Publications by authors named "Hikaru Sawai"

Biodegradable chelators and surfactants are promising alternatives to conventional washing agents for remediating soil contaminated with toxic elements, owing to their excellent extractability and environmental compatibility. Most previous studies have primarily aimed at maximizing removal efficiency. However, understanding their underlying extraction mechanism is essential to expand the application potential of chelator- or surfactant-assisted washing systems.

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Fluoride (F) contamination in industrial waste is a significant challenge for sustainable materials recycling. Existing techniques for mitigating F contamination focus on immobilization, converting F compounds to insoluble forms while leaving the total F content untreated. Chelator-assisted washing is considered a promising alternative remediation strategy that can indirectly release F by entrapping and dissolving F-bearing minerals.

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Precious corals belong to the family Coralliidae (Cnidaria, Octocorallia), and their axis, which consists of high magnesian calcium carbonate, has long been used in jewelry. With its low growth rate and long lifespan, precious coral is a representative taxon of the vulnerable marine ecosystem. Due to years of overfishing, coral fishery has become a controversial issue.

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The release of radiocesium (r-Cs) into natural aqueous systems is of concern because of its extended solubility as an alkaline metal ion and its facile incorporation into living beings. A technique for the selective separation of Cs from an aqueous matrix using dual solid-phase extraction (SPE) systems in a series is proposed in this paper. The SPEs equipped with chelates (Nobias Chelate-PA1 and Nobias Chelate-PB1), an ion-exchange resin (Nobias Ion SC-1), or macrocycles (MetaSEP AnaLig Cs-01 and MetaSEP AnaLig Cs-02) were evaluated in terms of selectivity and retention/recovery behavior toward Cs and other potentially competing ions (Li, Na, K, Rb, Ba, Ca, Mg, and Sr).

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Waste foundry sand (WFS) from the brass and bronze casting and molding process include various potentially toxic elements (PTEs), such as copper, zinc, tin, and lead. Hence, the utilization of WFS in construction and geotechnical applications evokes environmental concerns due to the rain-induced leaching of PTEs into the groundwater system. The present study investigated the extractive decontamination of WFS using mineral acids, e.

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Rare-earths (REs) are key components for the transition to a greener energy profile and low carbon society. The elements turn out to be of limited availability in the market, due to the supply-demand issues, exponential price rises, or geopolitics, which has led to a focus on the exploration of secondary sources for RE reclamation. End-of-life (EoL) nickel-metal hydride batteries, permanent magnets, and fluorescent lamps (FL) have been the primary sources for recyclable REs, while the recovery of REs in EoL FL (Ce, Eu, La, Tb, or Y) includes comparatively fewer processing steps than the other potential sources.

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End-of-life (EOL) ships contribute significantly to the flow of recycled industrial Fe and non-Fe metal materials in resource-poor developing countries. The ship scrapping (breaking) and recycling industry (SBRI) recycles 90-95% of the total weight of EOL ships and is currently concentrated in Bangladesh, India, Pakistan, Turkey, and China, due to the high demand for recyclable and reusable materials there, an abundance of low-cost labor, and lenient environmental regulations. However, the SBRI has long been criticized for non-compliance with standards relating to occupational health, labor safety, and to the management of hazardous materials.

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Organic-inorganic composites are novel bone substitutes that can ameliorate the mismatch of Young's moduli between natural bone and implanted ceramics. Phosphate groups contribute to the formation of apatite in a simulated body fluid (SBF) and the adhesion of osteoblast-like cells. Therefore, modification of a polymer with these functional groups is expected to enhance the ability of the organic-inorganic composite to bond with bone.

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A relatively rapid and precise method is presented for the determination of lead in aqueous matrix. The method consists of analyte quantitation using the liquid electrode plasma-optical emission spectrometry (LEP-OES) coupled with selective separation/preconcentration by solid-phase extraction (SPE). The impact of operating variables on the retention of lead in SPEs such as pH, flow rate of the sample solution; type, volume, flow rate of the eluent; and matrix effects were investigated.

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Sand filters devised with iron-rich adsorbents are extensively promoted and deployed in the arsenic-prone south and south-east Asian countries (e.g., Bangladesh).

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Indium is a rare metal that is mostly consumed as indium tin oxide (ITO) in the fabrication process of liquid crystal display (LCD) panels. The spent LCD panels, termed as LCD-waste hereafter, is an increasing contributor of electronic waste burden worldwide and can be an impending secondary source of indium. The present work reports a new technique for the reclamation of indium from the unground LCD-waste using aminopolycarboxylate chelants (APCs) as the solvent in a hyperbaric environment and at a high-temperature.

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Ex situ soil washing with synthetic extractants such as, aminopolycarboxylate chelants (APCs) is a viable treatment alternative for metal-contaminated site remediation. EDTA and its homologs are widely used among the APCs in the ex situ soil washing processes. These APCs are merely biodegradable and highly persistent in the aquatic environments leading to the post-use toxic effects.

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