Interference of aluminum in heavy metal biosorption by a seaweed biosorbent

Heavy metal and Al sorption capacities of Ca-loadedSargassum fluitans biomass were studied by using equilibrium methodology. An evaluation of sorption performance and modeling in a two-metal system was carried out with a modified multi-component Langmuir isotherm. The maximum uptakes of Cr, Pb, Cu, Cd, Zn and Al calculated from the Langmuir isotherm were 1.74 mmol/g, 1.65 mmol/g, 1.61 mmol/g, 1.15 mmol/g, 0.81 mmol/g, and 2.95 mmol/g at pH 4.5, respectively. The interference of Al in heavy metal biosorptive uptakes was assessed by ‘cutting’ the three-dimensional uptake isotherm surfaces at constant second-metal final concentrations. The reduction of Pb, Cu, Zn, Cd and Cr uptakes at its final equilibrium concentrations of 1 mM at pH 4.5 was 78.4%, 82.7%, 85.1%, 89.8% and 51.2% in the presence of 1mM Al ion, respectively. The presence of Al ion greatly affected the uptake of all heavy metals tested except Cr.     

Cadmium Uptake by Biosorbent Seaweeds: Adsorption Isotherms and Some Process Conditions

Abstract

Cadmium biosorption was evaluated in 15 samples of heat-inactivated seaweeds collected from the coast of Rio de Janeiro State, Brazil. The classical Langmuir and Freundlich sorption models were fitted to the results in order to test whether these equations could appropriately describe the process of passive biosorption uptake. Depending on the algal sample and on some assumptions, both models could be applied to this study. The possible ion-exchange mechanism associated with the adsorption process was also investigated, as well as the effect of pH on biosorption and re-use of the different biomasses through several biosorption/ desorption cycles.     

Chitin as biosorbent for phenol removal from aqueous solution: Equilibrium,kinetic and thermodynamic studies

Phenol removal from aqueous solution was studied employing chitin as low cost biosorbent. Initial biosorption tests carried out in the pH range 2–10 pointed out an optimum pH of 2. Temperature and initial phenol concentration were then varied in the ranges 15 ≤ T ≤ 50 °C and 10.4 ≤ C₀ ≤ 90.8 mg L⁻¹, respectively. The good applicability of Langmuir, Freundlich and Temkin models (R² = 0.990–0.993) to describe equilibrium isotherms suggested an intermediate mono-/multilayer biosorption mechanism along with a semi-homogeneous architecture of biosorbent surface. Biosorption capacity progressively increased from 3.56 to 12.7 mg g⁻¹ when starting phenol concentration was raised from 10.4 to 90.8 mg L⁻¹, and the related sorption kinetics was investigated by pseudo first-order, pseudo second-order and intraparticle diffusion models. The pseudo second-order model, which showed the best fit of experimental data (R² = 0.999), allowed estimating a second-order rate constant of 0.151 g mg⁻¹ h⁻¹ and a theoretical sorption capacity of 7.63 mg g⁻¹. Phenol biosorption capacity increased with temperature up to a maximum value, beyond which it decreased, suggesting the occurrence of a thermoinactivation equilibrium. Finally, to identify the main functional groups involved in phenol biosorption, both raw and phenol-bound materials were explored by FT-IR spectroscopy.     

Removal of Cadmium Ions from Aqueous Samples by Synechocystis sp.

Abstract

The biosorption of cadmium ions from aqueous solution by dried, immobilized dried and immobilized live Synechocystis sp. was investigated. Sorption of plain Ca-alginate beads, which were used as substrate for immobilization, was also studied for comparison. Removal efficiency of biosorbents was studied as a function of pH (2-8 Volesky , B. ( 1990 ) Biosorption of Heavy Metals ; CRC Press : Boca Raton , FL . Wase , J. , Forster , C.F. (1997) Biosorbents for Metal Ions ; Taylor & Francis : London. Malkoç , E. ; Nuho?lu , Y. ( 2005 ) Investigations of nickel (II) removal from aqueous solutions using tea factory waste . J. Hazard. Mater. , 127 : 120 – 128 . Lodeiro , P. ; Cordero , B. ; Barriada , J.L. ; Herrero , R. ; Sastre de Vicente , M.E. ( 2005 ) Biosorption of cadmium by biomass of brown marine macroalgae . Bioresource Technol. , 96 : 1796 – 1803 . Shen , J. ; Duvnjak , Z. ( 2005 ) Adsorption isotherms for cupric and cadmium ions on corncob particles . Sep. Sci. Technol. , 40 : 1461 – 1481 . Kat?rc?o?lu , H. ; Asl?m , B. ; Türker , A.R. ; At?c? , T. ; Beyatl? , Y. ( 2008 ) Removal of cadmium(II) ion from aqueous system by dry biomass, immobilized live and heat-dried Oscillatoria sp. H1 isolated from freshwater (Mogan Lake) . Bioresource Technol. , 99 ( 10 ): 4185 – 4191 . Pavasant , P. ; Apiratikul , R. ; Sungkhum , V. ; Suthiparinyanont , P. ; Wattanachira , S. ; Marhaba , T.F. ( 2006 ) Biosorption of Cu²⁺, Cd²⁺, Pb²⁺, and Zn²⁺ using dried marine green macroalga Caulerpa lentillifera. Bioresource Technol. , 97 : 2321 – 2329 . ), temperature (20–40°C), initial cadmium ion concentration (50–300 mg/L), and contact time (0–120 min). The maximum biosorption capacities of the dried, immobilized dried, and immobilized live Synechocystis sp. and plain Ca-alginate beads were found as 75.7, 4.9, 4.3, and 3.9 mg/g, respectively at optimum conditions. Biosorption equilibrium was established in about 15 min. Dried biomass of Synechocystis sp. was found to be more suitable and an efficient biosorbent for the removal of cadmium ion from aqueous solution. Both of the isotherm models (Langmuir and Freundlich) were suitable for describing the biosorption of cadmium by the dried biomass of Synechocystis sp. All the tested cyanobacterial forms could be recovered more than 90% and reused in five biosorption–desorption cycles without any considerable loss in the biosorption capacity.     

The biosorption of Cr(VI) ions by dried biomass obtained from a chromium-resistant bacterium

The biosorption potential of many different kinds of biomaterials has been widely studied. However, there is little data on the biosorption mechanism of Cr(VI) by dried biomass. So the bio-removal of Cr(VI) ions from aqueous solutions was investigated using dried biomass from a chromium-resistant bacterium. The bacterium was isolated from dewatered sludge samples that were obtained from a sewage treatment plant. Equilibrium and kinetic experiments were performed at different metal concentrations, pH values, and biosorbents dosages. The biomass was characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The functional groups in the Bacillus cereus biomass which may play a role in the biosorption process were identified by Fourier transform infrared spectroscopy. The biosorption process was found to be highly pH dependent and the optimum pH for the adsorption of Cr(VI) was 2.0±0.3 at 30±2 °C. The experimental data fit well with Langmuir and Freundlich models as well as a pseudo-second order kinetic model. The mechanism for the biosorption was also studied by fitting the kinetic data with an intra-particle diffusion model and a Boyd plot. External mass transfer was found to be the rate-determining step for the adsorption process. Biosorption could be an alternative mechanism besides bio-oxidation and bio-reduction for the bioremediation of heavy metals.     

Production of eicosapentaenoic acid by a bacterium isolated from mackerel intestines

Optimization of culture conditions for the growth rate, 5,8,11,14,17-cis-Eicosapentaenoic acid (EPA) content and EPA productivity of a bacterium isolated from Pacific mackerel intestines was investigated by use of a culture medium containing 1.00 wt% peptone and 0.50 wt% yeast extract in an artificial sea water (ASW). Cultivation temperature affected the growth rate and cellular EPA content of the bacterium. The cellular EPA content at 8°C was as great as 16.8 mg/g of dry cells, which was more than two times greater than that at 25°C (7.3 mg/g of dry cells), although the growth rate showed a maximum at 25°C. Both the yield of bacterial cells and the cellular EPA content at 25°C reached maximum values when the pH of the culture medium was nearly 7.0 and when the concentration of ASW was 100% (v/v). Under optimum culture conditions [25°C pH 7.0 and 100% (v/v) ASW], the amount of EPA accumulated in the cellular lipids reached 45.6 mg/L of culture broth after 8 hr.     

Analysis of equilibrium,kinetic, and thermodynamic parameters for biosorption of fluoride from water onto coconut (Cocos nucifera Linn.) root developed adsorbent

Drinking water with higher fluoride levels results in serious irremediable health problems that have attained a startle all over the world.Researches focused towards deflouridation through the application of biosorbents prepared from various plants are finding greater scope and significance.Present research is done on Cocos nucifera Linn.(coconut tree) one of the very commonly available plants throughout Kerala and around the globe.An adsorbent developed from the root portion of C.nucifera Linn.is used in the present study.Equilibrium study revealed that the fluoride uptake capacity is quite significant and linearly increases with initial adsorbate concentration.The adsorption data is analyzed for Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models at varying initial adsorbate concentrations(2–25 mg·L~(-1)).It is found that the adsorption of fluoride onto C.nucifera Linn.root adsorbent follows Langmuir isotherm.Langmuir isotherm constants "a" and "b" obtained are 2.037 mg·g~(-1) and 0.823 L·mg~(-1) at an adsorbent dose of 8 g·L~(-1) and temperature(26 ± 1) ℃.The mean free sorption energy, E obtained, is 9.13 kJ ·mol~(-1) which points out that the adsorption of fluoride onto C.nucifera Linn.root adsorbent is by chemisorption mechanism.The kinetic study also supports chemisorption with adsorption data fitting well with a pseudo-second-order kinetic model with an estimated rate constant K_2 of 0.2935 g·mg~(-1) min at an equilibrium contact time of 90 min.The thermodynamic study indicated the spontaneous and endothermic nature(ΔH =12.728 kJ·mol~(-1)) of fluoride adsorption onto the C.nucifera Linn.root adsorbent.Scanning Electron Microscopy(SEM), BET, FTIR, and EDX methods were used to analyze the surface morphology of adsorbent before and after fluoride adsorption process.Experiments on deflouridation using C.nucifera Linn.root adsorbent application on fluoride contaminated ground water samples from fields showed encouraging results.     

Removal of Cadmium from Dilute Solutions by Hydroxyapatite. III. Flocculation Studies

Abstract

Synthetic hydroxyapatite in a fine particulate dispersion has been used previously for the removal of Cd²⁺ cations from dilute aqueous solutions. In the present work the flocculation of these hydroxyapatite particulates was examined with and without the presence of Cd²⁺ ions by applying the conventional inorganic flocculents ferric chloride and aluminum sulfate. An optical technique was applied in order to monitor the flocculation dynamics of the dispersed particles, complemented by electrophoretic and turbidity measurements. The relative size of aggregates formed during flocculation, expressed as a “flocculation index,” could be continuously measured by this technique. Results indicated that the flocculation index provided important information about flocculation mechanisms. The main parameters examined included flocculent dose, solution pH, and mixing intensity. The optimum conditions for efficient flocculation were determined.     

Removal of several metal ions from aqueous solution using powdered stem of Arundo donax L. as a new biosorbent

Arundo donax L., a member of Poaceae, was washed, dried, selected, pulverized, and then used for removal of Cu(II), Cd(II), Ni(II), Pb(II) and Zn(II) from aqueous solution. Series batch experiments were conducted to investigate the effects of contact time, pretreatment, particle size of biomass and solution pH on the biosorption capability of A. donax L. powder. The desorption characteristics and renewability of the biomass were also studied. The applicability of Langmuir and Freundlich isotherms was examined for the experimental data, so did the pseudo-first-order, pseudo-second-order and Elovich kinetic models. Results showed that alkali-treated A. donax L. biomass was more appropriate to be the bio-material for biosorption when compared to acid-treated, washed and virgin A. donax L. Owing to its fast adsorption rate, high uptake capacity and the renewability of facility, stem of A. donax L. treated with NaOH seems to be a promising biosorbent for removal of heavy metals from wastewater.     

Adsorption of Methane,Ethane, Ethylene,and Carbon Dioxide on X,Y, L,and M Zeolites Using a Gas Chromatography Pulse Technique

Abstract

Sorption of methane, ethane, ethylene and carbon dioxide in NaX, NaY, HY, CeNaY, KL, HKL, NaM, and HM zeolites at 303–473 K has been investigated using a gas chromatography pulse technique. The zeolites have been compared for the heat of sorption of the sorbates at near-zero sorbate loading and also for the specific retention volume (or thermodynamic sorption equilibrium constant) of ethane, ethylene, and carbon dioxide relative to that of methane.     

Emissions of N2O from Scottish agricultural soils, as a function of fertilizer N

Potato fields and cut (ungrazed) grassland in SE Scotland gave greater annual N₂O emissions per ha (1.0–3.2 kg N₂O–N ha^-1) than spring barley or winter wheat fields (0.3–0.8 kg N₂O–N ha^-1), but in terms of emission per unit of N applied the order was potatoes > barley > grass > wheat. On the arable land, especially the potato fields, a large part of the emissions occurred after harvest.When the grassland data were combined with those for 2 years' earlier work at the same site, the mean emission over 3 years, for fertilization with ammonium nitrate, was 2.24 kg N₂O–N ha^-1 (0.62% of the N applied). Also, a very strong relationship between N₂O emission and soil nitrate content was found for the grassland, provided the water-filled pore space was > 70%. Significant relationships were also found between the emissions from potato fields and the soil mineral N content, with the added feature that the emission per unit of soil mineral N was an order of magnitude larger after harvest than before, possibly due to the effect of labile organic residues on denitrification.Generally the emissions measured were lower, as a function of the N applied, than those used as the basis for the current value adopted by IPCC, possibly because spring/early summer temperatures in SE Scotland are lower than those where the other data were obtained. The role of other factors contributing to emissions, e.g. winter freeze–thaw events and green manure inputs, are discussed, together with the possible implications of future increases in nitrogen fertilizer use in the tropics.     

Metal salts requisite for the production of eicosapentaenoic acid by a marine bacterium isolated from mackerel intestines

Metal salts important for the growth and 5,8,11,14,17- ciseicosapentaenoic acid EPA) production of a bacterium isolated from Pacific mackerel intestines were investigated at 25°C in culture media containing 1.0% peptone and 0.50% yeast extract, and the composition of an optimum culture medium was determined. This bacterium could grow in the media in which sodium chloride was the sole added inorganic component. By raising the concentration of sodium chloride from 1.2 to 2.4%, the yield of bacterial cells increased and the yield of EPA reached a maximum at 2.0% NaCl concentration. In contrast to calcium chloride, potassium chloride and magnesium chloride as second metal salts promoted the growth of this bacterium at relatively low concentrations without inhibiting the accumulation of EPA. The yield of EPA reached its maximum value of 51.9 mg/L of culture broth at 8 hr at 2.0% NaCl, 0.15% KCl and 0.16% MgCl₂ concentrations. This yield of EPA was 20% greater than that obtained with Jamarin S artificial sea water. *To whom correspondence should be addressed at Department of Chemical Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152, Japan. ¹Sagami Chemical Research Center, 4-4-1 Nishi-ohnuma, Sagamihara, Kanagawa 229, Japan.     

Elucidation of the chemical structure of a novel antioxidant,rosmaridiphenol, isolated from rosemary

A novel antioxidant compound has been isolated and identified from the leaves of theRosmarinus officinalis L. The compound, named rosmaridiphenol, is a diphenolic diterpene. When tested in lard, the antioxidant activity of this compound was superior to BHA. Structural elucidation of rosmaridiphenol was accomplished by infrared spectroscopy (IR), mass spectroscopy (MS),¹H-NMR (nuclear magnetic resonance) and¹³C-NMR spectroscopy.     

Using a boundary line approach to analyze N2O flux data from agricultural soils

Predicting the N₂O flux from soils is difficult because of the complex interplay of the various processes involved. In this study a boundary line approach was used to apply results from mechanistic experiments to N₂O flux data resulting from measurements on field scale in southern Germany. Boundary lines were fitted to the rim of the data points in scattergrams depicting readily obtainable soil variables against the measured N₂O flux. The boundary line approach is based on the hypothesis that this line depicts the functional dependency between the two variables. For determining these boundary lines a novel method was applied. The function best representing the relationship between the N₂O flux and soil temperature had a maximum above 23 °C and the one between the N₂O flux and the water filled pore space (WFPS, to represent water content) had a maximum at 72% WFPS. In the range of 0–20 mg N kg^-1 the relationship between N₂O flux and nitrate in the soil was best described by a linear function, whereas in the range of 0–35 mg N kg^-1 a Michaelis–Menten function was more appropriate. The boundary lines specified in this study are in agreement with existing theoretical concepts as well as experimental results obtained under controlled and field conditions as reported in the literature. Therefore, the boundary line approach can be used to improve empirical models for predicting the N₂O flux in the field.     

Investigation of the Column Performance of Cadmium(II) Biosorption by Cladophora crispata Flocs in a Packed Bed

ABSTRACT

In this study the biosorption of cadmium(II) ions to dried floes of Cladophora crispata, a kind of green algae, was investigated in a packed bed column. The cadmium(II) removal performance of the column was investigated as a function of the cadmium(II)-bearing solution flow rate and the inlet cadmium(II) concentration. Re- moval and total removal percentages of cadmium(II) related to flow volume were determined by evaluating the breakthrough curves obtained at three different flow rates for two different constant inlet concentrations. At the lowest flow rate the effect of inlet cadmium(II) concentration on the column capacity was also investigated. Data confirmed that early saturation and lower cadmium(II) removals were observed at higher flow rates and at higher cadmium(H) concentrations. Column experiments also showed that maximum specific cadmium(II) uptake values of C. crispata floes were as higher as those of other biomass sorbents.     

Cadmium(II) recovery from hydrochloric acid solutions using Amberlite XAD-7 impregnated with a tetraalkyl phosphonium ionic liquid

Cyphos® IL-101 (tetraalkyl phosphonium ionic liquid, IL) was immobilized in a synthetic resin (Amberlite XAD-7) for preparing an solvent impregnated resin (SIR). This SIR was tested for Cd(II) sorption in HCl solutions. Optimum sorption occurs for HCl concentrations close to 3–4 M through an ion exchange mechanism involving phosphonium cation and . Sorption capacity increased with IL loading, though a fraction of the IL remained inactive, being bound to the polymer support. Sorption capacity is poorly influenced by metal ions that do not form chloroanionic species. Uptake kinetics are controlled by the resistance to intraparticle diffusion. The intraparticle diffusivity coefficient increased with temperature, initial metal concentration but decreased with increasing IL loading (probably due to a decrease of the interfacial area and a slow diffusion of metal ions in the organic phase that fills the porous network). Metal desorption and resin recycling can be performed using nitric acid (0.1 M) with sorption and desorption performances maintained for at least five cycles.     

Prediction of cadmium and zinc concentration in wheat grain from soils affected by the application of phosphate fertilizers varying in Cd concentration

Cadmium is an undesirable contaminant in phosphate fertilizer, and may represent a threat to food safety given its tendency to be taken up by plants and translocated into the edible parts. In this context, predicting wheat grain cadmium concentration from preliminary data would help to prevent exceeding the threshold values. Our study compared different approaches to estimate the concentrations of cadmium and zinc in wheat grains based on either soil solution chemistry of these elements, their quantities added to the soil and various soil parameters. Whereas the predictions based on soil solution chemistry show positive correlations between predicted and measured values of cadmium for some experimental sites, it was more difficult to predict grain cadmium concentrations in other sites. Reverse-wise, predictions based on applied cadmium and some soil parameters yielded systematically good correlations between predicted and measured values. The prediction of the concentration of zinc in wheat grains could not be achieved as its content was neither related to the measured soil solution chemistry nor to the quantities of zinc applied to the soil. We suspect that zinc interacts with the phosphate fertilizer thus obscuring the regressions for plant uptake. The prediction of grain cadmium in wheat cultures is best achieved through empirical modeling from soil parameters and soil inputs rather than through estimates of the bioavailable fractions in the soil solution.     

Sorption of heavy metal ions from aqueous solution by a novel cast PVA/TiO2 nanohybrid adsorbent functionalized with amine groups

Sorption of Cd(II), Ni(II) and U(VI) ions onto a novel cast PVA/TiO₂/APTES nanohybrid adsorbent with variations in adsorbent dose, pH, contact time, initial metal concentration and temperature has been investigated. The adsorbent were characterized by SEM and FTIR analysis. BET surface area, pore diameter and pore volume of adsorbent were 35.98 m² g⁻¹, 3.08 nm and 0.059 cm³ g⁻¹, respectively. The kinetic and equilibrium data were accurately described by the double-exponential and Freundlich models for all metals. The maximum sorption capacities were 49.0, 13.1 and 36.1 mg g⁻¹ for Cd(II), Ni(II) and U(VI) ions with pH of 5.5, 5 and 4.5, respectively. Thermodynamic studies showed that the sorption process was favored at higher temperature. The adsorbent can be easily regenerated after 5 cycles of sorption–desorption.     

Biodegradation of slop wax by Bacillus species isolated from chronic crude oil contaminated soils

Slop wax waste by-product obtained through the lube oil manufacture was subjected to biotreatment using five isolated Bacillus species at 30 °C and various incubation periods, 7, 14 and 21 days. The results obtained from HPLC for the 15 samples showed that the aromatic contents decreased, especially, for that treated with Bacillus sp. MAM-27 which degrade PAHs faster at 1% (w/v) concentration of slop wax waste by-product and exhibited high biodegradation ability within 1 week. Bacillus sp. MAM-27 degraded 99.9% of PAHs, while Bacillus sp. MAM-24 degrades 99.8% of PAHs within 2 weeks and then the degradation ability is slightly increased afterwards. The gas chromatographic analysis of the samples before and after treatment with Bacillus spp. showed that, the aromatics, naphthenes and iso-alkanes were more degradable than saturated n-paraffins. Treatment by Bacillus sp. MAM-27 and Bacillus sp. MAM-24 can be an effective method for biodegradation of slop wax waste by-product leading to paraffin waxes match with plastic paraffin wax according to USSR 1121284 specifications.     

Nitric oxide emissions from agricultural soils in temperate and tropical climates: sources, controls and mitigation options

Global annual NO emissions from soil are of the order of 10 Tg NO-N. This is about half the amount fossil fuel combustion processes contribute to the annual global NO_x budget. Reducing the emissions of soil derived NO_x requires an understanding of the source of the flux and the processes that determine its magnitude. A thorough investigation of possible mitigation strategies and the consequences of their implementation is also necessary. The ratio of NO and N₂O emissions from soils can be used as an indicator of the dominant NO production pathway operating. Fertilizer application (rate, type and time of application), soil temperature, soil water content and soil management practices all affect the emission rate and are reviewed. Mitigation options include reduction in N fertilizer use through an increase in fertilizer use efficiency, preferential use of NH⁴NO₃ instead of urea, improved timing of fertilizer application, the use of nitrification and urease inhibitors, improving the fertilizer uptake efficiency of crops in tropical agriculture and changes in land management. Several of the viable mitigation strategies, mainly those increasing fertilizer use efficiency, have the capacity to reduce global annual NO emissions by 4% (0.4 Tg NO-N y^-1). For other strategies including use of inhibitors, changing cultivation or land use, the possible reductions are too uncertain to justify quantification on the basis of present knowledge.