Removal of Volatile Toluene Using K2CO3-Activated Carbon Adsorbents Prepared from Buckwheat Hull

Carbon adsorbents for use in the removal of gaseous toluene from the air were prepared from buckwheat (Fagopyrum esculentum Moench) hull. A chemically-activated adsorbent was prepared via the impregnation of raw hull powder with potassium carbonate, followed by thermal decomposition. The chemically-activated adsorbent exhibited improved adsorption capacity for toluene compared to the adsorbent prepared without chemical activation. Toluene concentration in the air decreased from 220 ppm to 160 ppm during 24 h of adsorption using unactivated adsorbent. Only a trace amount of toluene remained after the adsorption under the same conditions using K2CO3-activated adsorbent. This improvement was explained based on experimental results, specifically, iodine adsorption tests, methylene blue adsorption tests, and microscopic observations. Chemical activation dramatically increased the specific surface area of the adsorbent and created mesopores capable of adsorbing toluene. This study revealed that a mesoporous adsorbent for use in volatile toluene removal can be prepared from waste biomass (buckwheat hull) by chemical activation using potassium carbonate.

Polystyrene-Fe3O4-MWCNTs Nanocomposites for Toluene Removal from Water

In this research, multi-walled carbon nanotubes (MWCNTs) were functionalized by oxidation with strong acids HNO3, H2SO4, and H2O2. Then, magnetite/MWCNTs nanocomposites were prepared and polystyrene was added to prepare polystyrene/MWCNTs/magnetite (PS:MWCNTs:Fe) nanocomposites. The magnetic property of the prepared nano-adsorbent PS:MWCNTs:Fe was successfully checked. For characterization, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and BET surface area were used to determine the structure, morphology, chemical nature, functional groups, and surface area with pore volume of the prepared nano-adsorbents. The adsorption procedures were carried out for fresh MWCNTs, oxidized MWCNTs, MWCNTs-Fe, and PS:MWCNTs:Fe nanocomposites in batch experiments. Toluene standard was used to develop the calibration curve. The results of toluene adsorption experiments exhibited that the PS:MWCNTs:Fe nonabsorbent achieved the highest removal efficiency and adsorption capacity of toluene removal. The optimum parameters for toluene removal from water were found to be 60 min, 2 mg nano-sorbent dose, pH of 5, solution temperature of 35 °C at 50 mL volume, toluene concentration of 50 mg/L, and shaking speed of 240 rpm. The adsorption kinetic study of toluene followed the pseudo-second-order kinetics, with the best correlation (R2) value of 0.998, while the equilibrium adsorption study showed that the Langmuir isotherm was obeyed, which suggested that the adsorption is a monolayer and homogenous.

The Seasonality Impact of the BTEX Pollution on the Atmosphere of Arad City, Romania

Benzene, toluene, and total BTEX (benzene, toluene, ethylbenzene, and xylene) concentrations registered for one year (2016) have been determined every month for one high-density traffic area. The assessment was performed in Arad City, Romania, to evaluate these pollutants and their influence on the inhabitants’ health. The contaminants were sampled using a static sampling method and analyzed by gas chromatography coupled with mass spectrometry. Benzene was the most dominant among the BTEX compounds—the average concentrations ranged from 18.00 ± 1.32 µg m−3 in December to 2.47 ± 0.74 µg m−3 in August. The average toluene concentration over the year was 4.36 ± 2.42 µg m−3 (with a maximum of 9.60 ± 2.39 µg m−3 in November and a minimum of 1.04 ± 0.29 µg m−3 in May). The toluene/benzene ratio (T/B) was around 0.5, indicating substantial contributions from mobile sources (vehicles). The emission and accumulation of different aromatic compounds (especially benzene) could deteriorate the urban air quality. The lifetime cancer risk (LTCR) for benzene was found to be more than 10−5 in winter, including the inhabitants in the “probable cancer risk” category.

TOLUENE DEGRADATION BY FREE STAPHYLOCOCCUS GALLINARUM AND IMMOBILIZED ON MULTI-WALLED CARBON NANOTUBES

Hydrocarbons pollution is a most important environmental and healthanxiety . Using free and immobilized bacteria could be a suitable attitude to find a proper bioaugmentation agent. A toluene degrading bacterium was isolated from oil-contaminated environs (located in Bandar-Anzali, Guilan, Iran). The strain was molecularly identified as Staphylococcus gallinarum ATHH41 (Accession number: KX344723) by partial sequencing of 16SrDNA gene. The response surface methodology (RSM) was expended for biodegradation of the toluene by ATHH41. The central composite design (CCD) was utilized to optimize pH, temperature, and toluene concentration by ATHH41. In accordance with the optimization purpose of the Design-Expert software, the optimum circumstances of toluene degradation were obtained when pH, temperature and toluene concentration were adjusted to 7.68, 31.73°C and 630.04 mg.l-1, respectively. Multi-walled carbon nanotubes (MWCNTs) were used to immobilize the strain. Infrared spectroscopy and scanning electron microscopy showed that the cells adhered to the MWCNT surface and developed a biofilm. Results reveal that free cells were able to degrade 68.01% of the toluene as the sole carbon and energy source within 24 h under optimized conditions. The immobilized cells reached 95.68%.

Modeling of Poly(methylmethacrylate) Viscous Thin Films by Spin-Coating

A predictive film thickness model based on an accepted equation of state is applied to the spin-coating of sub-micron poly(methylmethacrylate) viscous thin films from toluene. Concentration effects on density and dynamic viscosity of the spin-coating solution are closely examined. The film thickness model is calibrated with a system-specific film drying rate and was observed to scale with the square root of spin speed. Process mapping is used to generate a three-dimensional design space for the control of film thickness.

Electrokinetic-enhanced removal of toluene from physically heterogeneous granular porous media

Electrokinetics (EK) was applied to enhance biodegradation of toluene in the low hydraulic conductivity (K) zone of a physically heterogeneous water-saturated granular porous media. The hypothesis tested was that EK transport processes, which operate independently of advection, can deliver a limiting amendment, nitrate, across a high-K–low-K boundary to stimulate bioremediation. Two types of experiment were evaluated: (1) bench-scale tests that represented the active EK system and physically heterogeneous sediment configuration; (2) microcosms that represented biodegradation in the bench-scale tests under ideal conditions. The bench-scale experiment results showed a rapid decrease in toluene concentration during the application of EK that was attributed to electroosmotic removal from low-K zones. Comparison of toluene removal rates by electroosmosis and biodegradation (microcosm) confirmed that electroosmosis was the most effective mechanism under the conditions evaluated. Overall, this work challenges the original hypothesis and indicates that, at the field scale, the most favourable conditions for biodegradation are likely to be achieved by applying EK to increase contaminant flux across the low-K–high-K boundary (out of the low-K zone) and allowing biodegradation to occur in the high-K zone either by natural attenuation or enhanced by amendment addition.Supplementary material: Supplementary material is available at https://doi.org/10.6084/m9.figshare.c.5174554

Moderate Temperature Treatment of Gas-Phase Volatile Organic Toluene Using NiO and NiO–TiO2 Nano-catalysts: Characterization and Kinetic Behaviors

For the first time, the potential of Ni/NiO and NiO–TiO2 nano-catalysts for the oxidation of toluene under moderate temperatures was investigated. The nano-catalysts were prepared using the solution combustion synthesis method (SCSM) and the effect of the composition of nano-catalysts, the inlet toluene concentration $$([\text{C}_{7} {\text{H}}_{8}]_{in})$$ ( [ C 7 H 8 ] in ) , the relative humidity (RH), and the temperature on the percentage of toluene conversion ($$\% {\text{TN}}_{Conv.} )$$ % TN C o n v . ) were subsequently examined. Results revealed that the nano-catalysts synthesized with a low fuel-to-metal ratio produced pure NiO, which has significant catalytic activity toward the conversion of toluene. Conversely, the high fuel-to-metal ratio generated a nano-catalysts that contains a mixture of Ni/NiO or pure Ni with low activity toward the conversion of toluene. Adding NiO to TiO2 increased the surface area of the catalyst, augmented the catalyst active sites, enhanced the oxidation of toluene, and increased CO2 selectivity ($${\text{S}}_{{{\text{CO}}_{2} }}$$ S CO 2 ). NiO and NiO–TiO2 nano-catalysts exhibited higher reaction rates, significant catalyst turnover frequency, and low activation energy. The obtained results revealed that the SCSM is a promising synthesis method for producing NiO or NiO–TiO2 nano-catalysts, which can be employed successfully for the removal of toluene from gas streams. Graphic Abstract

Determination of Carcinogenic Toluena Detox Mass In Printing Industrial Workers In Surabaya

Background This study aims to calculate the intake of foods rich in CYP2E1 enzymes and glutathione to increase toluene detoxification. Methods The research design used was a cross sectional method. The research location is printing industry in Surabaya, East Java. The number of respondents was 30 workers of the printing industry. The calculated variables included body weight, work duration (years), work frequency per week (days), average workday (hours) of the respondent and benzene concentration. After all variables were obtained, respiration rate and carcinogenic detox benzene food intake per respondent were determined. Results All respondents who were at work showed benzene concentrations below the threshold value (TLV). Foods containing CYP2E1 enzyme included beef liver, salmon and fish oil while food with glutathione included grapes, avocados and asparagus. Conclusion Adequacy levels of CYP2E1 enzymes and glutathione are different and varied. The effective dose required by each respondent depends on body weight, length of work, and toluene concentration at work. In sum, the greater the toluene concentration, the greater the dietary needs which are rich in enzymes and CYP2E1 glutathione. Each respondent can choose benzene detox food depending on their needs and appetite.