Journal Articles
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Item Metal organic frameworks as desulfurization adsorbents of DBT and 4,6-DMDBT from fuels(MDPI AG indexing@mdpi.com Postfach Basel CH-4005, 2019) Kampouraki, Z.-C.; Giannakoudakis, D.A.; Nair, V.; Hosseini-Bandegharaei, A.; Colmenares, J.C.; Deliyanni, E.A.Ultradeep desulfurization of fuels is a method of enormous demand due to the generation of harmful compounds during the burning of sulfur-containing fuels, which are a major source of environmental pollution. Among the various desulfurization methods in application, adsorptive desulfurization (ADS) has low energy demand and is feasible to be employed at ambient conditions without the addition of chemicals. The most crucial factor for ADS application is the selection of the adsorbent, and, currently, a new family of porous materials, metal organic frameworks (MOFs), has proved to be very effective towards this direction. In the current review, applications of MOFs and their functionalized composites for ADS are presented and discussed, as well as the main desulfurization mechanisms reported for the removal of thiophenic compounds by various frameworks. Prospective methods regarding the further improvement of MOF’s desulfurization capability are also suggested. © 2019 MDPI AG. All rights reserved.Item Role of catalyst supports in biocatalysis(John Wiley and Sons Ltd, 2023) Manikandan, S.K.; Giannakoudakis, D.A.; Prekodravac, J.R.; Nair, V.; Colmenares, J.C.Biocatalysis utilizes enzymes and microbial cells as catalysts for a wide range of applications in biotechnology. Immobilization of biocatalysts on various materials has several advantages, including the capacity for reuse, quick reaction termination, easy biocatalyst recovery and operational stability. The present article focuses on the use of material supports for developing immobilized biocatalysts in applications related to energy, environment and chemical synthesis. The work provides a comprehensive overview of a broad class of materials, including organic, inorganic and composites, that have been shown to be prosperous candidates to support the immobilization of enzymes and microbial cells. It also highlights the properties of nanomaterial support such as large surface area and comfort compartment for immobilization. The availability of different types of materials as catalyst support provides an opportunity to understand and develop efficient biocatalytic systems. The choice of selecting a catalyst support will mostly depend on the interaction of the material with the enzyme or microbial cell. Finally, potential challenges, future approaches in developing immobilized biocatalytic systems for various applications and novel material supports are suggested. © 2022 Society of Chemical Industry (SCI). © 2022 Society of Chemical Industry (SCI).Item Effective Usage of Biochar and Microorganisms for the Removal of Heavy Metal Ions and Pesticides(MDPI, 2023) Manikandan, S.K.; Pallavi, P.; Shetty K, V.; Bhattacharjee, D.; Giannakoudakis, D.A.; Katsoyiannis, I.A.; Nair, V.The bioremediation of heavy metal ions and pesticides is both cost-effective and environmentally friendly. Microbial remediation is considered superior to conventional abiotic remediation processes, due to its cost-effectiveness, decrement of biological and chemical sludge, selectivity toward specific metal ions, and high removal efficiency in dilute effluents. Immobilization technology using biochar as a carrier is one important approach for advancing microbial remediation. This article provides an overview of biochar-based materials, including their design and production strategies, physicochemical properties, and applications as adsorbents and support for microorganisms. Microorganisms that can cope with the various heavy metal ions and/or pesticides that enter the environment are also outlined in this review. Pesticide and heavy metal bioremediation can be influenced by microbial activity, pollutant bioavailability, and environmental factors, such as pH and temperature. Furthermore, by elucidating the interaction mechanisms, this paper summarizes the microbe-mediated remediation of heavy metals and pesticides. In this review, we also compile and discuss those works focusing on the study of various bioremediation strategies utilizing biochar and microorganisms and how the immobilized bacteria on biochar contribute to the improvement of bioremediation strategies. There is also a summary of the sources and harmful effects of pesticides and heavy metals. Finally, based on the research described above, this study outlines the future scope of this field. © 2023 by the authors.Item Advancing date palm cultivation in the Arabian Peninsula and beyond: Addressing stress tolerance, genetic diversity, and sustainable practices(Elsevier B.V., 2025) Manikandan, S.K.; Jenifer A, D.; Gowda, N.K.; Nair, V.; Al-Ruzouq, R.; Gibril, M.B.A.; Lamghari, F.; Klironomos, J.; Hmoudi, M.A.; Sheteiwy, M.; El-Keblawy, A.Date palm (Phoenix dactylifera L.) cultivation in the Arabian Peninsula is crucial for regional agriculture and global markets. The Arabian Peninsula is dominant in date production, contributing approximately 34 % of the global output. Recent advancements in agricultural technologies have improved fruit yield and quality, expanding date palm cultivation globally. However, sustainability challenges persist due to various abiotic stresses, such as salinity, temperature extremes, drought, soil factors, and biotic stresses, including diseases and pests. This review examines key environmental factors affecting date palm cultivation, with a focus on soil salinity, water scarcity, and climate change-related stresses. The genetic diversity among date palm varieties is emphasized, highlighting the need for breeding programs aimed at improving stress tolerance and yield. Biotechnological advancements, such as genetic transformation and genome editing, are discussed for their potential to enhance crop resilience and productivity. Additionally, remote sensing techniques are explored for their application in precision agriculture, particularly in the mapping and monitoring of date palm health and soil conditions. The significant role of artificial intelligence in accurately mapping date palm trees using multi-platform remotely sensed data is also reviewed, illustrating its potential to enhance geospatial databases and support sustainable management practices. The review concludes with recommendations for optimizing cultivar selection and management strategies tailored to local conditions, emphasizing the need for ongoing research to advance date palm cultivation on a global scale. © 2024Item Design and development of TiO2 coated microflow reactor for photocatalytic partial oxidation of benzyl alcohol(Elsevier B.V., 2020) Pradhan, S.R.; Nair, V.; Giannakoudakis, D.A.; Lisovytskiy, D.; Colmenares, J.C.The synthesis of valuable organic compounds from naturally available and renewable biomass is an open field of research towards adaptation in real-life applications. Photocatalytic valorization is assumed as a potential candidate, although the lower efficiency of the traditional batch photocatalytic reactor sets some drawbacks. Recently, photocatalytic microreactors revealed as a prosperous candidate for various photocatalytic reactions, especially for selective oxidation. This area of research is challenging due to the development of the proper photocatalytic microreactor for the targeted application. Deposition of the catalyst on the internal surface of the microreactor, the sufficient utilization of the irradiation, optimization of the reaction parameters are among the most vital parameters that should be considered upon the design. Although, to obtain the most active material and tune its crucial features to maximize its catalytic performance inside the microreactors is the uppermost important part. This work introduces ultrasound-assisted TiO2 deposition on the inner walls of a perfluoroalkoxyalkane microtube under mild conditions. The deposition experiments were carried out with commercial and sol-gel synthesized TiO2. The materials were characterized by XRD, UV–vis DRS, Scanning Electron Microscopy (SEM), and nitrogen sorption. The photocatalytic activities of the TiO2 nano-engineered fluoropolymer based microreactors were evaluated for the oxidation of benzyl alcohol in flow. © 2020 The Author(s)Item Ultrasound-assisted decoration of CuOx nanoclusters on TiO2 nanoparticles for additives free photocatalytic hydrogen production and biomass valorization by selective oxidation(Elsevier B.V., 2021) Giannakoudakis, D.A.; Qayyum, A.; Nair, V.; Khan, A.; Pradhan, S.R.; Prekodravac, J.; Rekos, K.; LaGrow, A.P.; Bondarchuk, O.; ?omot, D.; Triantafyllidis, K.S.; Colmenares, J.C.The herein presented ultrasound-assisted ultra-wet (US-UWet) impregnation synthetic approach was followed in order to avoid the drawbacks of the conventional wet impregnation synthesis. The goal was to homogeneously decorate the surface of the TiO2 nanoparticles with nanometric sized (< 4 nm) clusters of mixed cupric and cuprous oxides. The physicochemical features of the nanocomposite (TiO2[sbnd]CuOx) were determined by high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), and Diffuse reflectance (DR) spectroscopy. TiO2[sbnd]CuOx showed an enhanced and continuous capability to generate molecular hydrogen upon low power ultraviolet irradiation. The benchmark commercial TiO2 P25 did not reveal any H2 formation under these conditions. TiO2[sbnd]CuOx presented also a high efficiency for the additives-free selective partial oxidation of two well established biomass derived model platform chemicals/building blocks, 5-hydroxymethylfurfural (HMF) and benzyl alcohol (BnOH) to the value-added chemicals 2,5-diformylfuran (DFF) and benzyl aldehyde (PhCHO), respectively. The nanocomposite showed higher DFF and PhCHO yield compared to P25. © 2021Item Pseudomonas stutzeri Immobilized Sawdust Biochar for Nickel Ion Removal(MDPI, 2022) Manikandan, S.K.; Nair, V.Nickel ions generated from the electroplating industry and stainless steel and battery manufacturing industries contribute to water pollution, harm human health, and pose environmental risks. A long-term, sustainable, and efficient treatment method should be developed to address this issue. Bioremediation in the presence of biochar and microorganisms is a potential approach for metal ion abatement. This study evaluates the feasibility of Pseudomonas stutzeri immobilized sawdust biochar (PSDB) for Ni2+ removal. Sawdust biochar was prepared by pyrolyzing in a muffle furnace and was characterized using SEM, FTIR, and BET. The influence of biochar preparation parameters such as pyrolysis temperature, time on biochar yield, and impact on cell immobilization was investigated. The effect of various parameters, such as incubation time, pH, temperature, and biocatalyst dosage, was studied. The total Ni2+ in solution was analyzed using inductively coupled plasma optical emission spectrometry. PSDB showed an 83% Ni2+ removal efficiency and reusability up to three cycles. FT-IR analysis revealed that the mechanism of Ni2+ removal by PSDB was the synergistic effect of adsorption by biochar and bioaccumulation by P. stutzeri. This study presents a novel approach for environmental application by utilizing waste biomass-derived biochar as a carrier support for bacteria and an adsorbent for pollutants. © 2022 by the authors.Item Composites of Lignin-Based Biochar with BiOCl for Photocatalytic Water Treatment: RSM Studies for Process Optimization(MDPI, 2023) Singh, A.K.; Giannakoudakis, D.A.; Arkas, M.; Triantafyllidis, K.S.; Nair, V.Textile effluents pose a massive threat to the aquatic environment, so, sustainable approaches for environmentally friendly multifunctional remediation methods degradation are still a challenge. In this study, composites consisting of bismuth oxyhalide nanoparticles, specifically bismuth oxychloride (BiOCl) nanoplatelets, and lignin-based biochar were synthesized following a one-step hydrolysis synthesis. The simultaneous photocatalytic and adsorptive remediation efficiency of the Biochar–BiOCl composites were studied for the removal of a benchmark azo anionic dye, methyl orange dye (MO). The influence of various parameters (such as catalyst dosage, initial dye concentration, and pH) on the photo-assisted removal was carried out and optimized using the Box–Behnken Design of RSM. The physicochemical properties of the nanomaterials were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, nitrogen sorption, and UV–Vis diffuse reflectance spectroscopy (DRS). The maximum dye removal was observed at a catalyst dosage of 1.39 g/L, an initial dye concentration of 41.8 mg/L, and a pH of 3.15. The experiment performed under optimized conditions resulted in 100% degradation of the MO after 60 min of light exposure. The incorporation of activated biochar had a positive impact on the photocatalytic performance of the BiOCl photocatalyst for removing the MO due to favorable changes in the surface morphology, optical absorption, and specific surface area and hence the dispersion of the photo-active nanoparticles leading to more photocatalytic active sites. This study is within the frames of the design and development of green-oriented nanomaterials of low cost for advanced (waste)water treatment applications. © 2023 by the authors.Item Application of Box-Behnken Design in Optimization of the Okra (Abelmoschus esculentus L.) Plant Growth in Loamy Sand Soil(Springer Science and Business Media Deutschland GmbH, 2023) Shilli, A.; Manikandan, S.K.; Nair, V.Seedling emergence and its vigor index are the decisive steps for increasing vegetable crop yield performance using a sustainable approach. Response surface methodology (RSM) is an effective statistical method used to determine the significance of independent variables and the range of optimum conditions to maximize seedling growth in large-scale plant production. In this study, the RSM method was used to predict the maximum germination percentage and seed vigor index of an okra (Abelmoschus esculentus L.) plant in loamy sand soil. A Box-Behnken design of RSM having 15 triplicated runs was designed for okra seed germination experiments. A second-order polynomial model having three levels of biochar (10, 5.5, and 1%), cow dung (10, 5.5, and 1%), and water content (100, 70, and 40%) was used to optimize okra seed germination and seed vigor index. We evaluated the individual effect of biochar and cow dung manure on β-glucosidase and alkaline phosphatase activity in the soil. The results showed that the water content had a significant influence on the selected response variables. Based on the plant growth studies, the use of 5.5% of both biochar and cow dung concentration and 70% of water content in the soil resulted in the highest germination percentage and seed vigor index of 93% and 2479. The ANOVA studies revealed good agreement between the experimental data and the proposed model, indicating the suitability of the employed model in optimizing germination conditions. Enzyme activity analysis revealed that the amendment of 10% cow dung enhanced 55% β-glucosidase activity compared to control, while the application of 5.5% biochar along with cow dung improved 29% of alkaline phosphatase activity. The current study found that applying biochar and cow dung manure while maintaining water content can improve okra seedling emergence and growth in loamy sand soil. Future research includes long-term field experiments and studies on various biochar and their suitability for other soil types. Moreover, the RSM method can be used to study the effect of parameters like oxygen content, salt, heavy metals, and humus substance in soil on plant growth. © 2023, The Author(s) under exclusive licence to Sociedad Chilena de la Ciencia del Suelo.Item Developing a biocatalyst showcasing the synergistic effect of rice husk biochar and bacterial cells for the removal of heavy metals(Royal Society of Chemistry, 2023) Manikandan, S.K.; Nair, V.Heavy metals like cadmium (Cd) and nickel (Ni) are toxic pollutants that affect the environment and pose health risks. Removal of Cd and Ni through bioremediation in the presence of biochar is a sustainable strategy. This study investigated the removal of Cd and Ni by Pseudomonas stutzeri immobilized on rice husk biochar (PRHB). The removal efficiency was calculated by varying the culture incubation time, pH, temperature, biocatalyst dosage, and initial metal ion concentration. PRHB showed a maximum metal removal capacity of 95% Cd and 92% Ni. The removal efficiency of PRHB was higher than that of free cells, which could be attributed to simultaneous adsorption, ion exchange, complexation, precipitation, and bioaccumulation caused by the biochar carrier and bacteria. The rice husk biochar material served as both an adsorbent and a carrier supplying nutrients for the growth of the bacteria. Considering the excellent metal ion removal capability and reusability, the use of PRHB could be a promising, cost-effective, and environment-friendly strategy for treating wastewater containing heavy metals. © 2023 The Royal Society of Chemistry.