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Self-cleaning surfaces have excelled in recent years in energy and environmental fields. In particular, in solar energy area, these surfaces are used to avoid soiling accumulation on photovoltaic (PV) modules. So far TiO 2 has been widely used due to its photocatalytic activity and photo-induced superhydrophilicity. However, this oxide has some limitations since it reduces the glass transmittance and it rapidly reestablish the water contact angle in dark environments. In order to circumvent these limitations, composites TiO 2 /SiO 2 have been proposed. For photovoltaic application, besides a good transparency in the wavelength region 300-1800 nm and self-cleaning properties, the coating should also present long durability and adequate adhesion to endure the outdoor conditions. Aiming at developing a coating with these properties, in this work, TiO 2 /SiO 2 composites containing different titanium content have been synthesized and compared with pure TiO 2 films in relation to adhesion, transparency and hydrophilicity. Both films have been deposited over low iron float glass substrates by sol-gel dipcoating technique and different calcination temperatures (400, 500, 600°C) and Si/Ti molar rates (Si 86 Ti 14 , Si 40 Ti 60 ) have been considered. TiO 2 /SiO 2 films showed higher transmittance in visible range compared with pure TiO 2 . TiO 2 /SiO 2 films showed superhydrophilic character before and after ultraviolet irradiation, with water contact angles near to 0°. Furthermore, as predicted, TiO 2 /SiO 2 films could keep the superhydrophilic character in dark environments, in contrast with pure TiO 2 films. Both TiO 2 and TiO 2 /SiO 2 films exhibited good adherence and it is shown that higher calcination temperatures and higher titanium content enhance such property. All films presented abrasion resistant property in contact with sponge and detergent. It has been demonstrated that high transmittance, self-cleaning and adherent composite has been obtained by a simple sol-gel route presenting good potential to be applied on photovoltaics systems.

SUMMARYZeolites are hydrated crystalline aluminosilicate minerals of natural occurrence, structured in rigid third dimension net that can be used as slow release plant-nutrient source. The main objective of this study was to evaluate the effects of plant growth substrate under zeolite application, enriched with N, P and K, on dry matter yield and on nutrient contents in consecutive crops of lettuce, tomato, rice, and andropogon grass. The experiment was carried out in a greenhouse, with 3 kg pots with an inert substrate, evaluated in a randomized block design with three replications. Treatments consisted of four types of enrichment of concentrated natural zeolite: concentrated zeolite (Z) only, zeolite + KNO 3 (ZNK), zeolite + K 2 HPO 4 (ZPK) and zeolite + H 3 PO 4 + apatite (ZP), and a control grown in substrate fertilized with a zeolite-free nutrient solution. Four levels of enriched zeolite were tested: 20, 40, 80, and 160 g/pot. Four successive crops were grown on the same substrate in each pot: lettuce, tomato, rice, and andropogon grass. Results indicated that N, P and K enriched zeolite was an adequate slow-release nutrient source for plants. The total dry matter production of above-ground biomass of four successive crops followed a descending order: ZP > ZPK > ZNK > Z.Index terms: stilbite, Lactuca sativa, Lycopersicum esculentum, Oryza sativa, Andropogon gayanus, slow-release fertilizer, growth substrate.(

This report describes the characterization of a sedimentary occurrence from the Parnaíba Basin, Brazil, containing the zeolite stilbite intertwined with smectitic clay mineral. The head samples from different sites present a wide content range of the zeolitic phase -15% to 50%. The use of simple separation techniques -conventional gravitic treatmentsyields concentrates containing about 67% of the zeolitic component. Assays with the amendments of these concentrates with plant nutrients yield release rates matching those reported for similar commercial products.

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RESUMO-O objetivo do trabalho foi avaliar o efeito da adição de um concentrado zeolítico enriquecido com N, P e K ao substrato de cultivo sobre o crescimento, produção de matéria seca, área foliar, teores e extração de N, P e K e os teores de clorofila do limoeiro 'Cravo'. O porta-enxerto foi cultivado por 93 dias em tubetes de 150 cm 3 com substrato orgânico compostado de casca de coco e carvão vegetal (3:1) ao qual se adicionou o concentrado zeolítico. Este foi obtido com a concentração da zeólita natural (Z) e enriquecimento desta com KNO 3 (ZNK), e também com a acidificação com H 3 PO 4 e mistura com apatita (ZP). Utilizou-se uma mistura de 30%ZNK + 70%ZP nas doses de: 0; 2,5; 5; 10 e 15 g por planta. Os resultados indicaram que o fornecimento de nutrientes através do mineral zeólita adicionado ao substrato orgânico comprovou ser alternativa viável para a obtenção de porta-enxertos no sistema de produção em ambiente protegido. A adição de 6,4 g do concentrado zeolítico enriquecido com NPK aumentou significativamente a produção de matéria seca, área foliar, altura e diâmetro de caule. Este aumento foi de 37,5% em relação à testemunha que não recebeu o concentrado zeolítico. Houve aumentos nos teores e extração de N, P e K com o fornecimento da zeólita enriquecida. As leituras dos teores de clorofila relacionaram-se com os teores de N, indicando ser esta uma alternativa para o diagnóstico do estado nutricional para a cultura. Termos para indexação: Citrus limonia, estilbita, diagnose foliar, fertilizante de liberação lenta. GROWTH AND MINERAL NUTRITION OF RANGPUR LIME ROOTSTOCK CULTIVATED IN SUBSTRATE WITH ZEOLITE ENRICHED WITH NPKABSTRACT-The main objective of this research was to evaluated the growth, dry matter production, leaf area, N, P and K levels and exportation and chlorophyll levels of Rangpur Lime (Citrus limonia Osbeck) grown in a substrate with NPK enriched zeolite. Rootstocks were cultivated during 93 days in 150cm 3 -dibble tubes containing composted organic substrate of cocopeat and vegetal coal (3:1) with zeolite addition. Treatments comprised 4 levels (0, 2.5, 5, 10 and 15 g per plant) of a NPK-enriched zeolite, which was a mix of H 3 PO 4 /apatite-zeolite (70%) and KNO 3 -zeolite (30%). Results indicated that the supply of nutrients through the mineral zeolite enriched with NPK added to the organic substrate was a viable alternative for citrus rootstock production in protecting environment. The supply of 6,4 g of enriched zeolite significantly increased dry matter production, leaf area, height and steam diameter. These increases were 37,5% in relation to the control without zeolite. N, P and K foliar levels increased with zeolite enriched with NPK. Chlorophyll levels were related to N levels, pointed out to be a useful tool for Rangpur Lime nutritional status evaluation.

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