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Browsing by Author "Martins O. Omorogie"

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A review on the versatility of Carica papaya seed: an agrogenic waste for the removal of organic, inorganic and microbial contaminants in water
(John Wiley, 2023-05-21) Martins O. Omorogie
The advent of civilization, coupled with growing industrialization in many countries, is placing more demand on the available water sources. At the same time, the daily surge in wastes generated by man's anthropogenic activities has led to microbial, organic and inorganic contamination of water sources. Based on available evidence, signiﬁcant research efforts are being made into the use of low-cost agricultural materials such as Carica papaya seed (CPS) in the removal of these contaminants from water sources in a bid to provide clean water. In the present review, the organic, inorganic and microbial contaminants in waters were elucidated. Furthermore, the chemical composition of the CPS was illustrated. The adsorption capacity and efﬁciency of CPS and their composites in the remediation of the selected contaminants were discussed while identifying the various factors affecting the adsorption efﬁciency. Finally, the reusability of this agricultural material was discussed. Solution pH was identiﬁed as a major factor inﬂuencing the sorption process. The high removal efﬁciency reported in the studies that adopted CPS showed its vast potential in the elimination of contaminants from water sources. Also, the regenerative potential of the adsorbent over several cycles indicated its long-term use. The economic feasibility and environmental sustainability afforded by using CPS chart a path for further investigation into the use of other low-cost agricultural materials in the elimination of environmental contaminants.
Aerosol Assisted Chemical Vapour Deposition (AACVD) of Zinc dichalcogenoimidodiphosphinate Complexes for the Deposition of Zinc Selenide Thin Films
(John Wiley, 2024) Martins O. Omorogie
Dichalcogenoimidodiphosphinate complexes of zinc [Zn{(EPiPr2)2N}2], [E=Se,Se; S,Se] were synthesized through meta-thetical reactions from the dichalcogenoimidodiphosphinateligands [(EE’PiPr2NH)] (E, E’=Se, Se; S, Se). These complexes werecharacterized and used as single-source precursors throughAerosol-Assisted Chemical Vapour Deposition (AACVD) for thedeposition of cubic zinc selenide (ZnSe) films on glasssubstrates. The deposition temperature occurred at 500 and525 °C, while the flow rates of the carrier gas was 160 and240 standard cubic centimetre (sccm). The morphology of thedeposited films ranged between dense fibrous network andwoven fibres. X-ray photoelectron spectroscopy (XPS) con-firmed the presence of the constituent elements in zincselenide.
Applications of perovskite oxides for the cleanup and mechanism of action of emerging contaminants/steroid hormones in water
(Elsevier, 2024-01-01) Martins O. Omorogie
The contamination of water sources by emerging contaminants, specifically steroid hormones, is swiftly becoming a serious threat to both humans and the environment. However, a solution has emerged in the form of perovskite oxides, which show great potential in removing these contaminants from water sources. Perovskite oxides possess remarkable adsorption and catalytic properties, making them ideal for removing a wide range of emerging contaminants from water. Their unique crystal structure and surface features provide multiple active sites for adsorbing steroid hormones, utilizing surface interactions, ion exchange, and chemisorption to capture and retain these contaminants effectively. Furthermore, perovskite oxides can catalytically degrade steroid hormones through oxidation or reduction reactions, breaking down complex molecular structures and converting them into less harmful byproducts. They can also be engineered selectively for specific contaminants, allowing for a tailored approach to water treatment. Additionally, their regenerative capabilities make them sustainable, enabling multiple cycles of use while minimizing the environmental impact of water treatment processes. Overall, perovskite oxides offer a promising solution to cleaning up water contaminated with emerging contaminants, and their effectiveness in addressing the specific challenges posed by steroid hormones is particularly noteworthy.
Ascorbic and salicylic acids modulate the binding interactions of an emergency contraceptive pill levonorgestrel to a model transport protein
(Elsevier, 2024) Martins O. Omorogie
Serum proteins generally help to transport and distribute drug molecules within the body. In this study, the binding characteristics of bovine serum albumin (BSA) with levonorgestrel (LVG), an emergency contraceptive pill, and the influences of ascorbic acid (ASC) and salicylic acid (SAL) on the binding behaviour and protein structure were elucidated using multi-spectroscopic techniques and molecular docking. The results showed that levonorgestrel decreased BSA intrinsic fluorescence via static quenching mechanism. Binding constant (Ka) values for BSA-LVG complexes were 103 to 104 M-1, indicating their high stabilities. Site probing/docking analysis indicated LVG bound between BSA subdomains IIA and IIIA. UV–visible absorption, Fourier Transform-Infrared and 3D fluorescence spectroscopies affirmed LVG-induced changes in BSA structure, especially in α-helix and β-sheet contents. ASC and SAL influenced BSA conformation for LVG binding and reduced the Ka values by 3.37 and 5.43-folds, respectively. LVG altered the microenvironments of tyrosine residues, interacted with Arg-217, Lys-221, Val-292, Glu-443 etc. within the binding domains. The process was spontaneous (ΔG<0), entropy driven (TΔS>ΔH) and involved van der Waals forces and hydrogen bonding. The findings of the study offered details on the binding interaction between BSA and LVG, and also indicated that prior intake of ASC or SAL could suppress the binding affinity of BSA for levonorgestrel.
Biomass-tuned reduced graphene Oxide@ Zn/Cu: benign materials for the cleanup of selected nonsteroidal anti-inflammatory drugs in water
(American Chemical Society, 2023) Martins O. Omorogie
The persistent increase in the amount of nonsteroidal anti-inflammatory drugs such as ibuprofen (IBP) and diclofenac (DCF) in water bodies is alarming, thereby calling fora need to be addressed. To address this challenge, a bimetallic (copper and zinc) plantain-based adsorbent (CZPP) and reduced graphene oxide modified form (CZPPrgo) was prepared by facile synthesis for the removal of ibuprofen (IBP) and diclofenac (DCF) in water. Both the CZPP and CZPPrgo were characterized by different techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), scanning electron microscopy(SEM), and pHpzc analysis. FTIR and XRD confirmed the successful synthesis of the CZPP and CZPPrgo. The adsorption of the contaminants was carried out in a batch system, and several operational variables were optimized. The adsorption is affected by the initial concentration of the pollutants (5−30 mg·L−1), the adsorbent dose (0.05−0.20 g), and pH(2.0−12.0). The CZPPrgo has the best performance with maximum adsorption capacities of148 and 146 mg·g−1 for removing IBP and DCF from water, respectively. The experimental data were fitted into different kinetic and isotherm models; the removal of IBP and DCF follows the pseudo-second order, which can be best explained by the Freundlich isotherm model. The reuse efficiency was above 80% even after four adsorption cycles. This shows that the CZPPrgo is a promising adsorbent for removing IBP and DCF in water.
Current status and performance evaluation of emerging advanced remediation techniques for the removal of steroidal hormones in water
(Elsevier, 2024) Martins O. Omorogie
Micropollutants such as steroid hormones contaminate water worldwide and cause significant damage. Wastewater treatment plants (WWTPs) partially remove them, and they have low biodegradability leading to their persistence in water bodies. They are endocrine disruptor compounds in aquatic organisms. Various environmental conditions contribute to their persistence in the environment like soil pH, organic matter, soil conditions, and temperature. The aquatic environment is most threatened even when present at very low concentrations. The environment is exposed to steroid hormones from agricultural run-offs, pharmaceutical and industrial waste, and veterinary medicine. Since most WWTPs partially remove contaminants, there is a need for new and improved technologies for higher and more efficient removal of steroid hormones. This paper discusses the fate and toxicity of steroid hormones in the aquatic environment. It further elucidates the existing and emerging technologies in the treatment of steroid hormones in aquatic environments. Finally, the conclusion of this review along with the current limitations and future research perspectives of hormones present in the environment are elucidated.
Distribution and toxicity of dihydroxybenzenes in drinking water sources in Nigeria
(Royal Society of Chemistry, 2024-01-02) Martins O. Omorogie
hydroquinone (HQ) in drinking water sources from Africa. Groundwater (boreholes and hand-dug wells) and surface water in three Southwestern States in Nigeria served as sampling sites. The concentrations of CAT and HQ in groundwater and surface water were determined throughout a period of 12 months, evaluating the effects of seasonal variation (rainy and dry seasons). Mean concentrations of CAT in water samples were higher than those of HQ. In this study, CAT was more frequently detected, with its mean concentration in groundwater samples higher in the rainy season (430 mg L−1) than in the dry season (175 mg L−1). Multivariate analysis using the Principal Component Analysis Software suggests that in most sample sites, CAT and HQ in water samples were from entirely different anthropogenic sources. The most impacted population groups were the toddlers and infants. Similarly, maximum and median concentrations of CAT in water samples pose serious risks to Daphnia at both acute and chronic levels. The results from this study suggest the need for further control of these dihydroxybenzenes through regular monitoring and removal from drinking water during treatment.
Distribution, Correlations, and Risk Evaluation of Endocrine Disrupting Chemicals from Indoor Aerosols within Universities in Nigeria
(American Chemical Society, 2024-04-29) Martins O. Omorogie
Aerosols from filters in air conditioning systems in three indoor environments (staff offices, libraries, and laboratories) across nine universities in Southwest Nigeria were analysed for the presence of endocrine disrupting chemicals (EDCs): methylparaben (MeP), ethylparaben (EtP), propylparaben (PrP), butylparaben (BuP), triclosan (TCS), and bisphenol A (BPA). A total of 102 indoor aerosol samples were collected. The trend for the mean of mean concentrations (𝜇𝜒¯) of MeP (405 ng/g) < EtP (698.8 ng/g) < PrP (4326 ng/g) > BuP (2962 ng/g) < BPA (4316 ng/g) < TCS (4943 ng/g) in staff offices is consistent with those found in libraries (MeP = 452 ng/g; EtP = 1936 ng/g; PrP = 4046 ng/g; BuP = 2584 ng/g; BPA = 2472 ng/g; and TCS = 5109 ng/g). However, the 𝜇𝜒¯ values for EDCs in laboratory aerosols are higher than those found in either staff offices or libraries. Aerosols from indoor environments in universities located in high-population-density areas show higher concentrations of EDCs than in universities established in less populated areas. PrP and TCS were predominant in aerosols from staff offices and libraries, while BuP and TCS were the largest contributors to EDCs in aerosols from the laboratories. PrP is the main contributor to the Hazard Quotients of these EDCs, while PrP and BPA contribute more to the Hazard Index. Data for antimicrobials (parabens and TCS) in aerosols from libraries showed a strong correlation with those from staff offices and laboratories, while for BPA there was a strong correlation between data from libraries and laboratories. The strong correlations between pairs of EDCs in aerosols from different indoor environments suggest that they may have similar accumulation tendencies and the same anthropogenic sources, especially in laboratories. Aerosols in offices of most female staff had higher levels of EDCs compared to those of the male. There is a need to focus on regulating the amount of PrP, TCS, and BPA in pharmaceutical, plastics, and personal care products in Nigeria. This study is the first attempt to report the occurrence and distribution of parabens and TCS in indoor aerosols from the West African sub-region.
Environmental microplastics and their additives—a critical review on advanced oxidative techniques for their removal
(Springer, 2023) Martins O. Omorogie
Microplastics (MPs) and their additives are a major concern to the environment and public health due to their toxicity. MPs originate from different categories of plastics, namely polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). The removal of MPs and their additives including bisphenol A (BPA), nonylphenol (NP), and tetrabromobisphenol A (TBBPA) has been a major challenge. Recently, advanced oxidation processes (AOPs) have been demonstrated to be more effective for the removal of MPs and their additives than traditional methods. Meanwhile, there are still limited studies on the application AOPs for their remediation. Consequently, there is a need for more investigation on the remediation of MPs and their additives. This review investigates the degradation of common MPs (PE, PS, PVC, and PET) and their additives (NP, BPA, and TBBPA) using AOPs including photocatalysis (PC), (electrocatalysis) photoelectrocatalysis (PEC), electro-Fenton (EF), and sonocatalysis. In-depth analyses reveal reactive oxygen species (ROS) as a driving force for the efficiency of AOPs. The complete removal of environmental MPs and their additives is quite promising with the AOPs.
Environmental microplastics distribution, impact, and determination methods: a review
(Springer, 2023) Martins O. Omorogie
The widespread distribution and environmental impact of microplastics (MPs) have been a global challenge for several decades. There is an increasing interest in the dissemination, impact, and determination of MPs in the environment. Some reviews have emphasized the cause and effect of MPs, while others have reported on analytical techniques for their identification and quantification. However, there is still a research gap in the global distribution-impact evaluation of MPs. This review highlights the global distribution of MPs and their effects on humans and the ecosystem. Furthermore, we have classified the analytical techniques for the identification and quantification of MPs into three groups: traditional, post-traditional, and advanced. Having addressed the global distribution-impact analysis, we also presented some possible approaches for the removal of MPs including degradation and the use of biodegradable plastic substitutes. Lastly, we suggested perspectives for improving analyses, coverage, and sustainable approach toward MPs pollution control.
Exploring the Potential of Amino-Functionalized Zeolite Series/H3PO4-Biochar for Environmental Microplastic Removal
(American Chemical Society, 2024) Martins O. Omorogie
The problem of microplastics (MPs) in the environment has been an emerging concern to the world in recent times. This is because the migration of MPs in the environment has been identified as deleterious culprits of the entire ecosystem and by extension may cause a decrease in life expectancy and quality of life in humans, fauna, and flora. This threat is seriously militating against the continuous existence and well-being of the entire ecosystem. Therefore, this research attempts to provide a solution to this global problem through the application of amino-functionalized zeolite series/phosphoric acid-coffee waste biochar (AFZ) for the removal of polystyrene MPs in solutions, drinking water, and wastewater. Findings from this research showed that AFZ removed 4.78 to 4.85 mg g−1 of polystyrene MPs from solutions at 20 to 50 °C, respectively. This was achieved by a combination of chemisorption and physisorption mechanisms via hydrophobic interactions between the π-electrons of the sp2 carbon orbital and π−π aromatic moieties of AFZ and the π-electrons of the polystyrene MPs and electrostatic attraction between AFZ and polystyrene MPs, respectively. Surface characterization of AFZ before and after its uptake of polystyrene MPs revealed that functional moieties such as C−H, C−O, C=C, N−H, Al−O, and Si−O was majorly responsible for the adsorption process. Hence, this research revealed that AFZ has potential to treat polystyrene MP-contaminated drinking water and wastewater.
Occurrence profiling, risk assessment, and correlations of antimicrobials in surface water and groundwater systems in Southwest Nigeria
(Royal Society of Chemistry, 2024) Martins O. Omorogie
The presence of antimicrobials in water has grown into a major global health concern. This study thus focused on the presence, ecological implications, and potential health risks associated with nine antimicrobials: five antibiotics (ampicillin, chloramphenicol, ciprofloxacin, metronidazole, and tetracycline) and four parabens (methylparaben, ethylparaben, propylparaben, and butylparaben) in surface water and groundwater samples collected from three Southwestern States in Nigeria (Osun, Oyo, and Lagos States). These antimicrobials were widely detected across the three States with ciprofloxacin being the most dominant having maximum average concentrations of 189 mg L−1 and 319 mg L−1 in surface water and groundwater respectively. The range of average concentrations of antibiotics in surface water are 47.3–235 mg L−1 (Osun), 27.9–166 mg L−1 (Oyo) and 52.1–159 mg L−1 (Lagos). For groundwater, it is 35.3–180 mg L−1 (Osun), 26.5–181 mg L−1 (Oyo) and 32.3–319 mg L−1 (Lagos). The average concentrations of all parabens were 32.4–153 mg L−1, 53.4–80.1 mg L−1, and 83.2–132 mg L−1 for surface water and 46.7–55.7 mg L−1, 53–117 mg L−1, and 62.4–118 mg L−1 for groundwater in Osun, Oyo, and Lagos States respectively. Methylparaben was most frequently detected paraben with average concentrations of 153 mg L−1 and 117 mg L−1 in surface water and groundwater respectively. The measured environmental concentrations of these antimicrobials pose a significant ecological risk while those of ciprofloxacin and ampicillin pose a high health risk to all population groups studied. The average concentrations of antibiotics investigated in this study exceeded their threshold values for Predicted No-Effect Concentrations (PNEC) associated with resistance selection, except for tetracycline.
One‐Pot Synthesis of ZnO‐Activated Eggshell@ kaolinite: Sorbents for Phosphate Capture in Water
(John Wiley, 2024) Martins O. Omorogie
The availability of colossal amounts of phosphate in water bodies has led to serious environmental challenges all over the world. In this study, a new adsorbent was synthesized using treated kaolinite clay, pulverized eggshells, and ZnCl2. Surface characterizationof these adsorbents showed the availability of functional moieties, morphological variations, pore sizes, particle sizes, etc. Adsorption of phosphate occurs via multiple mechanisms, comprising ligand exchange, complexation, hydrogen bonding, and electrostatic interaction, among others. The effect of pH, showed that maximum adsorption of 93.3 % was achieved at pH 3.0. It was also shown that these cost-effective adsorbents could be regenerated in six cycles, hence increasing their applicability.
Overview of the Mechanism of Degradation of Pharmaceuticals by Persulfate/Peroxysulfate Catalysts
(John Wiley, 2024) Martins O. Omorogie
The leaching of pharmaceutical ingredients into water bodies poses an escalating threat, demanding urgent remediation strategies. Among several techniques advanced for their remediation, advanced oxidation methods utilizing persulfate (PS) and peroxymonosulfate (PMS) stand out as promising avenues for pharmaceutical degradation in wastewater. This article consolidates the research on photocatalytic degradation of pharmaceutical contaminants, focusing on PMS-based photoactive composites, and elucidates their efficacy in removing active pharmaceutical ingredients from water. Moreover, it delineates alternative techniques for activating PS and PMS, providing a holistic understanding of the field's advancements. By outlining research limitations and knowledge gaps, this review underscores the imperative for further investigation and innovation in pharmaceutical wastewater treatment.
Photocatalytic remediation of methylene blue using hydrothermally synthesized H-Titania and Na-Titania nanotubes
(Elsevier & Cell Publishers, 2022) Martins O. Omorogie
Although nanotube is among the most effective morphology of Titania due to its unilateral pathway for photo-generated charge transfer and mechanical stability, its performance is still hampered by high recombination. In the present study, to further improve the photocatalytic degradation performance of Titania, univalent elements of H and Na were respectively ion-exchanged into the Titania nanotubes (TNTs). The photocatalyst was characterized using XRD, TEM, ICP-AES, and FTIR. The modified samples displayed enhanced photocatalytic degradation performance over Degussa TiO2 under UV-A light illumination of MB. The rate constants of NaTNT and HTNT were 16 and 13 times that of Degussa TiO2. Specifically, the Na-TNTs showed better photocatalytic degradation activity than H-TNTs with a rate constant of 0.12 min−1 while the latter showed 0.09 min−1. The optimum adsorption and photocatalytic performance of NaTNT were determined at pH 6 achieving about 99% MB removal within 10 min of irradiation. The ion exchange NaTNT displayed excellent reusability after the fifth cycle of the photocatalytic tests and superoxide radicals were experimentally determined to be the main reactive oxygen species involved in the photocatalytic degradation of MB.
Pollution and risk assessment of phenolic compounds in drinking water sources from South-Western Nigeria
(Springer, 2023) Martins O. Omorogie
This study reports the occurrence and risk assessment of 2,4-dinitrophenol (2,4-DNP), phenol (PHE), and 2,4,6-trichlorophenol (2,4,6-TCP) in drinking water sources in three south-western States in Nigeria (Osun, Oyo, and Lagos). Groundwater (GW) and surface water (SW) were collected during dry and rainy seasons of a year. The detection frequency of the phenolic compounds followed the trend Phenol > 2,4-DNP > 2,4,6-TCP. The mean concentrations of 2,4-DNP, Phenol, and 2,4,6-TCP in GW/SW samples from Osun State were 639/553 μg L−1, 261/262 μg L−1, and 169/131 μg L−1 during the rainy season and 154/7 μg L−1, 78/37 μg L−1, and 123/15 μg L−1 during the dry season, respectively. In Oyo State, the mean concentrations were 165/391 μg L−1 for 2,4-DNP and 71/231 μg L−1 for Phenol in GW/SW samples, respectively, during the rainy season. Generally, in the dry season, these values decreased. In any case, these concentrations are higher than those previously reported in water from other countries. The concentration of 2,4-DNP in water posed serious ecological risks to Daphnia on the acute scale while it was algae on the chronic scale. Estimated daily intake and hazard quotient calculations suggest that 2,4-DNP and 2,4,6-TCP in water pose serious toxicity concerns to humans. Additionally, the concentration of 2,4,6-TCP in water from Osun State in both seasons of the year and in both groundwater and surface water poses significant carcinogenic risks to persons ingesting water from these sources in the State. Every exposure group studied were at risk from ingesting these phenolic compounds in water. However, this risk decreased with increasing age of the exposure group. Results from the principal component analysis indicate that 2,4-DNP in water samples is from an anthropogenic source different from that for Phenol and 2,4,6-TCP. There is a strong need to treat water from GW and SW systems in these States before ingesting while assessing their quality regularly.
Prevalence and health risk evaluations of mycotoxins in drinking water sources in Nigeria
(Royal Society of Chemistry, 2024) Martins O. Omorogie
Mycotoxins in drinking water are neglected pollutants that have serious health implications when ingested. Common mycotoxins with health concerns include deoxynivalenol (DON), ochratoxin A (OTA), and zearalenone (ZEN). This study considers the distribution and apparent health risks of these mycotoxins in drinking water sources (groundwater, surface water, bottled water, sachet water) in three Southwest Nigeria States: Osun, Oyo, and Lagos States, using the UHPLC-ESI-QTOF. ZEN and DON were found in all 95 water samples across all three states. ZEN in sachet water samples has the highest mean concentrations, with those from Osun, Oyo, and Lagos States having concentrations of 14.96 ± 4.46, 8.59 ± 3.86, and 10.56 ± 2.84 mg L−1, respectively. In contrast, the mean concentrations of all three mycotoxins (± Standard Error of Mean) in bottled water samples are the lowest across the three States. The mean concentrations of OTA in sachet water samples (2.93 ± 0.79, 1.24 ± 0.40, and 3.01 ± 1.50 mg L−1) are slightly higher than those in bottled water (1.47 ± 0.28, 1.53 ± 0.31, and 0.75 ± 0.31 mg L−1) for Osun, Oyo, and Lagos States, respectively. Groundwater samples across the three States had the lowest average pH values, below the WHO's lowest limit of 6.5. Principal Component Analysis studies indicate that all three mycotoxins in water samples are closely associated by source. Possible human exposure values for ZEN suggest some health concerns, especially with the use of sachet water type based on the estrogenicity of this mycotoxin. However, OTA values for all water samples analyzed, are much lower than the tolerable daily intake (TDI) of 4.73 mg kg−1 bw per day provided by European Food Safety Authority (EFSA). The levels of DON in all water sample types were of no serious health concern. However, human exposure levels to all three mycotoxins in bottled water fall within safe limits of health-based guidance values (HBGV) indicating that this drinking water type is better treated, unlike sachet water. Nevertheless, stakeholders need to re-examine water quality with respect to these mycotoxins and adopt stringent guidelines and new water treatment strategies to provide consumers with safe drinking water in line with the UN SDG #6.
Recent strategies for the remediation of Ivermectin from the environment
(Elsevier, 2023) Martins O. Omorogie
Ivermectin (IVM) is arguably one of the most widely consumed drugs due to its wide range of applications for various diseases such as viruses, cancer, parasites, and inflammation. Originally designed as an antiparasitic drug, preclinical studies have shown its potential as a possible antiviral drug for COVID-19. Since the pandemic began, there has been a rise in the consumption of IVM. A consequential effect of this is the release of IVM into the environment, resulting in ecological degradation. A significant number of reviews have reported the fate, distribution, and ecotoxicity of IVM. However, reviews on the remediation strategies of IVM have been grossly ignored. Hence, this review highlights the remediation strategies of IVM reported in the literature. Findings revealed adsorption as the most broadly adopted technique for IVM remediation. The various adsorbents employed so far for the adsorption of IVM are reported. Also, the adsorption kinetics, isotherms, thermodynamics modeling, mechanistic interaction, and reusability of the investigated adsorbents were discussed. Moreover, the application of a photocatalytic technique which has the potential for mineralizing IVM was also highlighted. Lastly, to foster the removal of IVM, further research needs to address cost-effectiveness, scalability potential, computational studies, risk-benefit analysis, and socio-economic aspects of remediation techniques to close the gaps.
Screening of Zeolites series: H-β/H-MOR/H-ZSM-5 as potential templates for photocatalyst heterostructure composites through photocatalytic degradation of tetracycline
(Elsevier, 2023) Martins O. Omorogie
The formation of Zeolites/semiconductor heterostructures has been demonstrated as one of the most promising strategies for enhancing the photocatalytic performance of semi-conductors. However, the choice of a suitable Zeolite template for photocatalyst composites remains a major challenge. Herein, a series of H-β, H-MOR and H-ZSM-5 Zeolites were studied as potential semi-conductor templates for the photocatalytic remediation of organic pollutants. Although, all the investigated Zeolite templates displayed similar functional groups and elemental components, their morphology and band gaps varied. The bandgap of H-MOR, H-ZSM-5 and H-β were estimated to be 3.74 eV, 3.64 eV and 3.30 eV, respectively. The H-MOR Zeolites were observed to be the most effective photocatalyst for the removal of tetracycline (TC) molecules. The kinetic rate constants for H-MOR, H-ZSM-5 and H-β were estimated to be 0.5269 h−1, 0.4841 h−1 and 0.3975 h−1, respectively. The superior performance of H-MOR Zeolite was ascribed to its higher activity under UV light irradiation (due to a larger band gap) and oxygen deficiency, as revealed from the Tauc plot and EDS analysis, respectively. The pH studies revealed a favorable TC removal under the alkaline region. Thus, H-MOR zeolite was established to be a promising photocatalyst template for the remediation of pollutants.
Self-assembly of ZnO-Biochar/Kaolinite/ Chitosan/GO with 1D/2D/3D heterojunctions for enhanced removal of estrogens and triclosan in water
(Springer Nature & BMC, 2024) Martins O. Omorogie
This Study focuses on the preparation of sustainable and efficient Chitosan catalyst for the removal of three organic pollutants, 17β-Estradiol (E2), 17α-ethynyl estradiol (EE2) and triclosan (TCS) from water. The prepared nanocomposites were characterized by different techniques which confirmed the presence of the key components Chitosan, Carica Papaya seed and Kaolinite. The optical characterization proved the nanocomposite is photoactive with a band gap of 1.81 eV and 1.77 eV for Chitosan/kaolinite biochar (CS/KBC) and Chitosan/kaolinite biochar/GO (CS/KBC/GO) respectively, confirming the ability of the nanocomposite to be active in the visible light region of the spectrum. The degradation experiment using CS/KBC/GO was observed better with 100% removal for 5 mg/L E2 and EE2 over 60 min and 97.8% over 120 min for 10 mg/L TCS at optimum conditions (pH 3 for E2, and EE2 and pH 7). It was observed that the superoxide radical played a major role in the degradation of the contaminants. Furthermore, the CS/KBC/GO was efficient over four cycles without any decrease in performance, which rules out the question of catalyst deactivation proving the sustainability of the catalyst. The toxicity test shows that the water is safe as it does not harm cerio daphnia silvestrii organism.; CS/KBC/GO efficiently removed the micropollutants from real-life waste samples and the performance was very good with a slight decrease in performance for the wastewater due to the complex matrix of the water sample that competes for the active site.

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