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Graphene & Diatom Desalination of Water

Using Diatoms and Graphene clean fresh water can be produced from sea water, or contaminated aquifer's.

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Fresh water our most important resource is becoming increasingly scarce around the world in arid and semi-arid regions. Would it not be great if we could take non-potable water from aquifers, drinking supplies or the sea and simply filter the dissolved solids out at an economically viable price compared to distillation.

Oil fields everywhere pump almost a gallon of salt water for every gallon of oil produced, this water can be reclaimed and used for agriculture.

Crystalline Diatomaceous earth is used as an excellent filter media, being that it is composed of micro and macroporous skeletons of silica.

Nano-porous Graphene is an excellent material known for its ability to be permeable to water alone.

Together these will solve all the water problems the world faces!

The challenge is to build a low cost desalination filter using graphite, diatomaceous earth pool filter media, acetone, distilled water, ball mill, sand and PVC pipe. The graphite will be mechanically exfoliated into graphene using the ball mill and a 200mL DI water to 60mL Acetone mix.

http://www.businessinsider.com/lockheed-martin-desalination-graphene-filters-2013-3 According to this article the main problem with current graphene desalination is scaling up CVD graphene. The bottom up approach is foolish as always and is directly attributed to too much money and resources. Here I show how in the garage using the simplest of materials a desalination filter can be produced.

Nanoporous graphene is permeable to water not pristine as is posited here http://scitation.aip.org/content/aip/journal/jcp/141/7/10.1063/1.4892638 my theory is that the natural graphite I use as a precursor has natural defects that are nano-porous.

Utilizing Hansen Solubility parameters this solution of acetone and water is almost perfect for separating individual layers of graphene from the bulk crystalline graphite the Diatomaceous earth gives the graphene a backbone on which to adhere. Why 1 gram graphite to 14 grams DE? The surface area of graphene is around 2700 meters squared per gram and the surface area of DE is around 200 meters squared per gram. This aims to wrap the DE in graphene sheets one layer thick. Ultimately providing a very high flow rate at very low pressures. By ball milling for 48 plus hours there is plenty of time for shear forces to seperate the layers of graphite and to pulverize the diatoms into sub 50 micron pieces. I will be acquiring a digital microscope soon to hopefully capture the light absorption from few layer graphene.

Moving forward I will acquire a TDS meter and utilize sea water concentrations of salt to determine total time to saturation of the filter and difficulty in removal of the captured solids.

By providing a cheap method for desalination/purification of ocean water, well head water, etc. this should give stability to regions affected by drought and pure water to regions with contaminated drinking supplies due to fracking and industrial waste.

This documentation describes Open Hardware and is licensed under the CERN OHL v. 1.2. You may redistribute and modify this documentation under the terms of the CERN OHL v.1.2. (http://ohwr.org/cernohl). This documentation is distributed WITHOUT ANY EXPRESS OR IMPLIED WARRANTY, INCLUDING OF MERCHANTABILITY, SATISFACTORY QUALITY AND FITNESS FOR A PARTICULAR PURPOSE. Please see the CERN OHL v.1.2 for applicable conditions

  • 1 × Rock Tumbler
  • 1 × Alumina Ball Bearings
  • 1 × Graphite 300 mesh 99.9% pure
  • 1 × Diatomaceous Earth Pool Filter Media
  • 1 × Distilled Water
  • 1 × Acetone
  • 1 × Whatmann #1 Filter Paper
  • 1 × Filter Flask
  • 1 × Filter Funnel
  • 1 × Vacuum Pump

View all 4 project logs

  • 1

    Add to a rock tumbler barrel 1/5th full of alumina ball bearings the following

    1 gram of high purity graphite

    14 grams of diatomaceous earth

    200mL of water

    60mL of acetone

  • 2

    Ball mill for 5 days

  • 3

    Filter through a whatman number 1 filter, suprisingly the DE will naturally filter the graphene out and keep it from going through the filter.

View all 5 instructions

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MECHANICUS wrote 06/30/2016 at 01:32 point

Wiss Kerz,

Thanks for the comment.  As with any nanomaterial, inhalation hazards are present and I am working on a safety video.  Also release to the environment is a legitimate concern that must be addressed. 

When inhaled the effects are mostly transient and do not present a lasting effect. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4750184/ As compared to carbon nanotubes which cannot be easily removed by cillia in the lungs. I do not think I am making anything but few layer graphene (or graphite as it really is) and the filtering is happening at the interface between the silica and graphite. I just put graphene on the title because that is all the rage these days. 

The larger concern here is using calcined diatomaceous earth (pool filter media) which is nearly all crystalline silica and presents a large danger to lungs while in a dry powder state. Using natural diatomaceous earth reduces this risk as it is mostly amorphous silica. 

Ingestion is of a greater concern. However dose is poison, and the effluent of graphene from one of these filters will be nearly non-existent.  The difference is eating spoon fulls will certainty affect you as will eating pretty much any nanomaterial. That being said I am not using graphene oxide so it may have a more lasting stay in the body but when released into the environment is hydrophobic and will not be nearly as motile as hydrophillic graphene oxide.

We have all heard of the danger's of Bisphenol-A and many bottle manufacturers have gone to different bisphenols as a result (which are probably worse endocrine disruptors) but you can't make plastic without it.  It is an acceptable risk in order to be able to carry water in a non breakable container. (yes i know glass or metal containers are better)

When looking at the real issue, that is drinking/watering crops with salt water or water contaminated with petroleum, fecal coli-form etc. The small risk posed by nanograms per liter of graphene is not an issue. In fact man has been eating graphene oxide for the foreseeable past http://www.rsc.org/chemistryworld/2014/07/graphene-bbq-meat-gripe-water

As with anything in this world there is a risk/reward scenario and thank you for helping to point that out.

MECHANICUS

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