Residual Metal Research Articles

Uniform Polymer Microspheres by Photoinduced Metal-Free Atom Transfer Radical Precipitation Polymerization.

Herein, a photoinduced method is introduced for the synthesis of highly cross-linked and uniform polymer microspheres by atom transfer radical polymerization (ATRP) at room temperature and in the absence of stabilizers or surfactants. Uniform particles are obtained at monomer concentrations as high as 10% (by volume), with polymers being exempt from contamination by residual transition metal catalysts, thereby overcoming the two major longstanding problems associated with thermally initiated ATRP-mediated precipitation polymerization. Moreover, the obtained particles have also immobilized ATRP initiators on their surface, which directly enables the controlled growth of densely grafted polymer layers with adjustable thickness and a well-defined chemical composition. The method is then employed successfully for the synthesis of molecularly imprinted polymer microspheres.

An infrared radiation-responsive high-entropy CoCaMgMnAlFe-LDHs for controllable hydrogen generation via NaBH4 hydrolysis: Utilization of steel slag and lithium-ion battery liquid waste

Green processing of steel slag and lithium-ion battery liquid waste poses a global environmental challenge. This study utilizes waste acid (containing Co2+, H+ and NO3–) and alkali solutions (containing Li+, Na+, OH– and CO32–) from lithium-ion battery manufacturing to recover metal cations from steel slag (containing Ca2+, Mg2+, Al3+, Fe3+, and Mn2+), preparing high-entropy CoCaMgMnAlFe-LDHs catalysts for controllable hydrogen generation via NaBH4 hydrolysis. The ultimate residue, without any residual hazardous metal cations, enabling safe reintroduction into the natural environment. The presence of Co2+ endows the CoCaMgMnAlFe-LDHs catalyst with rapid photo-thermal conversion capability, enabling it to rapidly heat up under infrared radiation and efficiently catalyze the reaction of NaBH4 hydrolysis. The hydrogen generation rate reaches 1.12 mol·h−1·g−1·W−1 driven by 1050 nm infrared radiation. This study provides a novel approach to the environmentally friendly treatment and high-value utilization of steel slag and lithium-ion battery liquid waste.

Wood Polymer Composites Based on the Recycled Polyethylene Blends from Municipal Waste and Ethiopian Indigenous Bamboo (Oxytenanthera abyssinica) Fibrous Particles Through Chemical Coupling Crosslinking.

Valorization of potential thermoplastic waste is an effective strategy to address resource scarcity and reduce valuable thermoplastic waste. In this study, new ecofriendly biomass-derived wood polymer composites (WPCs) were produced from three different types of recycled polyethylene (PE) municipal waste, namely linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), or high-density polyethylene (HDPE), and their blend with equal composition (33/33/33 by wt.%). Bamboo particle reinforcement derived from indigenous Ethiopian lowland bamboo (LLB), which had never been utilized before in a WPC formulation, was used as the dispersed phase. Before utilization, recycled LLDPE, MDPE, and HDPE were carefully characterized to determine their chemical compositions, residual metals, polycyclic aromatic hydrocarbons, and thermal properties. Similarly, the fundamental mechanical properties of the WPCs, such as tensile strength, modulus of elasticity, flexural strength, modulus of rupture, and unnotched impact strength, were evaluated. Finally, the thermal stability and interphase coupling efficiency of maleic-anhydride-grafted polypropylene (MAPP) were carefully investigated. WPCs formulated by melt-blending either of the recycled PEs or the blend of recycled PE with bamboo particles showed significant improvement due to MAPP enhancing interfacial adhesion and thermally induced crosslinking, despite inherent immiscibility. These results were confirmed using Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The formulated WPCs may promote PE waste cascading valorization, offering sustainable alternatives and maximizing LLB utilization. Furthermore, comparison with well-known standards for polyolefin-based WPCs indicated that the prepared WPCs can be used as alternative sustainable building materials and related applications.

Refining habitat selection for sulfate-reducing bacteria: Evaluating suitability and adaptability for sulfate-metal wastewater treatment during anaerobic-to-aerobic transitions

Inoculating sulfate-reducing bacteria (SRB) habitats offers an eco-friendly method for treating sulfate-metal laden wastewater, characterized by high sulfate levels, low pH, and elevated heavy metals. This study optimizes source habitat selection of SRB by evaluating groundwater, sewage sludge, and lake sediment, focusing on their suitability and adaptability to aerobic-anaerobic transitions in industrial settings. Sewage sludge, with its slightly acidic pH, reducing environment, and high nutrient levels (Total organic carbon: 207.53 g kg−1, Total nitrogen: 47.12 g kg−1), provides robust SRB potential, as supported by its highest diversity index. However, heavy metals and polycyclic aromatic hydrocarbons pose application challenges. All habitats effectively reduced metal concentrations anaerobically, with Cu removal reaching 95%–99%, and groundwater achieved the highest chemical oxygen demand reduction (63.6%) aerobically. Sludge and sediment showed high biomass and extracellular polymeric substances (EPS) accumulation, while groundwater's nucleic acid-rich EPS enhanced metal immobilization, resulting in stable residual metal forms but with potential remobilization under oxidative conditions. Microbial analysis revealed that Proteobacteria and Firmicutes were key players during transitions, with the highest SRB abundance in groundwater. SRB composition varied across habitats, with Sedimentibacter (13.04%), Desulfovibrio (6.33%), and Desulfomonile (8.1%) dominating in groundwater, sludge, and sediment, respectively, during the anaerobic stage. Functional analysis highlighted sludge's persistence in sulfate reduction under aerobic conditions, while groundwater's limited nitrogen cycle involvement indicated broader biogeochemical limitations. Collectively, these findings highlight strengths and limitations of each habitat as SRB inoculum source, emphasizing the importance of tailored anaerobic-to-aerobic strategies for effective wastewater management.

The curious case of the Dana platypus and what it can teach us about how lead shotgun pellets behave in fluid preserved museum specimens and may limit their scientific value.

Fluid preserved animal specimens in the collections of natural history museums constitute an invaluable archive of past and present animal diversity. Well-preserved specimens have a shelf-life spanning centuries and are widely used for e.g. anatomical, taxonomical and genetic studies. The way specimens were collected depended on the type of animal and the historical setting. As many small mammals and birds were historically collected by shooting, large quantities of heavy metal residues, primarily lead, may have been introduced into the sample in the form of lead shot pellets. Over time, these pellets may react with tissue fluids and/or the fixation and preservation agents and corrode into lead salts. As these chemicals are toxic, they could constitute a health issue to collection staff. Additionally, heavy element chemicals interfere with several imaging technologies increasingly used for non-invasive studies, and may confound anatomical and pathological investigations on affected specimens. Here we present a case-study based on platypus (Ornithorhynchus anatinus) and other small mammals containing lead pellets from the collection of The Natural History Museum of Denmark.

Robust Catalytic SEAr H/D Exchange of Arenes with D2O: Metal‐Free Deuteration of Natural Complexes and Drugs

AbstractA catalytic metal‐free approach for the H/D exchange in aromatic compounds using D2O as the terminal deuterating reagent has been developed. This metal‐free protocol employs a triaryl carbenium as the mediator and showcases a wide applicability in the late‐stage deuteration of various natural products and small‐molecule drugs. Gram‐scale deuteration was successfully demonstrated with β‐Estradiol, highlighting the method‘s practicability. Detailed mechanistic insights, supported by DFT calculations, unveiled the essential role of in situ generated acidic species in this electrophilic aromatic substitution process. This newly developed method offers a sustainable and versatile alternative to traditional metal‐catalyzed H/D exchange techniques, addressing challenges such as the use of expensive metals, impurity formation, and the necessity for residual metal removal from the final products.

Activation of periodate by CNT for selective catalytic oxidation: The overlooked significant role of residual metal species as catalytic sites

Carbon nanotubes (CNTs) catalyzed activation of peroxides has been extensively investigated, while the role of residual metal species in CNT in the catalysis is largely overlooked. In the study, calcination treatment of pristine CNT at high temperatures was employed as an approach to gain an insight into the role of residual metal species as catalytic sites in promoted catalytic activation of periodate (PI). Firstly, the calcination treatment at 500–1100 °C significantly promoted PI activation by calcined CNT. By constructing the quantitative structure–activity relationships (QSARs) between several surface and bulk properties of CNT (such as total surface oxygen content, surface carbonyl group, bulk defect and residual metal species) and PI activation performance, the residual metal species were identified as the catalytic sites. Moreover, the purification method of pristine CNT in the concentrated HNO3 was confirmed to be not efficient to remove these residual metals. The calcination treatment can tune the electronic structure of residual metal species, and promote their exposure and electron donation capacity for PI activation, thus significantly improving PI activation performance. Moreover, IO3• was identified as the dominant reactive species in CNT/PI system via a line of approaches including quenching experiments, PI decomposition in the presence/absence of organic pollutants, electrochemical testes, high selectivity in degradation of organic pollutants, QSARs of substituted phenols, and analysis of degradation products of 4-bromophenol. Furthermore, the CNT/PI system exhibited a wide pH application range of 3–11, high anti-interference to bicarbonate, chloride and phosphate in water. The study advances the understanding on the residual metal species in CNT and its overlooked catalytic role in PI activation, and also provides a high-performance oxidation process for wastewater purification.

In Situ Formation of Stable Dual-Layer Solid Electrolyte Interphase for Enhanced Stability and Cycle Life in All-Solid-State Lithium Metal Batteries.

All-solid-state lithium metal batteries have emerged as a promising solution to overcoming the energy density and safety challenges associated with conventional lithium-ion batteries. Solid polymer electrolytes, particularly those based on poly(vinylidene fluoride) (PVDF) and dimethylformamide (DMF), demonstrate significant potential. However, interfacial side reactions between residual DMF solvents and lithium metal present substantial challenges. In this study, we investigate the in situ formation of solid electrolyte interphase protective layers to mitigate these side reactions. By incorporating F-rich additives, such as fluoroethylene carbonate and lithium difluorophosphate, we successfully establish a dual-layer inorganic SEI structure characterized by an outer LiF layer and an inner Li2O layer. Consequently, our approach extends the cycle life of lithium symmetric batteries to 3000 h. Additionally, the Li||LiFePO4 solid-state battery demonstrates exceptional stability, enduring 400 cycles at a 1C rate with an impressive capacity retention of 84%. This strategic methodology effectively leverages the benefits of residual solvents, ensuring both enhanced battery efficiency and long-term operational stability for PVDF-based all-solid-state lithium metal batteries.

Cross-jurisdictional analysis and forecasting of North American nuclear fuel inventory using a standardized unit

This study fills the noted gap in comparative analyses of spent nuclear fuel (SNF) by assessing inventories from two key nuclear power regions, the USA and Canada, using a comprehensive analytical framework and standardized data from 2009 to 2021. In the USA, SNF inventory increased by 14.7 % in fuel assembly weight and 47 % in residual heavy metal content compared to Canada, in line with their use of light water reactors. Canada's SNF production is directly correlated to its nuclear power output, influenced by the lower burnup of natural uranium fuel used in CANDU reactors (R2 = 0.57; p-value < 0.05) while the USA shows insignificant correlation, likely due to a variety of reactor types and higher burnup rates (R2 = 0.008; p-value > 0.05). Further, the study identifies a strong negative correlation between uranium mine production and SNF inventory in the USA, indicating a reliance on imports amidst negligible domestic mining. In contrast, Canada also exhibits moderate negative dependency due to its position as a major uranium exporting jurisdiction. The obtained negative correlations with coal rents in both countries indicate a shift towards more nuclear energy use, impacting economic growth and energy patterns. The developed predictive models indicate a higher future SNF increase in Canada than in the USA. These findings are essential for planning the transition from temporary to permanent SNF disposal, ensuring safe long term management of radioactive waste.

Synergistic removal of malachite green and Cr(Ⅵ) using ethylenediamine disuccinic acid functionalized silica gel

As common industrial raw materials, malachite green (MG) and Cr(Ⅵ) generally coexist in waste liquids discharged from the paper printing, leather, and textile industries, causing serious harm to humans and the environment. Therefore, developing an effective method for the synergistic removal of MG and Cr(Ⅵ) from aquatic environments is of great research value. In this work, the non-homogeneous Fenton-like catalysts, namely, EDDS-Silica and EDDS-Co2+-Silica were successfully prepared using ethylenediamine disuccinic acid (EDDS) and silica gel (Silica) as raw materials, and a non-homogeneous Fenton-like catalytic method was developed for the efficient and synergistic removal of MG and Cr(Ⅵ) from wastewater. EDDS-Silica and EDDS-Co2+-Silica were analyzed using Fourier infrared spectroscopy and X-ray photoelectron spectroscopy to determine their structural composition and elemental contents. The catalytic degradation and removal effects of these materials in an MG single-waste system were also investigated. The results demonstrated that the incorporation of both materials can overcome the limitation of the conventional Fenton reaction, which is its applicability to acidic environments only. Moreover, EDDS-Co2+-Silica showed better degradation effects on MG than EDDS-Silica. Quantitative calculations based on density functional theory were used to predict the optimal coordination forms between Co2+and EDDS-Silica as well as the MG structure. The lowest unoccupied and highest occupied molecular orbitals of the catalysts were then used to predict the active sites on which MG tends to capture or release electrons during the degradation reaction. The optimal conditions for the synergistic removal of MG and Cr(Ⅵ) from a binary system using EDDS-Co2+-Silica were further investigated under different influencing factors. The results showed that EDDS-Co2+-Silica still had excellent catalytic effect on the degradation rate of MG in the range of pH 3-7, and the optimal conditions were as follows: solution pH, 7; degradation time, 1 h; temperature, 25 ℃; H2O2 concentration, 20 mmol/L; and the initial mass concentration of Cr(Ⅵ), 25 mg/L. Under the above conditions, the degradation rate was increased from 87.25% to 96.67% compared with that in the MG monosystem. Obvious enhancements in degradation effect and efficiency confirmed that the incorporation of EDDS-Co2+-Silica was favorable for the synergistic removal of MG and Cr(Ⅵ) in the binary system. Strongly oxidizing Cr(Ⅵ) can participate in the Fenton reaction, thus promoting MG degradation over a wide pH range. Thus, a positive synergistic effect exists between MG and Cr(Ⅵ). Considering that a large number of metal ions remained in the solution after the degradation reaction, EDDS-Silica was added to the degradation solution, and adsorption experiments were performed for 4 h at 30 ℃to adsorb and remove Cr and Fe via the strong chelating property of EDDS. The total residual mass concentrations of Cr and Fe were 4.96 and 1.02 mg/L, respectively, which meet national emission standards. These findings indicate that EDDS-Silica has good effects on the removal of residual metal ions after the nonhomogeneous Fenton reaction. As heterogeneous Fenton-like catalysts, the aminopolycarboxylic acid-modified materials proposed in this study can simultaneously promote the Fenton reaction and remove residual metal ions, thereby effectively removing MG and Cr(Ⅵ) from the binary system while ensuring that the content of residual metal ions in the system meets environmental emission standards. This study has broad application prospects in dye degradation and heavy-metal-ion wastewater treatment, and provides a reference value and theoretical basis for the development of other similar ligand-modified materials.

Overviews of heavy metals residues in some frozen fish and its biocontrol by probiotic

Overviews of heavy metals residues in some frozen fish and its biocontrol by probiotic

Comparison of environmental impacts from pyrolysis, gasification, and combustion of oily sludge

Thermochemical treatment of oily sludge (OS) has been demonstrated to be an effective approach for resource and energy recovery. However, the migration and emission of potential pollutants have limited its further development. In this study, the environmental impacts, including aromatic compounds in liquid products, N-, S-, and Cl-containing pollutants in gaseous products, and residual organic matter and heavy metals in solid residues, during the pyrolysis, gasification, and combustion processes of OS are comparatively investigated. The results indicate that the aromatics in the liquid products obtained from pyrolysis and gasification are primarily hydrocarbons with 10, 14, and 16 carbon atoms, and the corresponding degree of unsaturation is between 7 and 16. By contrast, the aromatics produced during combustion are mainly hydrocarbons with 10–12 carbon atoms and an unsaturation degree of 7. The liquid products from gasification of OS contain aromatics with more carbon atoms and a higher degree of unsaturation, suggesting potential issues of recalcitrant aromatics and tar by-products during the gasification process. The release behaviors of N-, S-, and Cl-containing pollutants during the thermochemical treatment of OS are closely related to the specific thermochemical technology and treatment temperature. At 550 °C, these pollutants are gradually released from the OS. By contrast, at 950 °C, they are released over a narrow temperature range with significantly higher concentrations. Furthermore, compared with the peak concentrations of SO2 and HCl during thermochemical processing at 550 °C, these values increase by 1–2 orders of magnitude at 950 °C. With the increase in treatment temperature, the loss on ignition (LOI) of residues from pyrolysis or gasification of OS gradually decreases and stabilizes around 0.5 %. On the other hand, the LOI from combustion fluctuates around 1.0 %. In addition, the removal rates of total organic carbon in the residues from all three thermochemical processes exceed 98.89 %. However, the potential ecological risks associated with heavy metals in the residues from thermochemical treatment of OS also increase to some extent. Cr, Cu, and Zn are found to evaporate and escape into liquid and gaseous products, while Pb is retained in the residues. Notably, the residue from combustion poses the highest environmental risks among the three processes.

The prenatal assimilation of minerals and metals in nestlings of a small passerine bird

Although certain metals can reach their highest concentrations in tissues of newly hatched nestlings, their sources have yet to be fully elucidated. Evidence for the differentiation of body reserves, including some chemical elements, during avian embryonic life and early post-hatching period is limited mostly to studies on poultry. Here, we present novel findings on the bioaccumulation and egg-to-nestling transfer of 10 minerals and metals, including non-essential potentially toxic chemical elements (Cu, Ni Cd, Pb, Zn, Ag, Mg, Fe, Co and Ca) in the tissues of the gastrointestinal tract (GT), whole body (WB) and carcass (CA) of nestlings of a small passerine bird, the Eurasian Reed Warbler Acrocephalus scirpaceus, breeding in an intensively fertilized fishpond habitat. Our findings show that concentrations of metals that are relevant to contaminated systems (Cu, Ni, Cd, Pb, Zn, Fe and Co) are the highest in GT tissues across all the nestling age classes examined (from hatching to day 9 of life). The important question emerged from our findings: why the hatchlings were characterized by higher metal concentrations in GT, WB and CA compared to older nestlings. We suggest that the prenatal accumulation of chemical elements assimilated from egg contents, and their subsequent utilization for building various tissues/internal organs by the growing embryo, is a reasonable explanation for this finding. More specifically, the potential functional mechanism explaining the highest concentrations of some trace metals in hatchlings seems to be associated with an extremely high rate of utilization of residual yolk metal resources that survived from the embryonic until the post-natal period. On the basis of our own work and literature data, we identified a presumable significant discrepancy in the actual rate of egg-to-nestling and egg-to-embryo metal transfer due to the eggshell being ignored (a commonly occurrence), and only the egg contents being treated as the basic repository of chemical elements for developing embryos. Much more research is needed on the prenatal assimilation and subsequent accumulation of chemical elements in a developing avian embryo, representing both the transition from near-to-hatching embryos to hatchlings, and then to older nestlings.

The Effect of Heavy Metals in Potato (Solanum tuberosum L.) Genotypes for Some Physiological Parameters

The main aim of this study is to identify physiological characteristics, including Chl a, b, total Chl "a+b" and carotenoids, in potato genotypes under the influence of lead (Pb+2) and cadmium (Cd+2) heavy metals. Two potato genotypes from the Netherlands, Riviera and Agria, were used in the study. Potato tubers were transferred to 2 kg compost pots and placed in a controlled environment with a 12 photoperiod, a day/night temperature of 25/19°C and a relative humidity of 75%. Since Pb+2 and Cd+2 poisoning was greater than in the control and different fractions of heavy metal residues in the substrate were transferred to plant organs, the amounts of these two metals in each treatment (outside the control) were measured. Plant pigments were extracted from fresh leaves in amounts ranging from 60 to 100 mg and these were then extracted into samples containing 80/20% (v/v) acetone/water with 0.5% w/v MgCO3 at room temperature for a full day. Photosynthetic pigments of each sample were extracted three times. The absorbances obtained at 663 nm, 644 nm and 452.5 nm for the maximum absorption of Chl a, Chl b and carotenoids, respectively, were used to measure the amount of chlorophyll and carotenoids. Differences between Pb+2 and Cd+2 and physiological markers were examined with the Duncan Multiple Range test. Information on Pb+2 and Cd+2 content in applications revealed wide variability. When potato genotype seedlings were exposed to varying levels of Pb+2 and Cd+2, the amount of chlorophyll and carotenoids in their leaves was lower than the control group. The results showed that there were significant and statistically significant changes in carotenoid and chlorophyll concentration at the LSD p = 0.01 level. Similar to Pb+2 and Cd+2 inhibiting plant growth, it had a negative effect on photosynthesis as well as chlorophyll and carotenoid contents. Moreover, these effects became more pronounced when the concentrations of two stress factors (Pb+2 and Cd+2) increased.

Seaweed as a feed additive to mitigate enteric methane emissions in ruminants: Opportunities and challenges1

Cutting farming-related methane emissions from ruminants is critical in the battle against climate change. Since scientists initially investigated the potential of marine macroalgae to reduce methane emissions, using seaweeds as an anti-methanogenic feed additive has become prevailing in recent years. Asparagopsis taxiformis is the preferred species because it contains a relatively higher concentration of bromoform. As a type of halogenated methane analogue, bromoform contained in A. taxiformis can specifically inhibit the activity of coenzyme M methyltransferase, thereby blocking the ruminal methanogenesis. However, bromoform is a potential toxin and ozone-depleting substance. In response, current research focuses on the effects of bromoform-enriched seaweed supplementation on ruminant productivity and safety, as well as the impact of large-scale cultivation of seaweeds on the atmospheric environment. The current research on seaweed still needs to be improved, especially in developing more species with low bromoform content, such as Bonnemaisonia hamifera, Dictyota bartayresii, and Cystoseira trinodis. Otherwise, seaweed is rich in bioactive substances and exhibits antibacterial, anti-inflammatory, and other physiological properties, but research on the role of these bioactive compounds in methane emissions is lacking. It is worthy of deeper investigation to identify more potential bioactive compounds. As a new focus of attention, seaweed has attracted the interest of many scientists. Nevertheless, seaweed still faces some challenges as a feed additive to ruminants, such as the residues of heavy metals (iodine and bromine) and bromoform in milk or meat, as well as the establishment of a supply chain for seaweed cultivation, preservation, and processing. We have concluded that the methane-reducing efficacy of seaweed is indisputable. However, its application as a commercial feed additive is still influenced by factors such as safety, costs, policy incentives, and regulations.

Ligand-free Ni-Cu bimetallic nanocatalyst: Laser synthesis, characterization and its high performance for borohydride assisted catalytic reduction of 4-nitrophenol

In the present work, nickel and copper bimetallic nanoparticles with three different concentration ratios of 70:30, 50:50, and 30:70 were synthesized by laser ablation of Ni and Cu in deionized water. The suitability of Ni-Cu bimetallics as nanocatalysts was investigated in the catalytic reduction of pollutant 4-nitrophenol. The nanocatalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV–Vis) spectroscopy. The morphology using SEM and TEM indicated that Cu had an elongated or flake-like structure, whereas Ni had a quasi-spherical structure. XPS investigation has been performed to study the elemental composition and chemical states near-surface regions of the generated Ni-Cu bimetallic nanoparticles. XRD and XPS confirm high oxidation of Cu to CuO with approximately no residual Cu metal. However, the XRD patterns did not show complete Ni oxidation to NiO, confirming the presence of a Ni dopant part in the Ni-Cu samples. The behavior of the photoelectron peaks in the XPS spectra suggested that the Ni-Cu nanocomposites exhibited surface charge transfer. Pulsed laser ablation developed ligand-free Ni-Cu nanoparticles, which affected the structure and catalytic properties. The nanocatalyst for 50:50 of Ni and Cu had the highest rate constant, corresponding to the shortest time required to achieve 100 % conversion/reduction of the pollutant dye. The apparent synergistic effect between Ni and Cu is clearly dictated by the amount of Cu embedded in the nanocomposites, with this becoming a key factor in lowering the band gap energy values. Overall, the surface charge transfer rate can enhance the catalytic performance by tuning the Ni and Cu concentrations.

Assessment tools for evaluating the efficiency of practices to control food safety performance indicators in cereal-based small-medium scale food manufacturing establishments in Bangladesh

Safe production in small-medium enterprises (SMEs)-based food processing industries is a challenge in developing countries due to limited resources and inefficient process control activities. For the development of the situations, we first need to identify the context characteristics and control activities that have an impact on the safety of the finished products. In the present study, a comprehensive target-oriented tool was designed to evaluate the efficiency of control practices with respect to contextual factors to understand the likelihood of common hazards in cereal-based small and medium factories. The identified 18 control activities, based on previous studies, were assigned to three food safety performance indicators, such as allergen contamination, pesticide residue or heavy metal contamination, and fungal contamination. The performance level of activities is a marker of whether the control practices are able to control the food safety performance indicators in cereal-based SME manufacturers. A Venn diagram is used to visually present the efficiency of control activities. Moreover, among the 18 control practices, 7 for mitigating pesticide residues or heavy metal contamination, 9 for allergen control, and 13 control practices for fungal contamination were identified. As comparatively lower control practices (water source, raw material control, testing, etc.) are involved in mitigating pesticide residues or heavy metal contamination, which proves context factors (Good Agricultural Practices, contamination-free soil, etc.) are more important to minimize the risk. We inspected the implementation of the developed tool in 44 cereal-based small-medium manufacturers in Bangladesh and calculated 59.06% efficiency in controlling fungal contamination. Most of the cereal-based SMEs in Bangladesh operate from a poor to a basic level, which is an indication of the high likelihood of occurring hazards.

Recovery of cadmium, lead, strontium and zinc from jarosite waste by using a combinatory approach of bioleaching and acid leaching

ABSTRACT Metallurgical processes commonly generate substantial volumes of hazardous waste, and the extraction of zinc is no exception, yielding a byproduct known as jarosite. This study aims to establish an environmentally conscious and economically viable method for recuperating residual metals from jarosite waste. Comprehensive morphological and physico-chemical characterisation of jarosite was performed using XRD, FTIR, SEM and EDS. To facilitate the selective biorecovery of cadmium, lead, strontium and zinc, Shewanella putrefaciens was employed. The efficacy of biorecovery was systematically assessed using both solid-state and liquid-state leaching methodologies. The results indicate that liquid-state leaching outperformed solid-state leaching for all four heavy metal ions. Notably, biotreated jarosite demonstrated markedly superior metal recovery (Cd, Pb, Sr and Zn) compared to non-biotreated jarosite. This investigation advocates for a hybrid approach, involving bioleaching followed by acid treatment, as a more efficacious strategy for the sustainable recovery of heavy metals from jarosite-like waste. These findings not only underscore the potential of environment-friendly biorecovery techniques but also offer a promising avenue for enhancing the ecological sustainability of waste management practices within the metallurgical industry.

N, N’-bidentate ligand anchored palladium catalysts on MOFs for efficient Heck reaction

Metal-organic frameworks (MOFs), recognized as advanced catalyst carriers due to their adjustable porous, diverse structure and highly exposed active sites, have earned increasing attention for their potential to address the longevity of catalytic centers. In this manuscript, we have devised and synthesized a multifunctional amino-pyridine benzoic acid (APBA) ligand to replace the modulator ligand of the MOF-808 and disperse the palladium catalytic centers atomically on the MOF-APBA. The resulting single-site catalytic system, Pd@MOF-APBA, demonstrates preeminent efficiency and stability, as evidenced by a high average turnover number (95000) and a low metal residue (4.8 ppm) in the Heck reaction. This catalyst has exhibited recyclability for multiple runs without significant loss of reactivity for gram-scale reactions. The catalyst’s high activity and efficiency can be attributed to the suitable electrical properties and structures of the N, N’-bidentate ligand for the catalytic palladium ions, postponing their deactivations, including leaching and agglomeration.

Fabrication of Raman reporter molecule–embedded magnetic SERS tag for ultrasensitive immunochromatographic monitoring of Cd ions and clenbuterol in complex samples

A rapid, simple but sensitive analytical method for the simultaneous monitoring of heavy metal ions and illegal additives in complex samples remains lacking. We reported a difunctional capture–detection surface-enhanced Raman scattering (SERS) immunochromatographic assay (ICA) for the direct detection of the heavy metal residue Cd ion (Cd2+) and illegal additive clenbuterol (CLE) with high sensitivity and specificity herein. A novel magnetic SERS tag (Fe@RAu) with a Raman reporter molecule–embedded raspberry-like Au shell was fabricated via a one-step reduction reaction that not only simplified the fabrication of common magnetic SERS nanomaterials but also improved SERS activity to increase detection sensitivity. The difunctional SERS–ICA enabled the fast magnetic enrichment of the target small molecules in complex specimens and ultrasensitive and quantitative determination of CLE/Cd2+ on the two test lines of the ICA system. The limits of detection of the developed method for CLE and Cd2+ were as low as 0.48 and 1.88 pg/mL, respectively, and about 2000 and 500 times lower than those of conventional AuNP-based ICA strips. The excellent practicability of Fe@RAu–ICA for real food samples analysis was also demonstrated, revealing the potential of the proposed assay for rapid and on-site screening of small-molecule pollutants.