Ziaeddin Bonyadi

Polystyrene microplastics (PS MPs) are widely distributed in aquatic environments and pose ecological and potential human-health risks. This study investigated the coagulation-assisted removal of PS MPs using MWCNTs@NH₂ in combination with okra extract as a natural coagulant aid. A Box-Behnken design was used to evaluate the effects of MWCNTs@NH₂ dose (0.2-1 g/L), initial PS concentration (50-400 mg/L), and pH (4-10), while maintaining the okra extract concentration at 0.5% (w/v). The maximum removal efficiency of 80.5% was achieved at 0.6 g/L MWCNTs@NH₂, 400 mg/L PS, and pH 10. The removal mechanism involved partial charge neutralization, interparticle bridging by okra polysaccharides, hydrophobic interaction between PS and the graphitic CNT backbone, and floc enmeshment. The combined use of MWCNTs@NH₂ and okra extract reduced the required nanomaterial dose and improved floc formation. The proposed hybrid coagulation system offers a natural-coagulant-assisted strategy for PS MP removal, although further validation in real water matrices and assessment of residual nanotube release are required.

Plastic pollution has emerged as a critical global concern, with microplastics increasingly detected across various ecosystems, including the atmosphere. Among indoor sources, hospital laundry units have been identified as significant contributors to airborne microplastic emissions. This study investigates the concentration of inhalable microplastics (MPs (in the air of a hospital laundry environment. In this study, air sampling was conducted at three different time points using a personal air sampler operating at a flow rate of 0.5 L/min for 40 min per sample. Microplastics were characterized using FTIR, SEM, and EDX to ensure accurate identification. FTIR analysis identified the predominant polymer as polyamide (nylon), with characteristic peaks consistent with CH₂, C = O, and N-H groups. EDX analysis indicated an elemental composition of C (59%), N (32%), O (7%), and P (0.07%). SEM images revealed pronounced diurnal and day-to-day variability, with particle concentrations ranging from 43575 to 66975 particles/m³, though statistical analysis showed these variations were not significantly influenced by environmental factors such as humidity and air velocity in this short-term study. Notably, black particles dominated the samples, representing 97% of the MPs. These results underscore the potential for direct inhalation exposure in occupational settings, raising concerns about respiratory health risks for laundry staff and patients. Therefore, further research is needed to inform the development of stricter ventilation standards, occupational safety measures, and regulatory policies to mitigate microplastic emissions in healthcare environments.

Microplastics (MPs), particularly polyvinyl chloride (PVC), have become a growing environmental concern due to their persistence in aquatic ecosystems and their capacity to interact with co-occurring pollutants. In this study, the effects of ozonation on the physical and chemical properties of PVC MPs, as well as their capacity to adsorb crystal violet (CV) dye, were systematically investigated. Aging was simulated by exposing PVC MPs to ozone in an aqueous medium at a concentration of 1.4 mg/L for 1 h. The results demonstrate that ozonation induced substantial surface and chemical modifications, including a reduction in chlorine-containing groups and a concurrent increase in oxygenated functional groups such as carbonyl and carboxyl moieties. Mild structural degradation and a decrease in particle size were also observed, along with a marked shift in surface charge, as reflected by a decrease in zeta potential from − 12.3 mV to − 26.7 mV. These transformations significantly altered the adsorption behavior of PVC, leading to an increase in CV removal efficiency from 52.62% (pristine PVC) to 76.55% (aged PVC). The adsorption process followed pseudo-first-order kinetics and was best described by the Langmuir isotherm model, with a maximum adsorption capacity (qₘₐₓ) of 5.55 mg/g. The findings indicate that ozonation, although commonly applied in water and wastewater treatment, may inadvertently enhance the pollutant-binding potential of PVC MPs, thereby intensifying their role as mobile vectors of contaminants in aquatic environments.

Phthalate esters (PAEs), a group of well-known endocrine-disrupting chemicals (EDCs), are extensively used in plastic manufacturing and are recognized for their contribution to environmental pollution and potential adverse health effects. Rivers in urban and recreational areas are increasingly threatened by plastic-derived pollutants, yet there is a lack of data on the occurrence, distribution, and risks of PAEs in such environments in Iran. The Torghabeh River, a popular recreational site near Mashhad, may be particularly vulnerable to phthalate pollution due to tourism, waste discharge, and urban runoff. Therefore, this study aimed to identify and quantify PAEs in the water and sediment of the Torghabeh River and to assess their associated human and ecological risks. Water and sediment samples were collected from various locations along the river. After extraction using solid-phase extraction (SPE) for water samples and ultrasonic extraction for sediment samples, PAEs were identified using gas chromatography-mass spectrometry (GC-MS). The results showed that the mean concentration of Σ6PAEs in water was 11,030.8 ng/L, ranging from non-detectable (ND) to 17,477.07 ng/L. In surface sediments, the mean concentration of Σ7PAEs was 9,714.98 ng/g (range: ND–29,226.06 ng/g), while deeper sediments had a mean concentration of 7858.46 ng/g (range ND–15,084.94 ng/g). Di (2-ethylhexyl) phthalate (DEHP) was the predominant compound detected in both water and sediment samples. PAE concentrations were generally higher in sediments than in water. The hazard quotient (HQ) and hazard index (HI) values for human exposure were below established threshold levels; however, DEHP posed a higher dermal exposure risk for children. Ecological risk assessment revealed that Diisobutyl phthalate (DiBP) had a risk quotient (RQ) greater than 1 for fish in both water and sediment, while DEHP exceeded an RQ of 1 for all aquatic species in water. In conclusion, phthalate esters were present at notable concentrations in both water and sediment of the Torghabeh River, with higher accumulation observed in sediments. Although human health risks were generally low, certain compounds—particularly DEHP and DiBP—posed significant ecological risks and increased dermal exposure concerns for children.

This study investigates the spatial distribution and severity of cigarette butt (CB) pollution in Mashhad, Iran, using the cigarette butt pollution index (CBPI). Sampling was conducted in 25 selected areas, and CB density was calculated for each location. The average CB density across the city was 0.79 CBs/m², with a mean CBPI of 8.89, indicating considerable levels of pollution. The highest recorded CBPI was 28, observed in areas characterized by high population density, commercial land use, and poor ground surface conditions. In contrast, the lowest CBPI was 1.85. Severe pollution (CBPI > 10) was detected in 33.33% of the studied areas. The results revealed that factors such as population density, land use patterns, ground surface quality, annual rainfall, and groundwater proximity significantly influenced CB distribution. A comparison of Mashhad’s CBPI with those of other cities worldwide indicated that while its pollution level is higher than in some Iranian regions, it remains lower than in cities like Santos, Brazil. These findings highlight the urgent need to implement effective management strategies to reduce cigarette butt pollution.

Microplastics (MPs) are increasingly recognized as pervasive pollutants in food and beverage products, posing potential risks to human health and ecosystems. The purpose of this research is to investigate the presence and concentration of MPs in various beverages and ice packs through quantitative analysis, and to evaluate the potential health risks associated with human exposure to these contaminants. Samples underwent filtration and organic matter digestion with hydrogen peroxide, followed by analysis using stereomicroscopy, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). The results indicated mean microplastic (MP) concentrations of 183.1 particles/L in beverages and 178.9 particles/L in ice packs, predominantly composed of polypropylene (PP) (80%) and poly (ethylene terephthalate) (PET) (20%). Morphologically, fragments comprised 54% of MPs in beverages and 53% in ice packs, while fibers accounted for 46% and 47%, respectively, with particle sizes ranging from 4.54 to 1,490 μm. Transparent MPs dominated (90%), likely due to prevalent packaging materials. The estimated daily intake (EDI) was higher in adults (5.49 particles/kg/day) than in children (2.19 particles/kg/day), with ingestion being the primary route of exposure. Microplastic contamination in beverage samples was assessed using the microplastic contamination factor (MPCF) and the microplastic pollution load index (MPLI). Brand C showed the highest contamination (MPCF: 9.34), while the average MPLI (8.26) indicated ecological risk level 1. This study confirms the widespread presence of microplastics in carbonated soft drinks and ice packs. Consequently, further research is essential to evaluate the long-term health effects and to develop strategies for reducing plastic usage in food packaging.