Flotation De-inking
Introduction
De-inking of fibres is an important step in waste paper recycling. Washing and flotation are the common techniques used for washing and flotation. For removing small ink particles (<20μm) wash de-inking process is effective. Large particles (20-300μm) are removed efficiently by flotation de-inking. Pulping is carried out to initially detach ink from fibres before washing and flotation. For efficient mixing, chemicals needed for flotation steps are added at pulping stage.
Long chain fatty acids in presence of calcium ions leads to formation of larger hydrophobic agglomerates which are then subsequently carried away by air bubbles to froth and then removed. Some other surfactant molecules are also added in the flotation cell for smoothening the attachment or detachment of ink particles to air bubbles by changing their hydrophilic/ hydrophobic balance. Bubble particle interactions are increased by agitation and aeration of the pulp. The effectiveness of removal of ink depends upon ink properties. Some other physical chemistry sub-processes are also there in addition to flotation illustrated in fig 1.
Fig. 1. Surface chemical sub-processes, which occur during de-inking flotation. (From ref. [6].)
Re-deposition of ink particles can be prevented by adding sodium silicate to pulp. This process was developed many years back but till now many process variables like added chemicals, temperature, gas flow rate are not fully understood. Bubble size, bubble shape, bubble-particle capture mechanism and rate, and stability of froth are affected by these variables. These parameters are summarized in fig 2.
Fig. 2. Parameters affecting the performance of de-inking flotation.
Parameters affecting flotation de-in...
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...lly surface tension decreases very rapidly in the de-inking plant although surfactant concentration was not very high. This is because some surfactants like wood extract originate from pulp. By comparing the inlet and accept values it was also observed that surface tension was higher at flotation because surfactant was consumed during the flotation process.
It was found from different studies interfacial tension could be directly related to the air ratio, higher the air ratio, higher concentrations of surfactant removed but when bubble rate is too high they don’t get sufficient time to adsorb surfactant and outlet surface tension is lower tha the inlet. In the flotation tank bubble must be stable to carry the ink to the surface but must break on reaching the weir. Optimum pH is also calculated corresponding to relative minimum in surface tension of pulping solution.
Thorough analysis of the graph displayed enough evidence suggesting that an increase in substrate concentration will increase the height of bubbles until it reaches the optimum amount of substrate concentration, resulting in a plateau in the graphs (figure 2). Hence; supported the hypothesis.
“Fiction is the truth inside the lie” (Stephen King). Figment of imagination helps improve brain connectivity and responsibilities which enables the brain to escape to a world of illusion. In a world of imagination students explore conflicts within the book. Anecdotes play a significant role in building the strategies used to deal with real world events. Ink and Ashes by Valynne E. Maetani, discusses how mistakes from the past has an impact on your life and may alter your future. Books intended to be read so that we as people can have a different mindset and perspective on things rather than just our own.
The papermaking process begins with pulp. Pulp is cellulosic fibrous material extracted from cellulosic fiber from wood. Glatfelter uses the Kraft Process to make both hardwood and softwood pulps. Hardwood pulps are taken from oaks, beeches, poplars, birches and eucalyptus tress. They have short fibre of average length of 1 millimeter. The primary purpose of hardwoods is for the paper to achieve bulkiness, smoothness and opacity. Softwood on the other hand is taken from pine and spruce with long fibre averaging 3 millimeters, it provides addition strength to paper. Both softwood and hardwood are produce independently of each other and are mixed end at desire ratio in the paper plant. The process starts from wood chips. Trees are chipped to make wood chips from half an inch to an inch long and up to two fifth inches thick. The chips are feed into a digester, which with cooking liquor would create a chemical reaction, which delignificate the wood. The cooking liquor is composed of white and black liquor. White liquor is composed of mainly sodium hy...
To start with, the first separation technique we performed on the heterogeneous mixture was filtration. According to our observations of the residue, we believed graphite was one of the substances in the mixture. Graphite, a known ingredient used in pencils, is black or dark grey in color, like the dark spots on the filter paper (Figure 1B), and has the ability to leave marks on paper and other objects. Of the potential components given to us, only graphite possessed the ability to make a mark on other surfaces. This was supported by the smudges left behind on our finger and filter paper (Figure 1A, bottom filter paper) when we touched the residue.
PURPOSE: The purpose of the experiment is to determine the specific types of pigments found in water-soluble marker pens by using paper chromatography and water as a solvent.
The essay “Tlilli Tlapalli: The Path of the Red and Black Ink” written by Gloria Anzaldua grants the reader insight into a writer's mind. The essay reveals the reasons and process of becoming a writer and therefore an artist.
A representation of the slow decrease in flux that can result from consolidation of the fouled layer is presented in figure 2.4.
In this lab, solutions were separated by polarity and affinity to solids by chromatography. Chromatography is the separation of a mixture, where the components move at different rates up a medium. The medium used was chromatography paper, matched with a series of developers to aid in movement of compounds upwards. The distance moved up the paper is measured and the rf is calculated. The distance the pigments traveled is divided by the distance developer traveled. The more polar a substance the further it travels up the paper. The paper works by capillary action and absorption to separate the compounds.
Organic inks, which are my personal professional preference, are the safest on the market. These types of inks are typically derived from plant matter. Vegan inks are also in the same class as the organic inks as well and are also ranked just as safe as organic inks.Organic inks are also safe to digest. I personally have no plans on digesting tattoo ink, but if I planned on doing so at least I know that it is safe.
In this experiment, the calcium carbonate was in the form of marble chips. The calcium carbonate reacted with hydrochloric acid when the acid was poured into marble chips. Due to calcium carbonate’s higher reactivity, it displaced hydrogen in the hydrochloric acid. As a result, products of calcium chloride, carbon dioxide and water were formed. As the chemical reaction occurred, the water in the measuring cylinder was displaced and gas bubbles that were blowing out represented carbon dioxide.
Paper recycling is the process of mixing used paper with water and chemicals to break it down. This mixture is then chopped up and heated to breaks it down further into strands of cellulose called pulp or slurry. It then strained through screens which remove any glue or plastic that may still be in the mixture. Finally it is cleaned, de-inked, bleached, mixed with water and then it can be made into new recycled paper.
Do you hate seeing litter on the streets, or seeing and smelling heaps of garbage sitting, and rotting away? Humans recycling more will help to reduce this. We throw many things that can be recycled. Recycling glass, plastics, paper, and metals will reduce solid waste dumped into the ecosystem daily. “96 percent of U.S. plastic, and 50 percent of its paper, goes into landfills. Mexico, not exactly a bastion of environmental awareness, recycles more glass than the U.S.” (Alice Horrigan 1). That’s 96 percent of the millions of tons of plastic, which will outlive most of us in a landfill that we could recycle and keep it out of our landfill. Paper is made from trees, if we recycle it, we can decrease our rate of ugly deforestation and the destruction of animal habitats. When paper gets to the landfill, it is guaranteed to get wet. The wetness and decomposition of paper atracts mold spores, which produce an odor and are potentially bad for your health. Also k...
There is a lot more to know about bubbles. Hopefully your amazing demonstration will get your students interested in learning more about the science of bubbles!
To prevent this, the research team sprayed dielectric substances before applying the conductive ink to prevent shortage. Espalin et al. (2013) the authors described a process in which a gyroscope was manufactured using FDM to be used on a NASA satellite. The porosity of the FDM substrate was improved by modifying the raster-to-raster air gaps, preventing the ink from leaking.
The two main ways printers work is either impact or nonimpact. Impact printers have a device that touches the paper and then creates an image while nonimpact does not touch the paper. The type we use most often in our homes is the nonimpact printers; these include the ink-jet and laser printers. The ink-jet printer drops ink from a nozzle onto the paper. The laser printer is a bit more complicated because it uses toner, static electricity, and heat to get the ink where you want it on the paper. This is nice though because it decreases the drying time that may cause ink to smear, especially when you are printing pictures. (Tyson)