Sustain. Chem., Volume 6, Issue 1 (March 2025) – 10 articles

Twelve marine-derived fungal strains were evaluated for their ability to synthesize silver nanoparticles (AgNPs). Mycogenic AgNPs were preliminarily characterized using different techniques, and their antimicrobial activities were assessed. Penicillium citrinum IBCLP11 and Aspergillus niger IBCLP20 were selected for AgNPs’ synthesis optimization by varying parameters such as AgNO₃ concentration, biomass, agitation, temperature, and pH. AgNP_IBCLP11 and AgNP_IBCLP20 were able to inhibit the growth of Pseudomonas aeruginosa IPT322, Staphylococcus aureus IPT246, and Klebsiella pneumoniae IPT412 at concentrations of 25 μg/mL or higher. Aspergillus niger IPT295 and Aspergillus parasiticus IPT729 were the most sensitive to AgNP_IBCLP20. Further studies are needed to fully elucidate the effects of all parameters influencing mycogenic AgNPs synthesis. However, it is evident that maintaining optimal conditions, such as temperature and pH during agitation, is crucial for preventing undesirable reactions and ensuring nanoparticle stability. Full article

Zeolites are amongst the most extensively explored crystalline microporous materials because of their variable chemical composition, framework geometry, pore dimensions, and tunability. Due to their high surface area, adsorption selectivity, mechanical, biological, chemical, and thermal stability, these molecular sieves are widely used in adsorption, catalysis, ion exchange, and separation technologies. This short review highlights the notable progress achieved in leveraging the properties of zeolite materials for multiple applications, including gas separation and storage, adsorption, catalysis, chemical sensing, and biomedical applications. The aim is to emphasize their capabilities by showcasing important achievements that have driven research in this field toward new and unforeseen areas of material chemistry. Full article

Heavy metal contamination of water sources has emerged as a major global environmental concern, affecting both aquatic ecosystems and human health. Therefore, this study aims to remove hexavalent chromium from an aqueous solution utilizing activated carbon developed from Spathodea campanulata. Chemical treatment with H₃PO₄ followed by thermal activation was employed to enhance the adsorption capability of the precursor material. On the other hand, a full factorial design of 2⁴ including pH (3 and 9), contact time (30 and 60 min), initial chromium concentration (40 and 100 mg/L), and adsorbent dosage of 0.2 and 0.6 g/100 mL was used to optimize the batch-wise adsorption of hexavalent chromium. The characterization results showed that the prepared activated carbon is composed of various functional groups (FTIR), a high specific surface area of 1054 m²/g (BET), morphological cracks (Scanning Electron Microscopy), and a pH point of zero charge of 5.8. The maximum removal efficiency of 96.5% was recorded at optimum working conditions of pH 3, contact time of 60 min, adsorbent dosage of 0.6 g/100 mL, and initial chromium concentration of 40 mg/L. Additionally, kinetics and isotherm studies revealed that the pseudo-second-order model with R² of 0.98 and the Sips model with R² of 0.99 were found to fit the adsorption data better, suggesting homogenous surface and chemisorption. Overall, this research suggests that Spathodea campanulata could be a promising natural source for the development of adsorbents with potential applications in remediating chromium-saturated wastewater at an industrial scale. Full article

Lithium-ion batteries that use lithium iron phosphate (LiFePO₄) as the cathode material and carbon (graphite or MCMB) as the anode have gained significant attention due to their cost-effectiveness, low environmental impact, and strong safety profile. These advantages make them suitable for a wide range of applications including electric vehicles, stationary energy storage, and backup power systems. However, their adoption is hindered by a critical challenge: capacity degradation at elevated temperatures. This review systematically summarizes the corresponding modification strategies including surface modification of the anode and cathode as well as modification of the electrolyte, separator, binder, and collector. We further discuss the control of the charge state, early warning prevention, control of thermal runaway, and the rational application of ML and DFT to enhance the LFP/C high temperature cycling stability. Finally, in light of the current research challenges, promising research directions are presented, aiming at enhancing their performance and stability in such harsh thermal environments. Full article

This study addresses the environmental challenge of surfactant removal from wastewater, focusing on the increased surfactant use during the COVID-19 pandemic. Polymeric waste, specifically polyurethane (PU) and polyamide (PA), was repurposed for surfactant adsorption to mitigate these environmental impacts. Methods included preparing surfactant solutions of sodium linear alkylbenzene sulfonate (LAS) and dodecyl pyridinium chloride (DPC) and the mechanical processing of polymeric residues. PU and PA were characterized by FTIR-ATR and by the pH at the point of zero charge, which yielded pH = 8.0 for both polymers. The adsorption efficiency was optimized using a central composite face-centered design, varying pH, temperature, and time. The results indicated that PU and PA effectively adsorbed anionic and cationic surfactants, with specific conditions enhancing performance. From the optimized experimental conditions, four assays were carried out to evaluate the adsorption isotherms and kinetics. Among the fitted models, the SIPS model was the most representative, indicating a heterogeneous surface. Regarding LAS, the maximum adsorption capacity values were ~90 and 15 mg g⁻¹, respectively, for PU and PA. Considering the DPC surfactant, lower values were obtained (~36 mg g⁻¹ for PU and 16 mg g⁻¹ for PA). The results are satisfactory because the adsorbents used in this study were second-generation waste and were used without treatment or complex modifications. The study concluded that using polymeric waste for surfactant removal offers a sustainable solution, transforming waste management while addressing environmental contamination. This approach provides a method for reducing surfactant levels in wastewater and adds value to otherwise discarded materials, promoting a circular economy and sustainable waste reuse. Full article

Heavy metal pollution in water resources, particularly cadmium and lead, poses a significant environmental and public health challenge, requiring the development of sustainable, efficient, and cost-effective water treatment methods. Therefore, this study investigates the biosorption capabilities of natural (SN) and surfactant-modified (SM) guava seed biosorbents to remove Cd and Pb from aqueous solutions. Guava seeds, an agricultural waste material, were treated with hexadecyltrimethylammonium bromide (HDTMA-Br) to enhance their adsorption efficiency. The biosorbents were characterized by FTIR, SEM-EDS, and zeta potential analysis to explain the surface modifications and their influence on the adsorption mechanisms. Batch experiments were performed to evaluate the effects of pH, contact time, temperature, biosorbent dosage, and concentration on Cd and Pb removal efficiencies. Adsorption isotherm and kinetic data were analyzed using mathematical models to obtain the basic parameters of the systems under study. The results showed that SM exhibited superior adsorption capacities of 328 mg/g for Cd and 594 mg/g for Pb at 25 °C, significantly outperforming SN. The study analyzed the thermodynamic parameters of adsorption systems, revealing endothermic and exothermic properties for SN and SM. Functional groups like hydroxyl and carbonyl were crucial for metal ion binding. HDTMA-Br introduced active sites and enhanced surface charge interactions. Regeneration tests showed reusability, maintaining over 85% efficiency after four cycles. Guava seeds could be cost-effective and sustainable biosorbents for heavy metal removal. Full article

The incorporation of Ag nanoparticles onto BiVO₄ (a known H₂O oxidising photocatalyst) through magnetron sputtering to form a composite was studied. ICP-OES results showed that the loading of Ag on BiVO₄ was below 1% in all cases. UV-Vis DRS and CO₂-TPD analyses demonstrated that upon incorporation of Ag onto BiVO₄, an increase in the extent of visible light absorption and CO₂ adsorption was seen. TEM imaging showed the presence of Ag particles on the surface of larger BiVO₄ particles, while XRD analysis provided evidence for some doping of Ag into BiVO₄ lattices. The effect of the composite formation on the activity of the materials in the artificial photosynthesis reaction was significant. BiVO₄ alone produces negligible amounts of gaseous products. However, the Ag-sputtered composites produce both CO and CH₄, with a higher loading of Ag leading to higher levels of product formation. This reactivity is ascribed to the generation of a heterojunction in the composite material. It is suggested that the generation of holes in BiVO₄ following photon absorption is used to provide protons (from H₂O oxidation), and the decay of an SPR response on the Ag NPs provides hot electrons, which together with the protons reduce CO₂ to produce CH₄, CO, and adsorbed hydrocarbonaceous species. Full article

The perovskite oxides CaMnO_3-δ, Ca_0.5Sr_0.5MnO_3-δ, and SrMnO_3-δ were synthesized in air using a solid-state method, and their structural, electrical, and electrocatalytic properties were studied in relation to their oxygen evolution reaction (OER) performance. Iodometric titration showed δ values of 0.05, 0.05, and 0.0, respectively, indicating that Mn is predominantly in the 4+ oxidation state across all materials, consistent with prior reports. Detailed characterization was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), iodometric titration, and variable-temperature conductivity measurements. Four-point probe DC measurements revealed that CaMnO_3-δ (δ = 0.05) has a semiconductive behavior over a temperature range from 25 °C to 300 °C, with its highest conductivity attributed to polaron activity. Cyclic voltammetry (CV) in 0.1 M KOH was employed to assess OER catalytic performance, which correlated with room-temperature conductivity. CaMnO_3-δ exhibited superior catalytic activity, followed by Ca_0.5Sr_0.5MnO_3-δ and SrMnO_3-δ, demonstrating that increased conductivity enhances OER performance. The conductivity trend, CaMnO_3-δ > Ca_0.5Sr_0.5MnO_3-δ > SrMnO_3-δ, aligns with OER activity, underscoring a direct link between electronic transport properties and catalytic efficiency within this series. Full article

This review explores both the positive and negative impacts of chemistry on society, focusing on the intersection between pharmaceutical, natural, and synthetic chemicals. On the one hand, drugs developed through medicinal chemistry have saved lives, improved people’s quality of life, and increased longevity. However, they also pose risks, including fatalities and environmental damage. Pharmaceutical chemistry has revolutionized medical practice by enabling the treatment and cure of fatal or debilitating diseases, significantly contributing to the rise in global life expectancy through the research and development of new bioactive substances. This article also highlights the harmful effects of toxic synthetic substances, which negatively impact human health and the environment, affecting plants, animals, air, water, soil, and food. Full article

The titanium dioxide (TiO₂) photocatalyst is an important semiconducting material that exhibits environmental purification functions when exposed to light. Elemental doping of TiO₂ is considered an important strategy to improve its photocatalytic activity. Herein, we have achieved the low-temperature, atmospheric-pressure synthesis of anatase TiO₂ particles with doping of 3d metals (Fe, Co, Ni and Cu) based on the liquid phase deposition technique. All products prepared by adding 3d metals were found to consist of TiO₂ crystals in the anatase phase with a fine protruding structure of about 40 nm on the surface, as was the case without the addition of metal ions. Iron and copper were observed to be incorporated at higher concentrations than cobalt and nickel, with an elemental addition of up to 4 at% and 1 at%, respectively, when 10 mM iron and copper nitrate were applied. Such doping efficiency could be explained by the difference in ionic radius and chemical stability. A narrowing of the optical band gap with doping elements was also observed, and it was found that optical sensitivity could be imparted down to the visible-light region of 2.4 eV (Fe: 4 at% addition). Furthermore, the 3d metal-doped TiO₂ demonstrated in this study was shown to exhibit photocatalytic methane degradation activity. The amount of methane degradation per unit area of the microparticles was twice as great when iron and copper were added, compared to the undoped counterpart. It has been demonstrated that the strategy of doping TiO₂ with 3d metal ions by low-temperature synthesis methods is effective in enhancing carrier dynamics and introducing surface active sites, thus increasing methane degradation activity. Full article