BITS Faculty Publications
Permanent URI for this communityhttp://localhost:4000/handle/123456789/1867
Browse
11 results
Search Results
Item Application of Chlorella pyrenoidosa embedded biochar beads for water treatment(Elsevier, 2021-04) Goonetilleke, AshanthaThe ability of biochar beads embedded with freshwater algae ̶ Chlorella pyrenoidosa (Bc-Cp beads) were investigated for their efficiency in the removal of pollutants. Combining these is an innovative concept which can result in improvements in pollutant removal since both, biochar and algae have the ability for adsorbing/absorbing pollutants. Additionally, only limited work on embedding freshwater algae (common algae existing in surface water and having low ecological risks since they are native species) into biochar for the removal of water pollutants has been undertaken to-date. It was found that Bc-Cp beads prepared using 10 mL of algae (9 × 108 cell/mL), 0.3 g of biochar, 40 g/L of sodium alginate, and 20 g/L of CaCl2 displayed the optimum characteristics including mechanical strength (2.548 N), promotion of algae growth (191.70 % growth rate) and pollutant removal ability with the removal efficiency of ammonia nitrogen, total nitrogen and total phosphorus, total organic carbon, zinc and copper were up to 69.2 %, 43.0 %, 73.8 %, 81.0 %, 74.4 % and 81.0 %, respectively. The algae within the beads were primarily responsible for the removal of nutrients by assimilation, while biochar mainly exerted influence on the removal of organic matter and heavy metals by chemisorption. The study outcomes also confirmed that Bc-Cp beads possess high potential to be used in estuarine environments and saline groundwater.Item Removal of heavy metals from water using engineered hydrochar: kinetics and mechanistic approach(Elsevier, 2021-04) Goonetilleke, AshanthaThe isotherm, kinetics, and thermodynamics parameters, and mechanisms involved in the adsorption of Pb2+ and Cu2+ ions from an aqueous solution using engineered hydrochar were investigated. The hydrochar was produced through catalytic hydrothermal carbonization of rice straw at 200 °C with (engineered hydrochar) and without (hydrochar) FeCl3 (1.2 %) as iron catalyst which has been reported to have the ability to enhance surface properties. Batch experiments were conducted to examine the effect of sorbent dosage, pH, and initial metal ion concentration on the adsorptive performance. The results obtained revealed that the addition of iron catalyst increased the surface functional groups, and exhibit better adsorptive performance compared to non-treated hydrochar. The adsorptive performance of engineered hydrochar was higher for Pb2+ compared to Cu2+, which can be explained by surface complexation, cationic- π interaction, and mass diffusion process with the initial removal performance limited by mass transfer process. The Langmuir isotherm model gave the best fit for the adsorption of both metals compared to the other models tested. The adsorption kinetics followed the Lagergren’s pseudo-second order model. Thermodynamic parameters revealed that Pb2+ and Cu2+ adsorption by engineered hydrochar is a spontaneous and endothermic process. Moreover, this study created new knowledge by providing an in-depth understanding of the effect of iron catalyst on the functional properties of engineered hydrochar and its adsorption mechanisms. Research on the use of catalysts in engineered hydrochar for pollutant removal is very limited. In addition, the study outcomes would contribute to the production of highly efficient magnetic hydrochars.Item Lab-scale engineered hydrochar production and techno-economic scaling-up analysis(Elsevier, 2024-02) Goonetilleke, AshanthaDespite the extensive use of engineered hydrochar (EHC) for contaminants adsorption in water, little is known about the scaling-up of EHC production which has kept the technology at a low readiness level (TRL). Full-scale EHC production was simulated to help bridge this knowledge gap. A systematic analysis was performed where EHC was produced from rice straw using hydrothermal carbonization (HTC) at 200 °C with iron addition. A techno-economic evaluation model was employed to simulate the production process and to estimate energy requirements, configuration, and cost scenarios for the HTC process. The minimum selling price (MSP) analysis of the engineered hydrochar was found to be almost half compared to the market price for other similar sorbents ($ 76/t vs. $136/t) suggesting that EHC production is feasible for scaling up. Finally, as a trial, the resulting material was tested for its efficacy in the adsorption of an anionic organic contaminant (e.g., Congo Red, C32H22N6Na2O6S2) in water to identify its potential for water treatment. Experimental results showed that EHC adsorbed > 95% CR suggesting significant adsorption capability and feasibility for production scale-up.Item Optimizing the upcycling of microplastics to a carbon-based adsorbent for water treatment: An integrated experimental and computational approach(Elsevier, 2026-05) Goonetilleke, AshanthaMicroplastics (MPs) are an escalating environmental hazard because they persist in aquatic ecosystems and resist removal by conventional water treatment technologies. A novel data-driven strategy that upcycles MPs into engineered carbonaceous adsorbents via hydrothermal carbonization (HTC) is presented. By systematically varying three synthesis variables – feedstock loading, acid type and acid concentration – a range of carbonaceous materials (CMs) was produced and evaluated for their ability to adsorb Reactive Orange 84 dye. An integrated full factorial design of experiments encompassing both, material synthesis variables (acid type, acid concentration, and polyester (PES) material concentration) and the application variables (CM dose) was implemented. Subsequent statistical analysis and PCA identified acid type, acid concentration, CM dose, and PES concentration as dominant factors controlling adsorption capacity (q_e) and removal percentage. To refine the optimization, several machine learning (ML) models – linear regression, support vector machines, ensemble methods, and neural networks – were trained on the experimental dataset. Acid treated CMs consistently outperformed those synthesized under neutral conditions, with optimal performance observed at moderate acid concentrations. The key innovation in this study lies in the integrated experimental-computational framework that models the entire process (synthesis −> application), coupling rigorous statistical screening with advanced ML prediction. This delivers actionable guidance for the rational design of acid-modified carbonaceous adsorbents and advances the upcycling of MPs for water treatment applications.Item Biogenic carbon matrix with dual-mode adsorption capability: synthesis, characterization and mechanistic insights(Elsevier, 2026-04) Goonetilleke, AshanthaThe transformation of biowaste into high-performance functional materials presents a promising strategy for sustainable environmental technologies. In this study, a novel biogenic carbon-based catalytic matrix (CBCM) was synthesized from prawn shell waste, integrating chitin-derived carbon and in-situ formed calcite to yield a hybrid material with distinctive structural and surface characteristics. Comprehensive characterization using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) revealed a composite architecture featuring both organic (Chitin) and inorganic (Calcite) crystalline domains, along with abundant surface oxygenated functional groups (Osingle bondH, Cdouble bondO, CO-NH, and Csingle bondO). These structural attributes underpin the CBCM's dual-mode adsorption capability, enabling simultaneous and efficient uptake of both cationic (Malachite green) and anionic (Congo red) dyes. Kinetic and isotherm analyses highlighted the dominant roles of hydrogen bonding and π-π interactions, directly linked to the material's functional groups and porous surface morphology. Response surface modeling confirmed strong agreement between predicted and experimental adsorption capacities (R2 = 0.978), underscoring the reliability of the structure-function correlation. This work demonstrates how rational design and valorization of marine biowaste can yield multifunctional materials, with the CBCM serving as a proof-of-concept platform for pollutant capture and broader environmental applications.Item Aluminium terephthalate (Al-BDC) based metal organic framework decorated carboxymethylated filter cloth for defluoridation application(Elsevier, 2023-06) Chatterjee, SomakCurrent work adopts a novel approach for deposition of aluminium terephthalate-based metal organic framework (MOF) on carboxymethylated filter paper for defluoridation purpose. Aluminium terephthalate-based MOF was prepared using an optimized technique and showed a fluoride uptake capacity of 665 mg/g. However, due to its low yield, synthesized MOF was immobilized on carboxymethylated filter paper, using hydrothermal method. MOF immobilized filter paper (MOF cloth) showed a fluoride uptake capacity of 88 mg/g. Different surface-based characterization for MOF and MOF cloth were performed. Synthesized MOF was quasi-spherical in shape, forming flower like structures, when coalesced together and it showed crystalline property, having lattice fringes of 0.2 nm. Uniform and dense distribution was observed during its deposition process on filter paper. Both functional groups and mineralogical phases present in the MOF were also imparted to the immobilized filter paper. Uptake of fluoride by MOF cloth was governed by monolayer adsorption, as evident from Langmuir isotherm analysis. Uptake capacity increased with temperature and the highest one was recorded at 318 K. Prepared MOF cloth was subjected to dynamic studies via glass-funnel based filtration, where, effects of pH, coexisting ions including an organic pollutant and real-life feed were carried out. Regeneration of the MOF cloth was also studied for four cycles. Leaching study was performed at different time intervals. Finally, comparison was made with different conventional MOF based adsorbents and it was observed that this cloth can be an adaptable and pollution free medium for defluoridation applications.Item Polyaniline-doped sawdust as a promising adsorbent for defluoridation(Elsevier, 2023-11) Chatterjee, SomakFluoride’s presence in groundwater is a growing concern, especially where access to safe drinking water is limited. Traditional water treatment methods have limitations in effectively removing fluoride. Thus, there is a need for an alternative, sustainable and cost-effective solution. This study develops an adsorbent where a conducting polymer (PAni) will be coated on agricultural byproduct (sawdust) for defluoridation application. Introduction of amino-tris-methylene-phosphonic acid (ATMPA) as a dopant into PAni enhances its exchange mechanism, thereby increasing its uptake capacity (58 mg/g). Potential application of this adsorbent lies in water treatment plants, which will cater needs of industry, mankind and agricultureItem Undoped polyaniline-modified sawdust as an adsorbent for lead removal(Elsevier, 2023-12) Chatterjee, SomakHeavy metal ion adsorption employing abundant natural and agricultural wastes appears to be promising. Biodegradable sawdust is promoted as a green and sustainable alternative. In this work, potential application of sawdust has been explored for uptake of lead ions from contaminated water. Specifically, undoped polyaniline, a highly conductive polymer, was added to sawdust to improve its uptake capacity. Highest lead uptake capacity of 218 mg/g was observed at 318 K. Different surface-based characterizations for this material were performed. Morphology of prepared sawdust revealed a one-dimensional flake-like structure having a porous nature. FTIR and XRD analysis inferred successful incorporation of polyaniline into sawdust. In addition, XPS analysis revealed the importance of polyaniline chains during electrostatic adsorption of lead ions. At an adsorbent dosage of 1 g/l, optimal equilibrium conditions were reached. In accordance with Langmuir isotherm analysis, lead ion uptake was mainly driven by monolayer adsorption. As-prepared adsorbent was subjected to batch studies, where, effects of pH and interfering ions were carried out. Regeneration was also studied for four cycles.Item Polyacrylonitrile and polyethersulfone based co-axial electrospun nanofibers for fluoride removal from contaminated stream(Elsevier, 2024-02) Chatterjee, SomakCoaxial electrospun polyacrylonitrile (PAN) and polyethersulfone (PES) based nanofibers were prepared and was used for filtration of fluoride from drinking water for the first time. Well defined fiber geometry was obtained at 1 ml/h of core polymer, i.e., PES flow rate, 1.4 ml/h of shell polymer, i.e., PAN flow rate, voltage of 22 kV, while the distance between the needle tip and the collector was 15–17 cm. Increase in bead like structure in fiber strands was observed with higher PAN concentration, while it decreased for lower PES concentration, thereby giving an optimum composition (6 wt% PAN and 10 wt% PES) for uniform fiber morphology. This nanofiber, abbreviated as N2 acted as an ultrafiltration membrane having permeability in the lower range, i.e., 0.5 × 10−11 m/s Pa and its fluoride removal efficacy was 46%. Fibers were also hydrophilic with considerable porous nature. Uptake of fluoride by this N2 nanofibers were evident from binding energy of 685.2 eV during XPS analysis. It is probable that nitrile and sulfone groups present in the core and shell of the nanofibers played an active in fluoride uptake, which was estimated as 110 mg/g at 298 K. Isoelectric point was in alkaline range which promoted negative fluoride ion uptake on positive nanofiber surface. Lead played higher masking effect in the uptake of fluoride in comparison to arsenic as coexisting ion. Dynamic cross flow filtration was also studied with this nanofiber in both synthetic and real life feed solution.Item Hydrogen storage using novel graphene-carbon nanotube hybrid(Elsevier, 2023) Ghosh, SarbaniHydrogen storage is an active area of research particularly due to urgent requirements for green energy technologies. In this paper, we study the storage of hydrogen gas molecules in terms of physical adsorption on a carbon-based nanomaterial, i.e., a novel graphene-carbon nanotube hybrid. The novel carbon nanostructures were prepared from pristine nanotubes and graphene sheets using molecular dynamics simulations and hydrogen storage quantified in terms of gravimetric capacity was simulated using grand canonical Monte Carlo Simulations. We found the highest storage capacity of 5.90 wt% at room temperature and 100 bar with high reversibility of operation