Biosorption properties of Morus alba L. for Cd (II) ions removal from aqueous solutions

The abundantly available industrial waste product Morus alba L. pomace (MAP) is one of the cost-effective biosorbent for removal of metal ions from aqueous solutions. Hence, in the present study, we aimed to test the ability of MAP to remove Cd(II) ions through batch biosorption process. Firstly, MAP was characterized using several techniques, and then the influence of various experimental parameters such as initial pH of the aqueous solution, initial Cd(II) concentration, contact time, MAP concentration, and temperature were evaluated upon the biosorption process. It was found that the maximum uptake of Cd(II) ions occurred at initial pH 6.0 and optimum contact time was observed as 60 min. Cd(II) ions adsorption on MAP analyzed by the Langmuir and Freundlich isotherm models and the maximum monolayer biosorption capacity of MAP was found to be 21.69 mg?g^?1 by using the Langmuir isotherm model. The pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models were employed to describe the biosorption kinetics. In order to investigate the thermodynamic properties of the biosorption process, the changes in the Gibbs free energy (?G), enthalpy (?H), and entropy (?S) were also evaluated and it has been concluded that the process was feasible, spontaneous, and endothermic in the temperature range of 5–40 °C.     

Effect of vegetation change from native broadleaf forest to coniferous plantation on selected soil properties

The objective of this study was to examine the effects of vegetation change from a native broadleaf forest to a coniferous plantation on selected soil properties, including soil texture, pH, organic matter, total nitrogen (N), total phosphorus (P), exchangeable cations (Ca²⁺, K⁺, Na⁺), and cation exchange capacity (CEC). Results showed that the amount of clay particles, Ca²⁺, and K⁺ values significantly increased, whereas Na⁺, total N, and organic matter and soil pH values decreased on the treatment plot after vegetation change. Soil acidity also increased and soil textural group changed from moderately fine-textured soils (clay loam) to medium-textured soils (loam) under both control and treatment plots. Organic matter, total N, and Na⁺ values increased, whereas Ca²⁺ concentration decreased through time on the control plot. Soil pH, total P, K⁺, and CEC did not show significant changes through time on the control plot.     

Accumulation of weathered polycyclic aromatic hydrocarbons (PAHs) by plant and earthworm species

Experiments were conducted to assess the bioavailability of polyclycic aromatic hydrocarbons (PAHs) in soil from a Manufactured Gas Plant site. Three plant species were cultivated for four consecutive growing cycles (28 days each) in soil contaminated with 36.3 microg/g total PAH. During the first growth period, Cucurbita pepo ssp. pepo (zucchini) tissues contained significantly greater quantities of PAHs than did Cucumis sativus (cucumber) and Cucurbita pepo ssp. ovifera (squash). During the first growth cycle, zucchini plants accumulated up to 5.47 times more total PAH than did the other plants, including up to three orders of magnitude greater levels of the six ring PAHs. Over growth cycles 2-4, PAH accumulation by zucchini decreased by 85%, whereas the uptake of the contaminants by cucumber and squash remained relatively constant. Over all four growth cycles, the removal of PAHs by zucchini was still twice that of the other species. Two earthworm species accumulated significantly different amounts of PAH from the soil; Eisenia foetida and Lumbricus terrestris contained 0.204 and 0.084 microg/g total PAH, respectively, but neither species accumulated measurable quantities 5 or 6 ring PAHs. Lastly, in abiotic desorption experiments with an aqueous phase of synthetically prepared organic acid solutions, the release of 3 and 4 ring PAHs from soil was unaffected by the treatments but the desorption of 5-6 ring constituents was increased by up to two orders of magnitude. The data show that not only is the accumulation of weathered PAHs species-specific but also that the bioavailability of individual PAH constituents is highly variable.     

Organochlorine levels in edible fish from the Marmara Sea, Turkey

Samples of 12 edible fish species from the Marmara Sea were analyzed for organochlorines (PCBs, DDTs, HCB, HCHs, toxaphene, etc.). The results showed that the total concentrations ranged from 329.41 ng/g fat to 1453.87 ng/g fat. DDT group components made up almost half or more of organochlorine contamination. Levels in red mullet were compared with those from neighbor seas. The sum of DDTs as well as HCHs concentrations were markedly lower than in the Black Sea but higher in the Aegean Sea and Mediterranean. Thus, inflow from the Black Sea might be considered as a contamination source for DDT and HCH contamination. On the other hand, total PCB concentration (sum of congeners 28, 52, 101, 118, 138, 153 and 180) detected in this study was comparable or lower than those from the Aegean Sea and Mediterranean. Toxaphene was a minor contaminant. Measured values were below maximum residue levels for human consumption.     

Removal of propham from water by using electro-Fenton technology: kinetics and mechanism

The removal of a carbamate herbicide, propham, from aqueous solution has been carried out by the electro-Fenton process. Hydroxyl radical, a strong oxidizing agent, was generated catalytically and used for the oxidation of propham aqueous solutions. The degradation kinetics of propham evidenced a pseudo-first order degradation. The absolute rate constant of second order reaction kinetics between propham and ()OH was determined as (2.2+/-0.10)x10(9)m(-1)s(-1). The mineralization of propham was followed by the organic carbon (TOC) removal. The optimal Fe(3+) concentration was found as 0.5mM at 300mA. The 94% of initial TOC of 0.25mM propham solution was removed in 8h at the optimal conditions by using the cathode area to solution volume ratio of 3.33dm(-1). The maximum mineralization current efficiency values were obtained at 60mA in the presence of 0.5mM Fe(3+). During the electro-Fenton treatment, several degradation products were formed. These intermediates were identified by using high performance liquid chromatography, liquid chromatography-mass spectrometry, gas chromatography-mass spectrometry and ion chromatography analysis. The identified by-products allowed proposing a pathway for the propham mineralization.     

Implications of climate change for evaporation from bare soils in a Mediterranean environment

The purpose of this study was to predict quantitative changes in evaporation from bare soils in the Mediterranean climate region of Turkey in response to the projections of a regional climate model developed in Japan (hereafter RCM). Daily RCM data for the estimation of reference evapotranspiration (ET _r) and soil evaporation were obtained for the periods of 1994–2003 and 2070–2079. Potential evaporation (E _p) from bare soils was calculated using the Penman–Monteith equation with a surface resistance of zero. Simulation of actual soil evaporation (E _a) was carried out using Aydin model (Aydin et al., Ecological Modelling 182:91–105, 2005) combined with Aydin and Uygur (2006, A model for estimating soil water potential of bare fields. In Proceedings of the 18th International Soil Meeting (ISM) on Soils Sustaining Life on Earth, Managing Soil and Technology, Sanliurfa, 477–480pp.) model of predicting soil water potential at the top surface layer of a bare soil, after performances of Aydin model (R ² = 94.0%) and Aydin and Uygur model (R ² = 97.6) were tested. The latter model is based on the relations among potential soil evaporation, hydraulic diffusivity, and soil wetness, with some simplified assumptions. Input parameters of the model are simple and easily obtainable such as climatic parameters used to compute the potential soil evaporation, average diffusivity for the drying soil, and volumetric water content at field capacity. The combination of Aydin and Aydin and Uygur models appeared to be useful in estimating water potential of soils and E _a from bare soils, with only a few parameters. Unlike ET _r and E _p projected to increase by 92 and 69 mm (equivalent to 8.0 and 7.3% increases) due to the elevated evaporative demand of the atmosphere, respectively, E _a from bare soils is projected to reduce by 50 mm (equivalent to a 16.5% decrease) in response to a decrease in rainfall by 46% in the Mediterranean region of Turkey by the 2070s predicted by RCM, and consequently, to decreased soil wetness in the future.     

Efficient removal of triphenylmethane dyes from aqueous medium by in situ electrogenerated Fenton's reagent at carbon-felt cathode

Fenton's reagent (Fe2+ +H2O2) has been electrogenerated in situ in an undivided electrolytic cell from the effective reduction of Fe3+ and O2 at carbon-felt cathode for the treatment of aqueous solutions of four triphenylmethane dyes (TPMs), namely malachite green (MG), crystal violet (CV), methyl green (MeG) and fast green FCF (FCF), at pH 3.0 and room temperature. MG has been used as a model among them to study the influence of some experimental parameters on the decay kinetics, COD removal and current efficiency. The results in such electro-Fenton system are explained in terms of the many parasitic reactions involving .OH. Higher efficiency values are obtained with rising organic content and decreasing applied current. The first stage of the mineralization process, involving aromatic by-products, leads to fast decoloration as well as quick initial COD removal that fit well to a pseudo-first-order kinetics. At prolonged electrolysis time, the mineralization rate and efficiency decrease due to the formation of hardly oxidizable compounds and the enhancement of wasting reactions. Solutions of all four TPMs are quickly degraded following a pseudo-first-order decay kinetics. The absolute rate constant (kTPM) for their reaction with .OH increases in the order MeG相似文献   

Degradation of anti-inflammatory drug ketoprofen by electro-oxidation: comparison of electro-Fenton and anodic oxidation processes

The electrochemical degradation of the nonsteroidal anti-inflammatory drug ketoprofen in tap water has been studied using electro-Fenton (EF) and anodic oxidation (AO) processes with platinium (Pt) and boron-doped diamond (BDD) anodes and carbon felt cathode. Fast degradation of the parent drug molecule and its degradation intermediates leading to complete mineralization was achieved by BDD/carbon felt, Pt/carbon felt, and AO with BDD anode. The obtained results showed that oxidative degradation rate of ketoprofen and mineralization of its aqueous solution increased by increasing applied current. Degradation kinetics fitted well to a pseudo-first-order reaction. Absolute rate constant of the oxidation of ketoprofen by electrochemically generated hydroxyl radicals was determined to be (2.8?±?0.1)?×?10⁹ M^?1 s^?1 by using competition kinetic method. Several reaction intermediates such as 3-hydroxybenzoic acid, pyrogallol, catechol, benzophenone, benzoic acid, and hydroquinone were identified by high-performance liquid chromatography (HPLC) analyses. The formation, identification, and evolution of short-chain aliphatic carboxylic acids like formic, acetic, oxalic, glycolic, and glyoxylic acids were monitored with ion exclusion chromatography. Based on the identified aromatic/cyclic intermediates and carboxylic acids as end products before mineralization, a plausible mineralization pathway was proposed. The evolution of the toxicity during treatments was also monitored using Microtox method, showing a faster detoxification with higher applied current values.     

Strength and durability characterization of pelletized coal–biomass household briquettes

Increase in waste sludge disposal is always seen as a problem from the point of production industry. However, it is clear that the reuse and recycle of sewage sludge could be a serious economic input. The most important action should be to determine the sludge characterizations and direct the producers towards appropriate reuse and recycling opportunities. In this study, reuse method was examined to produce coal briquette, which will constitute an example for waste sludge. In order to make use of the waste sludge, five different coal briquette samples were produced by mixing powdered coal and bitumen together with waste sludge, at different ratios. The overall results indicated that the sample named CB3 having 70% powdered coal, 20% waste sludge, and 10% bitumen was found to be the optimum coal briquette among the other samples produced. The proximate analysis of the optimum briquette sample was carried out according to the Turkish standards and regulations and it was found out that the produced briquette coal can have commercial value with a gross calorific value of 30.03 MJ/kg and 7.30% ash content.