Preparation of Pectin-Based Biosorbents for Cadmium and Lead Ions Removal

The optimal formation conditions of pectin-based, as well as new hybrid pectin-guar gum, biosorbents were found. The lead affinity for obtained biosorbents was very strong even in solution of pH = 1, in opposite to cadmium, which was adsorbed from solutions of pH ≥ 2. The sorption capacities in the studied conditions were about 0.6 and 0.8 mmol/g for cadmium and lead, respectively. The cadmium removal could be fast and it is almost quantitatively desorbed using 0.25 M HNO₃, while desorption of lead required 1 M HNO₃ to achieve a removal efficiency of ca. 75% from pectin-based beads. The possibility of biosorbents’ reuse was also proved. Addition of guar gum to pectin biosorbent did not change its sorption properties significantly.     

Sorption and desorption of cadmium and lead on pectin-based biosorbents – batch and column studies

ABSTRACT

The hybrid pectin-based beads containing carob, gellan and xanthan gum were studied to be suitable for removing the Cd(II) and Pb(II) from aqueous solution in column system. Desorption of the ions from studied materials was also determined in batch and continuous studies. It was possible to remove the Cd(II) and Pb(II) ions from solution of concentration ca. 130 and 250 mg/L, respectively, to the level permissible by law. Both ions may be completely removed from our biosorbents using mineral acid solutions (confirmed by mass balance). The minimal lifetime of sorbent was also determined to be at least 10 cycles.     

Binary Adsorption of a Zn(II)-Cu(II) Mixture onto Egeria densa and Eichhornia crassipes: Kinetic and Equilibrium Data Modeling by PSO

The adsorption of Zn(II) and Cu(II) ions onto two dry macrophytes used as biosorbents was investigated in batch systems. All single and binary metal sorption experiments using Egeria densa and Eicchornia crassipes biomasses as biosorbents were performed under constant shaking, at pH 5, with mixed grain size, and drying and sorption temperatures of 30°C. A 20–45 min equilibrium time range was attained with E. densa, whereas a 30–60 min equilibrium time was achieved with E. crassipes. It was also found that the overall adsorption kinetic data was best described by the pseudo second-order kinetic model, and that the intra-particle diffusion model was involved in the sorption process. An extended-to-multi-component Langmuir-type isotherm model and a parameter identification procedure based on the PSO method have been effectively used for the reproduction of the experimental data and the prediction of the maximum adsorption capacities of Zn(II) and Cu(II) ions in a binary metal ion solution. Finally, E. densa and E. crassipes biomasses exhibited opposite metal adsorption affinity order in the Zn(II)-Cu(II) binary system.     

Biosorption of heavy metals from aqueous solution using modified activated carbon: comparison of linear and nonlinear methods

BACKGROUND: Biosorption of heavy metals from aqueous solution by modified activated carbon with Phanerochaete chrysosporium immobilised in Ca‐alginate beads was investigated using a batch system and comparison of linear and nonlinear methods. RESULTS: The amount of Cu(II), Zn(II) and Pb(II) ion sorption by the beads was as follows: activated carbon with P. chrysosporium immobilised in Ca‐alginate beads (ACFCA) (193.4, 181.8, 136.6 mg g^?1) > activated carbon immobilised in Ca‐alginate beads (ACCA) (174.8, 162.0, 130.7 mg g^?1) > P. chrysosporium (F) (148.8, 125.6, 120.4 mg g^?1) > activated carbon (AC) (138.8, 112.3, 109.3 mg g^?1) > plain Ca‐alginate beads (PCA) (125.4, 105.2, 98.2 mg g^?1). The widely used Langmuir and Freundlich isotherm models were utilised to describe the biosorption equilibrium process. CONCLUSION: The results of this study suggest that the immobilisation of modified activated carbon with P. chrysosporium in Ca‐alginate beads is suitable for a batch system. The isotherm parameters were estimated using linear and nonlinear regression analyses. The surface charge density of the biosorbents varied with the pH of the medium; the maximum biosorption of heavy metal ions on the biosorbents was obtained when the pH was between 5.6 and 7.4. Copyright © 2008 Society of Chemical Industry     

Removal of Cadmium from Aqueous Solution using Wheat Stem,Corncob, and Rice Husk

Three kinds of agricultural by-products, wheat stem, corncob, and rice husk, were tested as biosorbents for cadmium removal from aqueous solution. The study was focused on the evaluation and comparison of the potential of the agriculture by-products as biosorbents of cadmium with the sorption isotherms determination. The impact of solution pH and kinetic study was also discussed. The result indicated that cadmium removal was strongly dependent on solution pH and the optimum pH range is 4.5 ～ 6.0. The sorption process was fast, and the sorption equilibrium can be attained within 60 min. The kinetic process fit well with the pseudo-second-order kinetic model. For the three kinds of biosorbents, the initial sorption rate as well as the maximum sorption capacity q _max calculated from the Langmuir isotherm equation showed the following tendency: rice husk > wheat stem > corncob. The maximum sorption capacity of the three kinds of biosorbents enhanced after being base treated, especially for wheat stem and corncob. This study indicated that wheat stem, corncob, and rice husk displayed the potential to be used as biosorbents for cadmium removal from aqueous solution.     

Effect of pH,flow rate and concentration on the sorption of Pb and Cd on montmorillonite: I. Experimental

Continuous column adsorption of lead (Pb) and cadmium (Cd) was studied using pH adjustment and calcium‐saturated montmorillonite in a short stainless steel column. Changing either pH or flow rate, while keeping inlet concentration of the ions constant, led to considerable changes in effluent concentrations and breakthrough curves (BTCs). At low pH values (2–4), H⁺ ions competed strongly with lead and cadmium ions; at intermediate pH (4–6), ionic size played the major role in adsorption and ion exchange and at high pH (6–9) precipitation was the major process taking place especially for lead sorption. At low flow rates less than 0.5 cm³ min⁻¹, sorption of both lead and cadmium increased due to the long retention time in the column. When both lead and cadmium ions were present in the feed, adsorption remained the same while that of cadmium decreased compared with single ion experiments. © 1999 Society of Chemical Industry     

Sol-gel synthesis and physicochemical properties of organosilicon materials functionalized by amino groups

The hybrid materials based on polysiloxane modified by amino groups have been synthesized by the sol-gel method. Aminated polysiloxane has been prepared by the copolycondensation reaction of tetraethoxysilane with γ-aminopropyltriethoxysilane (APS-1) and through the modification of the product (APS-2) of the hydrolysis of tetraethoxysilane by γ-aminopropyltriethoxysilane. The composition of sorbents has been confirmed by the elemental analysis and IR Fourier spectroscopy. The high degree of sorption extraction of copper(II), nickel(II), cobalt(II), zinc(II), cadmium(II), and lead(II) ions in the case of their coexistence in an ammonia-acetate buffer solution has been observed for polysiloxanes APS-2. The synthesized surface-modified materials exhibit the highest selectivity to nickel(II) and cobalt(II) ions.     

Sorption studies of manganese and cobalt from aqueous phase onto alginate beads and nano-graphite encapsulated alginate beads

Comparative sorption study of dissolved manganese and cobalt ions onto alginate beads (ABs) and thermally activated nano-carbon beads (NCBs) was performed. Acidic functionalities dominate over sorbent surface. Elemental analysis confirmed that divalent calcium replacement with heavy metal ions might be a possible sorption mechanism. Optimum metal uptake was observed at pH 8. Most of the metal ions (80–92%) were sorbed within 4 h, followed by a slower sorption stage. Mn(II) and Co(II) recovery was greater than 99% with 0.1 N HCl, and NCB could be repeatedly utilized for Mn(II) and Co(II) sorption with negligible loss in sorption capacity.     

Sorption studies of heavy metal ions on pectin-nano-titanium dioxide composite adsorbent

The Cu(II), Cd(II), Zn(II), and Pb(II) sorption kinetics and equilibrium on hybrid material, composed of pectin and titanium dioxide nanopowder, were examined. Parameters, such as pH and adsorbent dose, were also investigated. The experimental data were better described by the Langmuir model. The maximum adsorption capacities were 1.37, 0.68, 0.51, and 0.83 mmol/g for Cu(II), Cd(II), Zn(II), and Pb(II), respectively. The introduction of nano-TiO₂ improved the kinetics of the metal ion sorption. The titanium dioxide, despite its small content (6%), contributes to the removal of the examined metal ions and eventually to the adsorption capacity of hybrid beads.     

Functionalized galactoglucomannan‐based hydrogels for the removal of metal cations from aqueous solutions

New types of hydrogels derived from O‐acetyl galactoglucomannan (AcGGM) hemicellulose have been synthesized and characterized. The objective of this work was to analyze the sorption capacity (S) of three types of hydrogels containing AcGGM derivatives incorporated into the carboxylic groups of the polymer chain in the AA hydrogel, sulfonic groups in the APA hydrogel, and amide groups in the acrylamide (Aam) hydrogel. These hydrogels are capable of interacting and removing ions such as cadmium [Cd(II)], copper [Cu(II)], lead [Pb(II)], nickel [Ni(II)], and zinc [Zn(II)]. The results show that AA and Aam hydrogels had a lower sorption capacity of ions compared to the APA hydrogel, which had a high sorption capacity. The maximal sorption capacity was determined by the successive enrichment method, obtaining Pb(II) amount of 48.3 mg/g of AA hydrogel, 65.8 mg/g of APA hydrogel, and 40.8 mg/g of Aam hydrogel. Hence, Pb(II) ions are greatly retained by the three hydrogels. These results are promising for the development of new materials with potential applications in metal ion removal. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44093.     

Sorption isotherms of metal ions onto an N-(2-sulfoethyl)chitosan-based material from single- and multi-component solutions

The scope of work is to study the mutual influence of metal ions during their sorption by sulfoethylated chitosan. The sorption isotherms of metal ions from single- and multi-component solutions are obtained. The sorption capacity of the sorbent towards Ag(I) and Cu(II) is revealed to be 1.63 and 1.41 mmol/g in single-, and 1.40 and 0.85 mmol/g in five-component solution. By comparing the affinity parameter and capacity of sulfoethylated chitosan towards ions in single- and multi-component solutions, it is concluded that Ag(I) and Cu(II) ions suppress the sorption of cobalt(II), nickel(II), zinc(II), cadmium(II), magnesium(II), calcium(II), strontium(II), barium(II), manganese(II) and lead(II).     

Sorption of Trace Amounts of Pb(II) Ions on an Ion Imprinted Interpenetrating Polymer Network Based on Alginic Acid and Crosslinked Polyacrylamide

The removal of Pb(II) ion from our environment especially waste water is now shifting from the use of conventional adsorbents to the use of biosorbents. The presence of heavy metals in the environment is of major concern because of their toxicity and threat to human life and the environment. A new type of Pb(II) ion imprinted alginic acid interpenetrating polymer networks (IPN) were prepared for Pb(II) ion removal by ion imprinting strategy. The Pb(II) ion imprinted alginate and N,N’-methylene-bis-acrylamide(NNMBA)-crosslinked polyacrylamide based IPN were synthesized with acrylamide in the presence of alginic acid. The influence of matrix on the sorption efficiency for Pb(II) ion and selectivity against metal ions such as Zn(II), Cu(II), and Cd(II) ions on IPN were described. The structure and morphology of Pb(II) ion imprinted IPN were followed by various analytical methods. The separation characteristics of the IPN for Pb(II) ion were investigated by batch and column procedures and analyzed by AAS. Based on the packed columns with Pb(II) ion imprinted IPN, a highly selective sorbent for Pb(II) ion from aqueous solution was developed by the imprinting approach and the developed polymer could be used for the selective sorption of trace amounts of Pb(II) ions from coexisting metal ions and from waste water.     

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.     

Metal ion sorption by chitosan–tripolyphosphate beads

Heavy metal removal from wastewater is crucial for the proper management of discharged water from mining operations. This residual water is typically unusable for other purposes such as for human/animal, crop, or industrial consumption. Eco‐friendly adsorption materials are necessary to ensure the sustainable treatment of this wastewater. Therefore, the sorption of Cu(II), Cd(II), Pb(II), and Zn(II) ions onto chitosan–tripolyphosphate (CTPP) beads was investigated using real mining wastewater and prepared ion metal solutions. The effects of pH, contact time, temperature, selectivity, and maximum sorption capacity in successive batches at different concentrations were studied. The optimum sorption of cations, except for copper (pH 3) was found at pH 5. Equilibrium in the adsorption of all metals was reached at 24 h of contact. Studies of the maximum sorption capacity at different concentrations showed that the CTPP beads could adsorb 158, 55, 47, and 47 mg/g of Pb(II), Cu(II), Cd(II), and Zn(II), respectively. Experimental data for the sorption of Pb(II) were optimally correlated with the Langmuir model. The thermodynamic parameters such as the changes in enthalpy (ΔH⁰), entropy (ΔS⁰), and free energy (ΔG⁰) were determined. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45511.     

Sorption of cadmium and lead ions on modified groundnut (Arachis hypogea) husks

The removal of cadmium and lead ions from aqueous solutions by groundnut husks modified by reaction with EDTA (% N = 12.05) was examined by equilibrium sorption studies at 29°C. The maximum metal ion binding capacity of the EDTA-modified husk determined from the sorption isotherm from solutions of pH 6.8 was found to be 0.36 mmol g^?1 and 0.19 mmol g^?1 for Cd(II) and Pb(II) ions, respectively. It was found that the rate of sorption was particle-diffusion controlled, and the particle-diffusion control rate coefficient was determined to be of the order of 10^?2 min^?1.     

Mercury and lead sorption properties of poly(ethyleneimine) coated onto silica gel

In this article, we studied the sorption properties of poly(ethyleneimine) coated on silica gel for metal ions with impact on the environment, such as Zn(II), Cd(II), Hg(II), and Pb(II). The experiments were carried out by batch procedure and the effects of pH, concentration, and temperature were evaluated. In addition, the selectivity was studied for binary, ternary, and quaternary metal ion mixtures. Mercury and lead showed promising results, achieving higher than 65% of sorption after only 1 h of contact. Under competitive conditions, resin presented high selectivity toward Hg(II) reaching 91 and 87% of retention respect to total amount of ions for binary and quaternary mixtures, respectively. The effect of time on Pb(II) and Hg(II) sorption was studied by batch procedure and the experimental data were adjusted to pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. Pseudo-second-order model presented good agreement for Pb(II) sorption, while pseudo-first-order model fits better to Hg(II) sorption. Intra-particle diffusion model showed that sorption process is controlled mainly by film diffusion.     

Acid-basic and sorption properties of modified polyvinyl alcohol fibre containing polyethylenepolyamine groups

The function of formation of copper(II) ion complexes was determined, and the distribution and separation coefficients of heavy metal ions were calculated in sorption from complex salt solutions. The selectivity of polyamine-containing PVA fibre with respect to copper(II) and lead(II) ions was determined in sorption from complex salt solutions. It was found that the fibre exhibits sorption activity for platinum group metals. Translated from Khimicheskie Volokna, No. 1, pp. 32–36, January–February, 1998.     

Separation and preconcentration of some heavy‐metal ions using new chelating polymeric hydrogels

Two new chelating polymeric hydrogels, crosslinked polyacrylamide/triethylenetetraamine/CS₂Na (hydrogel I) and crosslinked polyacrylamide/diethylenetriamine/CS₂Na (hydrogel II), were prepared by the transamidation and dithiocarbamylation of crosslinked polyacrylamide. The products were characterized with elemental analysis and IR spectroscopy. In both polymeric hydrogels, the optimum pH for the removal of Cd(II), Pb(II), and Zn(II) ions ranged from 7 to 8, from 6 to 7, and from 7 to 8, respectively. The sorption isotherms of the investigated metal ions on the prepared hydrogels were developed, and the equilibrium data fitted the Langmuir and Freundlich isotherm models well. At the optimum pH for each metal ion, the maximum sorption capacities of hydrogel I toward Cd(II), Pb(II), and Zn(II) ions, estimated from the Langmuir model, were 5.3, 0.63, and 1.27 mmol/g, respectively, and those of hydrogel II were 4.1, 0.59, and 0.89 mmol/g, respectively. The experimental sorption capacities of hydrogel I toward Cd(II), Pb(II), and Zn(II) ions were 4.5, 0.6, and 1.2 mmol/g, respectively. In the case of hydrogel II, the capacities were 3.7, 0.52, and 0.88 mmol/g in the same prescribed order. The thermodynamic parameters (the free energy of sorption, enthalpy change, and entropy change) for cadmium, lead, and zinc sorption on the prepared polymers were also determined from the temperature dependence. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Diffusion kinetic study of cadmium(II) biosorption by Aeromonas caviae

The removal of cadmium from aqueous solution by sorption on Aeromonas caviae particles was investigated in a well‐stirred batch reactor. Equilibrium and kinetic experiments were performed at various initial bulk concentrations, biomass loads and temperatures. Biosorption equilibrium was established in about 1 h and biosorption was well described by the Langmuir and Freundlich biosorption isotherms. The maximum biosorption capacity was found as 155.32 mg Cd(II) g^?1 at 20 °C. The obtained sorption capacity is appreciably high for most experimental conditions; so A caviae may be considered as a suitable biosorbent for the removal of cadmium. Moreover, the sorption rate of cadmium onto A caviae particles was particularly sensitive to initial bulk concentration and solid load. A detailed analysis was conducted, examining several diffusion (external and intraparticle) kinetic models in order to identify a suitable rate expression. The results are discussed and indicate that biosorption of cadmium is a complex process that is described more correctly by more than one model. Copyright © 2004 Society of Chemical Industry     

Sorption Behavior of Y(III) from Chloride Medium with Polymer Composites Containing Di-2-ethyl Hexyl Phosphoric Acid and Multiwall Carbon Nanotube

Extractant impregnated polyethersulfone beads have been prepared by phase inversion method and investigated for yttrium recovery from aqueous medium. The effect of experimental parameters on yttrium sorption has been studied. Quantitative sorption of yttrium (> 90%) was attained after 8 hours of equilibration time in the case of D2EHPA impregnated composite beads. Analysis of sorption data by different kinetic and diffusion models suggested that the sorption of Y(III) followed the pseudo-second order model. Stability tests with polymeric composite beads by multiple cycles of sorption and desorption of Y(III) have established the feasibility of reusing the beads for sorption of metal ions.