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Fibrous amidoxime adsorbents were prepared by radiation-induced co-grafting of acrylonitrile (AN) and methacrylic acid (MAA) and subsequent amidoximation. Adsorption of uranium in seawater was evaluated by pumping seawater into the adsorbent column. The best monomer ratio of AN and MAA was 7 : 3 for continual usage of uranium adsorption. Though hydrochloric acid is an effective eluting agent for the metals adsorbed on the adsorbent, amidoxime groups were simultaneously damaged after five cycles of adsorption -desorption. This deterioration was reduced by an alkaline treatment of the adsorbents after each elution. Furthermore, various organic acids were examined as elution agents. It was found that the 80% of adsorption activity was still maintained after five cycles of adsorption -desorption when tartaric acid was used for eluting agent.

Secondary and tertiary amino groups were introduced into polymer chains grafted onto a polyethylene flat-sheet membrane to evaluate the effects of surface properties on the adhesion and viability of a strain of the Gram-negative bacterium Escherichia coli and a strain of the Gram-positive bacterium Bacillus subtilis. The characterization of the surfaces containing amino groups, i.e. ethylamino (EA) and diethylamino (DEA) groups, revealed that the membrane potentials are proportional to amino-group densities and contact angle hysteresis. A high bacterial adhesion rate constant k was observed at high membrane potential, which indicates that membrane potential could be used as an indicator for estimating bacterial adhesion to the EA and DEA sheets, especially in B. subtilis. The bacterial adhesion rate constant of E. coli markedly increased at a membrane potential higher than "7?8 mV, whereas that of B. subtilis increased at a membrane potential higher than "8?3 mV, at which the dominant effect on bacterial adhesion is expected to change. The viability experiments revealed that approximately 80 % of E. coli cells adhering to the sheets with high membrane potential were inactivated after a contact time of 8 h, whereas 60 % of B. subtilis cells were inactivated. Furthermore, E. coli viability significantly decreased at a membrane potential higher than "8 mV, whereas B. subtilis viability decreased as membrane potential increased, which reflects differences in cell wall structure between E. coli and B. subtilis.

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Methacrylic acid (MAA) and 2-hydroxyethyl methacrylate (HEMA) were cografted with acrylonitrile (AN) onto polyethylene fiber by radiation-induced graft polymerization. The cyano groups produced were converted to amidoxime groups (−C(NOH)NH2) by reaction with hydroxylamine (NH2OH) to recover uranium in seawater. Various weight ratios of AN/MAA or AN/HEMA in the monomer mixture for cografting generated MAA- and HEMA-cografted amidoxime (AO) fibers with various hydrophilicities. The amidoxime group density and water content were balanced to enhance the uranium adsorption from seawater. MAA-cografted AO fibers exhibited a higher adsorption rate than HEMA-cografted AO fibers. The optimum value of the weight ratio of AN/MAA = 60/40 in the monomer mixture was observed both in a submerged mode at an ocean site and in a flow-through mode in the laboratory. The amount of uranium adsorbed was 0.90 g/kg of the MAA-cografted AO fiber at 293−298 K after 20 days of contact at the ocean site.