Advanced Oxidation Processes for the degradation of organic water pollutants (PPCPs). (photocatalysis (nanomaterials)/ultrasound/UV-H2O2, Fenton, ZVINP etc):
The advanced oxidation processes AOP) based degradation protocols for the detected emerging contaminants (PPCPs) are developed and most of them were found to be highly effective in the complete mineralization of pollutants. We use almost all the processes which come under AOP, and the methods are optimized for an effective degradation strategy. Emerging contaminats like parabens, bishenols, metaprolol, propranolol, etc.; dyes like coumassie brilliant blue, acid red 1 are some of the molecules we used as model compounds.
Screening of emerging pollutants in water bodies in South India / drinking water in Kochi and in Arctic region using mass spectrometry (LC-MS, LC-Q-ToF-MS, ICP-MS, GC-MS, LC-MS/MS):
Pesticides and their degradation products migrate from their site of application to water, air and soil, plants and finally animals and humans through the food chain. So, the use of pesticides, numbered more than a thousand, is regulated by government. This necessitates the development of sensitive methods for the detection and quantification of the pesticides at trace levels. Mass spectrometry serves the purpose because of its high selectivity, sensitivity and the ability to analyse a wide range of compounds simultaneously. We do the analysis of pesticide and PPCPs in water samples collected from the water bodies (rivers and backwaters) near agriculture fields as well as drinking water in the highly urbanized area of Kochi. Analysis of sediment samples from Arctic region for detection/quantification of micropollutants has been initiated. The structure of the compounds is identified with the help of the high resolution mass spectra and MS/MS pattern and the quantification is done by using authentic standards. Protocols are developed for analysis of contaminants. Pre-concentration methods are adopted for bringing the analyte concentrations into the working range of the analytical instruments.
Investigation of the Fate of emerging pollutants in water bodies- Transformation protocols by Mass Spectrometry:
Some of the emerging contaminants are highly persistent and some are easily degraded by sunlight and the microbes. The transformation products of many abundant pharmaceuticals and pesticides are analyzed using mass spectrometry. There are chances that the transformed products are highly toxic than the parent compound itself, which necessitates their characterization. Experiments are carried out in fresh water and river water and the developed protocols are used for their detection in the real samples.
Development of multilayer membranes for water purification and protein separation:
Membrane based water treatment technology is now in the vogue as an effective strategy for purification. We use polyelectrolyte multilayer membrane, which are composite membranes with a layered and tunable architecture. They were found to be highly effective for the removal of these contaminants as separation can be possible based on the molecular weight cut off as well as by ion exchange. It is very interesting that these membranes find varied applications from water treatment to the development of biosensors. By properly selecting the conditions for separations, and the suitable polyectrolytes and support membranes, an optimized, reversible system can be developed for eater purification. Chitosan/poly (acrylic acid) (CHI/PAA) multilayers on nylon support membrane is found to be a very effective system according to our experience and we are trying to explore all the possibilities of this system.
The chitosan when paired with polystyrene sulfonate (PSS) resulted in a very interesting system for protein purifications. There was high rejection for lysozyme and low rejection for ovalbumin. This is a very good result as when properly optimized, these membranes can be used for separation of ovalbumin and lysozyme two major proteins in the egg white.
Grey water purification methodology (rediscover the existing technology):
Grey water purification and their reuse are of at most interest for a sustainable water usage in the household. Membrane technology promises a lot in this field and the membranes we developed are applicable to real samples and can be reused for a few cycles of operation. The surfactants, the major component of the grey water are removed completely by chitosan/poly (acrylic acid) (CHI/PAA) multilayers on nylon support membranes. It is found to be a promising system as far as the grey water or waste water from dye industry is concerned. In addition to this, there is research on the development of microbial fuel cells (MFCs) for the purification of grey water. We try the phyco-remediation also, with more indigenous algae species. Pulp and paper mill effluent, cashew nut processing waste water and distillery waste water are also treated using these techniques and are found to be highly effective. The main focuses are removal of nutrients, heavy metals and other organic substances.
Air pollution monitoring:
We are into all the areas of pollution monitoring, the air pollution monitoring being one of them. The study is extended state wide with major focus on highly urbanized areas. All the mass spectrometric techniques are employed for the detection and quantification of organic pollutants in the air. The water from the first rain from place to place is collected state wide and analyzed, as it is an indirect method of assessing the quality of air. Analysis of various VOCs (volatile organic carbons) in the atmosphere is another area of interest. Both LC and GC based mass spectrometry are being used for this purpose.
Protein –Pollutant interaction (multi spectroscopic and microscopic techniques): The interaction of the pollutants with model proteins is
monitored using a couple of spectroscopic techniques, fluorescence, infrared, UV-visible, Raman spectroscopy. The life time measurement, AFM studies also compliment the data. The structural changes in the protein were very well established for pollutants like bisphenols. These types of studies are having tremendous implications as these pollutants are having physiological actions resulting in health risks.
Analysis of chemically modified DNA constituents:
Analysis of oxidatively modified DNA constituents (nitrogen bases, nucleosides and nucleotides) helps to provide some idea about the mechanistic aspects of oxidative DNA damage. We simulate the transformation studies using the DNA constituents and their derivatives like chloropurine and aminopurine under various ROS and RNS producing conditions. From the end product analysis using mass spectrometry and the transient study, a possible mechanism of their formation is predicted, which in turn will contribute to the mechanism of cellular DNA damage. The analysis of the transformed products is of great importance due to their toxic and mutagenic effects and the role as the biomarkers for cancer.
Computer based theoretical calculations for free radical reactions (AOPs):
We explore the mechanisms of reaction of the emerging contaminants with the highly reactive OH radial, using theoretical calculations when and where it is necessary. It gives the stability of the intermediate structures formed and the possible site for the radical attack. It is used for the elucidation of the mass spectrometric fragmentations of the molecules (we are dealing exclusively with organic pollutants) giving light to the collisionally induced fragmentation pathways.