Lead and vanadium removal from a real industrial wastewater by gravitational settling/sedimentation and sorption onto Pinus sylvestris sawdust

Batch sorption with untreated Pinus sylvestris sawdust after settling/sedimentation phase to remove vanadium and lead from a real industrial wastewater was investigated using different adsorbent doses, initial pH, and contact time. The development of pH along the sorption test and a parallel investigation of metals release from sawdust in distilled water were carried out. In order to evaluate kinetic parameters and equilibrium isotherms, Lagergren first-order, pseudo-second-order, intra-particle diffusion and Freundlich models were explored. When the initial pH was reduced from 7.4 to 4.0, the sorption efficiency increased from 32% to 99% for Pb and from 43% to 95% for V. Whereas, V removal was positively correlated with the adsorbent dose, Pb removal was not. The sorption process was best described by pseudo-second-order kinetics. According to Freundlich parameters (K(f) and n) sawdust presented unfavourable intensity for sorption of V.     

Preparation and Characterization of Chemically Modified Silk Cotton Hull Activated Carbon and Its Effects on Cd(II) Removal from Aqueous Solutions

The novel biosorbent silk cotton hull, an agrowaste material, has been successfully utilized for the removal of cadmium(II) from aqueous solutions. The adsorption of cadmium onto three kinds of activated biosorbent has been studied: modified by concentrated sulfuric acid alone (AC), a mixture of concentrated sulfuric acid and hydrogen peroxide (AC1), and a mixture of concentrated sulfuric acid and ammonium persulfate (AC2). The adsorption studies were carried out to optimize the process parameters such as pH, adsorbent dosage, contact time, and initial metal ion concentration. Maximum metal removal was observed at pH 7.0 with a contact time of 90 min at stirring speed of 200 rpm with an adsorbent dosage of 4.0 g L^?1. The sorption isotherms were studied using the Langmuir, Freundlich, and Tempkin isotherm models. The maximum adsorption capacities were 100.00, 142.86, and 142.87 mg g^?1 for AC, AC1, and AC2, respectively. Accordingly, the surface modification of the activated carbons AC1 and AC2 enhanced cadmium removal greatly. The experiments demonstrated that the removal of metal ions followed the pseudo-second-order kinetic model. The sorption mechanism is discussed in terms of the activated surface properties. A relationship between the oxygen content and sorption was found in this novel material. Desorption experiments were carried out using hydrochloric acid with a view to generate the spent adsorbent and to recover the adsorbed metal ions.     

Liquid Chromatography of Aflatoxins

There are numerous reports on studies of aflatoxins, but there are only a few reports on the isolation and mutual separation of aflatoxins by liquid chromatography. Following the previous reports on the liquid chromatography of four kinds (B₁, B₂, G₁ and G₂) of aflatoxins, the authors carried out the chromatography of six kinds of aflatoxins including aflatoxins B_2a and G_2a. Various kinds of adsorbents and eluting solvents were examined, and then the good mutual separation of aflatoxins was obtained by using the Sephadex G-10 (CM), a newly prepared adsorbent containing carboxymethyl group, and pure water for eluting solvent. Aflatoxins G_2a, B_2a, G₂, B₂, G₁ and B₁ were eluted in this order.     

Prediction of removal efficiency of Lanaset Red G on walnut husk using artificial neural network model

An artificial neural network (ANN) model was used to predict removal efficiency of Lanaset Red (LR) G on walnut husk (WH). This adsorbent was characterized by FTIR-ATR. Effects of particle size, adsorbent dose, initial pH value, dye concentration, and contact time were investigated to optimize sorption process. Operating variables were used as the inputs to the constructed neural network to predict the dye uptake at any time as an output. Commonly used pseudo second-order model was fitted to the experimental data to compare with ANN model. According to error analyses and determination of coefficients, ANN was the more appropriate model to describe this sorption process. Results of ANN indicated that pH was the most efficient parameter (43%), followed by initial dye concentration (40%) for sorption of LR G on WH.     

Removal of perfluorooctane sulfonate from aqueous solution by crosslinked chitosan beads: sorption kinetics and uptake mechanism

The crosslinked chitosan beads were used as an efficient biosorbent to remove perfluorooctane sulfonate (PFOS) from aqueous solution. The chitosan biosorbent had a sorption capacity up to 5.5 mmol/g for PFOS at the equilibrium concentration of 0.33 mmol/L, much higher than some conventional adsorbents. The sorption kinetics indicated that the sorption equilibrium was reached quickly at high pH and low PFOS concentrations, and the adsorbent size also affected the sorption rate to some extent. The double-exponential model described the kinetic data well, and the sorption of PFOS on the chitosan beads was a diffusion-controlled process. Based on the sorption kinetics and adsorbent characterization, the uptake mechanisms including electrostatic and hydrophobic interactions were identified to be responsible for PFOS sorption, and the hemi-micelles and micelles may form in the porous structure due to high PFOS concentrations within the adsorbent, which had the main contribution to the high sorption capacity.     

Removal of heavy metals from water effluents using supermacroporous metal chelating cryogels

Applications of IDA in, for example, immobilized metal ion affinity chromatography for purification of His-tagged proteins are well recognized. The use of IDA as an efficient chelating adsorbent for environmental separations, that is, for the capture of heavy metals, is not studied. Adsorbents based on supermacroporous gels (cryogels) bearing metal chelating functionalities (IDA residues and ligand derived from derivatization of epoxy-cryogel with tris(2-aminoethyl)amine followed by the treatment with bromoacetic acid (defined as TBA ligand)) have been prepared and evaluated on capture of heavy metal ions. The cryogels were prepared in plastic carriers, resulting in desired mechanical stability and named as macroporous gel particles (MGPs). Sorption and desorption experiments for different metals (Cu2+, Zn2+, Cd2+, and Ni2+ with IDA adsorbent and Cu2+ and Zn2+ with TBA adsorbent) were carried out in batch and monolithic modes, respectively. Obtained capacities with Cu2+ were 74 μmol/mL (TBA) and 19 μmol/mL gel (IDA). The metal removal was higher for pH values between pH 3 and 5. Both adsorbents showed improved sorption at lower temperatures (10°C) than at higher (40°C) and the adsorption significantly dropped for the TBA adsorbent and Zn2+ at 40°C. Desorption of Cu2+ by using 1 M HCl and 0.1 M EDTA was successful for the IDA adsorbent whereas the desorption with the TBA adsorbent needs further attention. The result of this work has demonstrated that MGPs are potential treatment alternatives within the field of environmental separations and the removal of heavy metals from water effluents.     

Arsenic and fluoride removal by potato peel and rice husk (PPRH) ash in aqueous environments

Finding appropriate adsorbent may improve the quality of drinking water in those regions where arsenic (As) and fluoride (F^?) are present in geological formations. In this study, we evaluated the efficiency of potato peel and rice husk ash (PPRH-ash)-derived adsorbent for the removal of As and F from contaminated water. Evaluation was done in batch adsorption experiments, and the effect of pH, initial adsorbate concentration, contact time, and adsorbent dose were studied. Characteristics of adsorbents were analyzed using scanning electron micropcope (SEM) and Fourier transform infrared (FTIR) spectroscopy. Both the Langmuir and Freundlich isotherm models fitted well for F^? and As sorption process. The maximum adsorption capacity of adsorbent for As and F^? was 2.17 μg g^?1 and 2.91 mg g^?1, respectively. The As and Fi removal was observed between pH 7 and 9. The sorption process was well explained with pseudo-second order kinetic model. Arsenic adsorption was not decreased in the presence of carbonate and sulfate. Results from this study demonstrated potential utility of this agricultural biowaste, which could be developed into a viable filtration technology for As and F^? removal in As- and F-contaminated water streams.     

The influence of L-ascorbic acid on the antibacterial-toxic activity of aflatoxins on adsorbent layer

AIMS: To substantiate the role of formaldehyde (HCHO) and its reaction products in the mechanism of the antibacterial-toxic effect of aflatoxins B1 (AFB1), B2, G1 and G2. MATERIALS AND RESULTS: Toxins were separated by overpressured layer chromatography, which was followed by biological evaluation directly on the adsorbent layer (BioArena system with Pseudomonas savastanoi pv. phaseolicola indicator bacteria). HCHO formed in this system was eliminated with exogenously added capturer molecule dimedone and L-ascorbic acid (AA) and measured as the adduct of dimedone and HCHO. The amount of HCHO was higher in the toxin-containing spots, particularly in the most toxic AFB1 spot, compared to a toxinless background. 0.1 mg ml(-1)AA augmented, 0.2 mg ml(-1) dimedone or 0.5 and 1 mg ml(-1) AA reduced the antibacterial effect of all four aflatoxins. CONCLUSION: The antibacterial-toxic effect of aflatoxins may be mediated by HCHO (and/or its reaction products) generated from bound HCHO forms in the bacterial cells. Basis of antibacterial-toxic activity of the four aflatoxins appears the same. SIGNIFICANCE AND IMPACT OF THE STUDY: Involvement of HCHO as a key molecule in the effect of aflatoxins indicates a totally new mechanism of action of these dangerous molecules. The BioArena system is useful to dissect the mode of action of antimicrobial compounds from different biological matrices.     

Sorption of phosphate onto giant reed based adsorbent: FTIR, Raman spectrum analysis and dynamic sorption/desorption properties in filter bed

A sorption process for the removal of phosphate was evaluated under various conditions using a filter bed packed with giant reed (GR) based adsorbent. FTIR spectrum measurement validated the existence of grafted amine groups in the adsorbent and Raman spectrum displayed the characteristic peaks of different forms of phosphate. The column sorption capacity of the adsorbent for phosphate was 54.67 mg g⁻¹ in comparison with the raw GR of 0.863 mg g⁻¹. Influent pH demonstrated an essential effect on the performance of the filter bed as compared to other influent conditions (flow rates and influent concentrations) and the optimal pH was selected at 5.0-10.0. Eluents of HCl, NaOH and NaCl solutions with concentrations of 0.01-0.1 mol l⁻¹ showed the excellent capacities for desorption of phosphate from the adsorbent, and their elution processes could be finished in 90 min.     

The influence of biomass on the hydrodynamic behavior and stability of expanded beds

Expanded bed adsorption is an innovative chromatographic technology that allows the introduction of particle-containing feedstock without the risk of blocking the bed. Provided a perfectly classified fluidized bed (termed expanded bed) is formed in the crude feedstock and the biomass is not influencing protein transport towards the adsorbent surface, a sorption performance comparable to packed beds is found. The influence of biomass on the hydrodynamic stability of expanded beds is essential and was investigated systematically in this article. Residence-time distribution analyses were performed using model systems and a yeast suspension under various fluid-phase conditions. It is demonstrated that three factors (biomass/adsorbent interactions, biomass concentration, and flow rate) play an interdependent role disturbing the classified fluidization of an expanded bed. A clear correlation between the degree of aggregative fluidization--obtained by PDE modeling of RTD data--and the expansion behavior of the fluidized bed has been found. Thus, combining three analytical methods, namely cell transmission index analysis, expansion analysis, and RTD analysis provides a solid base for understanding and control of the fluidization behavior and thus further process design during the initial phase of process development.     

Possibility of purifying cholera toxin (choleragen) and its antibodies by an immunosorption method]

A study was made to establish the possibility of using an immune adsorbent based on polyacrylamide gel with the concentration of T = 10% and C = 25% for the purification of cholerogen and antibodies to it. For the isolation of cholera toxin the gamma globulin fraction of antitoxic serum was incorporated into the adsorbent; for obtaining antibodies an adsorbent with partially purified cholerogen was used. Desorption was made with 3 M sodium rhodanide solution. The yield of cholerogen was 41%, and the yield of antibodies was 4.5%. The non-specific sorption of the immune adsorbents was insignificant.     

Uptake of Cr3+ from aqueous solution by lignite-based humic acids

Humic acid (HA) produced from brown coal, a relatively abundant and inexpensive material is currently being investigated as an adsorbent to remove toxic metals from aqueous solution. The influence of five parameters (contact time, solution pH, initial metal concentration, temperature and amount of adsorbent) on the removal at 20+/-1 degrees C was studied. HAs were prepared from lignites by using alkaline extraction, sedimentation and acidic precipitation. Adsorption equilibrium was achieved in about 60 min for Cr3+ ion. The Langmuir adsorption isotherm was used to describe observed sorption phenomena. The maximum adsorption capacity of 0.17 mmol for Ilgin (HA1), 0.29 mmol for Beysehir (HA2) and 0.18 mmol Ermenek (HA3) and 0.17 mmol of Cr3+/g for activated carbon (AC) was achieved, respectively at pH of 4.1. More than 84% of Cr3+ was removed by HA2, 54% by HA3 and 51% by HA1 and 50% by AC from aqueous solution. The adsorption was strongly dependent on pH but independent of ionic strength and metal ions. The adsorption of Cr3+ was higher between pH 4.1 and 5.1 for all HAs and maximum sorption was observed at pH 4.1. The rise in temperature caused a slight decrease in the value of the equilibrium constant (Kc) for the sorption of Cr3+ ion. Complex mechanisms including ion exchange, complexation and adsorption and size exclusion are possible for sorption of Cr3+ ion on HAs.     

Biosorption of lead by cotton shells powder: Characterization and equilibrium modeling study

Lead (Pb) is a toxic heavy metal causing serious health risks to humans and animals. In the present study, cotton (Gossypium hirsutum L.) shells powder was used as adsorbent for the treatment of synthetic Pb-contaminated water. The batch scale biosorption capacity of cotton shells powder was evaluated to study the effects of Pb concentrations, adsorbent doses and contact time at constant pH (6) and temperature (25?°C). Results revealed that sorption of Pb increased (q?=?0.09–9.60?mg/g) with increasing Pb concentration (1–15?mg/L) and contact time (15–90?min) while decreasing adsorbent dose (1–0.1?g/100?mL). The maximum Pb removal (90%) was achieved at Pb concentration (1?mg/L), contact time (90?min) and adsorbent dose (1?g/100?mL). Freundlich isotherm model proved best fit for Pb sorption (R²?=?0.99). The cotton shells powder has microporous structure confirmed by SEM, and has BET surface area (45 m²/g) and pore size (2.3 µm). These surface moieties along with various functional groups (C-H, C-O, C=O, O-H, S=O) confirmed by FTIR analysis might involve in Pb removal by complexation and ion exchange mechanisms. The cotton shells powder biomass could be considered as promising adsorbent for the removal of Pb from contaminated water.     

Esterified coir pith as an adsorbent for the removal of Co(II) from aqueous solution

Coir pith was chemically modified for the adsorption of cobalt(II) ions from aqueous solution. Chemical modification was done by esterification using succinic anhydride followed by activation with NaHCO(3) in order to improve the adsorption of Co(II). Adsorptive removal of Co(II) from aqueous solution onto modified coir pith was evaluated in batch studies under varying conditions of agitation time and metal ion concentration to assess the kinetic and equilibrium parameters. A pseudo-second-order kinetic model fitted well for the sorption of Co(II) onto modified coir pith. Sorption kinetics showed that the loading of Co(II) by this material was quite fast under ambient conditions. The Langmuir and Freundlich equilibrium isotherm models provided excellent fits for the adsorption data, with R(2) of 0.99 and 0.98, respectively. After esterification, the maximum Co(II) sorption loading Q(0); was greatly improved. It is evident that chemically modified adsorbent exhibits better Co(II) removal capability than raw adsorbent suggesting that surface modification of the adsorbent generates more adsorption sites on its solid surface for metal adsorption. A complete recovery of the adsorbed metal ions from the spent adsorbent was achieved by using 1.0N HCl.     

Synthesis of beta-cyclodextrin and starch based polymers for sorption of azo dyes from aqueous solutions

Three beta-cyclodextrin (polymers 1-3) and a starch-based (polymer 4) polymers were synthesized using hexamethylene diisocyanate (HMDI) as a cross-linking agent in dry dimethylformamide and used as a sorbent for the removal of some selected azo dyes from aqueous solutions. The cross-linked polymers were characterized by Fourier transform infrared spectroscopy, thermogravimetric and differential scanning calorimetric analysis. Results of sorption showed that cyclodextrin and starch based polymers can be effectively used as a sorbent for the removal of anionic azo dyes. The Influence of the amide groups and the chemical structure of azo dyes are also studied. Results of sorption experiments showed that these adsorbent exhibited high sorption capacities toward Direct Violent 51 (80% for polymer 1, 69% for polymer 2, 70% for polymer 3 and 78% for polymer 4). The sorption capacity of dyes on the polymers was dependent on the presence of sulfonate groups of the anionic dyes. In order to explain the results an adsorption mechanism mainly physical adsorption and interactions such as hydrogen bonding, ion-exchange due to the nature of the polymer network and the formation of an inclusion complex due to the beta-CD molecules through host-guest interaction is proposed.     

Biosorption of Lead from Industrial Wastewater Using Chrysophyllum albidum Seed Shell

The shell of the seed of Chrysophyllum albidum carbon was used to adsorb lead (Pb) from aqueous solution, the sorption process with respect to its equilibria and kinetics as well as the effects of pH, contact time, adsorbent mass, adsorbate concentration, and particle size on adsorption were also studied. The most effective pH range was found to be between 4.5 and 5 for the sorption of the metal ion. The first-order rate equation by Lagergren was tested on the kinetic data and the adsorption process followed first-order rate kinetics. Isotherm data were analyzed for possible agreement with the Langmuir and Freundlich adsorption isotherms; the Freundlich and Langmuir models for dynamics of metal ion uptake proposed in this work fitted the experimental data reasonably well. However, equilibrium sorption data were better represented by Langmuir model than Freundlich. The adsorption capacity calculated from Langmuir isotherm was 72.1 mg Pb (II) g^{- 1} at initial pH of 5.0 at 30°C for the particle size of 1.00 to 1.25 mm with the use of 2.0 g/100 ml adsorbent mass. The structural features of the adsorbent were characterized by Fourier transform infrared (FTIR) spectrometry; the presence of hydroxyl, carbonyl, amide, and phosphate groups confirms the potential mechanism adsorption of the adsorbent. This readily available adsorbent is efficient in the uptake of Pb (II) ion in aqueous solution, thus, it could be an excellent alternative for the removal of heavy metals and organic matter from water and wastewater.     

Effect of hemosorption on the elimination of an amphotericin B derivative in experimental studies

Possible extracorporeal removal of a novel water soluble derivative of amphotericin B (NWSDA) from the host was studied. The bench tests demonstrated that actilen, a fibrous carbon adsorbent, was the optimal carbon sorbent for sorption of NWSDA. It was shown in the acute experiments on animals that during the hemosorption the antibiotic blood concentration on the outlet of the column was significantly lower than that on the inlet. Still, the NWSDA concentration in the blood lowered slowly which was likely due to the return of the antibiotic to the blood from the tissues.     

Effect of pH and Salinity on Sorption of Antimony (III and V) on Mangrove Sediment,Sundarban, India

The extent of toxic metalloid retention and bioavailability and mobility in the sediment is of interest for understanding their biogeochemical cycling and for accurate risk assessment in an ecosystem. Intensification of monsoon and rainfall, believed to be related to global warming, could drive future changes of temperature, salinity, and pH distribution pattern affecting antimony cycling in the Sundarbans. This study investigated sorption kinetics of antimony (Sb) (III and V) as a function of temperature, salinity, and pH following the Langmuir model, and demonstrated that clayey silt type mangrove sediment was an effective adsorbent with higher efficiency for Sb (V) than Sb (III). Background level of Sb in the sediment was 0.35–0.78% of the maximum adsorption capacity (Γ_m). Out of the two distinct type of sorption sites governing mobility and bioavailability of Sb in the sediment, site 1 (Humic acid) showed higher affinity for Sb than the site II (oxyhydroxide). Sb adsorption was strongly influenced by temperature, salinity, and pH, which may be altered by long-term changes in climate and rainfall pattern.     

Aflatoxin contamination in different fractions of rice from Pakistan and estimation of dietary intakes

The purpose of this study was to determine the distribution of aflatoxins in rice milling fractions and to estimate dietary intakes. A total of 413 rice samples (paddy 58, parboiled 69, brown 84, white 93, and broken 109) were analyzed by HPLC with fluorescence detector. The results showed that 64?% paddy (16.35?±?1.67???g/kg), 38?% parboiled (14.20?±?2.04???g/kg), 33?% brown (9.85?±?1.25???g/kg), 42?% white (7.10?±?1.39???g/kg), and 50?% broken (8.5?±?1.71???g/kg) rice samples were contaminated with aflatoxins. It was found that paddy rice was most contaminated with aflatoxins while white rice was least contaminated. The percentage of samples exceeding EU maximum contents for total aflatoxins in rice (4???g/kg) varied from 14 to 36?% when compared to the analyzed rice fractions. The total estimated amount of aflatoxin intake for average rice consumers ranged from 19.1 to 26.6?ng/kg body weight/day, much higher than the reference value of 1?ng/kg body weight/day. This is the first report discovering that rice is a major contributor to the dietary intake of aflatoxins in Pakistan.     

Function of the cypX and moxY genes in aflatoxin biosynthesis in Aspergillus parasiticus

The pathway oxoaverantin (OAVN) --> averufin (AVR) --> hydroxyversicolorone (HVN) --> versiconal hemiacetal acetate (VHA) is involved in aflatoxin biosynthesis, and the cypX and moxY genes, which are present in the aflatoxin gene cluster, have been previously suggested to be involved in this pathway. To clarify the function of these two genes in more detail, we disrupted the genes in aflatoxigenic Aspergillus parasiticus NRRL 2999. The cypX-deleted mutant lost aflatoxin productivity and accumulated AVR in the mycelia. Although this mutant converted HVN, versicolorone (VONE), VHA, and versiconol acetate (VOAc) to aflatoxins in feeding experiments, it could not produce aflatoxins from either OAVN or AVR. The moxY-deleted mutant also lost aflatoxin productivity, whereas it newly accumulated HVN and VONE. In feeding experiments, this mutant converted either VHA or VOAc to aflatoxins but did not convert OAVN, AVR, HVN, or VONE to aflatoxins. These results demonstrated that cypX encodes AVR monooxygenase, catalyzing the reaction from AVR to HVN, and moxY encodes HVN monooxygenase, catalyzing a Baeyer-Villiger reaction from HVN to VHA as well as from VONE to VOAc. In this work, we devised a simple and rapid method to extract DNA from many fungi for PCR analyses in which cell disruption with a shaker and phenol extraction were combined.