The esterification of hemicellulose with citric acid formed cross-linking structure and promoted the hydrophobicity and oxygen barrier performance of films.

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The effect of ferric ions (Fe 3+ ) on the flotation of zircon and cassiterite using sodium oleate (NaOL) was investigated by single mineral flotation tests, adsorption density tests, zeta potential measurements, solution chemistry analyses, and FTIR analyses. It is difficult for zircon to be separated from cassiterite by using NaOL alone. Nevertheless, the flotation of zircon was activated while that of cassiterite was depressed in the presence of Fe 3+ . Adsorption density tests indicated that the addition of Fe 3+ enhanced the adsorption of NaOL on zircon surfaces, whereas it receded on cassiterite surfaces. Zeta potential measurements and solution chemistry analyses found that H(OL) − 2 was the predominant species to determine the flotation behaviors of zircon and cassiterite. Furthermore, the addition of Fe 3+ at pH < 8 reduced the negative charges on the zircon and cassiterite surfaces. It was confirmed that the positive charges of zircon were caused by the positively charged species of Fe 3+ , including Fe 3+ , Fe(OH) 2+ , and Fe(OH) + 2 . Meanwhile, these results revealed that the hydroxy complex and the precipitate of Fe(OH) 3 (s) adsorbed onto the cassiterite surfaces caused the flotation of cassiterite to be inhibited. It can be concluded from FTIR analyses that the peaks of zircon at 894.14 cm −1 and 611.65 cm −1 were strengthened and the adsorption on zircon surfaces was found to be chemisorption due to the addition of Fe 3+ , whereas both chemical and physical adsorptions of NaOL on cassiterite surfaces were weakened, resulting in the different flotation behaviors of zircon and cassiterite in the presence of Fe 3+ .Minerals 2017, 7, 108 2 of 18 first stage, and the product of zircon from the first stage then needs further processing. However, gravity separation methods will perform well only when the particle size meets the requirements [6]. Both too fine and coarse particle sizes will negatively affect the results. Hence, the fine fraction of zircon concentrate from gravity separation still contains large amounts of impurities which cannot be removed effectively. To improve the quality of products, zircon is further separated from other heavy minerals, such as magnetite, ilmenite, and cassiterite, by a series of magnetic and electrostatic separation processes. Usually, the removal of magnetite and ilmenite from zircon is easier to achieve via magnetic separation because these two minerals are magnetic. The electrostatic separation method [7] based on the different electric properties between the gangue and the valuable minerals requires clean mineral surfaces. The mineral surfaces of zircon are usually coated with some electric metal minerals which contain titanium, iron, and other materials such as clay. These contaminants make it very difficult to achieve an effective separation using electrostatic separation. According to the information mentioned above, the light minerals and magnetic minerals can be removed, and cassiterite as the main contaminant in zircon concentrate cannot be removed effecti...

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A novel perfluoroalkyl-containing multi-epoxy compound (PFME), designed and syn thesized in our laboratory, is applied to cotton fabrics by the pad-dry-cure process to give durable water and oil repellency by developing permanent covalent bonds to the textile substrate. The specimens pretreated by citric acid are further treated with PFME. The dual finished cotton shows both durable water and oil repellent appearances and durable press properties. The optimum treatment conditions for the dual finishing are discussed.