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1.
The enzyme assisted extraction conditions of polysaccharide from Cordyceps militaris mycelia were firstly investigated by kinetics analysis and the optimal operating was found to be: extraction temperature 40 °C; solid-solvent ratio 1:20; extraction pH 4.0; cellulase concentration 2.0%. The polysaccharide extraction yield was 5.99% under these optimized conditions. Furthermore, a fundamental investigation of the biosorption of Pb2+ from aqueous solution by the C. militaris polysaccharide was performed under batch conditions. The suitable pH (5.0), polysaccharide concentration (0.20 g L?1), initial Pb2+ concentration (300 mg L?1) and contact time (40 min) were outlined to enhance Pb2+ biosorption from aqueous medium. The Langmuir isotherm model and pseudo first order kinetic model fitted well to the data of Pb2+ biosorption, suggesting the biosorption of Pb2+ onto C. militaris polysaccharide was monolayer biosorption and physical adsorption might be the rate-limiting step that controlled the adsorption process. FTIR analysis showed that the main functional groups of C. militaris polysaccharide involved in adsorption process were carbonyl, carboxyl, and hydroxyl groups.  相似文献   

2.
Calcium alginate hydrogel was prepared and used as a biosorbent for the removal of oil from aqueous solutions. Calcium alginate hydrogel was further chemically modified by esterification with maleic anhydride. The changes in the physicochemical properties of maleic anhydride modified calcium alginate were investigated via multiple techniques (FTIR, SEM, BET and DSC/TGA). Adsorption batch experiments were carried out to compare the oil adsorption capacities of native and modified calcium alginates. Adsorption experiments were carried out as a function of solution pH, temperature and ionic strength to determine the optimal conditions for the adsorption of oil. Equilibrium and kinetic studies were conducted for the modified alginate. Results revealed that the maleic anhydride modification of calcium alginate improved its adsorption capacity towards oil. Higher adsorption capacities of modified alginate were attained at lower temperatures (20 °C), higher ionic strengths (1.0 M NaCl) and within the pH range of 5–9. The oil adsorption data obtained for modified alginate could be better described by the first order kinetic model (R2?=?0.981) and the BET equilibrium isotherm (R2?=?0.984). The maximum monolayer adsorption capacity predicted by the BET model for the modified calcium alginate was found to be 143.0 mg/g.  相似文献   

3.
In this study, dl-malic acid and hydrogen peroxide were used as leaching agents to remove metals from e-waste (printed-circuit boards) and itaconic acid-grafted poly(vinyl alcohol)-encapsulated wood pulp (IA-g-PVA-en-WP) to uptake metals from leachate with high proficiency [11.63 mg g?1; 93.03 % for Cd(II), 11.90 mg g?1; 95.18 % for Pb(II), and 12.14 mg g?1; 97.08 % for Ni(II)]. Metals were recovered from the loaded biosorbent by desorption studies. The standard analytical techniques, such as elemental analysis, Fourier-transform-infrared spectroscopy, scanning electron microscopy, atomic force microscopy, and thermogravimetric analysis, were used to characterize the recovering agent (biosorbent). At equilibrium, the metal uptake data were fitted to Langmuir and D–R isotherms (R 2 > 0.99) significantly, revealing, the homogeneous distribution of active sites on biosorbent’s backbone. The possible mechanism appeared to be ion exchanges of metal ions with H+ together with binding over functionalities (COO?). Dimensionless equilibrium parameter (R L) showed the favourability of metal uptake at lower concentration, while mean adsorption energy (E) certified the physical binding of metal on functionalities which was further confirmed by sticking probability and activation energy parameters. Reusability studies were also conducted to state the performance of biosorbent.  相似文献   

4.
Poly(acrylamide-co-maleic acid)/montmorillonite nanocomposites, were synthesized via in situ polymerization with different maleic acid and MMT content. The capability of the hydrogel for adsorption of crystal violet (CV) was investigated in aqueous solutions at different pH values and temperatures. The pseudo-second-order kinetics model could fit successfully the adsorption kinetic data. The effects of maleic acid to acrylamide molar ratio (MAR), weight percent of MMT (MMT%), the pH of medium and the solution temperature (T) on the CV adsorption capacity (q e ) of adsorbents were studied by Taguchi experimental design approach. The results indicated that increasing the MMT% leads to a greater q e . The q e value of adsorbents increased also with increasing both MAR and pH, while reduced when the temperature of medium increased. The relatively optimum conditions to achieve a maximum CV adsorption capacity for P(AAm/MA)/MMT adsorbents were found as: 0.06 for MAR and 5 % of MMT%, medium pH = 7 and T = 20 °C.  相似文献   

5.
This research article describes, an eco-friendly activated carbon prepared from the Gracilaria corticata seaweeds which was employed for the preparation of biodegradable polymeric beads for the efficient removal of crystal violet dye in an aqueous solution. The presence of chemical functional groups in the adsorbent material was detected using FTIR spectroscopy. The morphology and physical phases of the adsorbent materials were analyzed using SEM and XRD studies respectively. Batch mode dye adsorption behavior of the activated carbon/Zn/alginate polymeric beads was investigated as a function of dosage, solution pH, contact time, initial dye concentration and temperature. Maximum dye removal was observed at a pH of 5.0, 1 g of adsorbent dosage with 60 mg/L dye concentration, 50 min of contact time and at 30 °C. The equilibrium modeling studies were analyzed with Freundlich and Langmuir adsorption isotherms and the adsorption dynamics was predicted with Lagergren’s pseudo-first order, pseudo-second order equations and intra particle diffusion models. The process of dye removal followed a pseudo second-order kinetics rather than pseudo first order. The thermodynamic parameters like standard Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) were determined and the results imply that the adsorption process was spontaneous, endothermic and increases the randomness between the adsorbent and adsorbate. The results from the experimental and correlation data reveal that the Gracilaria corticata activated carbon/Zn/alginate polymeric beads have proved to be an excellent adsorbent material for the removal of CV dye.  相似文献   

6.
Haloferax mediterranei is an extremely halophilic archaeon that is able to synthesize polyhydroxyalkanoate (PHA) in high salt environment with low sterility demand. In this study, a mathematical model was validated and calibrated for describing the kinetic behavior of H. mediterranei at 15, 20, 25, and 35 °C in synthetic molasses wastewater. Results showed that the production of PHA by H. mediterranei, ranging from 390 to 620 mg h?1 L?1, was strongly dependent on the temperature. The specific growth rate (µ max), specific substrate utilization rate (q max), and specific decay rate (k d) of H. mediterranei increased with temperature following Arrhenius equation prediction. The estimated activation energy was 58.31, 25.59, and 22.38 kJ mol?1 for the process of cell growth, substrate utilization, and cell decay of H. mediterranei, respectively. The high temperature triggered the increased PHA storage even without nitrogen limitation. Thus, working at high temperatures seems a good strategy for improving the PHA productivity of H. mediterranei.  相似文献   

7.
This paper was focused on the biosorption of phosphate ions from aqueous solution onto the cetyltrimethylammonium bromide (CTAB) modified multi-component biosorbent composed of pine, oak, hornbeam and fir sawdust biomasses. A series of batch tests were conducted and the effects of solution pH, ion concentration, quantity of biosorbent and contact time on the bioremoval of phosphate ions were investigated. The biosorption data of kinetic and equilibrium were modeled using various mathematical equations. The phosphate removal increased with increased ion concentration and decreased with increased pH and biosorbent quantity values. The equilibrium state was reached within 120 min of exposure time. The process kinetics was best described by Elovich model while the isotherm data of biosorption best obeyed Freundlich equation. The obtained results revealed that the use of CTAB modified mix sawdust biosorbent presented interesting options for bioremediation of contaminated environments and waste recycling (as nutrient fertilizer and compost material).  相似文献   

8.
The multiwall carbon nanotubes (MWCNTs) were modified by 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) via grafting reaction and γ-rays of 60Co source was used as initiator. The outcome product was called hydroxyethylated (HOEt-MWCNTs) graft poly(AMPS) and abbreviated as HOEt-MWCNTs-g-PAMPS. The parameters that affected the grafting yield were optimized. The maximum grafting obtained was ~20 %. HOEt-MWCNTs-g-PAMPS were characterized by Fourier transform infra red, scanning electron microscopy, high resolution transmission electron microscopy, thermal gravimetric analysis. The adsorptive removals of malachite green chloride (MGC) and reactive red 198 (RR-198) onto HOEt-MWCNTs-g-PAMPS were studied at variable conditions. The adsorption isotherms were analyzed using Langmuir, Redlich–Peterson, Freundlich, Khan and Sips models. The results referred that Sips model is the best fitting to adsorption of MGC and Freundlich model is the best fitting to RR-198 adsorption. The monolayer coverage capacities of HOEt-MWCNTs-g-PAMPS for MGC and RR-198 dyes were found 172 and 323 mg g?1, respectively. The rate of kinetic adsorption processes of MGC and RR-198 onto HOEt-MWCNTs-g-PAMPS were described by using pseudo-first order, pseudo-second order and intraparticle diffusion models. The pseudo-first order and pseudo-second order models were the best choice among the kinetic models to depict the adsorption behaviors of MGC and RR-198 dyes onto HOEt-MWCNTs-g-PAMPS, respectively. Further, the effect of temperature on the adsorption isotherms was investigated and the thermodynamic parameters were obtained. The results indicated that the adsorption process is spontaneous and endothermic. The values of ΔG° varied in range with the mean values showing a gradual increase from ?3.17 to ?3.64 kJ mol?1 for MGC and ?3.36 to ?3.73 kJ mol?1 for RR-198. The reusability and regeneration of adsorbent were investigated. The outcome data referred to that the efficiency of adsorbent >98 %. The outline results declared that there is a good potentiality for the HOEt-MWCNTs-g-PAMPS to be used as an adsorbent for the removal of MGC and RR-198 from aqueous solutions.  相似文献   

9.
Synthesis of sodium alginate-g-poly(acrylamide-co-N-methylacrylamide) [S-III], sodium alginate-g-poly(N-methylacrylamide-co-N,N-dimethylacrylamide) [S-II], sodium alginate-g-poly(acrylamide-co-N,N-dimethylacrylamide) [S-I]. Sodium alginate-g-poly(N,N-dimethylacrylamide) [SAG-g-PDMA] and sodium alginate-g-poly(acrylamide) [SAG-g-PAM] were prepared by solution polymerization technique using potassium peroxydisulfate as the initiator at 70?°C in water medium. The graft copolymers were characterized by FTIR and NMR (1H and 13C) spectroscopy, SEM and XRD studies. All the five graft copolymers were used to remove Pb(II) ions from the aqueous solution and also in flocculation studies of kaolin clay (1.0 wt%), silica (1.0 wt%) and iron ore slime (0.25 wt%) suspensions. A comparative studies of all the five graft copolymers were also made in both the two cases. The Pb(II) ion removal capacity of all the graft copolymers follows the order S-III?>?SAG-g-PAM?>?S-II?>?SAG-g-PDMA?>?S-I. But the flocculation performance of the graft copolymers follows the order S-II?>?S-I?>?S-III?>?SAG-g-PDMA?>?SAG-g-PAM. S-III was also used for the competitive metal ion removal with Hg(II), Cd(II), Cu(II) and Zn(II). Pb(II) adsorption of S-III (the best Pb(II) ion adsorber) follows pseudo second order rate equation and Langmuir adsorption isotherm.  相似文献   

10.
The continuous increase in generation of solid wastes and gradual declining of fossil fuels necessities the development of sustainable conversion technologies. Recent studies have shown that the addition of biomass with hydrogen-rich co-reactants (plastics) altogether enhances the quality of bio-fuels using pyrolysis process. It was observed that red mud (which is produced as by-product in Bayer process) was used as a catalyst in few conversion process. In this study, pyrolysis of biomass (Pterospermum acerifolium) and waste plastic mixture with activated red-mud catalyst was investigated using thermo-gravimetric analysis. The kinetic parameters (activation energy and pre-exponential factor) of this process were determined using distributed activation energy model (DAEM). The DAEM was effectively applied to decide the activation energy (E) and pre-exponential factor (A) for each sample at various conversions during the catalytic co-pyrolysis. The biomass, plastic, biomass–plastic, and biomass–plastic–catalyst exhibited activation energies in the ranges of 78–268, 172–218, 67–307, and 202–292 kJ/mol, respectively.  相似文献   

11.
Polyaniline (PANI) and polyaniline/Gördes-clinoptilolite (PANI/GC) composite materials were synthesized by the chemical oxidative polymerization technique and used in the adsorption of Acid Violet 90 metal-complex dye (AV 90). The samples were characterized by X-ray diffractions, nitrogen adsorption–desorption isotherms, scanning electron microscopes and Fourier transform infrared. The effect of initial pH (2–8), sorbent dosage (0.5–4.0 g/L) and initial dye concentrations (50400 mg/L) on adsorption onto PANI and PANI/GC were examined in a batch system. Langmuir, Freundlich and Temkin isotherm models were used to investigate the adsorption mechanism of AV 90 on PANI and PANI/GC. Langmuir isotherm model for PANI/GC and Freundlich isotherm model for PANI were fitted well with the experimental data. The highest dye uptake capacities were obtained with Langmuir isotherm model as 153.85 mg/g and 72.46 mg/g for PANI and PANI/GC, respectively. In order to determine the adsorption kinetics, pseudo first-order and second-order kinetic models were studied. As a result, the adsorption of AV 90 dye on PANI and PANI/GC was better identified with Pseudo second-order kinetic model than the first one.  相似文献   

12.
This work assessed biodegradation, by Aspergillus, Fusarium, Penicillium and Parengyodontium fungi, of four samples of poly-ε-caprolactone (PCL), three samples of poly-l-lactide (PLA) and one sample of poly-d,l-lactide (DL-PLA) produced by ring-opening polymerization initiated by aluminium complexes of corresponding lactones. Mesophilic fungal strains actively biodegrading PCL (F. solani) and PLA (Parengyodontium album and A. calidoustus) were selected. The rate of degradation by the selected fungi was found to depend on the physicochemical and mechanical properties of the polymers (molecular weight, polydispersity, crystallinity). The most degradable poly-ε-caprolactone sample was shown to have the lowest molecular weight; the most biodegradable polylactide DL-PLA had the lowest crystallinity. Mass spectral analysis of biodegraded polymer residues showed PCL to be degraded more intensively than PLA. It is established that in the case of Parengyodontium album the colonization of the films of polypropylene composites with DL-PLA is observed, which will undoubtedly contribute to their further destruction under the influence of abiotic factors in the environment.  相似文献   

13.
Based on pre-experimentation, three ornamental plants, Mirabilis jalapa, Impatiens Balsamin (I. Balsamin) and Tagetes erecta L., were selected as target plants to study the phytoextraction of chromium (Cr) in tannery sludge irrigated with four treatments according to Cr concentration gradient [Control (CK); 20.50 × 103 mg kg?1 (T1); 51.25 × 103 mg kg?1 (T2); 102.50 × 103 mg kg?1 (T3)]. Results of pot experiments showed that the biomass of Mirabilis jalapa and Tagetes erecta L. had no significant differences among the four treatments, while I. Balsamin showed a decline trend in the biomass with the increase of Cr concentration, probably due to some extent to the poisoning effect of Cr under treatment T2 or T3. Mirabilis jalapa accumulated Cr concentration, with 408.97, 124.97, 630.16 and 57.30 mg kg?1 in its roots, stems, leaves and inflorescence, respectively. The translocation factor and the bioaccumulation coefficient of Mirabilis jalapa are each greater than 1, indicating that Mirabilis jalapa has the strong ability to tolerate and enrich Cr by biological processes. Comparing accumulation properties of the three ornamental plants, in the amount and allocation, Mirabilis jalapa showed the highest phytoextraction efficiency and could grow well at the high Cr concentration. Our experiments suggest that Mirabilis jalapa is the expected flower species for Cr removal from tannery sludge.  相似文献   

14.
The main objective of this study was to determine whether methane potential of waste could be estimated more easily by a limited number of waste characterization variables. 36 samples were collected from 12 locations and 3 waste depths in order to represent almost all waste ages at the landfill. Actual remaining methane potential of all samples was determined by the biochemical methane potential (BMP) tests. The cumulative methane production of closed landfill (cLF) samples reached 75–125 mL at the end of experiment duration, while the samples from active landfill (aLF) produced in average 216–266 mL methane. The average experimental k and L 0 values of cLF and aLF were determined by non-linear regression using BMP data with first-order kinetic equation as 0.0269 day?1–30.38 mL/g dry MSW and 0.0125 day?1–102.1 mL/g dry MSW, respectively. The principal component analysis (PCA) was applied to analyze the results for cLF and aLF along with BMP results. Three PCs for the data set were extracted explaining 72.34 % variability. The best MLR model for BMP prediction was determined for seven variables (pH–Cl–TKN–NH4–TOC–LOI–Ca). R 2 and Adj. R 2 values of this best model were determined as 80.4 and 75.3 %, respectively.  相似文献   

15.
The selective modification of sodium montmorillonite (Na+-Mt) surface with polyionene followed by poly (succinimde-co-aspartate) has been considered. Na+-Mt was allowed to react with well characterized polyionene in two fold excess. The resulting polyionene/Mt (IC) was further modified with poly (succinimide-co-aspartate) through an ion exchange process. The obtained polyaspartate/Mt (IPS) composite was characterized by elemental analysis, X-ray diffraction, FTIR spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and BET surface analyzer. The adsorption efficiency of IPS composite was investigated for the removal of Pb(II) and Cd(II) from aqueous solution under different experimental conditions including initial metal ions concentration, temperature and single and binary mixture systems of metal ions. The experimental data were analyzed by Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models. Langmuir model reveals that the monolayer adsorption capacity of IPS was 92.59 and 67.57 mg/g for Pb(II) and Cd(II), respectively. The modification of parent Na+-Mt enhanced their adsorption capacity by about 87.91 and 29.84% for Pb(II) and Cd(II), respectively, due to inclusion of extra active sites of polyaspartate. The mean sorption energy, E calculated from Dubinin–Radushkevich isotherm were 2.75 and 1.98 kJ/mol for the adsorption of Pb(II) and Cd(II), respectively, indicating physical adsorption process. Also, The thermodynamic parameters were calculated and indicated that the adsorption was spontaneous and exothermic process. The mechanism of cation exchange and complexation of metal ions was suggested. IPS composite has a considerable potential for the removal of heavy metal ions from aqueous solution and wastewater stream.  相似文献   

16.
Copolymers of aniline and o-phenylenediamine/kaolinite composites were synthesized by 5:1 molar ratios of the respective monomers with different percentages of nanoclay via modified in situ chemical co-polymerization. The results were verified by measuring the FT-IR and UV–vis absorption spectra for PANI-o-PDA/kaolinite composites. The thermal behaviour of the copolymer and composites was studied. PANI-o-PDA/kaolinite composites were thermally more stable than pure copolymer. Surface morphology of copolymer composites was recorded at different magnification power by SEM which revealed whitish micrometric beads distributed all over the field with particle size in the range of 0.122–0.233 μm. This work demonstrates that the PANI-o-PDA/kaolinite composites particles can be considered as potential adsorbents for hazardous and toxic metal ions of water from lake El-Manzala, Egypt. All of Cd(II), Cu(II), and Pb(II) posed dangerous health risk to the local population via fish consumption.  相似文献   

17.
Naturally-based poly(acrylic acid) grafted sodium alginate di-block hydrogels were investigated as high efficiency biosorbents for copper(II) ion. The grafted di-block hydrogel was characterized using FTIR, TGA and SEM techniques. Blank and immobilized algal biosorbent beads formed via 2.0% (w/w) calcium ions were also investigated. Batch adsorption experiments revealed optimal pH dependence of copper(II) ion biosorption at pH 5.5 with high efficient copper(II) ion uptake of 98.5 mg/g. The dynamics studies showed that the high efficiency copper(II) ion biosorption followed pseudo-second order kinetics with significant contribution of intraparticle diffusion mechanism. The equilibrium data fitted to Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) adsorption isotherm models. Thermodynamics parameters for copper(II) biosorption on blank and immobilized algal beads depicted the spontaneous nature of the biosorption process. Such high efficiency, feasibility, simplicity, and low cost properties adapt the di-block biosorbent to be the next generation promising biosorbents for water decontamination and to help in the recovery of the missing ecologic harmony.  相似文献   

18.
The potential of lignocellulosic fibers obtained by dry grinding of pinhão coat as fillers in starch filmogenic solutions for packaging applications was evaluated in this work. To improve the incorporation of this waste into the starch solutions different physical and chemical treatments were conducted. Thereafter, morphology, chemical structure, crystallinity and water absorption of the pinhão coat powders were determined. The composites were also characterized regarding their morphology, chemical structure, crystallinity, mechanical properties, water vapor permeability and hydrophilicity. Poor fiber/matrix adhesion and high water absorption of the fibers were evidenced. Consequently, water vapor permeability of composites was increased by incorporating the fibers. Moreover, mechanical properties were improved and the morphological results were used to support the water absorption differences among the powders. Regarding the food packaging applications, starch/pinhão coat composites appeared as promising materials to reach the requirements of respiring food products.  相似文献   

19.
Biodegradable polymers are considered a feasible option to minimize the environment impacts of high disposal of solid waste. Nevertheless, environmental safety of these materials is a few explored issue. In this context, this study evaluated ecotoxicological effects in soil of the biodegradable materials poly(lactic acid)-PLA, poly(butylene adipate co-terephthalate)-PBAT and their blends compatibilized with a chain extender. The tool used for this analysis was the bioassay with Allium cepa as test organism. The studied materials were not phytotoxic, cytotoxic, genotoxic nor mutagenic for meristematic cells of A. cepa.  相似文献   

20.
The present work was to evaluate the stability potential of (E)-4-(3,4-dimethoxyphenyl)but-3-en-l-ol (Compound D) in polyherbal transdermal patches. The polyherbal formulation composed of the rhizomes of Zingiber cassumunar and Curcuma longa, leaves and stems of Cymbopogon citratus, rind and leaves of Citrus hystrix fruit, and leaves of Acacia rugata and Tamarindus indica. Polyvinyl alcohol and hydroxypropyl methylcellulose were used as a matrix film, and glycerine was used as a plasticizer. Stability testing was established for 6 months under accelerated conditions as according to International Conference on Harmonisation guidelines. Mechanical properties, moisture uptake, swelling ratio, and in vitro studies were evaluated. New Zealand white rabbits were used as the animal model. Results obtained after 6 months showed that the polyherbal transdermal patches were stable, with a good mechanical properties and hydrophilicity. In vitro study kinetics for active Compound D fitted to the Higuchi model for both release and skin permeation. The transdermal patch containing polyherbal formulation was safe to apply on the skin without irritation. Thus, transdermal patches containing this polyherbal formulation had good stability potential, with no irritation on application.  相似文献   

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