Rohan Weerasooriya

National Institute of Fundamental Studies - Sri Lanka | NIFS · Environmental Science Group

The dissolved organic matter (DOM) should be purified for safe drinking water due to disinfection by-products (DBPs) produced by disinfectants reaction with DOM. Current research on groundwater in the chronic kidney disease with unknown etiology (CKDu) zone of the North Central Province (NCP) in Sri Lanka has focused mainly on aquatic chemistry, wi...

Irregular removal methods of industrial waste have caused water source problems due to toxic materials such as heavy metals. These heavy metals are carcinogenic and pose serious health risks, which may accumulate in human bodies via water sources. Therefore, it is important to treat heavy metals in contaminated water before consuming them. Out of t...

Over 2 billion people in the world experience acute drinking water stress due to excess salinity. In most cases, water salinity and fluoride in water occur together. Water desalination is achieved by pressure-driven membranes technology that requires activated carbon pre-filtration to reduce turbidity. The water flow often follows a torturous route...

A highly efficient electrode materials, three‐dimensional reduced graphene oxide varying wrinkles and folds (WRGO), applied for electrochemical determination of Hg(II) was obtained by treating graphene oxide (GO) with KOH aqueous solution. After etching, the relatively flat graphene was altered, and its self‐aggregation was significantly alleviated...

Sustainable synthesis of zeolite is important since zeolites are employed in many industrial and environmental applications. However, the use of pure chemicals on large scale is not sustainable due to the high cost and production of hazardous chemical waste. To avoid these negative impacts natural aluminosilicate materials can be used. Among variou...

Recently, 1D ZnO nanorods have attracted intensive research attention due to their outstanding properties, such as high electron mobility in the growth direction, high surface-to-volume ratio, and good thermal and chemical stability. However, due to the higher presence of active surface atoms, deactivation (dramatic decrease in stability) by second...

Air pollution remediation is increasingly important due to the enhancement in the emission of hazardous vapours into the atmosphere due to rapid industrialization. Hazardous vapour can be removed by using various methods, and the common methods are adsorption, photocatalytic oxidation and catalytic oxidation. The main focus of this study is to iden...

Motor vehicle emissions are the primary air pollution source in cities worldwide. Changes in traffic flow in a city can drastically change overall levels of air pollution. The level of air pollution may vary significantly in some street segments compared to others, and a small number of stationary ambient air pollution monitors may not capture this...

In this research, the efficiency of reverse osmosis (RO) and nanofiltration (NF) treatment methods installed in the dry zone (Sri Lanka) were examined as a function of operation parameters, feed and product water quality, membrane type, user maintenance, and wastes handling. The quality of the feedwater varies as electrical conductivity (265–1329 m...

Sandwich assay employing gold nanoparticles and DNA is a common signal amplification strategy designed for surface plasmon resonance sensor. To further improve the sensitivity employing sandwich assay, sandwich-structured optical fiber surface plasmon resonance sensors based on AuNPs and MoS2 nanosheets has been theoretically studied. Au film depos...

Herein, we have developed a chemically modified glassy carbon electrode (GCE) using tea polyphenols mediated zero-valent iron/reduced graphene oxide nanocomposites (rGO-ZVI-P) for rapid determination of Hg²⁺ in water. Highly conductive rGO-ZVI-P were fabricated by a green chemical method using tea polyphenols as the reductant. The rGO-ZVI-P shows a...

Drinking water is largely from groundwater in Sri Lanka, so quality management is of great concern. In order to achieve the 6th goal of United Nations (UN) Sustainable Development Goals (SDG), more efforts are being undertaken to secure drinking water quality. In this paper, the current status, challenges and opportunities of groundwater quality ma...

Presently over three million people, mostly living in the dry zone of Sri Lanka, experiencing acute water stress due to excess salinity which results in palatability problems. In many parts of the world, reverse osmosis (RO) and nanofiltration (NF) technologies are successfully used for water desalination. However, in Sri Lanka, these methods show...

Mercury readily methylates to form extremely toxic methylmercury (CH3Hg⁺) that seriously imparts central nervous systems' functionality in humans and animals. Therefore, the development of rapid CH3Hg⁺ determination methods for the detection of environmentally relevant concentrations is a research priority. We developed an electrochemical technique...

Sinhalese and Vedda people are respectively the major ethnic group and the descendants of the probably earliest inhabitants of Sri Lanka, both believed to have a long history of settlement on the island. However, very little information is available on the origin and possible migration patterns of the two populations. Some studies have focused on (...

We fabricated iron-doped carbon nitride on a diatomite surface through a single-step polymerization (FGD-x, where x represents Fe loading content). The FGD-x efficiently degrades tetracycline hydrochloride by a collaborative photo-Fenton process. The FGD-3 (FeCl3 loading 75 mg) showed the best catalytic performance in TC degradation with minimal H2...

Humic substances (HS) are heterogeneous organic polymers that show monotonous properties. HS are present at different proportions in the terrestrial environment, and they implicate the performance of water desalination plants. Recently electrodialysis self-reversal (EDR) technology has been used to treat excess salinity, hardness and fluoride in HS...

Carbon forms a variety of ring structures. Non-catalytic carbon spheres (hereafter NCS) have received wide attention due to their simple and cost-effective synthesis protocols, size tunability, and environmental benignness. Tunable NCS can obtain by varying flow rates of precursor gases used as the carbon source and dilutant. We fabricated NCSs wit...

We fabricated non-catalytic carbon spheres (hereafter CSs) with controllable dimensions (diameter 0.3 µm to 1.5µm) by chemical vapour deposition at 1273 K using C2H2 (carbon source) and N2 (dilutant) gas precursors. By varying the flow rates of precursor gases, spherical or pseudo-spherical morphologies with chain-like hierarchical structures are d...

It has been estimated that more than 200 million people worldwide rely on drinking water with fluoride concentration that exceeds the WHO guideline of 1.5 mg/L and the recent reports showed very high concentrations of fluoride in some localized areas in the Dry zone of Sri Lanka. Keeping the view of toxic effects of fluoride on human health, there...

Clay content and mineralogy affect the behaviour of soils by influencing many soil properties. The soils of Sri Lanka were classified into 23 great soil groups (GSG) in 1972 and presently reclassified according to the international methods of soil taxonomy. Recently, the GSGs of latosols, namely, calcic red latosols, calcic yellow latosols (CRL and...

Rainwater plays a dominant role in aquifer recharging and determining groundwater composition. Therefore, the isolation of the relative contribution of rainwater for groundwater recharging is essential to determine the geochemical provenance of groundwater. The present study examined the geochemical provenance of groundwater in Netiyagama (area ~ 0...

A novel adsorbent, core-shell adsorbent granules, engineered from sand/graphene oxide nanocomposite showed a promise to mitigate calcium ion removal from aqueous solution. The novel adsorbent was characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectrometry (EDXAS) and Fourier Transform Infrared Spectroscopy (FTIR). T...

Chronic Kidney Disease of unknown etiology (CKDu) is a contemporary pre-eminent issue in Sri Lanka, mostly observed within the North Central Province (NCP). Consumption of groundwater could be a major contributor for the increased cases of CKDu patients reported in NCP, as the NCP groundwater has high hardness (20-750 mg/L), fluoride (0.2-8 mg/L),...

Although Sri Lanka is not a water scarce nation, over 3.5 million people currently suffer from acute drinking water stress due to high salinity. Both reverse osmosis (RO) and nanofiltration membranes (NM) pressure-driven methods are widely used in water desalination. However, the resulted water is often overtreated causing problems due to lack of s...

Over 3.8 million people living in the Dry Zone of Sri Lanka experience lack of drinking water largely due to palatability issues. As an interim measure, the National Water Supply and Drainage Board and private organizations introduced Reverse Osmosis (RO) technology to water desalination which removes almost all solutes in water. However, when inap...

Recently, the direct synthesis methods for zeolite modification have received much attention from scientists to improve zeolites as catalysts in a variety of applications. Unlike conventional methods, well advanced physicochemical properties could be introduced to zeolites through direct synthesis. During this work, Cu-loaded zeolite was directly s...

Nitrogen-doped reduced graphene oxide (N-rGO) was synthesized by a single-step facile hydrothermal method to modify glassy carbon electrode (GCE) for detection of Hg(II) in water. The electronic properties of graphene and N-rGO were modified using experimental and molecular modelling data. Compared to graphene, N-rGO modified GCE shows enhanced res...

Evidence of associations between exposure to ambient air pollution and health outcomes are sparse in the South Asian region due to limited air pollution exposure and quality health data. This study investigated the potential impacts of ambient particulate matter (PM) on respiratory disease hospitalization in Kandy, Sri Lanka for the year 2019. The...

When humic substances (HS) are present in the feed water, fouling of ion-exchange membranes is inevitable despite the built-in self-cleaning process of electrodialysis reversal systems (EDR). When Ca²⁺ is present in water, HS can readily chelate with them and form organic-Ca²⁺ complexes, which can foul anion exchange membranes (AEMs) in an irrevers...

Graphitized carbon spheres (GCSs) with varied diameters (500 nm to 4.5μm) and hierarchical surface morphologies were successfully produced on iron-particles coated silicon (100) substrate at 750°C by chemical vapour deposition (CVD). By varying the mass flow rate of the precursor gasses and the method of catalyst coating on silicon (100), GCSs with...

The COVID-19 pandemic has led to the complete lockdown of many cities worldwide. Lockdowns have significantly changed human behaviour, such as fewer or no industrial activities and limited road and air transport, affecting the environment. In this study, we aimed to assess the variability and trends of PM2.5 (mass concentration of airborne particul...

Water treatment based on electrocoagulation (EC) is attractive since required chemicals and colloids are produced in-situ. However, optimization of EC operation parameters is necessary to enhance its efficiency. We optimized EC cell parameters by the response surface method (RSM). The optimal removal efficiencies of hardness (63%) and fluoride (97%...

For the provision of safe drinking water supply in CKDu affected areas in Sri Lanka, t this study investigated the groundwater quality of Anuradhapura, North Central Province, Sri Lanka in both wet and dry seasons, and developed a nanofiltration (NF) membrane-based water supply technology for CKDu prevalence zones. Results showed that the average c...

Coagulation-based pre-treatment efficiency of high strength digestate of food waste (HSDFW) anaerobic digestion is negated by organic ligand-catalyzed decomposition of coagulants. In this study, an efficient HSDFW pre-treatment method, magnetic seeds (MS) coagulation, was employed by using highly stable Keggin Al30 nanocluster (PAC30), MS and polya...

Reverse osmosis (RO) drinking water stations have been introduced to provide safe drinking water for areas with prevailing chronic kidney disease with unknown (CKDu) etiology in the dry zone of Sri Lanka. In this investigation, RO drinking water stations established by community-based organizations (CBO) in the North Central Province (NCP) were exa...

Development of robust methods for rapid detection of heavy metal ions and associated chemical species in water is challenging. Different mercury species are ubiquitous in the environment; they bio-amplify and undergo methylation into organo-Hg species. We developed a new electrochemical method for rapid screening of free Hg²⁺ in water by square wav...

Antibiotic pollution of water resources is a global problem, and the development of new treatments for destroying antibiotics in water is a priority research. We successfully manufactured recyclable magnetic Fe3O4/g-C3N4 through the electrostatic self-assembly method. Selecting tetracycline (TC) as the target pollutant, using Fe3O4/g-C3N4 and H2O2...

Nano zerovalent iron is used to destruct a wide range of organic and inorganic contaminants in water. However, its performance is limited due to rapid aggregation and surface passivation. To minimise aggregation, we fabricated nano zerovalent iron on the reduced graphene oxide sheets using green tea derived polyphenols (hereafter rGO-nZVI-P) or bor...

Methylated mercury compounds are neurotoxins; they are ubiquitous in muddy sediments of water bodies under anaerobic conditions. A variety of coupled techniques such as capillary gas chromatography with inductively coupled plasma mass spectroscopy, or atomic fluorescence spectroscopy is used for detection of methylated mercury compounds. However, a...

The aim of this study was to investigate the impact of biomass fuel for cooking on adverse fetal growth outcomes in Sri Lanka. A cross-sectional study of mothers recruited at maternity clinics in rural communities in Sri Lanka’s Central Province was undertaken. Data pertaining to household air pollution and fetal growth parameters were collected us...

The chronic kidney disease of unknown etiology (CKDu) prevalent in certain regions of Sri Lanka poses a serious threat to human health. Previous epidemiological studies focused on the search of causative agents for CKDu etiology from the viewpoint of groundwater composition, but how CKDu prevalence affected the groundwater microbial composition, es...

Methylated mercury is a bio-magnifier that readily crosses the blood-brain barrier exerting neurotoxic effects. Therefore, the development of a rapid and in situ method of methylmercury (CH3Hg⁺) detection is research priority. We report a sensitive electrochemical method for the detection of CH3Hg⁺ using a modified glassy carbon electrode with Au n...

Harmless treatment of antibiotics, and recovery of precious metals from the spent Li-ion battery are two typical environmental issues with rapid development of the society. Presently, we reclaimed Mn from the spent Li-ion battery cathode materials for hydrothermally synthesizing MnO2/Fe (0) composites, which were used as the efficient heterogeneous...

An integration of two processes, magnetic coagulation (MC) and short-cut biological nitrogen removal (SBNR), coupled with a sequencing batch membrane bioreactor (SMBR) controlled by an automatic real-time control strategy (RTC), was developed to treat different characteristics of high strength wastewater. The treatment efficiency and microbial comm...

In drinking water treatment, sand filters are frequently used to remove turbidity. We enhanced the performance of the sand by a chemical modification using graphite oxide (GO). Repeated coating of sand granules with graphite oxide (GO) followed by low temperature (120 ⁰C) pyrolysis yielded hierarchical core-shell structures. The sand granules can b...

Classical Fenton and Fenton-like processes destruct organic pollutants in water non-selectively to complete mineralization. However, the usage of classical Fenton or Fenton-like processes is often limited due to the narrow operational pH window, sludge accumulation, inefficient H2O2 and efficiency decline. To overcome these constraints, in this stu...

Reverse osmosis (RO) drinking water stations have been introduced to provide safe drinking water for areas with prevailing chronic kidney disease with unknown (CKDu) etiology in the dry zone of Sri Lanka. In this investigation, RO drinking water stations established by communitybased organizations (CBO) in the North Central Province (NCP) were exam...

In recent years, different forms of carbon structures with extraordinary properties and multidisciplinary applications have been discovered. Among them, carbon spheres (CSs) are unique materials because they can be fabricated with significant characteristics, such as adjustable porosity, uniform geometry, surface functionality, flexible particle si...

Due to excess fluoride in drinking water, over millions of people are being affected globally with dental and bone problems. The World Health Organization (WHO) guidelines specify 1.5 mg /L fluoride in drinking water as the maximum permissible contaminant limit (MCL). However, in dry climatic zones and tropical countries, the water consumption is h...

Ambient air pollution is a global environmental hazard, particularly affecting urban areas. Sudden spikes of air pollution in the atmosphere in a given area can occur due to many factors, either individually or combined. Generally, local effects are due to anthropogenic sources, while large scale variations occur due to natural events such as dust...

Chromium readily undergoes redox speciation, and Cr(VI) oxidation state is ubiquitous and mobile in the environment. Under physiological conditions, Cr(VI) reduction yields species as Cr(V) or Cr(VI), which shows reactivity towards DNA damaging. Therefore, accurate detection of Cr species in the environmental compartment is of utmost importance. In...

The contamination of water systems due to the presence of fluoride ions creates major health problems for human beings. There exist various types of methods for the removal of excess fluoride ions from water. Among these, adsorptive methods are predominant, primarily due to their relatively lower cost. Among the different types of materials that ca...

Electrodialysis self-reversal (EDR) technology has attracted in the treatment of water for domestic and industrial uses. The self-reversal consists of a frequent reversal of the direction of current between the EDR-cell electrodes to combat fouling of ion exchange membranes (IEMs). Irrespective of the EDR self-cleaning processes, the role of natura...

Cd (II) is a biologically active element that requires rapid and reliable monitoring for its pollution control. We designed the electrochemical sensing nanocomposite with enhanced adsorption followed by redox processes, which was synthesized by incorporating ferric ions into cerium oxide substrate（hereafter CeFe2O5）via the sol-gel combustion method...

Potential of hardness removal using graphite-based Nano material Water is one of the basic needs for both living and non living beings. Due to some natural and anthropogenic reasons, safe drinking water scarcity is becoming a main problem throughout the country. Among the various problems water hardness creates a lot of problem for both life and in...

National Water Supply and Drainage Board (NWSDB) observed Kerosene oil type odour in the water supplied by bowsers from Chunnakam water supply scheme intake in 2012 and later in the pipe borne water supplied from Chunnakam intake as well. Wells Surrounding Ceylon Electricity Board's were also checked by NWSDB, and Oil &Grease residue was observed....

Installation of decentralized water-treatment plants is an ideal option to supply safe drinking water for rural communities. Presently in Sri Lanka, over 3.6 million villagers face acute water-quality problems, and chronic kidney disease of unknown etiology (CKDu) is also prevalent among this community. Most of the drinking water in these villages...

There is an urgent need to construct highly selective low-cost sensors for fast detection of toxic metal ions such as cadmium. When compared with 3D bulk materials, 2D layered materials after activation treatments show superior performances for electrochemical metal ion detection. The bulk graphitic carbon nitride (hereafter b-g-C3N4) was prepared...

Herein the sulfur/nitrogen contained groups, serving as the "hooks" for electrochemical determination of Hg(II), were assembled on the reduced graphene oxide (hereafter SN-rGO) via a one-step facile hydrothermal method. The thiourea acts as a precursor for sulfur/nitrogen doping and partial reduction of graphene oxide. The SN-rGO was used to modify...

It has recently been proposed that recalcitrant dissolved organic carbon (DOC) in groundwater plays a potent etiological role in the peculiar distribution of chronic kidney disease of unknown etiology (CKDu). This study aims to elucidate the interactions of Ca2+ and SO42- with a model organic fraction of humic acid (SHA) to determine the possible r...

A novel method using mesoporous g-C3N4 and β-cyclodextrin nanocomposite (mpg-C3N4/β-CD) for the electrochemical detection of 2,4,6-trinitrotoluene (TNT) is presented. The unique structure of the mesoporous g-C3N4/β-CD nanocomposite facilitates both mpg-C3N4 electrocatalysis and β-CD inclusion-complexation of the analytes. When compared to GCE or mp...