ni(II) < Cu(II) < UO2(VI). These adsorptive affinities are reasonably explained by the proton-binding and the metal ion-complexing abilities of the ligand, and are discussed from the standpoint of uranium recovery from seawater.

Selective Elution of Uranium from Amidoxime Polymer. II

Abstract The separative elution of uranium from an amidoxime polymer was examined by the column method with hydrochloric acid solutions. The amidoxime polymer was immersed in seawater for 40 d for preparation of an uranium-loaded polymer sample for the elution experiments; the metal ions adsorbed were Mg(II), Ca(II), Fe(III), Ni(II), Cu(II), and Zn(II) as well as UO2(VI). It was found from the pH dependence of elution extent by a batch method that the order of elution pH values is Fe(III) < UO2(VI) < Cu(II) < Ni(II) < Zn(II) < Ca(II) < Mg(II). In the elution by a column method, Mg(II), Ca(II), Zn(II), and Ni(II) were eluted completely by 0.1 M HC1 and the eluate of enriched uranium was obtained by a succeeding elution with 0.5 or 1 M HC1. This eluate contained Cu(II). and Fe(III), which could be removed in the succeeding step. The elution treatment with hydrochloric acid solutions hardly affected the adsorptivity for uranium in seawater. It was suggested that the elution of uranium with hydrochloric acid ...

Lithium Isotope Fractionations on Inorganic Ion-Exchangers with Different Ion-Sieve Properties

Abstract Lithium isotope fractionation properties were studied on five kinds of inorganic ion exchangers with different ion-sieve properties. The lithium isotope separation factors were determined batchwise in a LiOH or (LiCl + LiOH) solution at 25 or 20°C, respectively. The separation factor increased in the order birnessite-type manganese oxide ≤ hollandite-type manganese oxide ≤ spinel-type manganese oxides ≤ cubic antimonic acid in the LiOH solution. It was dependent on the pore radius (r is) of the ion-sieve and was a maximum at r is = 0.10 nm. The difference in the separation factor with r is could be well explained by considering two factors; the difference in hydration circumstances of Li+ between the ion-exchanger and the solution phase, and the influence of Li+ stabilization in the solid phase.

A novel polyethylene-chlorella composite. I. Characterization of chlorella biologically fixing CO2

Chlorella, a microalga massively produced from biological fixation of CO 2 , was investigated to evaluate the possibility of processing it with polyethylene. Chlorella grain, a hollow aggregate sphere constituted of chlorella cells binding with each other by hydrogen bonds, exhibits a higher thermal stability than cellulose and strong resistance to cracking under mechanical forces up to 150 MPa, possibly due to the spherical structure and unique manner of assembly of chlorella cells. These characteristics of chlorella strongly indicate that it can resist deformation and thermal decomposition in a compounding process with polyethylene.

Kinetics of Adsorption of Uranium on Amidoxime Polymers from Seawater

Abstract Distributions of uranium adsorbed on amidoxime polymers crosslinked with tetraethyleneglycol dimethacrylate (4EGDM) and/or divinylbenzene (DVB) from seawater were examined by x-ray microanalysis in order to elucidate the diffusion behavior of uranium into the polymer matrix. The uniform distribution of the ligands on the polymers was confirmed by the distribution of Cu(II) adsorbed from copper(II) dichloride solutions. It was found that the distribution of uranium adsorbed is changed significantly by the composition of 4EGDM and DVB. Thus, the polymer crosslinked with 4EGDM exhibits a uniform distribution of uranium; however, as the ratio of DVB to 4EGDM increases, a more predominant distribution of uranium near the periphery of the polymer particle appears and the intensity decreases. This suggests that the adsorption rate of uranium is governed by the diffusion of uranium into the polymer matrix, explaining well the dependence of the adsorption rate on the hydrophilicity of the polymer. On the ...

Utilization of micro-algae for building materials after CO2 fixation

Publisher Summary This chapter describes how to make eco-friendly building materials using the micro-algae as Chlorella sp.(hereafter chlorella) and synthetic polymer as polyvinyl chloride(PVC). After CO 2 fixation was completed by the micro-algae, carbon from fixed CO 2 should keep in their bodies for a long period. As long as the micro-algae are in the building materials such as floor tiles, laminated plastic boards, CO 2 would not come out to the air again. Nowadays some phthalate esters are used as plasticizer when PVC molding materials are made on commercial basis. The chapter started on some feasibility studies in which large amounts of chlorella discharged from the photo-bioreactor after CO 2 fixation became substitute to the conventional plasticizer.