This paper analyzes the mathematical modeling procedure to describe the decomposition of adsorbed phenanthrene in prototypical and real soil samples (sand and agricultural soil, respectively) by ozone. The modeling scheme considered a set of ordinary differential equations with time varying coefficients. This model used the adsorbed ozone in the soil, the ozone reacting with the contaminant and the phenanthrene concentration in the soil sample. The main parameters involved in the mathematical model included a time varying ozone saturation function (k ₛₐₜ (t)) and reaction constants (k ᵣ). These parameters were calculated using the ozone concentration variation at the reactor output, named as ozonogram, and the measurements of phenanthrene decomposition through ozonation. The model was validated using two series of experiments: (1) soil saturated with ozone in the absence of the contaminant and (2) soil artificially contaminated with phenanthrene. In both cases, the proposed parametric identification method yields to validate the mathematical model. This fact was confirmed by the correspondence between numerical simulations and experimental data. In particular, total decomposition of phenanthrene adsorbed in two different systems (ozone-sand and ozone-agricultural soil) was obtained after 15 and 30 min of reaction, respectively. This difference was obtained as a consequence of soil physicochemical characteristics: specific surface area and pore volume. The ozonation reaction rate constants of phenanthrene in the sand and agricultural soil were calculated using the same parameter identification scheme.

Metal nanoparticles such as Ni, Cu, and Co were prepared within polyethyleneimine (PEI) microgels and were used in the reduction of 4-nitrophenol (4-NP) and 2-nitrophenol (2-NP) to 4-aminophenol (4-AP) and 2-aminophenol (2-AP). The metal nanoparticle content of the prepared PEI-M composite catalyst system (M = Co, Ni, and Cu) was increased by multiple loading and reduction cycles into PEI microgels to provide faster and better reduction of 4-NP and 2-NP. The TOF value increased to 1.48 from 0.353 (mol 4-NP (mol catalyst min)⁻¹) for 4-NP reduction catalyzed by PEI-Ni after three cycles of metal loading and reduction. The effect of temperature on 4-NP and 2-NP reductions catalyzed by PEI-M illustrated that higher temperature resulted in very fast reductions, e.g., at 70 °C 4-NP and 2-NP reduction by PEI-Ni resulted in very fast reduction times of 1.2 and 0.67 min to 4-AP and 2-AP, respectively. The activation parameters, such as energy, entropy, and enthalpy, were also calculated and mild activation energies of 38.8 and 46.0 kJ mol⁻¹for 4-NP and 2-NP catalyzed by PEI-Ni were found, respectively, in comparison to similar studies in the literature. Moreover, it was demonstrated that PEI-Ni microgels are reusable five times consecutively, with almost 100 % conversion and 100 % of their catalytic activity.

Microbial Cr(VI) reduction is a significant process in detoxification of Cr(VI) pollution. In this study, a new Cr(VI)-reducing bacterial strain, Cr-4, was isolated from soil around the chromium-containing slag. The analysis of the 16S ribosomal RNA (rRNA) gene sequence revealed that the newly isolated strain was closely related to Bacillus anthracis. The response to Cr(VI) stress and reduction capacity of the isolate were investigated. Cell growth decreased with the increase of Cr(VI) concentration. Cell morphology varied and cell growth was inhibited remarkably in the presence of 125 mg/L Cr(VI). The strain grew well and removed Cr(VI) effectively at a Cr(VI) concentration lower than 50 mg/L. Cr(VI)-reducing activity was inhibited by Zn²⁺, while significantly stimulated by Cu²⁺. The activity of Cr(VI) reduction by cell-free extract was demonstrated. Total chromium analysis and the energy-dispersive X-ray analysis (EDAX) spectrum revealed that Cr(VI) removal was caused mainly by microbial reduction rather than by biosorption and the main part of the reduced Cr(III) existed as soluble form in solutions.

Surfactant can reduce the interfacial tension in liquid–gas system and may probably improve the rate and/or extent of dissolution. This study was conducted to evaluate the effect of three different surfactants (viz., sodium dodecyl sulfate (SDS), Triton X-100, and cetyltrimethylammonium chloride (CTAC)) on CO₂biomineralization by two ureolytic microorganism—Sporosarcina pasteurii and Bacillus megaterium. In S. pasteurii-mediated biomineralization, headspace CO₂content (2.5 mM) was decreased by 40, 52, and 68 % in the presence of SDS, Triton X-100 or CTAC, respectively within the first 8 h of incubation. CO₂removal with B. megaterium in the presence of Triton X-100 (64 %) and CTAC (56 %) was better in comparison to control without surfactant (48 %). However, appreciable CO₂depletion was not observed with SDS, which was just 4 %. On other hand, headspace CO₂loss in the presence of CTAC with B. megaterium did not get biomineralized, as no calcium carbonate was detected. Crystalline phase and morphology of CaCO₃precipitate also varied between ionic and nonionic surfactants. The result suggests that the effect of surfactant on CO₂capture and biomineralization can be largely different, depending on the surfactant and concerned microbial species involved.

The scarcity of clean water affecting many parts of the world encourages efforts to improve water reclamation processes, which rely on their capability to remove diverse types of water pollutants and contaminants. Thus, this study reports the application of bamboo fiber powders as potential low-cost sorbent for removal of noxious organic compounds in aqueous solution. Bisphenol A, a biorefractory endocrine disruptor compound, was chosen as model compound in order to easily follow the separation process. Principal component analysis of the FTIR spectra and BET surface area measurements were performed on treated bamboo fiber powders. Treatment of the raw powders with alkali, ionic and non-ionic surfactants appeared to improve the bisphenol A removal performance of the bamboo fiber powders with the best removal efficiency reached at 39 % for a sorbent dosage of 4 g L⁻¹ gained after a bamboo treatment using the cationic surfactant. Effects of contact time, sorbent dosage, and particle sizes (55, 300, and 1000 μm) of cationic surfactant-treated bamboo fiber powders towards removal of bisphenol A were further assessed in a batch system with an optimum removal observed for 55 μm in particle size.

Many products contain dyes, such as fabrics. However, most of the industry-generated waste is improperly handled, which causes serious environmental problems for the bodies of water that receive textile effluents. This study aimed to analyze the effect of biosorbents and biosorption techniques on decolorizing the textile azo dye Acid Blue 29 in an aqueous solution employing pine sawdust. Pine sawdust is low-cost substrate with minor environmental impact. A toxicity test was performed with Lactuca sativa seeds to determine the LC₅₀ of the dye. Subsequently, a biosorption test was performed to determine the toxicity of the resulting solutions. We observed that biosorption is a very feasible technique for the discoloration of the solutions and promotes reduction in their toxicity.

The expected growth of the coal seam gas industry in Australia requires baseline information for determining any potential long-term impacts of the industry. As such, a 1-year atmospheric time series measuring radon (²²²Rn), methane (CH₄), carbon dioxide (CO₂), δ¹³C-CO₂ and δ¹³C-CH₄ was conducted in an area where coal seam gas (CSG; also referred to as coal bed methane) extraction is proposed (Casino, New South Wales, Australia). We hypothesise that ²²²Rn can be used as a tracer of soil-atmosphere CH₄ and CO₂ exchange, and that carbon stable isotope values of atmospheric CH₄ and CO₂ can be used to identify the source of greenhouse gases. Radon, CO₂ and CH₄ followed a diurnal pattern related to increased concentrations during the formation of a nighttime inversion layer. The study found a significant inverse linear relationship between ²²²Rn concentrations and both rainfall (r ² = 0.43, p < 0.01) and temperature (r ² = 0.13, p < 0.01), while atmospheric pressure, wind speed and wind direction affected concentrations to a lesser degree over seasonal time scales. ²²²Rn had a significant, but weak positive correlation with both seasonal CO₂ (r ² = 0.15, p < 0.01) and CH₄ (r ² = 0.11, p < 0.01) concentrations. The uncoupling between ²²²Rn and CO₂ and CH₄ was likely due to biogenic sources and sinks of CO₂ and CH₄. δ¹³C values of CO₂ and CH₄ indicated variability in the source and sinks of the gases that seems to be linked to different seasonal, soil and spatial sources. This study provides baseline data from a proposed coal seam gas field from which future comparisons can be made.

The purpose of this review is to describe how plants take up lead and its distribution to plant parts, morphological, physiological, and biological effects of lead on plants, sequestration strategies, and tolerance mechanisms including detoxification. How lead despite its lack of essential function in plants, causes phytotoxicity by changing cell membrane permeability, by reacting with active groups of different enzymes involved in plant metabolism by reacting with the phosphate groups of adenosine diphosphate (ADP) or adenosine-5′-triphosphate (ATP). Moreover, we also address role of hyperaccumulating plants in lead absorption. How synthetic chelators such as ethylenediaminetetraacetic acid (EDTA) enhances the availability of heavy metal lead in soils and increase phytoextraction efficiency in aboveground harvestable plant parts through enhancing the metal solubility and translocation from roots to shoots, metal tolerance, and future prospectives to decrease lead pollution.

Upland swamps of the Blue Mountains are unique and legislatively protected peat swamp communities. This study investigated water chemistry of surface waters from seven Blue Mountains Upland Swamps (BMUS), four within urbanised catchments and three from naturally vegetated catchments. The purpose of the study was to investigate any ionic contamination from urban development. Water chemistry of non-urban BMUS was acidic (mean pH 4.7) and dilute (mean EC 26.6 μS/cm) and dominated by sodium and chloride ions with most other major ions at low concentrations, often below detection limits. In contrast, urban BMUS had higher pH (mean 6.6) and salinity (mean 153.9 μS/cm) and were dominated by calcium and bicarbonate ions. The results of this study support the hypothesis that urban concrete contamination is modifying the geochemistry of urban BMUS. Further research is required to investigate ecological implications of the contamination and also to explore measures to protect such sensitive wetlands of high conservation value from urban development.

Several laccases from different sources have been used in dye decolourization processes. However, only in a reduced number of studies have efforts been done to identify the metabolites produced by the enzymatic treatment as well as to evaluate the toxicity of degradation products. Taking these gaps into account, the objective of this work was to use a laccase from Ganoderma lucidum in the decolourization of the synthetic dye Congo red (C.I. No. 22120, Direct Red 28), largely used in the textile industry. After 6 h of treatment at pH 4.0 and 40 °C, the enzyme was able to decolourize 80 % of Congo red. Fourier transform infrared spectroscopy (FTIR), photoacoustic spectroscopy (PAS) and mass spectrometry allow concluding that laccase effectively changed the structure of Congo red, reducing the colour by modifying the chromophore groups and other parts of the molecule. Several degradation products with m/z ⁺ ranging from 298 to 745 were identified. It is proposed that the first degradation step could be an asymmetric cleavage of the azo bond present in the Congo red structure forming the intermediate with m/z ⁺ 298. The results also suggest a reduction in the toxicity of Congo red after laccase treatment, as indicated by the lettuce seed germination model. In conclusion, G. lucidum laccase could be used in a novel azo dye bioremediation strategy.