Organoclays as a solution for water decontamination
Drinking water supply crisis is already a reality in many parts of the world. A water conference held in 2018 pointed that 40% of all world population suffer with water scarcity and water contamination. Research around the world shows that about 80% of residual water is released on the environment without any previous treatment and 90% of all the catastrophes caused by human activity since 1990 had a direct impact on water quality.
Among the types of water contamination, oil products, has mobilized a large number of researchers in the search for decontamination solutions. Hydrocarbons presence in water courses can cause, among several problems, the death of living organisms as fish and algae, as well as when in contact with mankind, great toxic and carcinogenic potential. Main source of contamination are oil spils like the one at the Brazilian coast in 2019 where the oil traveled at least 3,000 km causing a major environmental disaster. Another water contamination sources includes surface runoff from urban areas and the undue eviction that occurs due to industrial activity.
Usual decontamination methods can include advanced oxidation processes (AOP’s), by biological decomposition, the use of membranes and adsorption processes. Many researchers report the development of new adsorbent materials due to its easy application, relatively inexpensive cost (compared to other methods) and the possibility to be designed depending on the contaminant.
Bentonite clays have been used as base material for many adsorbents developed for hydrocarbons water decontamination. This clay have a crystalline structure composed of tetrahedral and octahedral layers and between this layers there is an interlamellar space where functionalization processes are available and this is what consists the technique here called: organofunctionalization. In this process a quaternary ammonium salt is inserted into the interlamellar space of bentonite clays, giving rise to an adsorbent material capable of the remotion of organic contaminants from the water.
Zawrah et al., (2018) have studied the organoclay application in diesel, gasoline and kerosene removing, reaching up until 5 times on the own absorbent weight. Mihoc et al. (2014) used organoclays to remove phenol in water reporting total decontamination levels. But the application of these materials goes far beyond their use in the environment. A study carried out in Germany in collaboration with a Brazilian technological education institution developed an automotive filtration module based on organophilic clays.
The organoclay module is able to decontaminate hydrocarbon-water emulsions for safe release back to the environment. Diesel-water emulsion are formed in the vehicle by the fuel filters. Since diesel is normally contaminated with water, multi-stage separators are present in the car to prevent the water getting contact to the engine components. Water removed on the fuel filter can not directly be released on the environment since is contaminated with hydrocarbons as an emulsion. The organoclay module developed remove 99% of the hydrocarbons content allowing the safe water realease and preventing impacts on the environment.
In addition to the excellent potential for water decontamination of these materials, there are huge deposits of clays in the world, making the base material low-cost. The adsorbent based on organophilic clays are also regenerable, subjecting them to a treatment at mild temperatures, around 572 F to 752 F. At this range of temperature all the organic content is volatilized, recovering the base material, the bentonite clays.
Organoclays are a promissing material for water decontamination and may play an important role in future water treatment processes. It‘s use also depends on a greater knowledge of it’s properties and specific functionalization processes for each application. But without a doubt, this material can provide many solutions for water quality and treatment.