Environmental and Materials
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Assessment of solar radiation potential for solar drying technology of fruits and vegetables
Get PDFBackground: Malawi gets a lot of sunshine because it is positioned astride the equation. It is abundant since it is a renewable energy source. Absence of information about solar radiation availability is the main obstacle to resource use. With the goal of minimizing post-harvest losses, this study evaluates Malawi's sun radiation potential for drying fruits and vegetables. Methods: Using pyranometers as instruments, automatic weather stations in the districts of Mzimba, Lilongwe, Dedza, Ntcheu, Salima, Mwanza, Thyolo, Mulanje, and Chiradzulu were used to gather secondary data. The Department of Climate Change and Meteorological Services (DCCMS) supplied the primary data, which covered a brief three years (2017 to 2020). Three years' worth of historical data was taken into consideration in order to obtain more significant trends and data validation. Excel and Rstudio were used to evaluate the data in terms of daily and seasonal fluctuation and mapping, respectively. Findings: It is evident from the irradiation map and daily and seasonal variance trends that certain regions of Malawi experience more insolation than others. This results from ITCZ, which affects how the seasons change. These findings will be used to determine which Malawian districts will benefit from the installation of solar dryers by having higher levels of insolation. Conclusion: Further study on solar radiation received at inclined and horizontal planes is what I suggest doing. Novelty/Originality of this Study: This study introduces a novel approach to using solar drying methods for preserving fruits and vegetables in Malawi, addressing the high post-harvest losses in various districts. By focusing on the application of solar drying systems tailored to local solar radiation conditions, the research highlights the importance of harnessing diffuse solar radiation, which is often overlooked, thereby offering a more sustainable and cost-effective alternative to traditional drying methods
Advanced electrochemical detection of arsenic using platinum-modified boron-doped diamond by anodic stripping voltammetry
Get PDFBackground: Platinum-modified boron-doped diamond (BDD) electrodes were effectively fabricated through a combination of wet seeding and electrodeposition techniques. Methods: This research involved the utilization of various chemicals and apparatus, the modification of boron-doped diamond (BDD) electrodes with platinum using wet seeding and electrodeposition, and the detection of As3+ and As5+ using a phosphate buffer solution and anodic stripping voltammetry (ASV). Findings: Characterization using Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) confirmed the successful deposition of 1.54% platinum on the BDD surface. These modified electrodes were employed as sensors for arsenic species (As³⁺ and As⁵⁺) using anodic stripping voltammetry (ASV) in a 0.1 M phosphate buffer solution at pH 6. Under optimal conditions, including a deposition potential of -500 mV, a deposition time of 150 s, and a scan rate of 200 mV/s, the linear detection of As³⁺ and As⁵⁺ was achieved within a concentration range of 0 to 100 ppb (R² = 0.9797 and 0.9903, respectively). Prior to ASV detection of As⁵⁺, a pretreatment step involving the addition of 0.1 M NaBH₄ was necessary to reduce As⁵⁺ to As³⁺. The detection limits for As³⁺ and As⁵⁺ were determined to be 16.50 ppb and 8.19 ppb, respectively. Conclusion: This research highlights the potential of BDD/Pt electrodes in environmental monitoring and arsenic detection applications and demonstrates the method's efficacy for the speciation analysis of arsenic species. Novelty/Originality of this Study: This research pioneers the use of platinum-modified boron-doped diamond electrodes for the speciation analysis of arsenic, offering a promising new approach for environmental monitoring applications
Construction of an enzymatic biosensor for chlorpyrifos pesticide detection via acetylcholinesterase inhibition on oxidative boron-doped diamond electrode
Get PDFBackground: The extensive utilization of pesticides in agricultural practices presents considerable environmental and health hazards, which calls for the creation of precise and specialized detection techniques. Methods: This study focuses on the development of an enzymatic biosensor designed to detect chlorpyrifos pesticide residues. The biosensor employs an oxidative boron-doped diamond (OBDD) electrode as the transducer platform, offering exceptional sensitivity and stability. The detection mechanism is based on the inhibition of acetylcholinesterase (AChE) activity on the OBDD surface. Various factors were optimized to assess the precision and sensitivity limit of the developed sensor. The cyclic voltammetry (CV) results indicated that the presence of AChE is necessary for acetylthiocholine chloride (ATCl) to generate an electrical signal. To enhance detection, AChE was modified with magnetic beads. Findings: This modification facilitated the oxidation of ATCl to thiocholine chloride, an oxidation peak of thiocholine could be observed at the magnetic beads modified AChE-Biotin/OBDD at a potential of +0.804 V (vs. Ag/AgCl), formed by an enzymatic reaction of AChE in the presence of acetylthiocholine. The current signal decreased due to the inhibition of AChE activity by chlorpyrifos pesticide. The oxidation current of thiocholine chloride consistently decreased as the chlorpyrifos concentration increased within the range of 0.001nM to 10nM at the optimum condition of 50 mM phosphate buffer solution pH 7.6; 250 mu/5 mL AChE; and 1 mM ATCl in an inhibition and contact time of 30 and 15 min, respectively. The regression equation obtained using magnetic beads modified by AChE-Biotin is y = 0.043ln(x) + 1.074, with an R² value of 0.9062. The sensor demonstrated a lower limit of detection value of 0.6551nM. Conclusion: Furthermore, the developed sensor proved suitable for testing real samples of tap water, showing minimal interference with a % RSD value lower than 10%. Novelty/Originality of this Study: This study introduces a novel enzyme-based biosensor using oxidative boron-doped diamond (OBDD) electrodes for detecting chlorpyrifos pesticide. The originality lies in the use of electrochemically modified BDD, which enhances enzyme immobilization and stability, providing higher sensitivity and lower detection limits compared to traditional methods
A review of photoelectrochemical water oxidation using hematite photoanode
Get PDFBackground: The sun, as an abundant and renewable energy source, provides a sustainable alternative to fossil fuels, which contribute significantly to CO₂ emissions and global warming. With CO₂ emissions surpassing 35 billion tons in 2023, the need for clean energy solutions has become increasingly urgent. Solar energy utilization includes photoelectrochemical (PEC) water splitting, where hematite is widely recognized as an efficient photoanode material due to its availability, stability, and favorable band gap for visible light absorption. However, hematite faces challenges such as poor conductivity, surface recombination, and slow oxygen evolution reaction (OER) kinetics, which limit its performance. Methods: This review examines various strategies to enhance hematite photoanode performance for PEC water splitting. The study explores three key approaches: (1) using three-dimensional conductive substrates with high surface area to facilitate heterojunction formation, (2) doping with tetravalent metal ions (e.g., Ti⁴⁺) to improve conductivity and charge carrier density, and (3) integrating Bi₂WO₆ with hematite to enhance charge separation and photoelectrochemical efficiency. The hydrothermal method was applied for hematite fabrication due to its feasibility, cost-effectiveness, and scalability. Findings: The analysis highlights the effectiveness of each strategy in overcoming hematite’s inherent limitations. The use of 3D conductive substrates improves electron transport and surface reaction sites, while Ti⁴⁺ doping enhances charge carrier density and conductivity. Conclusion: Hematite remains a promising photoanode material for PEC water splitting, but its limitations must be addressed to maximize efficiency. The combination of 3D conductive substrates, metal ion doping, and Bi₂WO₆ integration has shown potential in improving hematite’s photoelectrochemical performance. Novelty/Originality of this article: This review provides a comprehensive analysis of hematite performance enhancement strategies, focusing on the synergistic effects of 3D conductive substrates, Ti⁴⁺ doping, and Bi₂WO₆ integration.
The effect of acetylcholine immobilization on the electrochemical properties of thiocholine on boron-doped diamond electrode for chlorpyrifos sensor
Get PDFBackground: The inhibition reactions of acetylcholinesterase (AChE) have been studied to develop chlorpyrifos biosensors. The performance of AChE, both as a free enzyme and when immobilized on avidin-functionalized magnetic beads (aMB), was evaluated for the hydrolysis of acetylthiocholine. Detection was conducted through the oxidation of thiocholine on a boron-doped diamond (BDD) electrode surface. Methods: The study compared the performance of free and immobilized AChE by analyzing their ability to oxidize thiocholine on the BDD electrode surface. The inhibitory effects of chlorpyrifos were assessed by determining IC10 and IC50 values for both enzyme forms. Additionally, the influence of metal ions (Fe²⁺ and Mn²⁺) on AChE activity was investigated to evaluate interference effects. Findings: Free AChE demonstrated superior performance in thiocholine oxidation compared to the immobilized enzyme. In chlorpyrifos detection, free AChE exhibited a significantly lower IC10 value (3.44 × 10⁻⁶ mM) compared to immobilized AChE (12.9 × 10⁻⁶ mM), and its IC50 value (3.8 × 10⁻⁴ mM) was approximately two orders of magnitude lower than that of the immobilized AChE (5.18 mM). Furthermore, AChE exhibited resistance to metal ion interference, with signal losses of 48.7% and 40.8% in the presence of Fe²⁺ and Mn²⁺ ions, respectively. These findings indicate that the immobilization of AChE must be carefully optimized for effective sensor application. Conclusion: The study highlights the superior performance of free AChE in chlorpyrifos detection compared to its immobilized counterpart. Immobilization significantly affects enzyme sensitivity, resulting in higher inhibitory concentration values. Additionally, AChE demonstrated notable resistance to interference from metal ions. These results emphasize the need for careful consideration when immobilizing AChE for sensor applications. Novelty/Originality or this article: This study provides a detailed comparison between free and immobilized AChE in chlorpyrifos biosensing, highlighting the impact of immobilization on enzyme sensitivity and performance. The findings contribute to the development of more efficient biosensors by emphasizing the importance of optimizing enzyme immobilization strategies
A study on spatio-temporal trend of rubber leaf fall phenomenon using planetscope multi-index vegetation imagery in relations to climatological conditions
Get PDFBackground: Rubber plants are one of the most important plantation commodities in Indonesia. However, rubber production has declined due to leaf fall disease caused by the pathogen Pestalotiopsis sp. This study aims to analyze the spatial and temporal distribution of rubber plant leaf fall disease using multi-vegetation indices from PlanetScope imagery, as well as to analyze the influence of climatological conditions on the disease. Methods: The research was conducted at the Sembawa Rubber Research Center Garden, South Sumatra, using PlanetScope imagery data and climatological data in 2017 (before leaf fall) and 2023 (after leaf fall). Finding: Spatially, the 2023 leaf fall occurred in almost the entire garden area with poor to moderate levels. Blocks 2013D, 2012F, and 2009F experienced the most severe levels, with a total defoliated area reaching 396.76 ha. Analysis of monthly variations in vegetation index values revealed a decrease in values during leaf fall due to Pestalotiopsis sp., specifically in February, May, and September 2023. Statistical test results showed significant differences in vegetation index values between 2017 and 2023. Furthermore, based on Spearman's correlation analysis, there was a positive correlation between vegetation index values and humidity, but no significant correlation with rainfall and temperature. Conclusion: This research provides insights into mapping and monitoring rubber leaf fall disease using remote sensing data and climatological factors, which can be used for more effective rubber plantation management. However, the study has some limitations: monthly Planet data for 2017 is not fully available, several Planet image scenes from 2017 still have more than 50% cloud cover, and there may be biases as plants falling into the low health class are included in the high range of vegetation index values. Novelty/Originality of this Study: By integrating spatial and temporal analyses with climatological data, the research provides a precise and comprehensive method for monitoring LFD and understanding its environmental determinants, thereby enhancing traditional rubber plantation management practices
Amine-modified Ni-DOBDC MOF for CO2 capture: CO2 adsorption capacity and reusability
Get PDFBackground: Anthropogenic carbon dioxide (CO₂) emissions have risen significantly due to the extensive use of fossil fuels, necessitating the development of effective CO₂ capture and conversion techniques. Adsorption using Metal-Organic Frameworks (MOFs) has shown great potential due to their high CO₂ adsorption capacity, particularly Ni-based MOFs. Enhancing their adsorption efficiency remains a key research focus to improve sustainability in CO₂ capture applications. Methods: Ni-based MOF (Ni-DOBDC) was synthesized using the solvothermal method, employing DMF as the solvent and 2,5-dihydroxyterephthalic acid (DOBDC) as the organic ligand. To enhance CO₂ adsorption capacity, Ni-DOBDC was further modified with ethylenediamine (EDA) via post-synthetic modification. Structural characterization was performed using XRD, confirming similarity to the Ni-DOBDC reference (CCDC 288477), and FTIR, which showed enhanced absorbance peaks. SEM-EDX analysis revealed a flower-like morphology with an average particle size of 0.75 μm. CO₂ adsorption tests were conducted on Ni-DOBDC and EDA/Ni-DOBDC (10%) using the titration method under controlled conditions. Findings: The CO₂ adsorption capacity of Ni-DOBDC and EDA/Ni-DOBDC was tested at 70°C with a CO₂ concentration of 50% in N₂. EDA modification significantly improved CO₂ adsorption capacity, with EDA/Ni-DOBDC achieving 9.95 mmol g⁻¹ compared to pristine Ni-DOBDC’s 6.44 mmol g⁻¹. However, Ni-DOBDC exhibited better regeneration ability in a three-cycle reusability test, likely due to EDA leaching during regeneration. Conclusion: EDA-modified Ni-DOBDC demonstrates enhanced CO₂ adsorption capacity, making it a promising material for CO₂ capture applications. However, its reduced regeneration stability suggests the need for further optimization to improve long-term performance. Future studies should explore strategies to minimize EDA leaching while maintaining high adsorption efficiency. Novelty/Originality of this article: This study provides new insights into improving Ni-based MOF performance for CO₂ capture through post-synthetic modification with EDA. The findings highlight a trade-off between increased adsorption capacity and material stability, emphasizing the need for further refinement in MOF functionalization strategies
Analysis of microbial diversity in pesticide-contaminated soil: A study of culturable microorganisms
Get PDFBackground: Pesticide contamination of soil often leads to significant alterations in the structure and diversity of microbial communities, potentially affecting overall ecosystem function. Understanding these changes is crucial for assessing the ecological impact of pesticide use in agricultural areas. This study analyzes microbial diversity in pesticide-contaminated soil using the Shannon-Wiener diversity index to evaluate the effects of pesticide exposure on microbial populations. Methods: A descriptive quantitative approach was used, incorporating the Total Plate Count (TPC) test and Shannon-Wiener Index analysis. The numerical data included the number of microbial individuals (bacteria and fungi) and the relative proportion of each group. Soil samples were purposively collected from three points in a pesticide-contaminated tomato farming area in Dunggala Village, Gorontalo Regency. Findings: The microbial community detected in the contaminated soil consisted of bacteria (2.5×10⁴ CFU/ml) and fungi (1.35×10³ CFU/ml). The Shannon-Wiener index value was 0.202, indicating low microbial diversity. This suggests that pesticide contamination negatively impacts microbial richness and evenness in the soil. Conclusion: Pesticide contamination significantly reduces microbial diversity, as reflected in the low Shannon-Wiener index value. This decline in microbial richness and evenness highlights the potential ecological consequences of pesticide use in agriculture. To mitigate these negative effects, implementing sustainable pest management practices, such as the use of biopesticides, is recommended. Novelty/Originality of this article: This study provides quantitative evidence of the decline in microbial diversity in pesticide-contaminated soil using the Shannon-Wiener index. By focusing on microbial community changes in a specific agricultural setting, the findings contribute to a better understanding of the ecological impacts of pesticide use and emphasize the need for sustainable pest management strategies
Bioremediation based on palm oil sludge as an intervention for heavy metal pollution risk in industrial residential
Get PDFBackground: The palm oil industry in Indonesia, often pollution the environment, especially water bodies, with waste containing hazardous metals. This can threaten the lives of aquatic organisms and damage ecosystems. Although the palm oil industry has become a pillar of the national economy with production reaching 46,986 tons in 2023, the waste problems generated, especially palm oil sludge, demand innovative and sustainable solutions. The limitations of existing technologies in handling heavy metal pollution drive the need for an interdisciplinary approach that not only reduces environmental risks but also provides economic added value through circular economy concepts and local resource empowerment. The aim of this study is to identify the characteristics of palm oil sludge-based bioremediation stones in the process of heavy metal adsorption. Methods: This study was conducted through descriptive analytical literature review with a qualitative approach. Findings: The results show that palm oil sludge-based bioremediation stones have microporosity characteristics and complex chemical compositions capable of absorbing heavy metals with efficiency reaching 85-92%. This innovation not only offers sustainable solutions, but also provides multidimensional benefits, including reduced public health risks and the creation of circular economic models. Conclusion: Through activation with sulfuric acid, the potential for heavy metal absorption can be increased by up to 35%, which implies a 70% reduction in environmental contamination in industrial areas. Novelty/Originality of this article: This innovation integrates an interdisciplinary approach combining environmental science, chemistry, and resource management, potentially creating a replicable risk intervention model for industrial areas, with economic value
Influence of NaBH4 on the sensitivity of As3+ and As5+ sensor using gold modified boron doped diamond electrodes
Get PDFBackground: Arsenic is known as one of the carcinogenic metalloids and can cause various health issues when ingested or inhaled over prolonged periods of time. Methods: In this work, boron-doped diamond (BDD) electrode was altered with gold particles (Au) arranged by seeding continued with electrodeposition of HAuCl4 solutions at the electrode surface, will be used as electrode to detect As3+ and As5+ in lake water. The deposited gold particles on the BDD surface were studied with scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). Detections of As3+, As5+, and mixture solutions of As3+ and As5+, carried out with anodic stripping voltammetry (ASV). Findings: The, pre-treatment using NaBH4 carried out for reduction from As5+ to As3+, indicate an improvement at the sensitivity of As3+ and As5+ detection with a good linear responses for each solution in range concentrations of 0.02-0.2 ppm for As3+ and As5+, with R2=0.9759 and R2= 0.9876, respectively. Conclusion: Furthermore, limit of detections of 0.0335 ppm and 0.0239 ppm can be attained for As3+ and As5+ displayed high linearity, revealing that detection of each species of As3+ and As5+ can be conducted in mixture of As3+ and As5+. Novelty/Originality of this Study: This study involves the modification of BDD electrodes with gold (Au) using a combined seeding and electrodeposition technique, which enhances stability and sensitivity for detecting arsenic (As³⁺ and As⁵⁺) at low concentrations. Additionally, the research introduces a pretreatment method using NaBH₄ to facilitate the detection of As⁵⁺ by reducing it to As³⁺, thereby improving the detection limits with anodic stripping voltammetry (ASV)