Environmental Nanotechnology, Monitoring and Management最新文献

Engineered nanoparticles (ENPs) are of particular concern due to their ubiquitous occurrence and potential to cause adverse effects on aquatic biota. Consequently, a comprehensive understanding of ENP interactions and the mechanisms that underpin their fate and behaviour in the aquatic system is important to support their long-term applications and protection of ecology. However, due to a wide range of physicochemical parameters, as well as possible dynamic interactions with natural colloid particles, it is not practical to undertake experimental testing for each variation of ENPs using different aquatic permutations. This study describes machine learning (ML) algorithms for prediction of nZnO dissolution in aquatic systems using experimental data. The input parameters with the highest correlation were size and pH. On the contrary, categorical input variables such as coating, coating type, salt, and NOM type had a low correlation. The random forest regression and the extreme gradient boost algorithms performed remarkably well, with coefficients of determination (R²) of 0.85 and 0.92, respectively. The least effective method was multiple linear regression, which had a root mean square error of 0.15 and an R² of 0.31. ML offers a convenient and low-cost approach for screening nZnO dissolution in aquatic systems.

Heavy metal pollutants, highly toxic and invisible, have garnered attention due to bioaccumulation. Increased manganese production from steel industries is expected to lead to harmful concentrations in water, adversely affecting the environment and public health. The sustainable approach of utilizing industrial by-products to synthesize geopolymers for the immobilization of heavy metal ions has gained research interest. The current study aims to verify the feasibility of Paper sludge ash (PSA) in conventional geopolymer (CGP) to immobilize manganese (Mn) heavy metal ions from aqueous solutions. CGP was prepared using Fly ash (FA) as resource material, which was replaced by PSA at a level of 30 %, by weight. The precursors were treated with alkali solutions, namely sodium hydroxide and sodium silicate, incorporating ambient curing. The characterization studies of precursors and CGP were investigated using XRD, XRF, SEM, EDS, FTIR, and Brunauer-Emmett-Teller surface area (BET) analysis techniques to outline the crystal structure, morphology, and pore parameters. Additionally, the experimental investigation comprehensively examined the impact of various pH levels, dosages, contact times, and initial concentrations on the removal efficiency of Mn heavy metal ions. The difference in concentration of Mn heavy metal ions quantified by atomic absorption spectrometry. The Langmuir models effectively explained the removal of Mn ions by CGP due to high fitting coefficients. The highest value of uptake capacity was found to be 28 mg/g at 30 °C with pH value of 4. Therefore, blending industrial wastes improves the potential of decontamination agents in removing heavy metals from wastewater, promoting environmental sustainability.

Developing advanced materials with efficient antibacterial properties to guarantee human health protection is urgent. This study aimed to evaluate the antibacterial performance of natural zeolite (NZ) functionalized with silver nanoparticles (Ag NPs), obtained from a green reducing method using Moringa oleifera seed extract (NZ-AgNPs), against a Gram-negative bacteria, namely Escherichia coli (E. coli). Moreover, two applications were tested: bacteria adsorption for water treatment, namely Escherichia coli, and its incorporation in commercial paints. The proposed modifications were confirmed by advanced characterization techniques (TEM, SEM, EDX, FTIR, XRD, and ZP). The antibacterial activity assay was conducted using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The results demonstrated the advantages of using an inorganic support for carrying biocidal agents. The required amount of Ag NPs, when it was supported onto NZ (NZ-AgNPs), was four times less to exhibit the bactericidal effect against Escherichia coli than Ag NPs on their own since they had the same MBC value (1.56 mg ml⁻¹). The observed adsorption behavior corroborates such findings and demonstrates that 0.01 g of the proposed composite achieved 100 % of E. coli removal and 9.85 log reduction. Regarding commercial paint experiments, the NZ-AgNPs successfully demonstrated the potential to inhibit bacterial growth with an inhibition zone (IZ) of 41 mm. Using inorganic carriers, as NZ, for controlling the biocidal compound release can bring economic and environmental advantages because zeolite is a natural material and the saved amount of biocidal agent, namely Ag NPs, are desirable features of a new antibacterial additive’s generation.

After being applied to pharmaceutics removal from water, the newly synthesized composite hydrogel based on chemically modified gelatin and PVA-containing graphene nanoparticles (CHGP-GOn), was now assessed for another application. The hydrogels were able to interact with Microcystis aeruginosa cells, resulting in the formation of small cell colonies and cell lysis related to exposure time. In the removal tests, the best general removal efficiency of cyanobacterial cells was achieved with the highest adsorbent mass at natural pH, achieving values of removal of 90 % for cells, 75 % chlorophyll-a, 63 % and 43 % for turbidity and visible colour removals, respectively. From the kinetic study, the results showed that cell inactivation has achieved removal equilibrium in 19 h, with a qe of 106 × 10⁶ cells/g of CHGP-GOn. Furthermore, with the results from the other parameters, the tests presented a removal equilibrium of just 14 h, there was a removal of 4670 µg/L of Chlorophyll-a and 6450 µg/L/g of MC-LR microcystin per gram of adsorbent. The experimental data best fitted to the Elovich model, indicating possible removal by chemisorption. Analysis of cellular integrity and morphology showed that within just 12 h, few cyanobacterial cells showed membrane disruption and release of intracellular toxins, with an increase in the toxicity medium related to extended exposure time, and presentation of morphological and superficial cellular damage within 24 h. In addition, other characteristic measurements presented an exceptional mechanical strength and resistance that was slightly reduced after swelling. However, showing good development during adsorption tests under agitation, without any detachment of material and an absence of GO leaching. Therefore, it can be concluded that the synthesized hydrogel should be applied in removing M. aeruginosa cells and their toxins from water treatment, serving as an excellent alternative to traditional adsorbents.

The inefficient use of conventional fertilizers has prompted the exploration of slow-release fertilizer (SRF) systems to enhance plant nutrient delivery and uptake. This study investigates the potential of the chitosan (CS) membrane modified with succinic acid (SA) and calcium ions (Ca²⁺) as an effective SRF system. The CS/SA-U/Ca-coated membrane can extend the release period of urea, thereby optimizing fertilizer efficiency and promoting plant growth. The structural and chemical features of the CS/SA-U/Ca membrane were comprehensively analyzed. The modification with Ca²⁺ increased the membrane’s thickness, decreased its swelling degree, and resulted in a rougher, more porous surface, all of which contributed to a more controlled release of urea. Urea release profiles were evaluated in both water and soil, demonstrating that the CS/SA-U/Ca coating extended the release period to 20 days in water and over 30 days in soil. Quantitative UV–Vis spectrophotometry and qualitative assessments were used to measure the urea release and evaluate the impact of the SRF on vegetable plant growth. Experimental results demonstrated a significant enhancement in plant growth, with a 46 % increase in stem growth and a doubling of leaf count compared to control plants without the SRF membrane. These findings suggest that the CS/SA-U/Ca-coated SRF system holds promise for optimizing fertilizer use and promoting plant growth by providing a more controlled nutrient release.

The presence of contaminants of emerging concern (CECs) in drinking water is a global issue of concern. Evidence galore of the potential impacts of CECs on human health, yet there are no concrete guidelines or regulatory oversight to effectively tackle CECs exposure from drinking water. As a result, CECs concentrations can be well-above the suggested thresholds, particularly in low and middle-income countries (LMICs) due to undeveloped or underdeveloped (waste)water treatment infrastructure and/or substandard treatment practices. Yet, CECs occurrence and particularly their persistence during drinking water treatment is not well-documented in such settings. For this reason, here, the occurrence of 19 CECs was monitored across the different treatment steps (coagulation, sedimentation, sand filtration, and chlorination) of a typical water treatment plant in South Africa using UPLC-MS/MS. The most dominant CEC was, by and large, efavirenz (1103.9 ± 743.1 ng/L in raw water) tracing back to antiretroviral treatment for the human immunodeficiency virus (HIV) and revealing unpleasant realities about the HIV epidemic crisis in Sub-Sahara Africa (Global South) and possible drug abuse for illicit drug (whoonga/nyaope) manufacturing. For the other examined CECs, their concentrations in drinking water were, from higher to lower score: 1,7 dimethylxanthine (403.3 ± 244.2 ng/L) ≥ emtricitabine (358.4 ± 250.8 ng/L) ≥ atrazine (227.0 ± 61.0 ng/L) ≥ caffeine (194.1 ± 216.5 ng/L) ≥ tramadol (189.5 ± 112.4 ng/L) ≥ carbamazepine (122.9 ± 24.5 ng/L) ≥ sulfamethoxazole (107.8 ± 55.1 ng/L) ≥ methaqualone (72.2 ± 20.5 ng/L) ≥ benzotriazole (61.2 ± 18.8 ng/L) ≥ trimethoprim (59.1 ± 30.4 ng/L) ≥ cetirizine (33.7 ± 19.6 ng/L) ≥ codeine (26.7 ± 57.2 ng/L) ≥ naproxen (25.7 ± 11.3 ng/L) ≥ venlafaxine (21.6 ± 16.3 ng/L) ≥ acetaminophen (17.7 ± 25.8 ng/L) ≥ benzoylecgonine (9.6 ± 5.1 ng/L) ≥ methamphetamine (8.6 ± 6.4 ng/L) ≥ diclofenac (5.2 ± 7.9 ng/L). The large standard deviations indicate the high temporal variations in CECs releases in freshwater. The silver lining is that in the final drinking water, CECs concentrations are greatly reduced, with percentage removals in the range of 9 % (diclofenac) to 75 % (efavirenz). Nonetheless, in LMICs tangible limits and regulatory frameworks for the effective removal of CECs from drinking water, along with more robust polishing techniques such as activated carbon treatment, are missing and should be introduced to avoid the worst effects of CECs exposure.

Zinc oxide (ZnO), a commonly used photocatalyst, suffers from the rapid recombination of photogenerated charge carriers, and the inability to harvest visible light. Therefore, the green synthesized ZnO from Garcinia mangostana pericarp is modified via non-metal (X) doping of N, P, S, Br, and B with a mass content of 5 % to tackle the aforementioned. The obtained materials were characterized through various modern characterization techniques. The results reveal that amongst the X-doped sample, ZnO-B demonstrates the highest photocatalytic performance. The characteristics of ZnO include good crystallinity as well as a low band gap energy of 2.094 eV, revealing an enhanced visible light absorption activity of the sample. The photoactivity of surveyed ZnO-B was investigated through the degradation of malachite green, methyl orange, and tetracycline, achieving a removal rate of 96.29, 86.59, and 90.32 %, respectively. Simultaneously, the antibacterial properties of the ZnO-X were evaluated for Staphylococcus aureus under sunlight illumination. Moreover, the photocatalysis mechanism of the studied materials was elucidated through the band structure, toxicity, and total organic carbon removal of the post-catalysis solution. The selected boron-doped zinc oxide catalyst also showed excellent reusability after 10 cycles of photocatalysis, retaining ∼ 80 % of its original activity. The obtained results reveal the potential application of non-metal-doped zinc oxide in environmental remediation and water disinfection.

The increasing amount of waste in various industries has led to the phenomenon that pellets contaminated with waste materials, such as plastics, binders of petrochemical origin, partly or wholly made from furniture waste, and shredded railway sleeper waste, which are saturated with creosote oils, are also entering the market. Solid biofuel contaminated by materials such as shredded railway sleeper waste lead to damage of the heating equipment and emissions can impact consumers’ health. Incinerating this type of hazardous waste and fuel contaminated in facilities not designed for this purpose (such as waste incinerators and cement plants) can lead to the emission of harmful organic compounds such as polycyclic aromatic hydrocarbons (PAHs). Given the health risks posed by the release of toxic chemicals into the atmosphere during the uncontrolled incineration of this type of hazardous waste, it is crucial to investigate methods for monitoring the purity of solid biofuels against contamination from shredded railway sleeper waste. This article presents research that has led to the preparation of reliable methodologies for the detection of contamination from railway sleeper waste in solid biofuel. Gas chromatography tests were able to find samples that had creosote oil components, which clearly showed that shredded railway sleeper waste had been added to the biofuel pellets. According to the research presented here, the most common indicators of the presence of railway sleeper waste in biomass pellets are acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene.

The biosynthesis of metallic nanoparticles is gaining prominence as an alternative to traditional physicochemical methods, offering several advantages such as simplicity, non-toxicity, lower energy requirements and short reaction times leading to environmentally sustainable processes. The aims of this work were: to study the extracellular biosynthesis of silver nanoparticles (AgNPs) by Pseudomonas extremaustralis 2E-UNGS, to characterise the shape, monodispersity and size of AgNPs, to explore their antimicrobial and antibiofilm activities, and to evaluate the role of nitrate reductase activity in the biosynthesis process. The novelty of this work relies on the development of a green and sustainable method for the synthesis of stable AgNPs with optimal properties for potential applications in antimicrobial materials, especially when incorporated into polymeric matrices or used as agrochemical substitutes. Optimal conditions for the biosynthesis of spherical AgNPs were determined to be pH 7, 38 °C, 4 h of darkness and 120 rpm using stationary phase culture supernatants of P. extremaustralis 2E-UNGS. The involvement of extracellular nitrate reductase in AgNP biosynthesis was confirmed by enzymatic assays and supported by bioinformatics analysis, which identified the presence of the napA2 gene linked to the nirBD cluster. Antimicrobial assays demonstrated the inhibitory effect of AgNPs against both Gram-positive and Gram-negative bacteria, including Pseudomonas aeruginosa PA01 in both planktonic and biofilm states. In addition, the potential application of AgNPs in innovative antibacterial polymers was explored by incorporating them into polyurethane matrices either alone (PU-AgNP) or in combination with crystal violet as a photosensitizer (PU-AgNP-CV). Subsequent inoculation with a clinical isolate of Pseudomonas aeruginosa resulted in significant reductions in viable bacterial counts on both PU-AgNP-CV and PU-AgNP. Biogenic AgNPs showed antibacterial and antibiofilm properties for new antimicrobial material development.