Metallurgical and Materials Data

Evaluating the Role of Hydrochars as Sustainable Adsorbents for Pollutant Removal

2025-06-12T10:37:49+00:00

Hydrothermal carbonization (HTC) produces biomass-derived hydrochar, a promising adsorbent for environmental remediation. Lignocellulosic biomass serves as the primary feedstock, and adsorption performance depends on biomass structure and HTC conditions, especially carbonization temperature. This review highlights hydrochar’s adsorption capabilities and modification strategies, including physical treatments to increase surface area and chemical treatments to introduce oxygen-containing functional groups. Heteroatom doping and acid-base modifications notably enhance the removal of metal ions and dyes. Hydrothermal treatment is key to producing tailored hydrochars for specific applications. Future research should focus on combining physico-chemical modifications, deepening understanding of adsorption mechanisms, and broadening hydrochar applications. These efforts will advance the use of biomass hydrochars as effective, sustainable adsorbents for pollution control while addressing waste management.

Removal of Organic Pollutants – Mycotoxin Ochratoxin A and Pharmaceutical Ketoprofen by Cationic Surfactant Modified Kaolinite

2025-07-17T07:44:59+00:00

The potential of kaolin modified with a cationic surfactant - hexadecyltrimethylammonium (HDTMA) bromide as an adsorbent for the removal of two different contaminants: mycotoxin - ochratoxin A (OCHRA) and the pharmaceutical - ketoprofen (KET) from buffer solutions (pH 7) was investigated. The amount of HDTMA used for modifcation was equal to 50% of kaolin's cation exchange capacity (CEC). The obtained material (HKR-50) was characterized using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry/thermogravimetric analysis (DSC/TG), and scanning electron microscopy (SEM), confirming successful surface modification of kaolinite with HDTMA. Adsorption experiments demonstrated that HKR-50 exhibited significantly enhanced removal efficiency for both OCHRA and KET compared to unmodified kaolin. Nonlinear adsorption isotherms suggested a complex mechanism involving both hydrophobic and electrostatic interactions between contaminants and HDTMA ions. The data fit well to the Langmuir model, with maximum adsorption capacities of 2.57 mg/g for OCHRA and 1.40 mg/g for KET. These findings indicate that surfactant-modified kaolin is a promising and cost-effective adsorbent for the removal of mycotoxins from animal feed and pharmaceuticals from contaminated water, contributing to environmental protection and public health.

Environmental Impacts of Microplastics in Contaminated Soils: Potential Implications for Cu, Mn, and Sr Phytoremediation

2025-07-01T14:08:59+00:00

Microplastics (MPs) are widespread environmental pollutants and have emerged as a growing global concern. In soil ecosystems, MPs frequently coexist with potentially toxic elements (PTEs), yet their combined effects on soil–plant interactions and phytoremediation processes remain insufficiently explored. This field-based study investigated the occurrence of MPs in urban soils from four Serbian cities and assessed their influence on the uptake of PTEs - copper (Cu), manganese (Mn), and strontium (Sr) - by Capsella bursa-pastoris (L.) Medik. MPs were extracted from soil using an optimized density separation method, while total (aqua regia) and phytoavailable (EDTA-extractable) fractions of PTEs were quantified in both soils and plant tissues. Maximum MPs abundance was recorded in Bor — 500 ± 100 MPs kg^-1.The highest total concentrations of Cu (516.14 µg g⁻¹), Mn (553.46 µg g⁻¹), and Sr (173.69 µg g⁻¹) were detected in soils from Bor. The geoaccumulation index (I_geo) indicated moderate to heavy contamination levels. Cu_EDTA accounted for UP to 50.7% of Cu_AR, Mn_EDTA for 34.4% of Mn_AR, and Sr_EDTA 27.3% of Sr_AR. After the uptake, C. bursa-pastoris primarily translocated the elements to the aerial parts, indicating shoot accumulation as the dominant strategy. Principal component analysis (PCA) revealed distinct clustering of samples by city, while Spearman correlation analysis highlighted significant associations between MPs and PTEs mobility in the soil-plant system. Strongest correlations were found between MPs phytoavailable Cu fraction (ρ =+0.49) and Cu content in shoots (ρ =+0.56). The highest BCF values were determined for Sr, ranging from 2,40 (SM) to 5,41 (BO). PTEs were mainly transferred to the shoots. TF range for Cu was 0.54 (BO) – 1.48 (VR), 0,68 (BO) to 1,42 (VR) for Mn, and 0,76 (BO) to 1,34 (VR) for Sr. Strong correlations among MPs abundance and Cu mobility and accumulation in shoots (ρ = +0.56), and Sr bioaccumulation potential (BCF up to 5.41), highlight the role of MPs in modifying element transfer within urban soil–plant systems and consequent phytoremediation potential.

Real-Sample Analysis of PMT Compounds Using Electrochemical Sensor Technology

2025-07-10T08:31:32+00:00

Persistent, mobile, and toxic (PMT) substances represent a serious threat to water systems due to their environmental persistence, high mobility, and adverse effects on both ecosystems and human health. Common examples of such compounds include bisphenols, benzisothiazolinone (BIT), and benzotriazole (BZT), which are frequently found in household and industrial products, therefore they can be easily found in environmental and also in the human body. Detection and monitoring of these chemicals are crucial for evaluating their environmental impact and informing mitigation measures. While conventional analytical techniques like chromatography provide reliable results, they are not suited for rapid field analysis. In contrast, electrochemical sensors offer a cost-effective, sensitive, and portable solution for on-site detection. This work presents the use of carbon-based screen-printed electrodes (SPEs) for the electrochemical detection of bisphenol S (BPS) in parking tickets and BIT in river water, while modified SPEs with composite material carbon-polymer layers for BZT detection. The results showed the effectiveness of the obtained electrochemical sensors for real-time detection of PMT compounds.

Enhanced Mechanical Strength and Controlled Biodegradability of Bio-Membranes Synthesized from Waste Hemp Fibers

2025-09-12T11:34:50+00:00

In this work, agricultural hemp waste was converted into cationically modified membranes through a two-step procedure. First, the post-harvest hemp fibers underwent delignification, after which they were quaternized using a Deep Eutectic Solvent (DES) composed of chlorocholine chloride and urea. The cationized fibers were then pressed and cross-linked with citric acid (CA), a natural cross-linker, to obtain membrane sheets. The untreated fibers (NtHF) and the resulting membranes were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Mechanical performance was evaluated by measuring the breaking force and determining the tensile strength using the Brazilian test. Biodegradation was monitored for 90 days in a controlled soil-burial environment at 24 °C, comparing membranes made from untreated versus cationized hemp fibers. The modified material exhibited a notable increase in tensile strength (2.41 MPa), attributed to the combined effects of enhanced intermolecular interactions within the cationic hemp matrix and the stronger cross-linking provided by citric acid. Signs of biodegradation appeared after just 14 days, with approximately 25% mass loss. In contrast, the untreated fibers degraded slightly faster, underscoring the stabilizing effect of citric acid.

Radiation Technology in Polymer Waste Recycling and Upcycling: Mechanisms, Applications, and Prospects

2025-09-12T11:14:38+00:00

Polymer waste represents a persistent environmental challenge, as conventional recycling methods often yield low-quality products and remain energy-intensive. Ionizing radiation, applied through gamma rays, electron beams, or X-rays, offers an alternative pathway for reprocessing and upcycling polymers. Radiation induces free radical formation, leading to two competing molecular transformations: chain scission, which lowers molecular weight and improves reprocessability, and cross-linking, which enhances mechanical strength and thermal stability. The outcome depends strongly on absorbed dose, dose rate, and irradiation conditions. Beyond molecular restructuring, irradiation can modify surface charge and polarity, enabling more effective sorting of mixed polymer streams. Reported applications include enhanced durability in rubber and polyethylene, improvements in food packaging films, and the production of wood–plastic composites with higher performance and market value. Comparative analyses indicate that, under optimized conditions, radiation-assisted recycling can match or surpass certain chemical methods in efficiency while delivering upcycled materials with extended service life. Current barriers include facility safety requirements, uniform treatment of heterogeneous waste, and integration into industrial recycling infrastructures. Future progress depends on pilot-scale demonstrations, dose–response optimization for common polymers, and comprehensive life-cycle assessments. These developments position radiation processing as a viable contribution to sustainable polymer waste management and the circular economy.