Adsorption tests .. You choose a material and you did a coating of a nano-particle on it!

All the best!

Sahar Hamzehzadeh-Nakhjavani

Membrane technology (Reverse osmosis) is most effective for all forms of chromium (inorganic ions as well as complexes) removal. It is one of the best available technology for chromium removal with Good (60–90%) to excellent (90–100%) removal for Cr(VI) and Cr(III). It can effectively remove wide range of contaminants simultaneously.

The limitations are a) high investment and operational costs b) Fouling of membrane and c) Brine disposal. But among all the other possible options (Coagulation– precipitation/ redox-assisted coagulation, adsorption and Ion exchange), this is the best.

This review paper will help you further

https://iwaponline.com/aqua/article-pdf/57/8/541/401336/541.pdf

All the best!

First identify the source of the chromium. Is it in coming from the waterworks or leaking from pipes in the distribution system. Sometimes the tap in new buildings are the main source. NExt look into if the chromium oxidation stage is III or VI.

Hello Dr. Henrik Rasmus Andersen,

How can the oxidation stage of chromium affect its removal from water? Is it related to its chemical interaction!

Thank you for your answers!

¡The simplest is to reduce to Cr(III) , add a little Al(III) and alkali,. Form (Cr(OH)3 not soluble and filter.

Hassan Elgharbi, Cr(IV) is an anion and it is difficult to sorbe and precipitate. Additionally Cr(IV) are much more toxic. Once it is reduced to Cr3+ it can be precipitated at high pH as Luis Bertello says or sorbe to activated carbon as Abdelkader Ouakouak suggested.

The aeration method can be applied as a pretreatment, by putting the water in close contact with air, increasing the oxygen content of the water. This process allows, among other things, to oxidize the minerals dissolved in the water, so that they can be removed by sedimentation and filtration.

Dear Sahar,

I have attached some papers below that used mineral adsorbents such as zeolite, perlite, pumice, lECA, and anthracite which has a great performance of adsorbing heavy metals. I hope you find them helpful.

Ehsan Teymouri , It seems your two papers are not about sorption of any heavy metals.

Henrik Rasmus Andersen

Dear Prof. Andersen,

Thanks for your notice. Here, I have attached to papers that successfully removed heavy metals using porous concrete containing mineral adsorbent. I hope you find them helpful.

All the best,

1. As a guideline value: 0.05 mg/L is admitted by WHO

2. Generally chromium is present at oxydation stage VI. So pass your water on an adsorption filter with activated carbon. Be care to change your filter in due time.

3. To reduce it to stage III and precipitate with NaOH 0.01M. The inconvenient of the method is to raise the pH around 12: so you must lower it around 6.5 -7.5 for potable water

Chromium can be removed through adsorption methods and some economical adsorbent material can be used. Many adsorbent materials can be taken from reusable wastes also. It ll reduce the cost of treatment.

Hi. you can choose between membranes and solid adsorbents in order to purify the water to your desired metal level. we recently have used a chitosan-based adsorbent to remove metal ions and industrial wastewater treatment. chitosan-based adsorbents usually offer cost-effectiveness and easy operation.

You can find enclosed an article that you can use:

the best methode for pretreatment of cromium water is adsorption with activated carbon.