Efficacy of modified distillation sludge of rose (Rosa centifolia) petals for lead(II) and zinc(II) removal from aqueous solutions

Removal of lead(II) and zinc(II) from aqueous solutions was studied using chemically modified distillation sludge of rose (Rosa centifolia) petals by pretreatment with NaOH, Ca(OH)(2), Al(OH)(3), C(6)H(6), C(6)H(5)CHO and HgCl(2). The adsorption capacity of biomass was found to be significantly improved. NaOH pretreated biomass showed remarkable increase in sorption capacity. Maximum adsorption of both metal ions was observed at pH 5. When Freundlich and Langmuir isotherms were tested, the latter had a better fit with the experimental data. The overall adsorption process was best described by pseudo second order kinetics. The thermodynamic assessment of the metal ion-Rosa centifolia biomass system indicated the feasibility and spontaneous nature of the process and DeltaG degrees was evaluated as ranging from -26.9501 to -31.652 KJmol(-1) and -24.1905 to -29.8923KJmol(-1) for lead(II) and zinc(II) sorption, respectively, in the concentration range 10-640mgL(-1). Distribution coefficient (D) showed that the concentration of metal ions at the sorbent-water interface is higher than the concentration in the continuous aqueous phase. Maximum adsorption capacity of biomass tends to be in the order Pb(II) (87.74mgg(-1))>Zn(II) (73.8mgg(-1)) by NaOH pretreated biomass.     

Biosorption of Cr(III) from aqueous solution using algal biomass spirogyra spp

In the present investigation, a fresh water green algae spirogyra spp. was used as an inexpensive and efficient biosorbent for Cr(III) removal from aqueous solution. The algal biomass was treated with 0.1M NaOH, 0.2M CaCl(2) and 5% HCHO. The biosorption efficiency was compared with untreated biomass. The effects of various physico-chemical parameters were studied, e.g. pH 3.0-6.0, initial metal ions concentration 20-150mgL(-1), algal dose 1.0-3.0gL(-1), and contact time 15-180min, respectively. Biosorption of Cr(III) is highly pH dependent. Maximum 81.02% adsorption of Cr(III) was observed with 0.2M CaCl(2) treated biomass at pH 5.0. Removal of Cr(III) was more than 70% in 45min of contact time with different treated and untreated algal biomass at concentration 30mgL(-1). Maximum metal uptake (Q(max)) was observed as 30.21mgg(-1) with 0.2M CaCl(2) treated algal biomass indicate good biosorbents than other treated and untreated biomass. The high values of correlation coefficient (r(2)<0.90) indicate equilibrium data of treated and untreated form of algal biomass well fitted in Freundlich than Langmuir isotherms model equations.     

Comparison of adsorption equilibrium models for the study of CL-, NO3- and SO4(2-) removal from aqueous solutions by an anion exchange resin

The removal of chloride, nitrate and sulfate ions from aqueous solutions by a macroporous resin is studied through the ion exchange systems OH(-)/Cl(-), OH(-)/NO(3)(-), OH(-)/SO(4)(2-), and HCO(3)(-)/Cl(-), Cl(-)/NO(3)(-), Cl(-)/SO(4)(2-). They are investigated by means of Langmuir, Freundlich, Dubinin-Radushkevitch (D-R) and Dubinin-Astakhov (D-A) single-component adsorption isotherms. The sorption parameters and the fitting of the models are determined by nonlinear regression and discussed. The Langmuir model provides a fair estimation of the sorption capacity whatever the system under study, on the contrary to Freundlich and D-R models. The adsorption energies deduced from Dubinin and Langmuir isotherms are in good agreement, and the surface parameter of the D-A isotherm appears consistent. All models agree on the order of affinity OH(-)相似文献   

Calcium Phosphate Phase Identification Using XPS and Time-of-Flight Cluster SIMS

Reproducible time-of-flight cluster static secondary ion mass spectra (ToF-SSIMS) were obtained for various standard calcium phosphate (CP) powders, which allowed for phase identification. X-ray diffraction was not able to detect signals from microscopic amounts of CP (～15 mmol m(-)(2)). The phases studied were α-tricalcium phosphate [α-Ca(3)(PO(4))(2)], β-tricalcium phosphate [β-Ca(3)(PO(4))(2)], amorphous calcium phosphate [Ca(3)(PO(4))(2)·xH(2)O], octacalcium phosphate [Ca(8)H(2)(PO(4))(6)·H(2)O], brushite (CaHPO(4)·2H(2)O), and hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2)]. The SIMS spectra were obtained via bombardment with (CsI)Cs(+) projectiles. X-ray photoelectron spectroscopy (XPS) core levels of the P 2p, Ca 2p, and O 1s orbitals and the relative O 1s loss intensity were examined. The PO(3)(-)/PO(2)(-) ratios from ToF-SSIMS spectra in conjunction with XPS of the CP powders showed much promise in differentiating between these phases at microscopic CP coverages on the metal oxide surface.     

Phosphate removal using sludge from fuller's earth production

This study assesses the phosphate removal capacity and mechanism of precipitation or adsorption from aqueous solutions in batch experiments by an industrial sludge containing gypsum (CaSO(4).2H(2)O) obtained as a by-product from a fuller's earth process. The potential capacity for phosphate removal was tested using various solution concentrations, pH values, reaction times, and amount of sludge. The maximum phosphate adsorption capacity calculated using the Langmuir equation was 2.0 g kg(-1). The pH for the maximum adsorption by the sludge was neutral to alkaline (pH 7-12). Over 99% of phosphate was removed from a phosphate solution of 30 mg L(-1) using 0.15 g of sludge in a 9-h reaction. Sulfate (SO(4)(2-)) concentration increased with increasing initial phosphate concentration, possibly because of dissolution of gypsum and adsorption of both sulfate and phosphate. At high phosphate concentration (>1000 mg L(-1)), relative constant concentration of Ca(2+) was not consistent with adsorption of the most important phosphate removal mechanism. Results suggest that precipitation of calcium phosphate is principally responsible for phosphate removal under its high concentration. Agglomerated precipitate in the reaction sludge was observed by SEM and identified as brushite (CaHPO(4).2H(2)O) by XRD, FT-IR, and DTA. Based on thermodynamic considerations, it is suggested that the brushite will readily transform to more stable phases, such as hydroxyapatite (Ca(5)(PO(4))(3).OH).     

Studies on the Condensation Pathway to and Properties of Diiron Azadithiolate Carbonyls

Reaction of Fe(2)(SH)(2)(CO)(6) and HCHO, which gives Fe(2)[(SCH(2))(2)NH](CO)(6) in the presence of NH(3), affords the possible intermediate Fe(2)(SCH(2)OH)(2)(CO)(6), which has been characterized crystallographically as its axial-equatorial isomer. Fe(2)(SCH(2)OH)(2)(CO)(6) was shown to react with ammonia and amines to give Fe(2)[(SCH(2))(2)NR](CO)(6) (R = H, alkyl). Related hemithioacetal intermediates were generated by treatment of Fe(2)(SH)(2)(CO)(6) with RC(O)C(O)R (R = H, Ph, 4-F-C(6)H(4)) to give cycloadducts. The benzil derivative Fe(2)[S(2)C(2)(OH)(2)Ph(2)](CO)(6), a C(2)-symmetric species, was also characterized crystallographically. The acylated azadithiolate Fe(2)[(SCH(2))(2)NAc](CO)(6) was prepared by reaction of Li(2)Fe(2)S(2)(CO)(6) with (ClCH(2))(2)NC(O)Me. DNMR experiments show that the free energies of activation for rotation of the amide bond are the same for Fe(2)[(SCH(2))(2)NAc](CO)(6) and Fe(2)[(SCH(2))(2)NAc](CO)(4)(PMe(3))(2), which implies that the ligands on the iron centers do not strongly affect the basicity of the nitrogen. As a control, we showed that the thioamide Fe(2)[(SCH(2))(2)NC(S)Me](CO)(6) does exhibit a significantly higher barrier to rotation, attributable to the increased double-bond character of the N-C(S) bond.     

Spectroscopic investigation in the mid- and far-infrared regions of phosphorus fertilizers derived from thermochemically treated sewage sludge ash

Inorganic phosphorus and nitrogen-phosphorus-potassium (NPK) fertilizers based on phosphates from thermochemically treated sewage sludge ash were analyzed using mid-infrared (mid-IR) and far-infrared (FIR) spectroscopy. The different compounds present in the fertilizers were qualitatively determined with the help of recorded reference spectra of pure substances. Differentiation between various phosphates and other compounds such as sulfates, nitrates, and oxides was possible using combined interpretation of the mid-IR and FIR spectra. The results are in agreement with previous X-ray diffraction (XRD) measurements of the same samples. The main phosphate phases detected were NH(4)H(2)PO(4), MgHPO(4)·3H(2)O, Mg(3)(PO(4))(2), Ca(5)(PO(4))(5)Cl, CaHPO(4)·2H(2)O, Ca(H(2-)PO(4))(2)·H(2)O, and AlPO(4). Furthermore, K(2)SO(4), NH(4)NO(3), Fe(2)O(3), and SiO(2) were identified in the IR spectra. However, ammonium and sulfate compounds were only identified in the mid-IR region but were not detectable in the FIR region.     

Highly Cooperative Tetrametallic Ruthenium-mu-Oxo-mu-Hydroxo Catalyst for the Alcohol Oxidation Reaction

The tetrametallic ruthenium-oxo-hydroxo-hydride complex {[(PCy(3))(CO)RuH](4)(mu(4)-O)(mu(3)-OH)(mu(2)-OH)} (1) was synthesized in two steps from the monomeric complex (PCy(3))(CO)RuHCl (2). The tetrameric complex 1 was found to be a highly effective catalyst for the transfer dehydrogenation of alcohols. Complex 1 showed a different catalytic activity pattern towards primary and secondary benzyl alcohols, as indicated by the Hammett correlation for the oxidation reaction of p-X-C(6)H(4)CH(2)OH (rho = -0.45) and p-X-C(6)H(4)CH(OH)CH(3) (rho = +0.22) (X = OMe, CH(3), H, Cl, CF(3)). Both a sigmoidal curve from the plot of initial rate vs [PhCH(OH)CH(3)] (K(0.5) = 0.34 M; Hill coefficient, n = 4.2+/-0.1) and the phosphine inhibition kinetics revealed the highly cooperative nature of the complex for the oxidation of secondary alcohols.     

Growth mechanism of titanium dioxide nanowires for dye-sensitized solar cells

Mesoporous films made of titanium dioxide nanowires are desirable for dye-sensitized solar cells because nanowires provide direct conduction pathways for photogenerated electrons. Anatase titanium dioxide nanowires with polycrystalline microstructure were synthesized on titanium foil using a three-step process. First, the top surface of the titanium foil was transformed to Na(2)Ti(2)O(4)(OH)(2) nanotubes through hydrothermal oxidation in NaOH. Next, the Na(2)Ti(2)O(4)(OH)(2) nanotubes were converted to H(2)Ti(2)O(4)(OH)(2) nanotubes by ion exchange. Finally, the H(2)Ti(2)O(4)(OH)(2) nanotubes were converted to polycrystalline anatase nanowires through a topotactic transformation. The film morphology evolution, crystal structure transformations and growth mechanism are described in detail. Titanium foil reacts with NaOH to form Na(2)Ti(2)O(4)(OH)(2) sheets, which exfoliate and spiral into nanotubes. The Na(2)Ti(2)O(4)(OH)(2) nanotubes are immersed in HCl solution to replace the Na(+) ions with H(+) ions. During the topotactic transformation of H(2)Ti(2)O(4)(OH)(2) nanotubes to anatase TiO(2) nanowires, the sheets made of edge bonded TiO(6) octahedra in the H(2)Ti(2)O(4)(OH)(2) nanotubes dehydrate and move towards each other to form anatase crystals oriented along the nanotube axis which creates a polycrystalline nanowire. These mesoporous TiO(2) nanowire films were suitable for use as dye-sensitized solar cell photoanodes.     

Modeling the effect of pH on biosorption of heavy metals by citrus peels

Biosorption by materials such as citrus peels could be a cost effective technique for removing toxic heavy metals from wastewater. Orange peels, lemon peels and lemon-based protonated pectin peels (PPP) had Langmuir sorption capacities of 0.7-1.2 mequiv./g (39-67 mg/g) of Cd per biosorbent dry weight. A potentiometric titration was interpreted using a continuous pK(a) spectrum approach. It revealed four acidic sites with pK(a) values of 3.8, 6.4, 8.4 and 10.7, and a total site quantity of 1.14 mequiv./g. Sorption isotherms of untreated citrus peels showed an unusual shape with two plateau values. Protonated pectin peels on the other hand showed a typical Langmuir behavior with a higher sorption capacity than untreated peels. At lower pH, metal binding was reduced due to increased competition by protons. This was modeled using pH-sensitive isotherm equations. It was not necessary to assume four binding sites; using one site with pK(a) 3.8 and a quantity of 1.14 mequiv./g was sufficient. It was possible to accurately predict metal uptake at one pH using the metal binding constant determined at a different pH. A 1:1 stoichiometry model fit the sorption isotherms shape better than a 1:2 stoichiometry. For constant pH, the 1:1 stoichiometry reduces to the Langmuir model.     

Biosorption of nickel from protonated rice bran

In the present study biosorption technique, the accumulation of metals by biomass was used for the removal of nickel from aqueous medium. The rice bran in its acid treated (H(3)PO(4)) form was used as a low cost sorbent. The adsorption characteristics of nickel on protonated rice bran were evaluated as a function of pH, biosorbent size, biosorbent dosage, initial concentration of nickel and time. Within the tested pH range (pH 1-7), the protonated rice bran displayed more resistance to pH variation, retaining up to 102 mg/g of the nickel binding capacity at pH 6. Meanwhile, at lower pH values the uptake capacity decreased. The % age removal of nickel was maximum at 0.25 g of biosorbent dose and 0.25 mm biosorbent size. At the optimal conditions, metal ion uptake was increased as the initial metal ion concentration increased up to 100mg/L. Kinetic and isotherm experiments were carried out at the optimal pH 6.0 for nickel. The metal removal rate was rapid, with 57% of the total adsorption taking place within 15-30 min. The Freundlich and Langmuir models were used to describe the uptake of nickel on protonated rice bran. The Langmuir and Freundlich model parameters were evaluated. The equilibrium adsorption data was better fitted to Langmuir adsorption isotherm model. The adsorption followed pseudo second-order kinetic model. The thermodynamic assessment of the metal ion-rice bran biomass system indicated the feasibility and spontaneous nature of the process and DeltaG degrees values were evaluated as ranging from -22.82 to -24.04 kJ/mol for nickel sorption. The order of magnitude of the DeltaG degrees values indicated an ion-exchange physiochemical sorption process.     

Untreated coffee husks as biosorbents for the removal of heavy metals from aqueous solutions

The objective of this work was to propose an alternative use for coffee husks (CH), a coffee processing residue, as untreated sorbents for the removal of heavy metal ions from aqueous solutions. Biosorption studies were conducted in a batch system as a function of contact time, initial metal ion concentration, biosorbent concentration and pH of the solution. A contact time of 72 h assured attainment of equilibrium for Cu(II), Cd(II) and Zn(II). The sorption efficiency after equilibrium was higher for Cu(II) (89-98% adsorption), followed by Cd(II) (65-85%) and Zn(II) (48-79%). Even though equilibrium was not attained in the case of Cr(VI) ions, sorption efficiency ranged from 79 to 86%. Sorption performance improved as metal ions concentrations were lowered. The experimental sorption equilibrium data were fitted by both Langmuir and Freundlich sorption models, with Langmuir providing the best fit (R2>0.95). The biosorption kinetics was determined by fitting first and second-order kinetic models to the experimental data, being better described by the pseudo-second-order model (R2>0.99). The amount of metal ions sorbed increased with the biosorbent concentration in the case of Cu(II) and Cr(VI) and did not present significant variations for the other metal ions. The effect of the initial pH in the biosorption efficiency was verified in the pH range of 4-7, and the results showed that the highest adsorption capacity occurred at distinct pH values for each metal ion. A comparison of the maximum sorption capacity of several untreated biomaterial-based residues showed that coffee husks are suitable candidates for use as biosorbents in the removal of heavy metals from aqueous solutions.     

NiO nanorings and their unexpected catalytic property for CO oxidation

Nickel oxide (NiO) nanorings were synthesized by controllable thermal decomposition of precursor Ni(OH)(2) nanoplates obtained via the reaction between Ni(NO(3))·6H(2)O and NaOH under hydrothermal conditions. The process of their formation was investigated and an unexpected catalytic property of this novel-shaped material is reported for CO oxidation.     

Synthesis of a novel layered double hydroxides [MgAl(4)(OH)(12)](Cl)(2)·2.4H(2)O and its anion-exchange properties

A novel layered double hydroxide of Mg and Al with composition [Mg(0.96)Al(4.00)(OH)(12)]Cl(1.86)(CO(3))(0.03)·2.4H(2)O, designated as MgAl(4)-Cl, was synthesized by mixing crystalline gibbsite (γ-Al(OH)(3)) and solid MgCl(2)·6H(2)O with subsequent hydrothermal treatment at 160 °C for 72h. The MgAl(4)-Cl exhibited a crystalline material of a layered structure, as evidenced from X-ray diffraction. Anion uptake experiments with the MgAl(4)-Cl showed that Cl(-) in the interlayer space can be exchanged with anions such as Br(-), H(2)PO(4)(-), CO(3)(2-) or dodecyl sulfate (DS(-)) from aqueous solutions with preservation of the layered structure. Uptake of NO(3)(-), BrO(3)(-) or SO(4)(2-) on the MgAl(4)-Cl showed different behavior; these anions can be exchanged within 1h maintaining the layered structure, but a release of Mg(2+) cations from the sample was observed with increased reaction time, resulting in collapse of the layered structure and formation of the gibbsite phase, as determined from chemical analyses and X-ray diffraction.     

Raman and infrared spectroscopic investigations on aqueous alkali metal phosphate solutions and density functional theory calculations of phosphate-water clusters

Phosphate (PO(4)(3-)) solutions in water and heavy water have been studied by Raman and infrared spectroscopy over a broad concentration range (0.0091-5.280 mol/L) including a hydrate melt at 23 degrees C. In the low wavenumber range, spectra in R-format have been constructed and the R normalization procedure has been briefly discussed. The vibrational modes of the tetrahedral PO(4)(3-)(aq) (T(d) symmetry) have been assigned and compared to the calculated values derived from the density functional theory (DFT) method for the unhydrated PO(4)(3-)(T(d)) and phosphate-water clusters: PO(4)(3-).H(2)O (C(2v)), PO(4)(3-).2H(2)O (D(2d)), PO(4)(3-).4H(2)O (D(2d)), PO(4)(3-).6H(2)O (T(d)), and PO(4)(3-).12H(2)O (T), a cluster with a complete first hydration sphere of water molecules. A cluster with a second hydration sphere of 12 water molecules and 6 in the first sphere, PO(4)(3-).18H(2)O (T), has also been calculated. Agreement between measured and calculated vibrational modes is best in the case of the PO(4)(3-).12H(2)O cluster and the PO(4)(3-).18H(2)O cluster but far less so in the case of the unhydrated PO(4)(3-) or phosphate-water cluster with a lower number of water molecules than 12. The asymmetric, broad band shape of v(1)(a(1)) PO(4)(3-) in aqueous solutions has been measured as a function of concentration and the asymmetric and broad band shape was explained. However, the same mode in heavy water has only half the full width at half-height compared to the mode in normal water. The PO(4)(3-) is strongly hydrated in aqueous solutions. This has been verified by Raman spectroscopy comparing v(2)(H(2)O), the deformation mode of water, and the stretching modes, the v(1)OH and v(3)OH of water, in K(3)PO(4) solutions as a function of concentration and comparison with the same modes in pure water. A mode at approximately 240 cm(-1) (isotropic R spectrum) has been detected and assigned to the restricted translational mode of the strong hydrogen bonds formed between phosphate and water, P-O...HOH. In very concentrated K(3)PO(4) solutions (C(0) > or = 3.70 mol/L) and in the hydrate melt, formation of contact ion pairs (CIPs) could be detected. The phosphate in the CIPs shows a symmetry lowering of the T(d) symmetry to C(3v). In the less concentrated solutions, PO(4)(3-)(aq) solvent separated ion pairs and doubly solvent separated ion pairs exist, while in very dilute solutions fully hydrated ions are present (C(0) < or = 0.005 mol/L). Quantitative Raman measurements have been carried out to follow the hydrolysis of PO(4)(3-)(aq) over a very broad concentration range. From the hydrolysis data, the pK(3) value for H(3)PO(4) has been determined to be 12.45 at 23 degrees C.     

Synthesis of hierarchical Ni(OH)(2) and NiO nanosheets and their adsorption kinetics and isotherms to Congo red in water

Ni(OH)(2) and NiO nanosheets with hierarchical porous structures were synthesized by a simple chemical precipitation method using nickel chloride as precursors and urea as precipitating agent. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy and nitrogen adsorption-desorption isotherms. Adsorption of Congo red (CR) onto the as-prepared samples from aqueous solutions was investigated and discussed. The pore structure analyses indicate that Ni(OH)(2) and NiO nanosheets are composed of at least three levels of hierarchical porous organization: small mesopores (ca. 3-5 nm), large mesopores (ca. 10-50 nm) and macropores (100-500 nm). The equilibrium adsorption data of CR on the as-prepared samples were analyzed by Langmuir and Freundlich models, suggesting that the Langmuir model provides the better correlation of the experimental data. The adsorption capacities for removal of CR was determined using the Langmuir equation and found to be 82.9, 151.7 and 39.7 mg/g for Ni(OH)(2) nanosheets, NiO nanosheets and NiO nanoparticles, respectively. Adsorption data were modeled using the pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetics equations. The results indicate that pseudo-second-order kinetic equation and intra-particle diffusion model can better describe the adsorption kinetics. The as-prepared Ni(OH)(2) and NiO nanosheets are found to be effective adsorbents for the removal of Congo red pollutant from wastewater as a result of their unique hierarchical porous structures and high specific surface areas.     

Arsenate removal from aqueous solution by cellulose-carbonated hydroxyapatite nanocomposites

Microwave-assisted synthesis of the cellulose-carbonated hydroxyapatite nanocomposites (CCHA) with CHA nanostructures dispersed in the cellulose matrix was carried out by using cellulose solution, CaCl(2), and NaH(2)PO(4). The cellulose solution was previously prepared by the dissolution of microcrystalline cellulose in NaOH-urea aqueous solution. Study was carried out to evaluate the feasibility of synthetic CCHA for As(V) removal from aqueous solution. Batch experiments were performed to investigate effects of various experimental parameters such as contact time (5 min - 8h), initial As(V) concentration (1-50mg/L), temperature (25, 35 and 45°C), pH (2-10) and the presence of competing anions on As(V) adsorption on the synthetic CCHA. Kinetic data reveal that the uptake rate of As(V) was rapid at the beginning and equilibrium was achieved within 1h. The adsorption process was well described by pseudo-first-order kinetics model. The adsorption data better fitted Langmuir isotherm. The maximum adsorption capacity calculated from Langmuir isotherm model was up to 12.72 mg/g. Thermodynamic study indicates an endothermic nature of adsorption and a spontaneous and favorable process. The optimum pH for As(V) removal was broad, ranging from 4 to 8. The As(V) adsorption was impeded by the presence of SiO(3)(2-), followed by PO(4)(3-) and NO(3)(-). The adsorption process appeared to be controlled by the chemical process.     

Utilization of fermentation waste (Corynebacterium glutamicum) for biosorption of Reactive Black 5 from aqueous solution

A fermentation waste, Corynebacterium glutamicum, was successfully employed as a biosorbent for Reactive Black 5 (RB5) from aqueous solution. This paper initially studied the effect of pretreatment on the biosorption capacity of C. glutamicum toward RB5, using several chemical agents, such as HCl, H(2)SO(4), HNO(3), NaOH, Na(2)CO(3), CaCl(2) and NaCl. Among these reagents, 0.1M HNO(3) gave the maximum enhancement of the RB5 uptake, exhibiting 195mg/g at pH 1 with an initial RB5 concentration of 500mg/l. The solution pH and temperature were found to affect the biosorption capacity, and the biosorption isotherms derived at different pHs and temperatures revealed that a low pH (pH 1) and high temperature (35 degrees C) favored biosorption. The biosorption isotherm was well represented using three-parameter models (Redlich-Peterson and Sips) compared to two-parameter models (Langmuir and Freundlich models). As a result, high correlation coefficients and low average percentage error values were observed for three-parameter models. A maximum RB5 uptake of 419mg/g was obtained at pH 1 and a temperature of 35 degrees C, according to the Langmuir model. The kinetics of the biosorption process with different initial concentrations (500-2000mg/l) was also monitored, and the data were analyzed using pseudo-first and pseudo-second order models, with the latter describing the data well. Various thermodynamic parameters, such as DeltaG degrees, DeltaH degrees and DeltaS degrees, were calculated, indicating that the present system was a spontaneous and endothermic process. The use of a 0.1M NaOH solution successfully desorbed almost all the dye molecules from dye-loaded C. glutamicum biomass at different solid-to-liquid ratios examined.     

Multifunctional microsized modified kaolin and its application in wastewater treatment

The multifunctional microsized ZnO-PO(4)(3-)-modified kaolin of average diameter about 500nm with the composition Na(2)O:ZnO:Na(3)PO(4):SiO(2):Al(2)O(3)=2.5-8.5:0.04-0.65:0.8-4.5:1.5-2.5:1 (molar ratio) were firstly synthesized from ZnO, Na(3)PO(4), NaOH and kaolin and characterized by standard techniques, its application in oilfield produced wastewater purification was also studied. It was found that the physical properties of ZnO-PO(4)(3-)-modified kaolin such as specific surface area, porous volume and pore diameter increased independently compared to the starting kaolin. It was also found that the prepared kaolin has multifunctional properties to decrease COD and BOD value, remove scaling ion (Fe(n+), Ca(2+) and Mg(2+)), improve MF, decrease bacteria and inhibit corrosion and can be used effectively in oilfield wastewater purification.     

Preparation and photocatalytic activity of iron oxide-loaded potassium titanate layered compounds

Iron oxide-loaded hydrous potassium tetratitanate (K0.3Ti4O7.3(OH)1.7) compounds consisting of 1.48 wt% (sample 'B'), 1.87 wt% (sample 'C') and 5.60 wt% (sample 'D') of iron oxide were synthesized by suspending the K0.3Ti4O7.3(OH)1.7 (sample 'A') in Fe2(SO4)3 solution for 24 h, followed by washing several times with deionized water and then dried at 120 degrees C for 24 h. The K0.3Ti4O7.3(OH)1.7 was synthesized by refluxing the K2Ti4O9 x 2H2O in 1 M HNO3 solution. Band-gap energies of the K0.3Ti4O7.3(OH)1.7 and the iron oxide-loaded samples are 3.12 +/- 0.6 eV and 2.23 +/- 0.09 eV, respectively. Photooxidation activity towards methylene blue decomposition under fluorescence irradiation was found to decrease as follow: sample 'B' > sample 'C' > Sample 'A' > sample 'D' > commercial Fe2O3-Blank. The photoactivity under sunlight irradiation was found to decrease as follow: sample 'B' > sample 'A' > Sample 'C' > sample 'D' > commercial Fe2O3-Blank.