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In this paper the possibility of implementing the new biosorbent composed of chemically modified short hemp fibers impregnated with alginate gel for adsorption of lead(II) and zinc (II) ions was investigated. Waste hemp fibers, alkaly treated, were used as an alginate carrier in order to improve the mechanical stability of alginate. Morphological characteristics of obtained alginate-hemp composite were investigated by scanning electron microscopy (SEM), while the Fourier transform infrared spectroscopy (FT-IR) was used for examination of surface chemistry. Alginate immobilization on the hemp fibers surface leads to the morphological changes, by decreasing the roughness of short hemp fibers. FT-IR analysis showed that surface chemistry was changed after alginate immobilization, primarily by increasing the amount of carboxyl groups. The presence of surface groups characteristic for hemp fibers, on the surface of biocomposite, indicate that the surface of hemp fibers is not completely covered by alginate. Adsorption characteristics of alginate-hemp biosorbent were examined through the adsorption of lead and zinc ions, and compared with the adsorption characteristics of alkali treated hemp fibers. Biosorption of lead and zinc ions onto both hemp fibers and alginate-hemp composite, represent fast process since 80 % of initial ions amount were adsorbed in first five minutes. Obtained adsorption data were analyzed by Lagergren pseudo-first and pseudo-second order kinetic models, as well as intraparticle diffusion model. It was found that biosorption of lead and zinc ions on alkali treated hemp fibers and alginate-hemp composite obey the pseudo-second order adsorption kinetics, indicating that adsorption/binding of ions is mediated by chemical forces rather than physical forces of attraction. This observation was confirmed by results of FT-IR analysis of alginate composite surface before and after ions adsorption. It was found that lead and zinc ions predominantly bind on c, U ovom radu ispitana je mogućnost primene novog biosorbenta, na bazi kratkih hemijski modifikovanih vlakana konoplje impregniranih alginatnim gelom, za adsorpciju jona olova(II) i cinka(II). Biosorbent na bazi alginata i alkalno tretiranih vlakana konoplje okarakterisan je sa aspekta strukture i morfologije primenom skenirajuće elektronske mikroskopije (SEM) i prirode funkcionalnih grupa korišćenjem infracrvene spektroskopije sa Furijeovim transformacijama (FT-IR). Adsorpcione karakteristike ovog kompozita, ispitivane su praćenjem kinetike adsorpcije jona olova i cinka, i upoređene su sa adsorpcionim karakteristikama alkalno tretiranih vlakana konoplje. Podaci dobijeni tokom adsorpcije, testirani su korišćenjem Lagergrenovog modela pseudo-prvog reda i pseudo-drugog reda, kao i modela intračestične difuzije. Slaganje modelnih i eksperimentalnih podataka pokazuje da adsorpcioni proces prati kinetiku pseudo-drugog reda, što upućuje na zaključak da tokom adsorpcije jona olova i cinka na površini ispitivanih uzoraka konoplje i kompozita alginat-konoplja, preovladava mehanizam hemisorpcije. Ova zapažanja su potvrđena i rezultatima FT-IR analize, koji pokazuju da se joni teških metala vezuju na karboksilnim, i delimično hidroksilnim grupama prisutnim na površini ispitivanog biokompozita. Na osnovu dobijenih rezultata zaključuje se da se novi biosorbent može uspešno koristiti, kao jeftin i efikasan adsorbent za uklanjanje jona teških metala iz vode.

A structural study of the surface complexation of Pb(II) on the (View the MathML source) surface of hematite was undertaken using crystal truncation rod (CTR) X-ray diffraction measurements under in situ conditions. The sorbed Pb was found to form inner sphere (IS) complexes at two types of edge-sharing sites on the half layer termination of the hematite (View the MathML source) surface. The best fit model contains Pb in distorted trigonal pyramids with an average Pbsingle bondO bond length of 2.27(4) Å and two characteristic Pb-Fe distances of 3.19(1) Å and 3.59(1) Å. In addition, a site coverage model was developed to simulate coverage as a function of sorbate-sorbate distance. The simulation results suggest a plausible Pb-Pb distance of 5.42 Å, which is slightly larger than the diameter of Pb’s first hydration shell. This relates the best fit surface coverage of 0.59(4) Pb per unit cell at monolayer saturation to steric constraints as well as electrostatic repulsion imposed by the hydrated Pb complex. Based on the structural results we propose a stoichiometry of the surface complexation reaction of Pb(II) on the hematite (1-102) surface and use bond valence analysis to assign the protonation schemes of surface oxygens. Surface reaction stoichiometry suggests that the proton release in the course of surface complexation occurs from the Pb-bound surface O atoms at pH 5.5.

In this paper the possibility of implementing the new biosorbent composed of chemically modified short hemp fibers impregnated with alginate gel for adsorption of lead(II) and zinc (II) ions was investigated. Waste hemp fibers, alkaly treated, were used as an alginate carrier in order to improve the mechanical stability of alginate. Morphological characteristics of obtained alginate-hemp composite were investigated by scanning electron microscopy (SEM), while the Fourier transform infrared spectroscopy (FT-IR) was used for examination of surface chemistry. Alginate immobilization on the hemp fibers surface leads to the morphological changes, by decreasing the roughness of short hemp fibers. FT-IR analysis showed that surface chemistry was changed after alginate immobilization, primarily by increasing the amount of carboxyl groups. The presence of surface groups characteristic for hemp fibers, on the surface of biocomposite, indicate that the surface of hemp fibers is not completely covered by alginate. Adsorption characteristics of alginate-hemp biosorbent were examined through the adsorption of lead and zinc ions, and compared with the adsorption characteristics of alkali treated hemp fibers. Biosorption of lead and zinc ions onto both hemp fibers and alginate-hemp composite, represent fast process since 80 % of initial ions amount were adsorbed in first five minutes. Obtained adsorption data were analyzed by Lagergren pseudo-first and pseudo-second order kinetic models, as well as intraparticle diffusion model. It was found that biosorption of lead and zinc ions on alkali treated hemp fibers and alginate-hemp composite obey the pseudo-second order adsorption kinetics, indicating that adsorption/binding of ions is mediated by chemical forces rather than physical forces of attraction. This observation was confirmed by results of FT-IR analysis of alginate composite surface before and after ions adsorption. It was found that lead and zinc ions predominantly bind on c, U ovom radu ispitana je mogućnost primene novog biosorbenta, na bazi kratkih hemijski modifikovanih vlakana konoplje impregniranih alginatnim gelom, za adsorpciju jona olova(II) i cinka(II). Biosorbent na bazi alginata i alkalno tretiranih vlakana konoplje okarakterisan je sa aspekta strukture i morfologije primenom skenirajuće elektronske mikroskopije (SEM) i prirode funkcionalnih grupa korišćenjem infracrvene spektroskopije sa Furijeovim transformacijama (FT-IR). Adsorpcione karakteristike ovog kompozita, ispitivane su praćenjem kinetike adsorpcije jona olova i cinka, i upoređene su sa adsorpcionim karakteristikama alkalno tretiranih vlakana konoplje. Podaci dobijeni tokom adsorpcije, testirani su korišćenjem Lagergrenovog modela pseudo-prvog reda i pseudo-drugog reda, kao i modela intračestične difuzije. Slaganje modelnih i eksperimentalnih podataka pokazuje da adsorpcioni proces prati kinetiku pseudo-drugog reda, što upućuje na zaključak da tokom adsorpcije jona olova i cinka na površini ispitivanih uzoraka konoplje i kompozita alginat-konoplja, preovladava mehanizam hemisorpcije. Ova zapažanja su potvrđena i rezultatima FT-IR analize, koji pokazuju da se joni teških metala vezuju na karboksilnim, i delimično hidroksilnim grupama prisutnim na površini ispitivanog biokompozita. Na osnovu dobijenih rezultata zaključuje se da se novi biosorbent može uspešno koristiti, kao jeftin i efikasan adsorbent za uklanjanje jona teških metala iz vode.

This study reports creative preparation of MnO2-biochar (MBR) via MnO2 modification of biochar (BR) derived from aerobically composted swine manure. SEM coupled with EDX analyzer, TEM, XRD, BET, and FT-IR were employed to examine the surface properties and pore structures of MBR and BR. Adsorption experiments of Pb(II) and Cd(II) including isotherms, kinetics, and thermodynamics as well as the influence of pH on zeta-potential were also investigated. The results indicated that MBR showed rougher and larger surface area and pore volume than BR. In batch adsorption, MBR showed superior adsorption performance (maximum capacity for Pb 268.0 mg/g and Cd 45.8 mg/g) to BR (Pb 127.75 and Cd 14.41 mg/g). The adsorption process was pH-dependent, and the removal efficiency reached its maximum at 0.2 g/L dosage of MBR, after which it declined. Finally, X-ray photoelectron spectrometer (XPS) studies indicated the oxidative Mn4+ on MBR, and suggested that apart from electrostatic attachment, specific adsorption (i.e., Pb/Cd-O or hydroxyl binding) and ion exchange were the removal mechanisms of metal ions. Therefore, this modification method toward BR was promising for wastewater treatment of heavy metal pollution. © 2017 American Chemical Society.

This study reports creative preparation of MnO2-biochar (MBR) via MnO2 modification of biochar (BR) derived from aerobically composted swine manure. SEM coupled with EDX analyzer, TEM, XRD, BET, and FT-IR were employed to examine the surface properties and pore structures of MBR and BR. Adsorption experiments of Pb(II) and Cd(II) including isotherms, kinetics, and thermodynamics as well as the influence of pH on zeta-potential were also investigated. The results indicated that MBR showed rougher and larger surface area and pore volume than BR. In batch adsorption, MBR showed superior adsorption performance (maximum capacity for Pb 268.0 mg/g and Cd 45.8 mg/g) to BR (Pb 127.75 and Cd 14.41 mg/g). The adsorption process was pH-dependent, and the removal efficiency reached its maximum at 0.2 g/L dosage of MBR, after which it declined. Finally, X-ray photoelectron spectrometer (XPS) studies indicated the oxidative Mn4+ on MBR, and suggested that apart from electrostatic attachment, specific adsorption (i.e., Pb/Cd-O or hydroxyl binding) and ion exchange were the removal mechanisms of metal ions. Therefore, this modification method toward BR was promising for wastewater treatment of heavy metal pollution. © 2017 American Chemical Society.

This study reports creative preparation of MnO2-biochar (MBR) via MnO2 modification of biochar (BR) derived from aerobically composted swine manure. SEM coupled with EDX analyzer, TEM, XRD, BET, and FT-IR were employed to examine the surface properties and pore structures of MBR and BR. Adsorption experiments of Pb(II) and Cd(II) including isotherms, kinetics, and thermodynamics as well as the influence of pH on zeta-potential were also investigated. The results indicated that MBR showed rougher and larger surface area and pore volume than BR. In batch adsorption, MBR showed superior adsorption performance (maximum capacity for Pb 268.0 mg/g and Cd 45.8 mg/g) to BR (Pb 127.75 and Cd 14.41 mg/g). The adsorption process was pH-dependent, and the removal efficiency reached its maximum at 0.2 g/L dosage of MBR, after which it declined. Finally, X-ray photoelectron spectrometer (XPS) studies indicated the oxidative Mn4+ on MBR, and suggested that apart from electrostatic attachment, specific adsorption (i.e., Pb/Cd-O or hydroxyl binding) and ion exchange were the removal mechanisms of metal ions. Therefore, this modification method toward BR was promising for wastewater treatment of heavy metal pollution. © 2017 American Chemical Society.

In this work, corn silk was chemically modified by 0.5 M HNO3 and used as biosorbent for removal of Pb (II) ions from aqueous solutions. The effect of biosorbent dosage was studied in batch experiments with 25 mL of aqueous lead solution of concentration 200 mg/L, at pH 5, 120 min of contact time and room temperature. The modified corn silk was characterized by pHPZC The maximum biosorption capacity was found to be 39.5 mg/g at 0.025 g of biosorbent dosage. The biosorption capacity decreased with increasing of biosorbent dosage.

The aim of this study is to investigate the use of keratin colloidal solution, which was obtained from wool, for the removal of Pb(II) from water. The addition of keratin colloidal solution (15 g L-1, 0.30 mL) to a Pb(II) solution (1.0 mM, 0.90 mL, pH 5.0) resulted in the formation and precipitation of a Pb-keratin aggregate. Measurement of the Pb(II) and protein concentrations in the supernatant solution revealed that 88 and 99 % of the Pb(II) and keratin protein were removed from the solution, respectively. The maximum Pb(II) uptake capacity of keratin in the colloidal solution was 43.3 mg g(-1). In addition, the Pb-keratin aggregate was easily decomposed via the addition of nitric acid, which enabled the recovery of Pb(II). However, aggregation did not occur in solutions with Pb(II) concentrations below 0.10 mM. Therefore, we used a keratin colloidal solution encapsulated in a dialysis cellulose tube to remove Pb(II) from 0.10 mM solutions, which enabled the removal of 95 % of the Pb(II). From these results, we conclude that keratin colloidal solution is useful for the treatment of water polluted with Pb(II).

In this article, a new typ of non-mercury metal-based electrode, antimony trifluoridebulk- modified carbon paste electrode (SbF3-CPE) is for the first time reported and examined for electrochemical stripping analysis of selected heavy metal ions at their trace concentration level. In the role of bulk modifier and a source of antimony film generated in state nascenti, SbF3 in a content of 3% (w/w) in the carbon paste mixture was the ultimate choice. All important experimental parameters have been optimised by using Cd(II) and Pb(II) as the model ions and employing the square-wave anodic stripping voltammetry (SWASV) as the proper technique. As found out, the SbF3-CPE has exhibited a finely linear response (with R2 = 0.999) in the concentration range of 20–120 g·L-1 Me(II), while the signal of interest could be reproduced with a relative error of 6.5% for Cd and 1.2% for Pb (n = 7).

Batch experiments were conducted to elucidate the adsorption of Pb(II) and three types of widely used surfactants (sodium dodecylbenzene sulfonate (SDBS), octyl-phenol-ethoxylate (TX-100), and benzalkonium chloride (BKC)) from aqueous solutions by using oxidized multiwall carbon nanotubes (OMWCNTs). The effect of each kind of surfactant on the adsorption of Pb(II) and vice versa were studied in detail. The results indicated that the pH values affected the adsorption of Pb(II). TX-100 and BKC to OMWCNTs dramatically, whereas the adsorption of SDBS was almost pH-independent at pH < 9 and then decreased with increasing pH at pH > 9. The adsorption of Pb(II) was enhanced obviously by the presence of SDBS, but slightly inhibited by the presence of BKC. The adsorption of Pb(II) can be well described by Langmuir model. The adsorption process in the Pb-surfactant-OMWCNT ternary system was attributed to electrostatic, hydrophobic and pi-pi interactions. XPS analysis showed that the adsorption mechanism was mainly due to chemical interaction between Pb(II) and the surface functional groups of OMWCNTs and the surfactants. (C) 2010 Elsevier B.V. All rights reserved.

Batch experiments were conducted to elucidate the adsorption of Pb(II) and three types of widely used surfactants (sodium dodecylbenzene sulfonate (SDBS), octyl-phenol-ethoxylate (TX-100), and benzalkonium chloride (BKC)) from aqueous solutions by using oxidized multiwall carbon nanotubes (OMWCNTs). The effect of each kind of surfactant on the adsorption of Pb(II) and vice versa were studied in detail. The results indicated that the pH values affected the adsorption of Pb(II). TX-100 and BKC to OMWCNTs dramatically, whereas the adsorption of SDBS was almost pH-independent at pH < 9 and then decreased with increasing pH at pH > 9. The adsorption of Pb(II) was enhanced obviously by the presence of SDBS, but slightly inhibited by the presence of BKC. The adsorption of Pb(II) can be well described by Langmuir model. The adsorption process in the Pb-surfactant-OMWCNT ternary system was attributed to electrostatic, hydrophobic and pi-pi interactions. XPS analysis showed that the adsorption mechanism was mainly due to chemical interaction between Pb(II) and the surface functional groups of OMWCNTs and the surfactants. (C) 2010 Elsevier B.V. All rights reserved.

Batch experiments were conducted to elucidate the adsorption of Pb(II) and three types of widely used surfactants (sodium dodecylbenzene sulfonate (SDBS), octyl-phenol-ethoxylate (TX-100), and benzalkonium chloride (BKC)) from aqueous solutions by using oxidized multiwall carbon nanotubes (OMWCNTs). The effect of each kind of surfactant on the adsorption of Pb(II) and vice versa were studied in detail. The results indicated that the pH values affected the adsorption of Pb(II). TX-100 and BKC to OMWCNTs dramatically, whereas the adsorption of SDBS was almost pH-independent at pH < 9 and then decreased with increasing pH at pH > 9. The adsorption of Pb(II) was enhanced obviously by the presence of SDBS, but slightly inhibited by the presence of BKC. The adsorption of Pb(II) can be well described by Langmuir model. The adsorption process in the Pb-surfactant-OMWCNT ternary system was attributed to electrostatic, hydrophobic and pi-pi interactions. XPS analysis showed that the adsorption mechanism was mainly due to chemical interaction between Pb(II) and the surface functional groups of OMWCNTs and the surfactants. (C) 2010 Elsevier B.V. All rights reserved.

This thesis is a summary and discussion of eight papers dealing with failures and structural aspects of Ni-Cd industrial pocket plate batteries, applications of voltammetry in adsorption studies on goethite (a-FeOOH) surfaces and synthesis and characterisation of nanostructured carbons. The work consists of different areas of chemistry; electrochemistry, structural chemistry and solution chemistry. Several experimental methods have been used; voltammetric methods, potentiometric titrations, X-ray diffraction methods, SEM, EDS, TEM and electrical testing. An in-situ X-ray diffraction method was developed to study the positive active material in the Ni-Cd industrial pocket plate battery. Voltammetry was used to study the battery materials electrochemically. The literature structural model of b-NiOOH (charged positive material) was questioned, the complexity of the positive material was shown and a new positive discharged phase of b-Ni(OH)2 was observed in this study. The failures of the batteries investigated were mainly connected to the presence of graphite in the positive electrodes and the extent of carbonation. The voltammetric technique, anodic stripping voltammetry, was thoroughly studied and was found to work satisfactory for determination of low metal ion concentrations in aqueous solution, as well as in goethite suspensions at different pH, using a mercury plated GC electrode and a Teflon cell. It was shown that the recently developed equilibrium models for Pb(II), Zn(II) and Cu(II) complexation on goethite at different pH could be used to predict the speciation in a wide concentration range, in single-metal as well as in the different two-metal systems. A chlorination synthesis method, by which it may be possible to produce bulk amounts, was used in order to produce nanostructured carbons. The initial carbide structure and the synthesis temperature were important parameters to determine the final carbon structure. The carbon structure formed from Al4C3 and C, Härtill 8 uppsatser