Adsorption of Antimony on Sediments from Typical Water Systems in China: A Comparison of Sb(III) and Sb(V) Pattern

The present work investigated the adsorption of Sb(III) and Sb(V) on five sediment samples (Pearl River, Yangtze River, Yellow River, Yongding River, and Liao River) from typical water systems in China and the adsorption of Sb(V) on Pearl River sediment with different organic carbon (OC) fractions using batch experiments. In order to assess the contributions of sedimentary organic components to the overall adsorption of pentavalent Sb on sediments, one sediment sample was treated by commonly used chemical and physical methods to remove different organic components. Experimental data of Sb(III) and Sb(V) adsorption on five sediments were successfully modeled using the Freundlich (r² > 0.96) isotherm. In general, the sediments with high Fe and Al oxide contents and total organic carbon (TOC) had higher Sb(III) and Sb(V) adsorption than the sediments containing small amounts of Fe and Al oxides and TOC. Dissolved organic carbon (DOC) in sediment promoted the adsorption of Sb(V), and humin fractions and black carbon-like material in sediment had a high affinity for Sb(V).     

Production of granular activated carbons from select agricultural by-products and evaluation of their physical,chemical and adsorption properties

Representative samples of soft, low density, group 1 (rice straw, rice hulls, sugarcane bagasse) and hard, high density, group 2 agricultural by-products (pecan shells) were converted into granular activated carbons (GACs). GACs were produced from group 1 and 2 materials by physical activation or from group 2 materials by chemical activation. Carbons were evaluated for their physical (hardness, bulk density), chemical (ash, conductivity, pH), surface (total surface area), and adsorption properties (molasses color removal, sugar decolorization) and compared with two commercial reference carbons. The results show that the type of by-product, binder, and activation method determine the properties of GACs. Regardless of the binder, sugarcane bagasse showed a better potential than rice straw or rice hulls as precursor of GACs with the desirable properties of a sugar decolorizing carbon. Pecan shells produced GACs that were closest to the reference carbons in terms of all the properties investigated.     

Adsorption of heavy metals onto sewage sludge-derived materials

Two materials were produced from sewage sludge by: (1) pyrolysis of dried sewage sludge (PS); (2) chemical activation of dried sewage sludge with ZnCl(2) followed by pyrolysis (AS). The aim was to study the application of these materials for metal purification from water and to determine the efficiency of each material. Although AS displayed higher capacity, both PS and AS were able to adsorb these metals and the preferential order was equal: Hg(II)>Pb(II)>Cu(II)>Cr(III). For each metal-adsorbent pair, metal adsorption was highly pH dependent. In all cases the equilibrium was well described both by the Langmuir and the Freundlich isotherms. At the corresponding optimum pH, AS showed the following adsorption capacities: 175.4, 64.1, 30.7 and 15.4 mg/g of Hg(II), Pb(II), Cu(II) and Cr(III), respectively. These results indicate the potential application of these sewage sludge based adsorbents for the treatment of metal polluted effluents.     

Soil phosphorus fractions and adsorption as affected by organic and inorganic sources

The effect of organic and inorganic sources of phosphorus (P) on soil P fractions and P adsorption was studied in a field without plant growth on a Kandiudalf in western Kenya. A high-quality organic source, Tithonia diversifolia (Hemsley) A. Gray leaves, and a low-quality source, maize (Zea mays L.) stover, were applied alone or in combination with triple superphosphate (TSP). The P rate was kept constant at 15 kg P ha^-1. Soil extractable P (resin, bicarbonate and sodium hydroxide), microbial biomass P and C and P adsorption isotherms were determined during 16 weeks after application of treatments. Application of tithonia either alone or with TSP increased resin P, bicarbonate P, microbial P, and sodium hydroxide inorganic P. Tithonia alone reduced P adsorption at 2–16 weeks. Maize stover had no effect on any of the P fractions or P adsorption. At 8 weeks, the application of tithonia reduced microbial C-to-P ratio (20) as compared to maize stover, TSP and the control (31–34). The reduction in P adsorption by tithonia was accompanied by increases in all measured P fractions, the sum of P in those fractions (resin, bicarbonate and sodium hydroxide) being larger than the P added. The reduction in P adsorption apparently resulted from competition for adsorption sites, probably by organic anions produced during decomposition of the high quality tithonia. Integration of inorganic P (TSP) with organic materials had little added benefit compared to sole application of TSP, except that combination of tithonia with TSP increased microbial biomass. The results indicate that a high quality organic input can be comparable to or more effective than inorganic P in increasing P availability in the soil.     

Cadmium adsorption by the non-living biomass of microalgae grown in axenic mass culture

The freeze-dried (extracted and non-extracted) biomass of 15 microalgal species grown in axenic mass culture and belonging to the Cyanobacteria, Chloro-, Eustigmato-, Phaeo-, Rhodo- and Tribophyceae were investigated for their ability to adsorb cadmium (Cd) ions from aqueous solutions. For comparison, other standard adsorbing materials (activated carbon, silica gel, siliceous earth) were included in the studies. The biomass of 11 microalgae exhibited a higher Cd adsorption than the standard materials. Extraction of the algal biomass increased the Cd adsorption capability of some, but not all microalgae. High Cd adsorption was found inAnabaena lutea, Nodularia harveyana, andNostoc commune (Cyanobacteria),Chlamydomonas sp. (Chlorophyceae),Bumilleriopsis filiformis (Tribophyceae), and inEctocarpus siliculosus, Halopteris scoparia andSpermatochnus paradoxus (Phaeophyceae). The specific surface (m² cm^–3) of the various microalgae was determined by means of laser diffractometry.Anabaena inaequalis andA. lutea (Cyanobacteria) and the Phaeophyceae had especially high Cd adsorption per surface unit. Most of the Cd adsorbed to these various materials could be desorbed subsequently with diluted mineral acid (pH 2).     

Adsorption of Clostridium thermocellum cellulases onto pretreated mixed hardwood, avicel, and lignin

Adsorption of Avicel-hydrolyzing activity was examined with respect to: mixed hardwood flour pretreated with 1% sulfuric acid for 9 s at 220 degrees C (PTW220), lignin prepared from PTW220 by either acid or enzymatic hydrolysis, and Avicel. Experiments were conducted at 60 degrees C for all materials, and also at 25 degrees C for PTW220. Based on transient adsorption results and reaction rates, times were selected at which to characterize adsorption at 60 degrees C as follows: PTW220, 1 min; lignin, 30 min; and Avicel, 45 min. Similar results were obtained for adsorption of cellulase activity to PTW220 at 25 and 60 degrees C, and for lignin prepared by enzymatic and acid hydrolysis. For all materials, adsorption was described well by a Langmuir equation, although the reversibility of adsorption was not investigated. Langmuir affinity constants (L/g) were: PTW220, 109; lignin, 17.9; Avicel, 4.3; cellulose from PTW220, >/=187. Langmuir capacity constants were 760 for PTW220 and 42 for Avicel; the cellulase binding capacity of lignin appeared to be very high under the conditions examined, and could not be determined. At low and moderate cellulase loadings at least, the majority of cellulase activity adsorbed to PTW220 is bound to the cellulosic component. The results indicate that PTW220, and its cellulose component in particular, differ radically from Avicel with respect to adsorption. Avicel-hydrolyzing activity and CMC-hydrolyzing activities were found to bind to Avicel with a constant ratio of essentially one, consistent with adsorption of a multi-activity complex. (c) 1993 John Wiley & Sons, Inc.     

Adsorption of copper and zinc by biochars produced from pyrolysis of hardwood and corn straw in aqueous solution

Biochars produced by pyrolysis of hardwood at 450 °C (HW450) and corn straw at 600 °C (CS600) were characterized and investigated as adsorbents for the removal of Cu(II) and Zn(II) from aqueous solution. The adsorption data were well described by a Langmuir isotherm, with maximum Cu(II) and Zn(II) adsorption capacities of 12.52 and 11.0 mg/g for CS600, 6.79 and 4.54 mg/g for HW450, respectively. Thermodynamic analysis suggested that the adsorption was an endothermic process and did not occur spontaneously. Although Cu(II) adsorption was only marginally affected by Zn(II), Cu(II) competed with Zn(II) for binding sites at Cu(II) and Zn(II) concentrations ?1.0 mM. Results from this study indicated that plant-residue or agricultural waste derived biochar can act as effective surface sorbent, but their ability to treat mixed waste streams needs to be carefully evaluated on an individual basis.     

Biochar derived from anaerobically digested sugar beet tailings: characterization and phosphate removal potential

Two biochars were produced from anaerobically digested and undigested sugar beet tailings through slow-pyrolysis at 600 °C. The digested sugar beet tailing biochar (DSTC) and raw sugar beet tailing biochar (STC) yields were around 45.5% and 36.3% of initial dry weight, respectively. Compared to STC, DSTC had similar pH and surface functional groups, but higher surface area, and its surface was less negatively charged. SEM-EDS and XRD analyses showed that colloidal and nano-sized periclase (MgO) was presented on the surface of DSTC. Laboratory adsorption experiments were conducted to assess the phosphate removal ability of the two biochars, an activated carbon (AC), and three Fe-modified biochar/AC adsorbents. The DSTC showed the highest phosphate removal ability with a removal rate around 73%. Our results suggest that anaerobically digested sugar beet tailings can be used as feedstock materials to produce high quality biochars, which could be used as adsorbents to reclaim phosphate.     

Large-scale purification of recombinant human angiostatin

A process for the purification of recombinant human angiostatin (rhAngiostatin), produced by Pichia pastoris fermentation operated at the 2000-L scale, is reported. rhAngiostatin was recovered and purified directly from crude fermentation broth by cation exchange expanded bed adsorption chromatography. Anion exchange chromatography, hydroxyapatite chromatography, and hydrophobic interaction chromatography were used for further purification. Full-length rhAngiostatin was separated from rhAngiostatin molecules fragmented by endoproteolysis. On average, 140 g of rhAngiostatin was produced per batch, with an overall yield of 59% (n = 9). The purification process was completed in approximately 48 h and used only inexpensive and nontoxic raw materials. Methods development, process synthesis, and process scale-up data are presented and discussed.     

Upgrading sewage sludges for adsorbent preparation by different treatments

Addressing the adequate management of sludges produced at sewage plants is becoming a fundamental need as a consequence of the high production volumes, both current and forecasted, of this byproduct. European waste-treatment policies consider reuse of sludges as one of the preferred actions; along those lines this study proposes using sewage sludges as adsorbents for pollutants contained in wastewaters. As potential adsorbents, sludges dried at 105 degrees C, dried and pyrolyzed, or dried and chemically activated were tried. As adsorbate, methylene blue was used in order to characterize the adsorption capacity of the different materials. Although surface areas corresponding to pyrolyzed and chemically activated sludges were around 80 and 390 m2/g, respectively, both these materials exhibited poor levels of methylene blue adsorption which may have been due to their high proportions of micropores. Sludges only dried, on the contrary, showed significant methylene blue adsorption capacities.     

Efficient decolorization of an anthraquinone dye by recombinant dye-decolorizing peroxidase (rDyP) immobilized in silica-based mesocellular foam

A recombinant dye-decolorizing peroxidase (rDyP) produced from Aspergillus oryzae was immobilized in synthesized silica-based mesocellular foam (MCF: average pore size 25 nm) and used for decolorization of the anthraquinone dye, Remazol Brilliant Blue R (RBBR). The adsorption yields of rDyP immobilized in MCF increased as the pH decreased from 6 to 3. However, the activity yields of the immobilized rDyP decreased with decreasing pH. The overall efficiency, defined as adsorption yield × activity yield, reached its maximum of 83% at pH 5. In repeated dye-decolorization tests, 20 batches of RBBR could be decolorized by the MCF-immobilized rDyP. MCF showed significantly better performance for rDyP immobilization in term of retaining enzyme activity and dye-decolorization ability compared to previous studies using other mesoporous materials.     

Antifouling poly(β-peptoid)s

A new type of polymer highly resistant to nonspecific protein adsorption is reported. Poly(N-methyl-β-alanine) (PMeA) and poly(N-ethyl-β-alanine) (PEtA) synthesized via cobalt-catalyzed carbonylative polymerization of N-methylaziridine and N-ethylaziridine were end-functionalized with thiol groups and grafted onto Au surfaces. Protein adsorption was studied by the surface plasmon resonance (SPR) method. The amounts of representative single proteins adsorbed onto the PMeA- and PEtA-grafted surfaces were below the detection limit of SPR at the pg/mm(2) level. After exposure to full blood plasma and serum for 10 min, protein adsorption was at the level of ～ 100 pg/mm(2), similar to the level of protein adsorption on poly(ethylene glycol) surfaces subjected to identical conditions. These poly(β-peptoid)s therefore provide excellent protein resistance comparable to the best antifouling materials known to date. The strong proton-accepting ability when forming hydrogen bonds is suggested to be an important attribute for these poly(β-peptoid)s as well as other poly(tertiary amide)s as antifouling materials.     

Impacts of drinking water pretreatments on the formation of nitrogenous disinfection by-products

The formation of disinfection by-products (DBPs), including both nitrogenous DBPs (N-DBPs) and carbonaceous DBPs (C-DBPs), was investigated by analyzing chlorinated water samples following the application of three pretreatment processes: (i) powdered activated carbon (PAC) adsorption; (ii) KMnO(4) oxidation and (iii) biological contact oxidation (BCO), coupled with conventional water treatment processes. PAC adsorption can remove effectively the precursors of chloroform (42.7%), dichloroacetonitrile (28.6%), dichloroacetamide (DCAcAm) (27.2%) and trichloronitromethane (35.7%), which were higher than that pretreated by KMnO(4) oxidation and/or BCO process. The removal efficiency of dissolved organic carbon by BCO process (76.5%)--was superior to that by PAC adsorption (69.9%) and KMnO(4) oxidation (61.4%). However, BCO increased the dissolved organic nitrogen (DON) concentration which caused more N-DBPs to be formed during subsequent chlorination. Soluble microbial products including numerous DON compounds were produced in the BCO process and were observed to play an essential role in the formation of DCAcAm in particular.     

Nanoconfined gases,liquids and liquid crystals in porous materials

We propose here to give an overview of gases and liquids adsorption in the materials of Institute Lavoisier (MIL)-101(Cr), MIL-53(Cr) and silica materials. We present some recent results of systems of interests such as the H₂ adsorption in MIL-101(Cr) and CO₂ and H₂S adsorption in the MIL-53(Cr) material. In addition, we will examine the sensitivity in water force field for water adsorption in hydrophilic and hydrophobic silica nanopores and we evaluate the Gay–Berne liquid crystal adsorption in the smooth and rough pores.     

Different phyllosilicates as supports for lipase immobilisation

The aim of this work was to determine the enzymatic activities resulting from the adsorption of Rhizomucor miehei lipase (RML) and Candida cylindracea lipase (CCL) onto three different phyllosilicates (sepiolite, palygorskite and montmorillonite), comparing the resultant activities with those obtained following similar immobilisation technique on a widely used resin (Duolite A-568). Due to the different adsorption mechanisms produced, different derivatives with higher hydrolytic activities can be obtained. Comparing the clays tested, the results showed that, in comparison with the laminar silicate (montmorillonite sample) and Duolite A-568 (spherical particles), fibrous materials (palygorskite and sepiolite) resulted in derivatives with higher hydrolytic activities in the hydrolysis of different ethyl esters. Moreover, according to the data obtained with the electrophoresis, the selectivity of immobilisation for RML in the case of fibrous silicates was optimal. As a conclusion, and according to the activities and selectivities measured, at least two out of the four studied materials (sepiolite and palygorskite) would be useful as supports for immobilisation for proteins of relatively low molecular weight (such as RML) for further use in biotransformations, while for C. cylindracea the immobilisation onto duolite rendered a derivative specially active in the hydrolysis of ethyl formiate (esterasic activity).     

Enzyme adsorption on SO2 catalyzed steam-pretreated wheat and spruce material

Lignocellulose is widely recognized as a sustainable substrate for biofuels production, and the enzymatic hydrolysis is regarded as a critical step for the development of an effective process for the conversion of cellulose into ethanol. One key factor affecting the overall conversion rate is the adsorption capacity of the cellulase enzymes to the surface of the insoluble substrate. Pretreatment has a strong impact on hydrolysis, which could be related to both chemical changes and morphological changes of the material. In the current work, the accessibility of four differently pretreated wheat straw substrates, two differently pretreated spruce materials, and Avicel cellulose was investigated. Adsorption isotherms (at 4 °C and 30 °C) for a cellulase preparation were obtained, and the rates of hydrolysis were determined for the different materials. Furthermore, the surface area and pore size distribution of the various materials were measured and compared to adsorption and hydrolysis properties, and the structures of the pretreated materials were examined using scanning electron microscopy (SEM).The results demonstrated a positive correlation between enzyme adsorption and the substrate specific surface area within each feedstock. Overall, the amount of enzyme adsorbed was higher for pretreated spruce than for the pretreated wheat straw, but this was not accompanied by a higher initial rate of hydrolysis for spruce. Also, the difference in the measured endoglucanase adsorption and overall FPU adsorption suggests that a larger fraction of the enzyme adsorbed on spruce was unproductive binding. The SEM analysis of the material illustrated the structural effects of pretreatment harshness on the materials, and suggested that increased porosity explains the higher rate of hydrolysis of more severely pretreated biomass.     

Adsorption of Various Enzymes Onto Talcs Scope and Limitations of This New Immobilization System

The adsorption of various enzymes (proteases, lipases and peroxidases) onto the surface of talc (a hydrophobic support) and non- talc materials was investigated. In general, adsorption was favored by the hydrophobicity of the support. We found little evidence for the ionic interactions that characterize adsorption onto mineral supports (clays, porous glasses). Modification of the hydrophobic-hydrophilic balance of the talc support produced new immobilized biocatalysts with high enzyme activity (both lipases and horseradish peroxidase). This represents the first example of this type of talc-protein interaction.     

The removal of mercury (II) from water by Ag supported on nanomesoporous silica

In this study, the synthesis of SBA-15/Ag nanocomposite materials with different amounts of silver (2.5, 5, and 10 %) has been investigated under acidic conditions by using P123 as a template via the direct method. The nanocomposites of SBA-15 were synthesized by the same method and by the addition of silver salt. Finally, the nanocomposite materials were examined for the removal of mercury ions from wastewater as an adsorbent by the reverse titration method. Characterization was carried out through x-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N₂ adsorption-desorption (Brunauer–Emmett–Teller). XRD spectra confirmed the presence of silver nanoparticles within the amorphous silica matrix of SBA-15. The Barrett–Joyner–Halenda analysis showed that SBA-15 and SBA-15/Ag have a narrow pore size distribution. SEM images demonstrated that the morphology of the matrix of SBA-15 is in spherical state. Furthermore, wavelength dispersive x-ray spectroscopy identified the presence and distribution of silver nanoparticles inside the pore channels and outside of them. Typical TEM images of SBA-15 and SBA-15/Ag (5 wt.%) indicated a regular hexagonal pore structure with long-range order and long channels. In SBA-15/Ag (5 wt.%) sample, the nanoparticles of silver was found into the pores and outside of them. The removal of mercury ions from wastewater using mesoporous silica nanocomposite containing silver nanoparticles was studied by the reverse titration analysis. The best capacity of adsorption of mercury ions from wastewater was obtained for SBA-15/Ag (5 wt.%) sample, which was equal to 42.26 mg/g in 20 min at pH of 7. The Freundlich model was used to explain the adsorption characteristics for the heterogeneous surface, and \( {K}_{\mathrm{f}} \) (adsorption capacity) and n (adsorption intensity) were determined for Hg (II) ion adsorption on SBA-15/Ag nanocomposite materials with different amounts of silver (2.5, 5, and 10 %). The value of R ² was about 0.99, 0.99, 0.98, and 0.98 and K _f was about 42, 48, 58, and 58 mg/g for SBA-15/Ag, SBA-15/Ag (2.5 %), SBA-15/Ag (5 %), and SBA-15/Ag (10 %), respectively. Furthermore, the values of n >1 show a favorable adsorption process for Hg (II) ion adsorption on SBA-15/Ag nanocomposite materials. Moreover, the Langmuir isotherm model evaluation showed that the correlation coefficients for all concentrations were R ² >0.99, indicating that Hg (II) ions were adsorbed on the surface of SBA-15/Ag via chemical and physical interaction. Additionally, the analytic hierarchy process (AHP) and Technique of Order Preference Similarity to the Ideal Solution (TOPSIS) methods that depend on the criteria of the surface area, amount of adsorbent, pore volume, and cost of synthesis were used. The evaluation of results showed that the best sample was SBA-15/Ag (5 wt.%). Furthermore, the research work highlighted the antibacterial nanocomposite with suitable adsorption of Hg (II) ions from water solutions and supported its potential for environmental applications. This nanocomposite can be used in the absorption domain of Hg (II) ions from water solutions.     

Recovery and purification of aprotinin from industrial insulin-processing effluent by immobilized chymotrypsin and negative IMAC chromatographies

Aprotinin, a bovine protease inhibitor currently also produced in recombinant bacteria, yeast, and corn, has valuable applications as a human therapeutic and in tissue culture. The objective of this work was to develop the basis of a large-scale aprotinin purification process centered on immobilized metal ion affinity chromatography (IMAC). This technique uses ligands—metal ions—of a lower cost and higher stability than those traditionally used in affinity chromatography. Since aprotinin does not interact with IMAC ligands, collection is from the nonretained fractions (negative chromatography). Stirred-tank batch IMAC adsorption experiments indicated that one-step aprotinin purification could not be successful. Immobilized chymotrypsin chromatography was then used as a prepurification step, yielding a suitable feed for IMAC (with purification factors as high as 476). IMAC column fed with these prepurified materials produced purified aprotinin in the nonretained fractions with purification factors as high as 952.     

Metal-Induced Production of a Novel Bioadsorbent Exopolysaccharide in a Native Rhodotorula mucilaginosa from the Mexican Northeastern Region

There is a current need to develop low-cost strategies to degrade and eliminate industrially used colorants discharged into the environment. Colorants discharged into natural water streams pose various threats, including: toxicity, degradation of aesthetics and inhibiting sunlight penetration into aquatic ecosystems. Dyes and colorants usually have complex aromatic molecular structures, which make them very stable and difficult to degrade and eliminate by conventional water treatment systems. The results in this work demonstrated that heavy metal-resistant Rhodotorula mucilaginosa strain UANL-001L isolated from the northeast region of Mexico produce an exopolysaccharide (EPS), during growth, which has colorant adsorption potential. The EPS produced was purified by precipitation and dialysis and was then physically and chemically characterized by Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and chemical elemental analysis. Here, the ability of the purified EPS produced to adsorb methylene blue (MB), which served as a model colorant, is studied. MB adsorption by the EPS is found to follow Langmuir Adsorption Isotherm kinetics at 25°C. Further, by calculating the Langmuir constant the adsorption capabilities of the EPS produced by the Rhodotorula mucilaginosa strain UANL-001L is compared to that of other adsorbents, both, microbially produced and from agroindustrial waste. The total adsorption capacity of the EPS, from the Rhodotorula mucilaginosa strain UANL-001L, was found to be two-fold greater than the best bioadsorbents reported in the literature. Finally, apart from determining which heavy metals stimulated EPS production in the strain, the optimal conditions of pH, heavy metal concentration, and rate of agitation of the growing culture for EPS production, was determined. The EPS reported here has the potential of aiding in the efficient removal of colorants both in water treatment plants and in situ in natural water streams.