Friendly Approach Research Articles

Photodegradation of RB5 dye with modified zeolites: influence of temperature and UV irradiation

Abstract This study explores the photocatalytic degradation of Reactive Black 5 (RB5) dye using thermally modified natural zeolites, aiming to improve water purification methods. Zeolites were calcined at 250 °C, 350 °C, and 500 °C, and characterized through x–ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR) to analyze their structural and morphological transformations. The results reveal that calcination significantly enhances the photocatalytic performance, particularly for ZNM500, which exhibited the highest efficiency, reaching a 60% removal rate of RB5. The degradation process follows a pseudo-first-order kinetic model at lower dye concentrations but adheres more closely to the Langmuir–Hinshelwood equation at higher concentrations, emphasizing the role of surface adsorption in catalysis. UV irradiation was a key factor in boosting reaction rates, with shorter wavelengths (254 nm) providing greater energy, leading to more effective dye breakdown by facilitating the generation of reactive hydroxyl radicals (·OH). These findings suggest that thermally modified zeolites, especially ZNM500, represent a promising solution for wastewater treatment, offering an efficient, cost–effective, and environmentally friendly approach to removing synthetic dyes from contaminated water sources.

Copper nanoparticles synthesis from Andrographis paniculata leaf extract– characterization and its application

Copper nanoparticle synthesis and characterization are now being done widely due to its broad nanotechnology research interest, especially in medical applications. The current work set out to produce copper nanoparticles(CuNPs) by employing the herb Andrographis paniculata for medicinal purposes. Andrographis paniculata leaf extract was used to make CuNPs using copper sulphate (CuSO4). For monitoring the synthesis of CuNPs, the UV-vis absorption spectra were obtained and Surface Plasmon resonance (SPR) peaks at 500nm. The X-ray diffraction (XRD) pattern reveals the average size of the crystallites is 5.876 nm. This environmentally friendly approach yields homogenous, spherical particles, as demonstrated by images of Scanning and Transmission electron microscopy (TEM and SEM). The outcomes demonstrated that leaf extract is most suited for producing CuNPs. It shows a greater zone of inhibition and inhibitory action against tested bacteria such as Bacillus cereus, Escherichia Coli, Klebsiella pneumoniae and Staphylococcus aureus, and it can be used for the inhibition of several harmful microbes. Because the synthesized CuNPs are non-toxic, environmentally benign, and suitable for usage in pharmaceutical and other fields, they can be applied in a variety of ways in future.

Whiteness and greenness assessments of a sensitive HPLC method with fluorimetric detection for dapagliflozin quantitation in human plasma: Application to a healthy human volunteer.

The evident ecological impact of human actions, like air pollution, global warming, and ozone depletion, underscores the need for environmentally friendly approaches across various domains, including analytical chemistry. This study aimed to establish a validated, eco-friendly, and sustainable approach utilizing a fluorescence detector coupled with high-performance liquid chromatography for quantifying the antihyperglycemic agent dapagliflozin (DAPA), in human plasma. This method employed a C18 Microsorb MV (4.5 × 250 mm, 5 μm [particle size]) column at 40°C, with 40:60% v/v isocratic elution of acetonitrile and (0.1%) orthophosphoric acid as the mobile phase at 1 mL/min flow rate. DAPA and the internal standard demonstrated their greatest response by performing excitation at 225 nm (λex) and recording chromatograms at an emission wavelength (λem) equal to 305 nm. The presented approach demonstrated high linearity between 50 and 2000 ng/mL and full adherence to the guidelines of the US Food and Drug Administration regarding the validation of bioanalytical methods. The described technique was effectively used for quantification of DAPA in human plasma samples from a healthy male participant who received a tablet of 10 mg DAPA. Analytical Eco-Scale, Analytical GREEnness metric, and the recently created ChlorTox Scale were utilized for greenness assessment. Additionally, the "Red, Green, and Blue 12" model was used in whiteness evaluation.

With a Little Help from Our Friends: Applying a Critical Friends Orientation to Critical Literature Reviews

ABSTRACTThis paper describes how we developed and applied an exploratory critical friends orientation to a critical literature review that explores how feminist theories and approaches have been used in archival studies literature and reports on insights generated by this method. A critical friend is a trusted ally and critic who both values our ideas and can push them forward. Our “critical friends” critical literature review includes two parts; using traditional critical review methods we identify and synthesize how critical feminist approaches have been employed in archival studies literature. Atypically, and in part two, we also pay attention to those scholarly articles that discussed relevant or related concepts but were ultimately excluded from our final literature review corpus during the appraisal process. These peripheral articles act as critical friends to the research area under review. We describe how this approach identifies disciplinary boundaries and traditions and explores areas of overlap across intersecting and adjacent fields. A critical friends approach allows us to generously interpret and analyze the complex concepts of “feminisms” and “archives” across disciplinary fields in order to identify, learn from, and engage across fields that have much in common as well as fundamental differences.

The Potentiality of Eco-Library Design in Medan City Towards Sustainability Development

Abstract Sustainable development has become an important concern over the last three decades. The Eco-library design concept has gained popularity due to its environmentally friendly approach. However, the government and citizens of Medan must continue discussing this matter. The library serves as an information hub, significantly promoting sustainable development. This study investigates the benefits of the green building concept and the design strategy for the Eco-Library in Medan City through literature reviews, interviews, and questionnaires distributed to local visitors and experts. In the past, the conventional library used only an air conditioner to maintain its collection, contributing to high electricity expenses. By analysing the context of climate of Medan city, this paper demonstrates how the concept of Eco-Library can reduce negative environmental impacts through the use of sustainable materials, renewable energy sources, solar panels, rainwater harvesting, floating boxes concept, motion-sensor lighting systems, and eco-friendly air conditioners. Contemporary tropical architecture was utilized in the design of this Eco-Library, which includes an overhanging roof and a double facade-oriented east and west, with the longest side facing north and south. In addition, encouraging the use of rooftop gardens in Medan can help reduce indoor heat and air pollution.

Manufacturing floor mapping and presence tracking with a physics-based game engine

The manufacturing shop floor exists in a dynamic environment with constantly changing components regarding position and features. Presence tracking on the manufacturing shop floor is essential to enhance effective operations and safety. Internet of Things technology solutions have been developed to track and monitor machine and operators’ movements and materials on the shop floor to enhance machine availability and worker safety and improve overall operational effectiveness. However, for SMMs with limited financial resources and infrastructure, there is a need for a financially friendly approach to shop floor presence tracking and monitoring. This work presents the use of Internet-of-things and physics-based engines to develop a scalable and customizable solution to track presence on a manufacturing floor. The paper aims to improve and promote the adoption of I-4.0 technologies and digital manufacturing by SMMs with the development of an affordable, repeatable, customizable, open-source solution. The article describes a methodology for mapping, modeling, monitoring, and reporting presence on a manufacturing floor using physics-based engines. The methodology describes mapping the manufacturing floor into zones, the design of the IoT solution, selecting and placing sensors, and presenting the data using dashboards and physics-based engines. The paper investigates the methodology by implementing a case study on the Interdisciplinary Center for Advanced Manufacturing Systems (ICAMS) manufacturing floor using the Unity3D game engine, open-source software, and off-the-shelf motion sensors.

Additive-Free, In Situ Rapid Repair of Vacancies in Fe[Fe(CN)6] Electrodes for Efficient Capacitive Deionization.

Fe[Fe(CN)6] (FeHCF) is considered a promising material for capacitive deionization-desalination of saline wastewater due to its excellent structure. However, additives are usually introduced during the synthesis of FeHCF in order to avoid [Fe(CN)6]3- vacancy defects filled by ligand water, which can result in the appearance of harmful byproducts and additional water treatment costs. In this study, an additive-free in situ vacancy repair strategy is proposed for the rapid synthesis of high-quality FeHCF in a saturated K3Fe(CN)6 solution. During the process of synthesizing FeHCF in solution, a high concentration of [Fe(CN)6]3- is found to facilitate the binding of Fe3+ to [Fe(CN)6]3- and hinder the hydrolysis and coordination reaction of Fe3+. After undergoing repair, FeHCF4 demonstrates an increased capacity and highly reversible electrochemical performance due to the robust structure. When utilized as Faraday cathodes in hybrid capacitive deionization (HCDI) systems, FeHCF4 exhibits a higher salt removal capacity (65.67 mg g-1) and lower energy consumption (0.68 kWh kg-1-NaCl) compared to unrepaired FeHCF1, while still maintaining excellent cycling performance. This environmentally friendly approach of repairing vacancies serves as a source of inspiration for the advancement of high-performance Prussian Blue analogues as capacitive sodium-removing materials.

A novel use of incineration bottom ash for H2 aeration in the production of artificial lightweight aggregates

Cold bonding is an energy-efficient method for producing artificial aggregate (AA). However, the relatively high density of AA restricts its use in lightweight concrete products. This study aims to fully upcycle aluminum (Al) content in municipal solid waste incineration bottom ash (IBA) for H2 aeration in the production of lightweight artificial aggregate through alkali activation. To achieve this, the glass particles (GP) in IBA were ground into powder and used as the precursor for NaOH, while the remaining IBA (RIBA), rich in Al, served as the foaming agent. The results showed that RIBA particles (<300 μm) can be used to produce lightweight AA with a loose bulk density ranging from 780 to 840 kg/m3, comparable to sintered fly ash aggregates, and a wide pore size distribution ranging from 0.02 mm to over 1 mm. The inclusion of finer RIBA particles (<75 μm) enhanced the homogeneity of the pore structure, resulting in aggregate strengths of 0.4–0.6 MPa. Moreover, increasing the GP content in IBA up to 40% further boosted the aggregate strength to 1.1 MPa by refining the pore structure and promoting more (C)-N-A-S-H gels with Q4 structures. To ensure sufficient geopolymerization reactions and achieve high strength in the AAs, the alkali concentration should be kept above 3 mol/L. The proposed strategy for lightweight AA production reduced the global warming potential by about 20% compared to the conventional sintered method, offering a more environmentally friendly approach.

Antioxidant Compounds and Activities of Roselle (Hibiscus sabdariffa L.) Decoction Residues from Cordial and Juice Production

Roselle is a popular plant in Malaysia, especially for its use in food and beverage production. The calyces of the roselle plant are commonly decocted to make roselle juice and cordial, resulting in a significant amount of waste in the form of decocted calyces. Surprisingly, these decocted calyces retain their dark red colour and are still intact although soften. However, to date, there is no research on the antioxidant compounds and activities of roselle decoction residues from cordial and juice production have been reported. Therefore, the aim of this study is to determine the phenolic compounds and antioxidant activities of the roselle decoction residues. The roselle decoction residues were evaluated for colour, Delta E (∆E), pH, total anthocyanin content (TAC), total phenolic content (TPC), total flavonoid content (TFC), DPPH radical scavenging assay, ferric reducing ability assay (FRAP), and ferrous ion chelating (FIC). All assays were also correlated and show positive effect among themselves. The decocted residues reported were still in acidic conditions ranged of pH 2 to 4. The decocted cordial residue (DCR) showed similar colour with control or fresh roselle calyx (FRC), and a bit duller in decocted juice residue (DJR). The DCR showed similar and slightly lower antioxidant content and activity of TAC, TPC, TFC, DPPH, FRAP and FIC to FRC but much better than DJR. Therefore, the DCR were still rich in anthocyanin contents and had good antioxidant activity without having colour changes. These residues have the capacity to be converted to wealth and could be an alternative source for natural antioxidants. Further research is needed to explore their potential applications in functional foods, dietary supplements, and pharmaceuticals. By harnessing the potential of roselle decoction residues, we can contribute to a more sustainable and environmentally friendly approach to food and beverage production.

Rice husk-derived nitrogen-doped graphitic carbon/graphene nanosheets self-assembly for high-performance supercapacitors with chemical blowing method

Carbon materials derived from waste biomass are increasingly popular in energy devices due to their renewability, environmental benefits, and rich heteroatom functionalization. Herein, a simple and low-cost method for synthesising rice husk-derived nitrogen-doped graphitic carbon/graphene nanosheets (RNGNs) by chemical blowing was developed. Carbon was derived from rice husk (RH), while nitrogen was sourced from ethylenediaminetetraacetic acid and iron sodium salt hydrate (EDTA-FE), serving multiple roles as a blowing agent, an activating agent and a graphitization catalyst in a closed system. This approach facilitates the formation of a unique 3D structure of 2D graphene self-assembly on the wrinkled surface of graphitic carbon. As an electrode material for supercapacitors, the obtained RNGN800–1:1 with high nitrogen content (5.02 %) shows good electrical conductivity and a large specific surface area (1130 m2 g−1). These characteristics bring about an impressive electrochemical performance (334.5 F g−1 at 0.5 A g−1, 75.6 % retention at 20 A g−1). Moreover, when assembled into symmetrical device, the RNGN800–1:1 demonstrates a high power density of 9.4 kW kg−1and an excellent energy density of 15.2 Wh kg−1 with outstanding long-term cyclability (remains 94.77 % after 25000 cycles). This study introduces a straightforward and environmentally friendly approach for synthesizing nitrogen-doped graphitic carbon/graphene nanosheets from sustainable biomass resources. The resulting material is expected to have broad applications across various areas, including adsorption, catalysis, and energy storage.

Solar Hydrogen Production and Storage in Solid Form: Prospects for Materials and Methods.

Climatic changes are reaching alarming levels globally, seriously impacting the environment. To address this environmental crisis and achieve carbon neutrality, transitioning to hydrogen energy is crucial. Hydrogen is a clean energy source that produces no carbon emissions, making it essential in the technological era for meeting energy needs while reducing environmental pollution. Abundant in nature as water and hydrocarbons, hydrogen must be converted into a usable form for practical applications. Various techniques are employed to generate hydrogen from water, with solar hydrogen production-using solar light to split water-standing out as a cost-effective and environmentally friendly approach. However, the widespread adoption of hydrogen energy is challenged by transportation and storage issues, as it requires compressed and liquefied gas storage tanks. Solid hydrogen storage offers a promising solution, providing an effective and low-cost method for storing and releasing hydrogen. Solar hydrogen generation by water splitting is more efficient than other methods, as it uses self-generated power. Similarly, solid storage of hydrogen is also attractive in many ways, including efficiency and cost-effectiveness. This can be achieved through chemical adsorption in materials such as hydrides and other forms. These methods seem to be costly initially, but once the materials and methods are established, they will become more attractive considering rising fuel prices, depletion of fossil fuel resources, and advancements in science and technology. Solid oxide fuel cells (SOFCs) are highly efficient for converting hydrogen into electrical energy, producing clean electricity with no emissions. If proper materials and methods are established for solar hydrogen generation and solid hydrogen storage under ambient conditions, solar light used for hydrogen generation and utilization via solid oxide fuel cells (SOFCs) will be an efficient, safe, and cost-effective technique. With the ongoing development in materials for solar hydrogen generation and solid storage techniques, this method is expected to soon become more feasible and cost-effective. This review comprehensively consolidates research on solar hydrogen generation and solid hydrogen storage, focusing on global standards such as 6.5 wt% gravimetric capacity at temperatures between -40 and 60 °C. It summarizes various materials used for efficient hydrogen generation through water splitting and solid storage, and discusses current challenges in hydrogen generation and storage. This includes material selection, and the structural and chemical modifications needed for optimal performance and potential applications.

Integral fractionation of Arundo donax using biphasic mixtures of solvents derived from biomass: An environmentally friendly approach

Arundo donax, one of the most invasive plants in the world, but also a promising source of lignocellulose materials was employed as a feedstock for a biorefinery process. Water-extracted Arundo donax samples were subjected to one-step biphasic fractionation in catalyzed media containing water and 1-butanol, an environmentally-friendly solvent. The effects of selected operational variables (catalyst concentration, temperature and reaction time) on the measured effects (solid recovery yield and compositions of the solid, aqueous and organic phases resulting from treatments) were assessed using statistical methods. The results allowed a quantitative discussion on aspects regarding the selectivity of component separation (lignin, glucan, and hemicelluloses), the overall recovery of valuable products, and the selection of operational conditions enabling extensive delignification (around to 90 %) and high recovery rates of glucan and hemicellulose-derived sugars (above 80 % and 75 %, respectively). This study provides new insights into biphasic fractionation, highlighting the selective separation of hemicellulose, cellulose and lignin into a single and sustainable process, thereby by enhancing biomass resource while reducing environmental impact.

Water purification and biological efficacy of green synthesized Co/Zn-Doped α-Fe2O3 nanoparticles

In the present study, Co/Zn doped α-Fe2O3 (Hematite) nanoparticles (NPs) were synthesized using polyvinylpyrrolidone (PVP) and Azadirachta indica (AI) leaves aqueous extract. The analytical techniques including XRD, UV, SEM, EDX, VSM, Raman, and FTIR, we were able to identify and characterize the structural, morphological and magnetic attributes of the synthesized NPs. The findings demonstrated that the synthesized NPs exhibit homogeneous spherical shapes with particle sizes ranging from 8.64 to 15.32 nm. The NPs have rhombohedral crystal lattices, with crystallite sizes of 23.25 nm for chemically synthesized doped α-Fe2O3 NPs and 12.52 nm for those synthesized using green methods. The magnetic study has shown that the saturation magnetization (Ms) value of NPs, which ranges from 36 to 45 emu/g at ambient temperature, exhibits superparamagnetic properties (300 K). The treatment of industrial wastewater and its reuse for agricultural purposes are the subjects of the current study. Different concentrations of doped α-Fe2O3 NPs were used as photocatalysts to degrade dyes in a bioreactor under UV light in a heterogeneous mixture. The degradation rates achieved were 96.42 % for Congo Red (CR) and 98.36 % for Eosin Yellow (EY). DPPH assays were conducted to evaluate the antioxidant activity of the synthesized doped α-Fe2O3 NPs. The percentage inhibition of DPPH radicals ranged from 71.13 % to 90.35 %. Our findings indicate that AI leaf extract holds promise as a valuable resource for the development of bioactive compounds and environmentally friendly approaches to synthesizing green NPs. This is primarily attributed to the increased accessibility of bioactive components with potent antioxidant properties. The combination of these benefits provides opportunities for novel uses in environmental cleanup, biological applications, and energy conversion.

PREPARING NANOPARTICLES USING SOME BIOLOGICAL METHODS AND STUDYING THEIR EFFECT ON SOME MYCOTOXINS

General Background: Mycotoxins, toxic substances produced by certain fungi and bacteria, pose significant health risks to humans and animals, necessitating effective remediation strategies. Specific Background: The use of environmentally friendly approaches to mitigate the impact of these toxins is crucial. Nanotechnology, particularly in conjunction with plant extracts, has emerged as a promising method for toxin remediation due to its cost-effectiveness and efficiency. Knowledge Gap: Despite the potential of nanomaterials in mycotoxin management, there is limited research exploring the interaction between plant extracts and nanotechnology in inhibiting toxin-producing fungi. Aims: This study aims to investigate the efficacy of zinc oxide nanomaterials synthesized from mint plant extracts in mitigating the effects of mycotoxins and inhibiting the growth of mycotoxin-producing fungi. Results: Mint leaves were collected from various locations in Al-Qadisiyah Governorate over an eight-week period. The extracted plant materials were used to synthesize zinc oxide nanoparticles, which demonstrated significant inhibitory effects on the growth of specific fungi responsible for mycotoxin production, thereby reducing mycotoxin formation. Novelty: This research highlights the innovative application of mint-derived zinc oxide nanoparticles as a dual-action agent—suppressing fungal growth while simultaneously preventing mycotoxin synthesis. Implications: The findings provide valuable insights into sustainable agricultural practices and mycotoxin management, paving the way for the development of natural, eco-friendly solutions to enhance food safety and protect public health.

Noncanonical Amino Acids: Bringing New-to-Nature Functionalities to Biocatalysis.

Biocatalysis has become an important component of modern organic chemistry, presenting an efficient and environmentally friendly approach to synthetic transformations. Advances in molecular biology, computational modeling, and protein engineering have unlocked the full potential of enzymes in various industrial applications. However, the inherent limitations of the natural building blocks have sparked a revolutionary shift. In vivo genetic incorporation of noncanonical amino acids exceeds the conventional 20 amino acids, opening new avenues for innovation. This review provides a comprehensive overview of applications of noncanonical amino acids in biocatalysis. We aim to examine the field from multiple perspectives, ranging from their impact on enzymatic reactions to the creation of novel active sites, and subsequent catalysis of new-to-nature reactions. Finally, we discuss the challenges, limitations, and promising opportunities within this dynamic research domain.

Sustainable remediation of acid mine drainage (AMD)- and crude oil-contaminated sites through wastewater-enhanced Pseudomonas aeruginosa ATCC 15442 treatment

The increasing rate of soil contamination poses a major challenge to the sustainability of the ecosystem. Acid mine drainage (AMD) and crude oil are among the major soil contaminants contributing to the degradation of soil organic matter. This study aims to evaluate the application of Pseudomonas aeruginosa ATCC 15442 (PA-15442) and wastewater for the treatment of AMD- and crude oil-contaminated soils. A microcosm containing 1 kg each of AMD- and crude oil-contaminated soils was inoculated with PA-15442, and brewery and domestic wastewater were added for the bioaugmentation study. The result of the 28-day study conducted under mesophilic conditions showed an average TPH and metal removal efficiency of 58.84% and 52.75%, corresponding to 51.07, 47.29, 59.32, 58.98, and 47.1% for the individual metals (Fe, Al, Cu, Zn, and Mn), respectively, and 49% for the average sulfate removal after the treatment period. This study has shown that bioaugmentation of contaminated soils with the strain of PA-15442, and the addition of wastewater could be an environmentally friendly and sustainable approach for the remediation of AMD- and petroleum-contaminated soils.Graphical

Batch and continuous adsorptive removal of brilliant green dye using modified jamun seed powder: RSM based optimization

Indian jamun seeds (JSs) were surface-modified with sulfuric acid in a 1:1 ratio of acid to adsorbent. The modified JS (MJS) was characterized using Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDX) techniques. Response surface methodology (RSM) via central composite design (CCD) was utilized to investigate critical parameters like pH, contact time, and initial concentrations. At the optimal condition, the MJS exhibited a maximum adsorption capacity of 123.5 mg g−1 for brilliant green (BG). The adsorption process followed Langmuir and Freundlich models, supported by the correlation coefficients. Kinetic studies suggest that the pseudo-second-order model better explains the experimental data compared to the first-order kinetic equation, indicating that intraparticle diffusion is not the sole rate-limiting step. Thermodynamically, the process was found to be spontaneous, exothermic, and with increased entropy. Regeneration studies revealed that the MJSs can be reused for three cycles without compromising their efficiency. Continuous studies showed that lower flow rates, lower initial concentrations, and higher bed depths resulted in better adsorption efficiency. In essence, this study demonstrates that JS offer a simpler and environmentally friendly approach to remediating wastewater containing BG.

Comprehensive Evaluation of Process Parameters in the Green Synthesis of Iron Oxide Nanoparticles Using Moringa olifera extract.

This study investigates the green synthesis of iron oxide nanoparticles using Moringa olifera ethanolic extract and evaluates the impact of various process parameters on their physicochemical characteristics. The parameters examined include synthesis time, temperature, pH, stirring speed (RPM), and the ratio of extract to iron precursors. The findings reveal that a lower proportion of the extract increases the entrapment efficiency of the nanoparticles. Specifically, batch ME3 (3:1 ratio) produced the smallest nanoparticles at 117.8 nm, with a drug release of 75.54% and the highest entrapment efficiency at 60.28%. Extending the synthesis time to three hours in batch TM3 resulted in a drug release of 74.23% and a particle size of 116.3 nm. Batch TEM1, synthesized at 70°C, showed the highest entrapment efficiency and a favorable drug release profile of 71.09%, with the smallest particle size of 105.24 nm, suggesting that higher synthesis temperatures favor smaller particle sizes. Adjusting the pH to 10 in batch PM3 achieved a drug release efficiency of 76.02%. Batch RM5, synthesized with a stirring speed of 750 RPM, demonstrated a particle size of 95.7 nm and a drug release of 78.26%, indicating that higher stirring rates produce smaller nanoparticles and enhance drug release. These results highlight the significance of optimizing synthesis conditions to produce nanoparticles with desired properties. The use of M. olifera extract as a sustainable reducing and stabilizing agent presents an environmentally friendly approach to nanotechnology. This method has potential applications in drug delivery systems and various other industries, emphasizing the importance of green synthesis in creating sustainable and efficient nanomaterials.

Advances in the structure and function of MHETase

Polyethylene terephthalate (PET) is one of the widely used plastics, but its waste pollution has become a global environmental issue. The discovery of polyethylene terephthalate hydrolase (PETase) has provided a green and environmentally friendly approach for PET degradation. However, PETase produces intermediate products that inhibit the enzyme's further activity, leading to a decrease in enzyme efficiency. Mono(2-hydroxyethyl) terephthalate hydrolase (MHETase) works synergistically with PETase to further degrade the intermediate product MHET into ethylene glycol (EG) and terephthalic acid (TPA). MHETase exhibits extremely high specificity for MHET and is crucial for the complete degradation of PET. This article comprehensively reviews MHETase from various perspectives, including its three-dimensional structure, substrate binding, and catalytic mechanism. It demonstrates the structural features and key residues associated with the enzyme's degrading activity and discusses the progress in enzyme engineering modifications. Additionally, the study envisions the development of a two-enzyme PET degradation system by combining MHETase with PETase, aiming to provide valuable references for designing and developing more efficient PET hydrolytic enzyme systems.

Sorption-spectrophotometric determination of bismuth ion (III) using immobilised xylenol orange on modified polyacrylonitrile

ABSTRACT This study presents a new sorption-spectrophotometric method for determining bismuth (III) ions using a new adsorbent for PPM-1 fibre immobilised with xylenol orange. The complex exhibited a maximum reflectance at 550 nm and absorption at 530 nm, indicating stable formation. The method demonstrated high sensitivity with a detection limit of 0.1 µg/mL and high selectivity, minimising interference from other metal ions. Optimal pH for complex formation was 1.37, with faster response and higher sensitivity in the immobilised state (detection limit 0.12 µg/mL, formation time 10 minutes). The complex adhered to the Bouguer-Lambert-Beer law within 3–42 µg/25 mL. Interferences from Cu2+, Ag+, Pd2+, and Fe3+ were reduced when the reagent was immobilised. Conductometric analysis confirmed the stable formation of the complex. Validation using model mixtures and pharmaceutical preparations showed accurate bismuth determination with an error margin of 0.005. For example, a mixture containing 25 µg of bismuth with zinc and cadmium yielded 25.20 µg, and De-nol had a found content of 49.50 µg for 50.00 µg added. IR spectroscopy confirmed complex formation with significant shifts in absorption bands. SEM and EDS analysis validated the reagent’s effective immobilisation and interaction with bismuth ions. The method provides a rapid, accurate, and environmentally friendly approach for bismuth analysis, demonstrating high reproducibility, sensitivity, and selectivity, suitable for environmental monitoring and pharmaceutical quality control.