Abstract Neodymium-iron-boron alloy, Nd2Fe14B, is used as a material for magnets. Neodymium is one of the valuable and expensive rare earth elements and is often recovered to reduce costs and environmental impact. Recently, a method for recovering neodymium as neodymium phosphate from mixed solutions was reported. This method was very useful because the main component of rare earth ores is rare earth phosphates, and there are well-established methods for refining rare earths from rare earth phosphates. This study attempts to obtain neodymium phosphate using acid to dissolve waste magnets, reducing agent, phosphoric acid, and pH adjuster. The diluted acid (hydrochloric acid and nitric acid), amount of ascorbic acid and phosphoric acid, and the pH values were studied to clear the suitable conditions. The color of the heat-treated product, the precipitate yield, and the Fe/Nd molar ratio indicated that a low concentration of acid is suitable and ascorbic acid is required. Excessive use of phosphoric acid improved the precipitate composition. The high pH value decreased the selectivity of neodymium phosphate due to the easy formation of iron phosphate and hydroxide. The process addressed in this study is very promising because it does not require heating at high temperatures or special reagents.

Abstract Zinc oxide, which has photocatalytic activity, is used as a white pigment in cosmetics. With cosmetics containing zinc oxide, some sebum on the skin is broken down by the UV rays of the sun. In this study, in order to suppress the photocatalytic activity of zinc oxide, zinc oxide was added to an aqueous solution of sodium pyrophosphate and shaken, so that novel white pigment coated with zinc phosphate having no photocatalytic activity was prepared for use in cosmetics. The chemical composition, powder properties, photocatalytic activity, hue (visible light reflectance and L* a* b* values), and smoothness of the resulting powder material were studied. Part of the zinc oxide reacted to zinc phosphate by this pyrophosphate treatment. The photocatalytic activity of zinc oxide was suppressed by this zinc phosphate coating. The resulting sample had sufficiently high reflectance in the visible light region and a high L* value in the L*a*b* color space. The treated samples had lower static friction resistance than the original zinc oxide. Judging from the results of photocatalytic activity, L* value, and smoothness, the optimum conditions were the molar ratio P/Zn of 1/4 for 6 h of shaking the mixture.

Resumo Como novo pigmento azul, vários fosfatos hidratados de cobre e alumínio imitando turquesa, CuAl6(PO4)4(OH)8.4H2O, foram preparados misturando solução de nitrato de cobre, solução de nitrato de alumínio, ácido fosfórico e solução de hidróxido de sódio. Amostras com composição química semelhante à turquesa foram preparadas. Os pós obtidos foram avaliados com difração de raios X, espectros de infravermelho, espectros de refletância no ultravioleta-visível e espaço de cores L*a*b*. Além disso, outras composições relacionadas também foram investigadas. Amostras aquecidas a baixas temperaturas resultaram em pós de cor azul claro. Ao aquecer a 700 ºC, a cor dos materiais mudou para verde intenso. Amostras com alta proporção de cobre indicaram menor valor de L* e pequenos valores de a* e b*. A baixa proporção de cobre foi adequada para obter pigmentos de fosfato azul claro e verde escuro.

Abstract As a novel blue pigment, various hydrated copper aluminum phosphate imitating turquoise, CuAl6(PO4)4(OH)8.4H2O, were prepared by mixing copper nitrate solution, aluminum nitrate solution, phosphoric acid, and sodium hydroxide solution. Samples with similar chemical composition with turquoise were prepared. The obtained powders were evaluated with X-ray diffraction, infrared spectra, ultraviolet-visible reflectance spectra, and L*a*b* color space. Further, other related compositions were also investigated. Samples heated at low temperature were light blue powder. By heating at 700 ºC, the color of materials changed to deep green. Samples with high copper ratio indicated lower L* value and small a* and b* values. The low copper ratio was suitable to obtain light blue and deep green phosphate pigments.

Resumo Um novo pigmento vermelho, fosfato de sódio e manganês (NaMnPO4), imitando a natrofilita, foi sintetizado a partir de carbonato de manganês por aquecimento em várias condições. Os pós obtidos foram investigados por análise de difração de raios X, espectroscopia no infravermelho, espectroscopia de reflectância ultravioleta-visível e espaço de cor L*a *b*. Amostras sintetizadas a 500-800 °C apresentaram difratogramas de raios X associados ao NaMnPO4. Ao aquecer em temperatura mais elevada, as amostras exibiram cor mais clara. A amostra sintetizada a 700 °C indicou o maior valor a*. Além disso, os efeitos de diferentes quantidades relativas de constituintes também foram estudados. A temperatura e o tempo de aquecimento, volume de água e teor de fosfato afetaram a cor dos pigmentos.

Abstract A novel red pigment, sodium manganese phosphate (NaMnPO4), imitating natrophilite, was synthesized from manganese carbonate by heating under various conditions. The powders obtained were investigated by X-ray diffraction (XRD) analysis, infrared spectroscopy, ultraviolet-visible reflectance spectroscopy, and L*a*b* color space. Samples synthesized at 500-800 °C presented XRD patterns associated with NaMnPO4. By heating at a higher temperature, the samples exhibited lighter color. The sample synthesized at 700 °C indicated the highest a* value. Furthermore, the effects of varying relative amounts of constituents were also studied. The temperature and period of heating, volume of water, and phosphate content affected the color phase of the pigments.

Resumo O óxido de zinco é comumente usado como um pigmento branco para cosméticos; entretanto, apresenta atividade fotocatalítica que provoca a decomposição do sebo na pele quando exposto à radiação ultravioleta na luz solar. Neste trabalho, o óxido de zinco foi reagido com ácido fosfórico em vários valores de pH para sintetizar um novo pigmento branco para cosméticos. Foram estudadas a composição química, as propriedades do pó, as atividades fotocatalíticas, as cores e a lisura desses pigmentos. Os materiais obtidos exibiram picos de difração de raios X relacionados com óxido e fosfato de zinco após tratamento com ácido fosfórico. A proporção de fosfato de zinco para óxido de zinco foi estimada a partir de resultados de espectrometria de emissão atômica por plasma acoplado indutivamente. As amostras tratadas em pH 4 a 7 produziram pequenas partículas com tamanhos submicrométricos. A atividade fotocatalítica do óxido de zinco tornou-se menor após o tratamento com ácido fosfórico. As amostras tratadas em pH 4 a 7 apresentaram a mesma reflectância que o óxido de zinco nas faixas do ultravioleta e visível. Verificou-se que o ajuste do pH foi importante no tratamento do óxido de zinco com ácido fosfórico.

Abstract Zinc oxide is often used as a white pigment for cosmetics; however, it shows photocatalytic activity that causes decomposition of sebum on the skin when exposed to the ultraviolet radiation in sunlight. In this work, zinc oxide was reacted with phosphoric acid at various pH values to synthesize a novel white pigment for cosmetics. The chemical composition, powder properties, photocatalytic activities, colors, and smoothness of these pigments were studied. The obtained materials exhibited X-ray diffraction peaks relating to zinc oxide and phosphate after phosphoric acid treatment. The ratio of zinc phosphate to zinc oxide was estimated from inductively coupled plasma - atomic emission spectroscopy results. Samples treated at pH 4-7 yielded small particles with sub-micrometer sizes. The photocatalytic activity of zinc oxide became lower after phosphoric acid treatment. Samples treated at pH 4-7 showed the same reflectance as zinc oxide in both the ultraviolet and visible ranges. Adjustment of the pH was found to be important in the phosphoric acid treatment of zinc oxide.

Neste trabalho, os fosfatos de zinco foram preparados a partir de nitrato de zinco e ácido fosfórico variando Zn/P como um novo pigmento branco para utilização em cosméticos. A composição química, propriedades dos pós, atividade fotocatalítica, cor, humidade e textura dos fosfatos de zinco foram estudadas. Amostras preparadas de Zn/P = 2/1, 3/2, e 1/1 indicaram DRX de Zn3(PO4)2•4H2O. As partículas foram observadas por imagens de MEV das amostras preparadas de Zn/P = 2/1, 3/2 e 1/1. A atividade fotocatalítica destas partículas de fosfato de zinco foi muito menor para proteger o sebo da pele. Os materiais preparados de Zn/P = 2/1, 3/2 e 1/1 e os seus produtos térmicos a 100 °C mostrou uma alta reflectância na faixa da luz visível. Amostras preparadas em alta proporção de Zn/P indicaram pequeno valor MIU.

In this work, zinc phosphates were prepared from zinc nitrate and phosphoric acid at various Zn/P ratios as a novel white pigment for use in cosmetics. The chemical composition, powder properties, photocatalytic activity, color phase, moisture retention, and smoothness of the zinc phosphates were studied. Samples prepared at Zn/P = 2/1, 3/2, and 1/1 indicated XRD pattern of Zn3(PO4)2•4H2O. The plane particles were observed in SEM images of sample prepared at Zn/P = 2/1, 3/2 and 1/1. The photocatalytic activity of these zinc phosphate particles was too less to protect the sebum on the skin. The materials prepared at Zn/P = 2/1, 3/2 and 1/1 and their thermal products at 100 °C showed a high reflectance within the range of visible light. Samples prepared at high Zn/P ratio indicated small MIU value.

Fosfato de ferro foi preparado a partir do nitrato de ferro e ácido fosfórico com um surfactante éter monododecil pentaetileno glicol. A composição química das amostras obtidas foi estimada a partir de medidas por ICP e DRX. A distribuição e forma das partículas foram observadas por imagens de MEV e o pelo método de espalhamento de laser. A atividade catalítica foi estudada com a decomposição do complexo entre formaldeido, acetato de amônio e acetilacetona. Os picos de FePO4 foram observados nos padrões de DRX das amostras preparadas Fe/Ce=10/0 e então aquecidas a 600 ºC. Outras amostras foram de padrões de DRX amorfo. Ferro-fosfatos de cério tiveram alta atividade catalítica para a decomposição do complexo.

Iron phosphate was prepared from iron nitrate and phosphoric acid with a surfactant, pentaethylene glycol mono dodecyl ether. The chemical composition of the obtained samples was estimated from ICP and XRD measurements. Particle shape and size distribution were observed by SEM images and laser diffraction / scattering methods. Further, the catalytic activity was studied with the decomposition of the complex between formaldehyde, ammonium acetate, and acetylacetone. The peaks of FePO4 were observed in XRD patterns of samples prepared in Fe/Ce=10/0 and then heated at 600 ºC. Other samples were amorphous in XRD patterns. Iron-cerium phosphates had high catalytic activity for the decomposition of the complex.