Asked 16th Jan, 2015

What are the methods to remove fluoride naturally or biologically?

I just entered into a new scenario of life with high concentrated fluoride levels in groundwater. i wish to do something to the area by without altering their natural system; hence i wish to know what are the various methods avail to reduce the level of fluoride by naturally or biologically 

Most recent answer

29th Mar, 2018
Vivek Chavan
Institute of Chemical Technology, Mumbai
Please let me know method for removal fluoride from phosphorus trichloride (PCL3)

All Answers (6)

16th Jan, 2015
Fidelis O. Ajibade
Chinese Academy of Sciences
Dear Dr. K. Mophin Kani, from my experience in the waterworks station and also from literature, the most simple methods of doing so are by Reverse Osmosis, Distillation and Activated Alumina Defluoridation. The first two methods are superb for water purification in general though one must add supplements to distilled water, due to its lack of minerals it is potentially unsafe to drink in large quantities. A fourth way is by use of Bone Char Carbon which is 90% effective, this method is best used in tandem with other purification techniques.
Reverse osmosis is now used in medicine and industry as a means of purifying or separating water and other solvents from other components. In recent years, it has been used increasingly for making pure water for dialysis in hospitals and for producing Water for Injection.
Distillation is a process that relies on evaporation to purify water. Contaminated water is heated to form steam. Inorganic compounds and large non-volatile organic molecules do not evaporate with the water and are left behind. The steam then cools and condenses to form purified water. Distillation is most effective in removing inorganic compounds such as metals (iron and lead) and nitrate; hardness (calcium and magnesium); and particulates from a contaminated water supply
Activated Alumina: The Superior Solution for Environmental Cleanup, Pharmaceutical Purification and Clean Energy Applications .Activated alumina is an inorganic substance produced by the dehydration of alumina hydroxide at high temperature. The material is highly porous and exhibits tremendous surface area, resulting in superior adsorbent capabilities. It is resistant to thermal shock and abrasion and does not shrink, swell, soften or disintegrate when immersed in water.
Bone Char Carbon: “Bone char is a granular material produced by charring animal bones: the bones are heated to high temperatures (in the range of 400 to 500 °C) in an oxygen-depleted atmosphere to control the quality of the product as related to its adsorption capacity for applications such as defluoridation of water and removal of heavy metals from aqueous solutions.”
2 Recommendations
17th Jan, 2015
Mophin Kani Kani
Indian Institute of Science
Thank you so much for your valuable suggestions in this regard. i will be back soon
2nd Feb, 2015
Nirmala S.V.S.G
Narayana Dental College and Hospital
     Fidelis O. Ajibade given a detailed expalanation  and i think you got answer and i doagree with it.
10th Sep, 2016
Asit Kumar Batabyal
Central Mechanical Engineering Research Institute
Dr Kani, you can see the write-up given below - A brief account on fluoride removal, of course you may get these in some literatures:  
Various techniques and materials were explored throughout the world for defluoridation of groundwater.
The techniques can broadly be classified into four categories:
Adsorption technique, Ion-exchange technique, Precipitation technique, and Other techniques, which include electro chemical defluoridation and reverse osmosis.
Materials used as defluoridation agents in these four techniques are:
Adsorption: Carbon materials, Activated Alumina, Magnesia, Tricalcium phosphate, Calcite, Hydroxy apatite, Wood, Lignite, Activated char coal, Fish bone char, Processed bone, Nut shells, Avaram bark, Paddy husk, Coffee husk, Tea waste, Jute waste, Coir pitch, Fly ash, Bauxite, Serpentine
Ion-exchange : a) Anion exchange resins-  NCL poly anion resin, Tulsion A27, Lewatit-MIH-59, Amberlite IRA-400, Deacedodite FF-IP, Waso resin-14, Polystyrene. b) Cation exchange resins: Defluoron-1, Defluoron-2, Carbion.
Precipitation: Lime, Alum, Lime & Alum (Nalgonda technique), Alum flock blanket method, Poly Aluminium Chloride (PAC), Poly Aluminium Hydroxy Sulphate (PAHS), Brushite.
Others:  Electrochemical method (Aluminium electrode), Electro dialysis, Electrolysis, Reverse Osmosis.
The basic characteristics of an ideal defluoridation process are the following:
o   Cost-effective
o   Independent of input fluoride concentration, alkalinity, pH, temperature
o   Easy to handle/operate by rural population - the major sufferer
o   Not affect the taste of water
o   Not add other undesirable substances (eg. Aluminum) to treated water
Defluoridation can be introduced at two organizational levels; as household defluoridation for consumption of single household members, and as community defluoridation  for the public use in a village.
The domestic defluoridation processes available today are not totally successful. Nalgonda and  Krass processes for defluoridation have some merits.
This is for your kind information that at CSIR-CMERI, Durgapur we are working on the defluoridation of groundwater. We have already developed a process (adsorption technique) for defluoridation and filed a patent in April, 2016.
We have also designed and developed a Domestic Defluoridation Unit for reducing the fluoride content in water. In addition to the removal of fluoride, the Unit also arrests other common contaminants found in the groundwater. This unit is suitable for domestic purposes in the fluoride affected rural areas.
·         No electricity
·         No chlorine, no bromine, no iodine used
·         No running water required
·         Flow rate: 5 L / hour
·         Adsorbent life (proposed): ~2000 L
·         Storage capacity: 18 L
 Techno- Socio-Economic analysis
·         Adsorbent replacement cost: Rs. 600/-
·         Maintenance cost/month: 150/- (~500 L p.m.)
·         The commercial filtration unit addressing the defluoridation of water for domestic purposes is not  available in the market. The developed filtration unit could be promising for commercialization.
·         Unit can be deployed in the fluoride rich regions of India through Govt./ NGO support 
We are conducting a research project entitled “Geochemical modelling of fluoride contamination in groundwater of the Birbhum District, West Bengal” which primarily aims to explore the origin and enrichment mechanism of fluoride in groundwater. This study has encouraged us to undertake the work on defluoridation of groundwater.
We have a plan to deploy some working models of the ‘Defluoridation Unit’ in the fluoride affected villages of Birbhum district, West Bengal.

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How to Prepare 1 M KOH solution with 85% KOH pellets?
5 answers
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I need to prepare large quantities of 1M KOH solution (20 Litres) in Deionised water. I have KOH pellets which are around 85% KOH, the rest being water. The pellets are from Reactolab and the details of the composition are in the attachment.
1M KOH = 14 pH.
I tried the method which included Molar Mass/concentration of KOH = 56.11/0.85 which leads to 66g. I reach pH around 13.65 and not 14. The pH sensor has been calibrated with pH 7 and pH 10. I reach pH around 13.93 with 77g of KOH pellets in 1L of Deionised water. Currently, I'm hand stirring the dissolution process.
I also want to know if I need to stir for a longer duration for the dissolution process to stabilize.

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