Dear friends, I have a waste water which is a waste of a factory which its precursor is provided from mineral stones. I am looking for and applicable (industrial) method fro the extraction and separation of the above mentioned elements from this wastewater?
It would be so much appreciated if someone introduce me a protocol for this purpose?
Dear Mohammad,
You question can be divided to two sub-questions:
1-How to remove heavy metals such as Cd, Cr, Cu, Ni, As, Pb, Mg and Zn
2-How to remove Na and K salts.
For class number 1, there are many different methods, among them:
adsorption on new adsorbents, membrane filtration, electrodialysis, and photocatalysis
For class 2, the most efficient method is RO (reverse osmosis) membrane.
Methods for class 1:
1Arabian Journal of Chemistry Volume 4, Issue 4, October 2011, Pages 361–377 (SEE ATTACHED REVIEW).
New trends in removing heavy metals from industrial wastewater
Abstract
Innovative processes for treating industrial wastewater containing heavy metals often involve technologies for reduction of toxicity in order to meet technology-based treatment standards. This article reviews the recent developments and technical applicability of various treatments for the removal of heavy metals from industrial wastewater. A particular focus is given to innovative physico-chemical removal processes such as; adsorption on new adsorbents, membrane filtration, electrodialysis, and photocatalysis. Their advantages and limitations in application are evaluated. The main operating conditions such as pH and treatment performance are presented. Published studies of 94 cited references (1999–2008) are reviewed.
It is evident from survey that new adsorbents and membrane filtration are the most frequently studied and widely applied for the treatment of metal-contaminated wastewater. However, in the near future, the most promising methods to treat such complex systems will be the photocatalytic ones which consume cheap photons from the UV-near visible region. They induce both degradation of organic pollutants and recovery of metals in one-pot systems. On the other hand, from the conventional processes, lime precipitation has been found as one of the most effective means to treat inorganic effluent with a metal concentration of >1000 mg/L. It is important to note that the overall treatment cost of metal-contaminated water varies, depending on the process employed and the local conditions. In general, the technical applicability, plant simplicity and cost-effectiveness are the key factors in selecting the most suitable treatment for inorganic effluent
2-Removal of heavy metals from wastewater using agricultural and industrial wastes as adsorbents (SEE ATTACHED PAPER).
HBRC Journal
Volume 9, Issue 3, December 2013, Pages 276–282
Abstract
Adsorption processes are being widely used by various researchers for the removal of heavy metals from waste streams and activated carbon has been frequently used as an adsorbent. Despite its extensive use in water and wastewater treatment industries, activated carbon remains an expensive material. In recent years, the need for safe and economical methods for the elimination of heavy metals from contaminated waters has necessitated research interest toward the production of low cost alternatives to commercially available activated carbon. Therefore, there is an urgent need that all possible sources of agro-based inexpensive adsorbents should be explored and their feasibility for the removal of heavy metals should be studied in detail. The objective of this research is to study the utilization possibilities of less expensive adsorbents for the elimination of heavy metals from wastewater. Agricultural and industrial waste by-products such as rice husk and fly ash have be used for the elimination of heavy metals from wastewater for the treatment of the EL-AHLIA Company wastewater for electroplating industries as an actual case study.
Results showed that low cost adsorbents can be fruitfully used for the removal of heavy metals with a concentration range of 20–60 mg/l also, using real wastewater showed that rice husk was effective in the simultaneous removal of Fe, Pb and Ni, where fly ash was effective in the removal of Cd and Cu.
3-Journal of Advanced Research
Volume 2, Issue 4, October 2011, Pages 297–303 (SEE ATTACHED FILE).
A study of the removal characteristics of heavy metals from wastewater by low-cost adsorbents
Abstract
In this study, the adsorption behavior of some low-cost adsorbents such as peanut husk charcoal, fly ash, and natural zeolite, with respect to Cu2+, and Zn2+ ions, has been studied in order to consider its application to the purification of metal finishing wastewater. The batch method was employed: parameters such as pH, contact time, and initial metal concentration were studied. The influence of the pH of the metal ion solutions on the uptake levels of the metal ions by the different adsorbents used were carried out between pH 4 and pH 11. The optimum pH for copper and zinc removal was 6 in the case of peanut husk charcoal and natural zeolite, and it was 8 in case of fly ash. An equilibrium time of 2 h was required for the adsorption of Cu(II) and Zn(II) ions onto peanut husk charcoal and fly ash and an equilibrium time 3 h was required for the adsorption of Cu(II) and Zn(II) ions onto natural zeolite. Adsorption parameters were determined using both Langmuir and Freundlich isotherms, but the experimental data were better fitted to the Langmuir equation than to Freundlich equation. The results showed that peanut husk charcoal, fly ash and natural zeolite all hold potential to remove cationic heavy metal species from industrial wastewater in the order fly ash
Dear Esmail and Rafik,
Many thanks for your kind answers,
In fact, I have a wastewater full of magnesium and I want to separate it through a low cost and efficient way as it is supposed to be done in a factory and should have Economic justification.
So, it would be so much appreciated if you could introduce me such a protocol.
Regards,
Mohammad.
Dear Mohammad,
In my previous answer I sent a review which describes all methods used for the removal of divalent ions (heavy metals).
The following paper describes the removal of Mg+2:
J Environ Sci Health A Tox Hazard Subst Environ Eng. 2013;48(10):1225-30. doi: 10.1080/10934529.2013.776855.
The simultaneous removal of calcium, magnesium and chloride ions from industrial wastewater using magnesium-aluminum oxide.
Hamidi R1, Kahforoushan D, Fatehifar E.
Author information
Abstract
In this article, a method for simultaneous removal of calcium, magnesium and chloride by using Mg0.80Al0.20O1.10 as a Magnesium-Aluminum oxide (Mg‒Al oxide) was investigated. Mg‒Al oxide obtained by thermal decomposition of the Mg-Al layered double hydroxide (Mg-Al LDH). The synthesized Mg‒Al oxide were characterized with respect to nitrogen physicosorption, X-ray diffraction (XRD) and field emission scan electron microscopy (FESEM) morphology. Due to high anion-exchange capacity of Mg‒Al oxide, it was employed in simultaneously removal of Cl(-), Mg(+2) and Ca(+2) from distiller waste of a sodium carbonate production factory. For this purpose, experiments were designed to evaluate the effects of quantity of Mg‒Al oxide, temperature and time on the removal process. The removal of Cl(-), Mg(+2) and Ca(+2) from wastewater was found 93.9%, 93.74% and 93.25% at 60°C after 0.5 h, respectively. Results showed that the removal of Cl(-), Mg(+2) and Ca(+2) by Mg‒Al oxide increased with increasing temperature, time and Mg‒Al oxide quantity.
Hoping this will be helpful,
Rafik
The easiest way may be chemical precipitation. Rasing the pH by NaOH and you will get Mg(OH)2 precipitated out.
If your waste water has high concentration of Mg, K and Na, it is possible to crystallize these elements to MPP (Magnesium Potassium Phosphate) and MSP (Magnesium Sodium Phosphate). MPP is crystallized at pH 11.6 in our reserch. But about MSD we don't know. It's easy way to remove (extract?) those elements. Because you just control pH. But, oher elements would inhibit the crystallization. It's problem.
Dear Rafik,
Many thanks for you follow and it is so much appreciated to have your excellent comments again.
Regarding the effectuality of these methods, my colleagues and I should work on these methods. but the key notes for us are the cost, easiness (handy), and availability of materials. as it is supposed to be applied within a factory.
Dear Xiong,
Many thanks for your kind answer, please note that ii is a mix of some metal ions and please consider this issue, so, is it applicable by the definitions I mentioned?
Dear Satoshi,
Many thanks for your kind answer,
Imagine I do as you said, so then, how can i separate the Mg from precipitated Mg---MPP/MSP? and make it as pure as possible?
Well..., yeah, you are right. It's difficult to separate Mg from precipitation. How about adding acid to MPP/MSP? Mg can solve. Sorry for poor idea...
Dear Satoshi,
Do not mention it my friend. as I have told you before we have to get i n practice the we can get more about the subject.
you know, in fact it should be a selective method just for the separation of Mg as we are working on it right now.
Bests my friend.
As proposed above by Rihua Xiong, alkalinisation to promote precipitation seems a viable straightforward approach. I would like to further suggest washing the obtained precipitate with icy water, to better discriminate between the alkaline-earth hydroxides Mg(OH)2 and Ca(OH)2. The solubility in cold water is much smaller for Mg(OH)2 (and also for MgO) compared with Ca(OH)2. The precipitate can be recovered (e.g. by vacuum filtering), washed with icy water, dried, and calcined, to burn out coprecipitated organic matter while recovering most of the Mg(OH)2 as MgO.