Major ion chemistry (2000–2009) from 208 lakes (342 sample dates and 600 samples) in class I and II wilderness areas of the Sierra Nevada was used in the Steady-State Water Chemistry (SSWC) model to estimate critical loads for acid deposition and investigate the current vulnerability of high elevation lakes to acid deposition. The majority of the lakes were dilute (mean specific conductance = 8.0 μS cm⁻¹) and characterized by low acid neutralizing capacity (ANC; mean = 56.8 μeq L⁻¹). Two variants of the SSWC model were employed: (1) one model used the F-factor and (2) the alternate model used empirical estimates of atmospheric deposition and mineral weathering rates. A comparison between the results from both model variants resulted in a nearly 1:1 slope and an R²value of 0.98, suggesting that the deposition and mineral weathering rates used were appropriate. Using an ANCₗᵢₘᵢₜof 10 μeq L⁻¹, both models predicted a median critical load value of 149 eq ha⁻¹ year⁻¹of H⁺for granitic catchments. Median exceedances for the empirical approach and F-factor approach were −81 and −77 eq ha⁻¹ year⁻¹, respectively. Based on the F-factor and empirical models, 36 (17 %) and 34 (16 %) lakes exceeded their critical loads for acid deposition. Our analyses suggest that high elevation lakes in the Sierra Nevada have not fully recovered from the effects of acid deposition despite substantial improvement in air quality since the 1970s.

Anthropogenic CO₂ emission is identified as the major cause of climate change. The use of fossil fuels has to be accommodated, possibly with a CO₂ capture process. Sequestration of captured CO₂ at high pressure is proposed as a feasible option for future mitigation of climate change, though using fossil fuels. However, this needs significant energy input and carries the potential threat of a possible future catastrophe. Capture of CO₂ with possible recycling is a long-term sustainable option. In this paper, a process involving a chain of reactions using solid sodium to capture both CO₂ and SO₂ from a flue gas is described. A significantly detailed description of both chemical reactions and physical processes is discussed. Recycling of captured CO₂ and SO₂ in the form of solid graphite and elemental sulphur (as the by-products) is the special feature of this process. However, critical selection of intermediate process liquids and equipment in this process needs further study for real-life implementation of this scheme.

In this study, the magnetic cellulose nanomaterials, containing magnetic nanoscale zerovalent iron (nZVI) and cellulose, were prepared by a novel reduction method and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM). The XRD and XPS results demonstrated the formation of zerovalent iron nanoparticles in the nanocomposite materials. With a saturation magnetization of 57.2 emu g⁻¹, the cellulose@nZVI composites could be easily separated from solutions in 30 s through the external magnetic field. We investigated the adsorption performance of the magnetic cellulose nanomaterials for As(III) removal from aqueous solutions. The experimental results showed that arsenite adsorption followed the pseudo-second-order kinetic model and Langmuir isotherm model. A maximum removal of 99.27 % was observed for an initial concentration 10 mg L⁻¹, at pH 8.0, and an adsorbent dose of 1.0 g L⁻¹. Considering the high adsorption capacity, fast adsorption rate, and quick magnetic separation from treated water, the cellulose@nZVI composites were expected to be an efficient magnetic adsorbent for arsenic removal from aqueous solutions.

Lake Eğirdir is one of the most important freshwater resources in Turkey. The lake is located at the border of Isparta province in South West Turkey, an area known as the “Lakes District”. Lake Eğirdir is very important to the regional economy, but knowledge of its water quality is somewhat limited. Our objective was to assess the current water quality in Lake Eğirdir and its major tributaries, in order to provide information for future management decisions. The temperature, pH, electrical conductivity (EC), dissolved oxygen (DO) concentration, chemical oxygen demand (COD), nitrogen species concentrations, phosphorus species concentrations, and Chl-a concentrations were monitored monthly at seven sampling points in the lake between December 2010 and November 2011. The total nitrogen (TN) and total phosphorus (TP) loads were determined in the three main tributaries of Lake Eğirdir over the same period. At the end of the water quality assessment period, we determined that the lake water has the characteristics of class 1 waters for nitrogen species and class 2 waters for TP, according to the Turkish surface water quality management regulations. The Chl-a values measured in the lake were lower than expected from the trophic state index (TSI) values because of macrophyte growth in the lake. Interestingly, the total nitrogen/total phosphorus (TN/TP) ratios in the lake were low, possibly indicating that the sediment is a significant internal phosphorus resource in Lake Eğirdir.

The aim of this work was to investigate the biosorption of a cationic dye (methylene blue (MB)) by Salvinia minima. Biomass was characterized using the point of zero charge and scanning electron microscopy. The effects of pH (2–10), biosorbent dose (1–6 g/L), initial MB concentration (49.14 ± 1.03, 99.60 ± 0.67, 148.91 ± 2.00, 198.24 ± 1.91, 243.74 ± 2.32 mg/L), and time (20, 40, 60, 120, 180, 240, 300, 360 min) on MB biosorption and removal were evaluated. The MB biosorption kinetics were analyzed using pseudo-first- and pseudo-second-order kinetic models, as well as Elovich and intraparticle diffusion models, and Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms were used to analyze the equilibrium biosorption. A positive effect of pH on MB biosorption and removal was observed when pH was increased from 2 to 4 (28.18 ± 0.30 and 110 ± 0.05 mg/g, 23.20 ± 0.27 and 90.50 ± 0.01 %, respectively), while an increase in the biomass dose from 1 to 6 g/L reduced biosorbent efficiency from 157.30 ± 2.59 to 38.23 ± 0.02 mg/g. The adsorption kinetic data fit the pseudo-second-order equation, suggesting that chemisorption was the rate-determining step during MB biosorption by S. minima biomass. Equilibrium biosorption was described by the Freundlich model, implying that MB multilayers form on the heterogeneous surface of the biomass. S. minima biomass can be used as a biosorbent for the removal and adsorption of cationic dyes from water or wastewater.

The textile industry often releases effluents into the environment without proper treatment or complete dye removal. Azo dyes, which are characterized by azo groups (―N═N―), are frequently used in the textile industry. Among the different wastewater treatment methods available, biological treatment has been extensively studied. The aim of the present study was to compare the biodegradation of the azo dye Direct Blue 71 by the fungi Phanerochaete chrysosporium and Aspergillus oryzae in paramorphogenic form using a 100 μg/ml dye solution. Biodegradation tests were performed within 240 h. The absorbance values obtained with UV-VIS spectrophotometry were used to determine the absorbance ratio and the percentage of dye discoloration following the biodegradation test. FTIR analysis allowed the identification of molecular compounds in the solution before and after biodegradation. Both A. oryzae and P. chrysosporium demonstrated considerable potential regarding the biodegradation of dyes in wastewater. These results may contribute toward improving effluent treatment systems in the textile industry.

Clay minerals have been utilized for the remediation of heavy metal-polluted soil. However, information on the remediation stability of various clay minerals with different performances is limited. In this study, a kind of palygorskite (PAL) with a sorption amount for Cd²⁺about 40 mg/g, which is much larger than common minerals, was selected as amendment for in situ immobilization field demonstration. Besides, sorption stability which is essential for remediation was investigated in an ideal solid solution system by sorption and desorption behaviors of Cd²⁺on PAL, including isotherms, kinetics, and various stimulated environmental factors such as pH, temperature, and background electrolytes. The calculated thermodynamic parameters confirmed the sorption process was endothermic and driven by entropy changes. Only minimal desorption was caused by stimulated irrigation or runoff and acid rain. The temperature, pH, and background electrolyte dependence confirmed that the sorption of Cd²⁺on PAL was stable. Various characterization results including X-ray photoelectron spectroscopy (XPS), scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) mapping, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) confirmed the sorption mechanisms were surface precipitation of CdCO₃and surface complexation with hydroxyl groups.

Adsorption onto powdered activated carbon (PAC) is a promising option to remove organic micro-pollutants (OMP) from drinking water sources or wastewater. Since this treatment option requires continuous PAC dosing, sufficient contact time and subsequent separation of the PAC, the integration into existing process chains is challenging. In the present investigation, the pre-loading of a deep bed filter with PAC used as fixed bed adsorber was investigated. The retention and distribution of an exemplary PAC in a pumice rapid filter were determined. Gravimetry combined with combustion of the PAC at 550 °C was applied to differentiate between PAC and filter material residues and revealed comparably high PAC immobilization in the upper third of the pumice filter. Comparative adsorption experiments in batch with suspended PAC and continuous filtration tests with immobilized PAC showed advantageous results for immobilized PAC with regard to the removal of OMP and the sum parameters dissolved organic carbon and UV light absorption at 254 nm wavelength. The results indicate that a conventional rapid filter together with PAC can be effectively utilized as fixed bed adsorption filter.

The increased industrial and economic developments that have occurred in recent decades, particularly in mining, agricultural and metal recycling activities have decisively contributed to the increased concentration of heavy metals in soil. This study was carried out to evaluate the performance of Sorghum bicolor and Chrysopogon zizanioides in the citric acid-assisted phytoextraction of Pb in a field experiment setup in an area contaminated by automotive battery waste. Two soils amendments were used and they were dolomitic limestone and silicate slag at doses of 4.74 and 12.80 t ha⁻¹, respectively. Commercial citric acid was applied in each experimental parcel on the 63rd day of the cultivation in order to enhance Pb solubilisation and plant availability. Citric acid, which was applied at a dose of 40 mmol kg⁻¹of soil, was efficient in the solubilisation of Pb in soil and in the induction assisting of the removal of Pb from soil by the both species tested. Commercial citric acid is indicated for use in the area, due to its low cost and high biodegradability. Due to the low natural solubility of Pb and the large amount of time required, i.e. more than 900 years, phytoextraction without the application of chelating agents is not viable for remediation of the study area. Sorghum grown in soil amended with silicate slag combined with the application of the chelating agent commercial citric acid is the recommended phytoextraction programme for the remediation of an area with moderate Pb contamination.

Carbonaceous material obtained from industrial sewage sludge and Na-zeolitic tuff were used to adsorb cadmium from aqueous solutions in column systems. The Bohart, Thomas, Yoon–Nelson, and mass transfer models were successfully used to fit the adsorption data at different depths, and the constant rates were evaluated. The parameters such as breakthrough and saturation times, bed volumes, kinetic constants, adsorption capacities, and adsorbent usage rates (AUR) were determined. The results show that the breakthrough time increases proportionally with increasing bed height. The adsorption capacity for cadmium for Na-zeolitic tuff was higher than carbonaceous material. The results indicated that the Na-zeolitic tuff is a good adsorbent for cadmium removal.