Interaction forces between ink particles, cellulose fibers and mineral fillers as determined by AFM

Journal ArticleRecycling of wastepaper is an important industrial activity for the conservation of our natural resources. Wastepaper is mostly generated from newspaper and office waste (from photocopiers and laser printers) [1]. One important step in wastepaper recycling is the separation of ink from cellulose fibers and fillers. The efficiency of ink separation from wastepaper depends on the type of printing process, the type of ink, and the type of paper. For example, it is relatively easy to separate ink from newspaper waste; whereas, the separation of electrophotographic toners from office waste is more difficult mostly because the ink particles are fused during the printing process [2] and their surface properties change

Interaction forces between toner surfaces

Journal ArticleThe interaction of toner particles in aqueous solution is of interest with regard to both fundamental and practical aspects of de-inking processes. It has been established for the toner studied that the toner polymeric resin, that is, the block copolymer styrene-methyl methacrylate, more specifically the polymethyl methacrylate, has a tremendous influence on the interaction between toner particle surfaces. Interaction force profiles for toners are dependent oil the pH conditions, going from attraction to repulsion as the alkalinity of the aqueous medium increases. Both the attraction and repulsion behavior is largely a result of the conformation of polymethyl methacrylate (PMMA) segments. Under strongly acidic conditions the PMMA segments are coiled and toner particles are attracted to each other due to hydrophobic interaction while for alkaline conditions the PMMA segments are more extended into the solution and the toner particles remain dispersed due to steric forces

Determinação do melhor substrato e temperatura para germinação de sementes de araçá (Psidium cattleianum).

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Magnetic separation for wastepaper recycle mills

Journal ArticleAn alternative approach to the conventional washing and flotation techniques for de-inking of mixed office waste (MOW) is magnetic separation. The use of magnetic de-inking has great potential to improve the efficiency of ink removal due to the magnetic content of toners. It is shown experimentally that the magnetic susceptibility of toners typically found in MOW varies from weakly paramagnetic to ferromagnetic. The magnetic de-inking of MOW in itself is not sufficient to achieve a high quality final product due to variations in the magnetic susceptibility of the toner particles. Nevertheless a combination of magnetic separation with flotation appears to be able to produce a final product of superior quality with 92.7% of the dirt removed. Considering these findings appropriate flowsheet modifications are suggested for improved plant performanc

Surface chemistry of pulping and flotation for mixed office wastepaper

Journal ArticleThe effect of pulping reagents on the de-inking flotation of laser printed wastepaper was investigated with regard to the removal efficiency of toner and mineral filler particles at different pH values. These results show that caustic pulping causes the toner to be released from the fibers as larger particles with a reduced hydrophobicity. On the other hand, neutral pulping not only causes the toner to be released as smaller particles but also increases the simultaneous flotation removal of mineral filler particles

Pressure effect in the X-ray intrinsic position resolution in noble gases and mixtures

A study of the gas pressure effect in the position resolution of an interacting X- or gamma-ray photon in a gas medium is performed. The intrinsic position resolution for pure noble gases (Argon and Xenon) and their mixtures with CO2 and CH4 were calculated for several gas pressures (1-10bar) and for photon energies between 5.4 and 60.0 keV, being possible to establish a linear match between the intrinsic position resolution and the inverse of the gas pressure in that energy range. In order to evaluate the quality of the method here described, a comparison between the available experimental data and the calculated one in this work, is done and discussed. In the majority of the cases, a strong agreement is observed

Primavera: arroz precoce 'agulhinha' para os cerrados de Rondonia.

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Avaliação de linhagens de arroz de terras altas no cerrado de Rondônia.

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Resposta de arroz de sequeiro à abudação mineral no cerrado de Rondônia.

O presente trabalho teve como objetivo avaliar a resposta da cultura do arroz de sequeiro a diferentes níveis de adubação mineral NPK, na região de cerrado do Estadobitstream/item/79276/1/FOL-6151-0001.pd