This study explores the potential of modified shrimp-based chitosan (MSC) as an innovative adsorbent for eliminating heavy metals (HMs) from contaminated water sources. The modifications encompassed ...various chemical treatments, surface functionalization, and structural optimization to enhance the chitosan’s adsorption capabilities. Comprehensive analyses using FT-IR and SEM-EDS were conducted to evaluate the properties of the chitosan. The adsorption capacity of MSC was assessed using ICP-MS before and after the adsorption process. Moreover, the study investigated the efficiency of HM removal by MSC under different conditions, including variations in pH, adsorbent dosage, and contact time. Under neutral pH conditions, the highest adsorption rates of copper, zinc, cadmium, and lead were determined as 99.72%, 84.74%, 91.35%, and 99.92%, respectively, with corresponding adsorption capacities of 20.30 mg/g for copper, 7.50 mg/g for zinc, 15.00 mg/g for cadmium, and 76.34 mg/g for lead. Analysis based on the Langmuir and Freundlich isotherm models revealed highly significant adsorption of HMs, supported by strong correlation coefficients (r2 > 0.98) obtained from the data. The pseudo-second-order kinetic model with linear coefficients (r2) greater than 0.97 effectively explained the kinetic studies of metal adsorption employing modified shrimp shells. These coefficients indicate a robust fit of the models to the experimental adsorption data for heavy metals. Further confirmation of the effectiveness of the adsorbent was obtained through FT-IR spectroscopy, which confirmed the presence of specific functional groups on the adsorbent, such as N–H joined with –COO−, H–O, C−O−C, and C–H. Additionally, the SEM-EDS analysis detected the presence of elements on the surface of MSC chitosan. The results emphasize that MSC is a highly effective and cost-efficient adsorbent for eliminating Cu, Zn, Cd, and Pb from wastewater, making it a promising eco-friendly choice.
Environmental sustainability has become a major concern for policymakers across the globe. In this regard, understanding the factors responsible for environmental degradation is particularly ...important for developing nations. Against this backdrop, this study aims to evaluate the impacts of environmental regulations and other vital macroeconomic aggregates on the ecological footprints in the context of four fossil fuel-dependent South Asian countries: Bangladesh, India, Pakistan, and Sri Lanka. The major findings from the econometric analysis, accounting for cross-sectional dependency, slope heterogeneity, and structural break issues in the data, reveal that environmental regulations portray significant roles in directly and indirectly reducing the ecological footprints across South Asia. Besides, the elasticity estimates verify the authenticity of the environmental Kuznets curve and the pollution haven hypotheses. On the other hand, non-renewable and renewable energy consumptions are found to increase and decrease the ecological footprints, respectively. Moreover, renewable energy use and environmental regulations are found to jointly reduce the ecological footprints further. More importantly, environmental regulations are predicted to reduce the adverse environmental impacts of economic growth, non-renewable energy use, and foreign direct investment inflows while increasing the favorable environmental impacts associated with renewable energy use. Furthermore, the country-specific impacts of environmental regulations on the ecological footprints are found to be more or less homogeneous to the corresponding panel estimates. The environmental Kuznets curve and pollution haven hypotheses are evidenced to hold for the majority of the four South Asia nations. In line with these findings, several relevant policy-level suggestions are put forward.
The prevalence of overweightness in Bangladesh is increasing, while underweightness also continues to persist. A better understanding of the patterns and socioeconomic risk factors of both ...conditions, particularly among women, is critical in order to promote the development of interventions to improve maternal health in Bangladesh. This study therefore sought to assess the patterns of under- and overweightness between 2004 and 2014 and to examine the predictors of individual and community-level inequalities of under- and overnutrition in Bangladesh.
Cross-sectional data of 10, 431, and 16,478 ever-married nonpregnant women aged between 15 and 49 years who did not give birth in the two months preceding the survey were extracted from the 2004 and 2014 Bangladesh Demographic and Health Surveys, respectively. Body mass index was used to measure weight status, and underweightness, at-risk for overweightness, overweightness, and obesity were the main outcome variables. Patterns of nutritional change over time was examined by considering the annual average rate of change. Multilevel multinomial logistic regression and quantile regression were used to identify the inequalities.
In 2014, the age-adjusted prevalence values of underweightness, at-risk for overweightness, overweightness, and obesity were 19.7%, 14.9%, 18.1% and 4.0%, respectively. A higher average annual rate of reduction of underweightness was found among wealthier, highly educated, and wealthier community-living women, while a rate of increase of overweightness was found among poorer, uneducated, and poor community-living women. Individual and community-level inequalities of malnutrition were observed among these populations. In comparison with women living in low wealth communities, women from wealthier communities were at an increased risk of being at-risk for overweightness adjusted odds ratio (AOR): 1.53, 95% confidence interval (CI): 1.23-1.91, overweight (AOR: 1.60, 95% CI: 1.27-2.00), and obese (AOR: 2.12, 95% CI: 1.42-3.18).
This study suggests the coexistence of a double burden of under- and overnutrition in Bangladesh and that the prevalence of overweightness surpasses that of underweightness. The burdens of under- and overnutrition are strongly associated with women's individual socioeconomic positions and the nature of the community in which they live.
Background Exclusive breastfeeding (EBF) means that an infant should be breastfed only for the first six months of life to achieve optimal child development and to prevent infant morbidity and ...mortality. The aim of this analysis was to determine the individual-, household-, and community-level factors associated with EBF practice in Bangladesh. Methods A total of 1,440 women-child pairs data were analysed extracted from 2011 and 2014 Bangladesh Demographic and Health Survey. Multilevel logistic regression models were used separately for individual-, household-, and community level factors to identify the different level of factors associated with EBF practice. Results Around 61% women in Bangladesh practiced EBF with significant variation across several individual-, household-, and community-level factors. At the individual level, higher odds of EBF practice was found among mothers' received higher number of antenatal care and lower age of child. Mothers' higher education and engagement in formal jobs were found negatively associated with EBF practice. At the community level, higher odds of EBF was found among women live in Barishal, Dhaka, and Rajshahi divisions, and resided in the community with moderate level of female education, higher level of fertility, and higher use of antenatal and delivery care. Conclusions One in every three children in Bangladesh do not breastfeed exclusively which needs special attention for the policymakers. In this case, educated women engaged in income generating activities and women did not use antenatal care should be given priority. At the community level, priority should be given for the women's resides in the community with lower level of antenatal and delivery healthcare services use.
An electrochemical nanoimmunosensor based on multiwall carbon nanotubes (MWCNTs)/gold nanoparticles (AuNPs) was developed for the amplified detection of prostate specific antigen (PSA). The amplified ...detection was achieved by the enhanced precipitation of 4-chloro-1-naphthol (CN) using a higher number of horseradish peroxidase (HRP) molecules attached on MWCNTs. The PSA nanoimmunosensor was fabricated by immobilizing a monoclonal anti-PSA antibody (anti-PSA) on the AuNP-attached thiolated MWCNT on a gold electrode. The sensor surface was characterized using scanning electron microscope, transmission electron microscope, quartz crystal microbalance, and electrochemical techniques. Cyclic and square wave voltammetric techniques were used to monitor the enhanced precipitation of CN that accumulated on the electrode surface and subsequent decrement in the electrode surface area by monitoring the reduction process of the Fe(CN)6 3–/Fe(CN)6 4– redox couple. Under the optimized experimental condition, the linear range and the detection limit of PSA immunosensor were determined to be 1.0 pg/mL to 10.0 ng/mL and 0.40 ± 0.03 pg/mL, respectively. The validity of the proposed method was compared with an enzyme-linked immunosorbent assay method in various PSA spiked human serum samples.
This research was undertaken to investigate the suitability of recycled construction and demolition materials as alternative pipe backfilling materials for stormwater and sewer pipes. Three commonly ...found recycled construction and demolition waste materials, (crushed brick, recycled concrete aggregate and reclaimed asphalt pavement) were investigated to assess their suitability as a pipe backfilling material. The physical, geotechnical and chemical properties of these construction and demolition materials were compared with local engineering and water authorities specifications for typical quarried materials so as to assess their performance as a viable substitute for virgin quarried aggregates in pipe backfilling applications. Physical and geotechnical characterisation tests such as particle size distribution, specific gravity, water absorption, Los Angeles abrasion, California Bearing Ratio and modified Proctor compaction tests were undertaken. Chemical properties were also determined, including organic content, pH, trace element or total concentration and leachate testing of the construction and demolition materials for a range of contaminant constituents. In terms of physical, geotechnical and chemical assessment for pipe backfilling applications, recycled concrete aggregate and crushed brick were found to have the properties recommended by environmental protection authorities while reclaimed asphalt pavement material did not meet some of the specified requirements. Also shear strength properties were found to be equivalent or superior to those of typical quarry backfilling materials. This research indicates that traditional considered waste materials can be reused viably as alternate pipe backfilling materials.
•Physical properties of recycled construction materials were assessed.•The compaction characteristics were found to be within the requirements.•Total concentration and leachate values satisfied the allowable limits.•The requirements for pipe backfilling and sub-base applications were compared.•Recycled construction materials are suitable for pipe backfilling applications.
For the rapid growth of population electrical and electronics equipment waste are generated 20 to 50 million tones in world-wide. Half a tonne of e-waste creates by the resident of advanced country ...in every year. E-waste contains different toxic substances including metals, plastics and refractory oxides which are hazardous or risky for our environment and human wellbeing, thus e-waste management is an essential. Hence, this review outlined the global status of e-waste and its current progress on management worldwide. An exhaustive survey of literature was made on the latest technological approaches in noble and base metals recovery from waste printed circuit boards (PCBs) of electrical and electronic equipment. An emphasis was given to review the most important features of existing industrial routes associated with the metal recovery systems from PCBs. The discussions of green technologies as alternatives of conventional approaches to obtain precious metals from e-waste were overviewed. The application of microbial bioleaching approaches in the extraction metals from e-waste was highlighted. Finally, the concern for the challenges and barriers associated with the e-waste management process in Bangladesh was outlined.
•Current approaches for noble meal recovery from e-waste are reviewed.•Green technologies as alternatives of conformist approaches are discussed.•Contribution of microorganisms to recover noble metal from e-waste is highlighted.
The direct electrochemistry of laccase was promoted by Au nanoparticle (AuNP)-encapsulated dendrimers (Den), which was applied for the detection of catechin. To increase the electrical properties, ...AuNPs were captured in the interiors of the dendrimer (Den-AuNPs) as opposed to attachment at the periphery of dendrimer. To prepare Den-AuNPs, the Au(III) ions were first coordinated in the interior of dendrimer with nitrogen ligands and then reduced to form AuNPs. The size of AuNPs encapsulated within the interior of the dendrimer was determined to be 1.7 ± 0.4 nm. AuNPs-encapsulated dendrimers were then used to covalently immobilize laccase (PDATT/ Den(AuNPs)/laccase) through the formation of amide bonds between carboxylic acid groups of the dendrimer and the amine groups of laccase. Each layer of the PDATT/Den(AuNPs)/laccase probe was characterized using CV, EIS, QCM, XPS, SEM, and TEM. The PDATT/Den(AuNPs)/laccase probe displayed a well-defined direct electron-transfer (DET) process of laccase. The quasi-reversible redox peak of the Cu redox center of the laccase molecule was observed at −0.03/+0.13 V vs Ag/AgCl, and the electron-transfer rate constant was determined to be 1.28 s−1. A catechin biosensor based on the electrocatalytic process by direct electrochemistry of laccase was developed. The linear range and the detection limit in the catechin analysis were determined to be 0.1−10 and 0.05 ± 0.003 μM, respectively. Interference effects from various phenolic and polyphenolic compounds were also studied, and the general applicability of the biosensor was evaluated by selective analysis of real samples of catechin.
Antimony (Sb) is increasingly being recognized as an important contaminant due to its various industrial applications and mining operations. Environmental remediation approaches for Sb are still ...lacking, as is the understanding of Sb environmental chemistry. In this study, biosolid biochar (BSBC) was produced and utilized to remove antimonate (Sb(V)) from aqueous solution. Zirconium (Zr), Zirconium-iron (Zr-Fe) and Fe-O coated BSBC were synthesized for enhancing Sb(V) sorption capacities of BSBC. The combined results of specific surface area, FTIR, SEM-EDS, TEM-EDS, and XPS confirmed that Zr and/or Zr-Fe were successfully coated onto BSBC. The effects of reaction time, pH, initial Sb(V) concentration, adsorbate doses, ionic strength, temperature, and the influence of major competitive co-existing anions and cations on the adsorption of Sb(V) were investigated. The maximum sorption capacity of Zr-O, Zr-Fe, Zr-FeCl
, Fe-O, and FeCl
coated BSBC were 66.67, 98.04, 85.47, 39.68, and 31.54 mg/g respectively under acidic conditions. The XPS results revealed redox transformation of Sb(V) species to Sb(III) occurred under oxic conditions, demonstrating the biochar's ability to behave as an electron shuttle during sorption. The sorption study suggests that Zr-O and Zr-O-Fe coated BSBC could perform as favourable adsorbents for mitigating Sb(V) contaminated waters.
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