Your browser doesn't support javascript.
loading
Montrer: 20 | 50 | 100
Résultats 1 - 20 de 81
Filtrer
Plus de filtres











Base de données
Gamme d'année
1.
Carbohydr Polym ; 346: 122662, 2024 Dec 15.
Article de Anglais | MEDLINE | ID: mdl-39245516

RÉSUMÉ

Chitosan materials are much important in adsorption, separation and water treatment due to their hydrophilicity, biodegradability and easy functionalization. However, they were difficult to form structural materials, which limited its application in engineering. In this paper, a new type of chitosan porous materials was prepared with two-step strategy involving the freezing crosslinking of chitosan with glutaraldehyde to form cryogels, and their subsequent reduction with NaBH4 to transform CN bonds into CN bonds, resulting in remarkable improvement of mechanical property. That is, the strength remained almost unchanged after 80 % deformation. The abundant -NH2 and -OH on the surface of materials, as well as the unique pore structure from cryogels, gave relatively high adsorption capacity for metals and dyes (88.73 ± 4.25 mg·g-1 for Cu(II) and 3261.05 ± 36.10 mg·g-1 for Congo red). The surface hydrophilicity of materials made it possible for selective water permeation with over 95 % separation efficiency for oil-water mixtures. In addition, simple hydrophobic modification using bromotetradecane achieved selective oil permeation with over 96 % separation efficiency for oil-water mixtures. This study not only provides a new strategy to endow chitosan materials with excellent mechanical property, large adsorption capacity and good oil-water separation performance, but also offers environmentally friendly materials for sewage treatment applications.

2.
Environ Geochem Health ; 46(10): 396, 2024 Aug 24.
Article de Anglais | MEDLINE | ID: mdl-39180627

RÉSUMÉ

The reutilization of municipal wastes has always been one of the hottest subjects of sustainable development study. In this study, a novel biochar co-pyrolyzed from municipal sewage sludge and phosphorus tailings was produced to enhance the adsorption performance of the composite on Cu2+ and Cd2+. The maximum Cu2+ and Cd2+ adsorption capacity of SSB-PT were 44.34 and 45.91 mg/g, respectively, which were much higher than that of sewage sludge biochar (5.21 and 4.58 mg/g). Chemisorption dominated the whole adsorption process while multilayer adsorption and indirect interaction were also involved. According to the result of X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectrum (XPS), the load of CO32-, Mg2+, and Ca2+ on the surface of SSB-PT enhanced the precipitation and ion exchange effect. Posnjakite and CdCO3 were formed after the adsorption of Cu2+ and Cd2+, respectively. Besides, complexation, and metal-π interaction were also involved during the adsorption process. Therefore, this study offered a promising method to reuse sewage sludge and phosphorus tailings as an effective adsorbent.


Sujet(s)
Cadmium , Charbon de bois , Cuivre , Phosphore , Eaux d'égout , Cuivre/composition chimique , Charbon de bois/composition chimique , Adsorption , Cadmium/composition chimique , Eaux d'égout/composition chimique , Phosphore/composition chimique , Pyrolyse , Polluants chimiques de l'eau/composition chimique , Spectroscopie infrarouge à transformée de Fourier , Diffraction des rayons X
3.
J Hazard Mater ; 477: 135267, 2024 Sep 15.
Article de Anglais | MEDLINE | ID: mdl-39047552

RÉSUMÉ

Developing multifunctional materials for water treatment remains a significant challenge. Bacterial cellulose (BC) holds immense potential as an adsorbent with high pollutant-binding capacity, hydrophilicity, and biosafety. In this study, N-acetylglucosamine was used as a carbon source to ferment BC, incorporating amide bonds in situ. Bentonite, renowned for its adsorption properties, was added to the culture medium, resulting in BC-bentonite composite membranes via a one-step fermentation process. Polyethyleneimine (PEI) was crosslinked with amide bonds on the membrane via glutaraldehyde through Schiff base reactions to enhance the performance of the composite membrane. The obtained membrane exhibited increased hydrophilicity, enhanced active adsorption sites, and enlarged specific surface area. It not only physically adsorbed contaminants through its unique structure but also effectively captured dye molecules (Congo red, Methylene blue, Malachite green) via electrostatic interactions. Additionally, it formed stable complexes with metal ions (Cd²âº, Pb²âº, Cu²âº) through coordination and effectively adsorbed their mixtures. Moreover, the composite membrane demonstrated the broad-spectrum antibacterial activity, effectively inhibiting the growth of tested bacteria. This study introduces an innovative method for fabricating composite membranes as adsorbents for complex water pollutants, showing significant potential for long-term wastewater treatment of organic dyes, heavy metal ions, and pathogens.


Sujet(s)
Antibactériens , Bentonite , Cellulose , Agents colorants , Membrane artificielle , Polyéthylèneimine , Polluants chimiques de l'eau , Purification de l'eau , Adsorption , Cellulose/composition chimique , Bentonite/composition chimique , Agents colorants/composition chimique , Polyéthylèneimine/composition chimique , Purification de l'eau/méthodes , Antibactériens/composition chimique , Antibactériens/pharmacologie , Polluants chimiques de l'eau/composition chimique , Métaux lourds/composition chimique
4.
Environ Technol ; : 1-13, 2024 Jul 02.
Article de Anglais | MEDLINE | ID: mdl-38955513

RÉSUMÉ

Pyrolysis is an effective process for disposing of municipal sewage sludge (SS). Plastics can affect the SS pyrolysis behaviour and pyrolysis products due to their low ash and high hydrocarbon ratio. The secondary pollutants from the pyrolysis process may also be affected. Therefore, polyethylene terephthalate (PET), a typical plastic, was chosen to investigate the release characteristics of pollutants containing nitrogen, sulphur, and chlorine via SS pyrolysis, and the changes of biochar to adsorb two typical heavy metals, Pb and Cu. The pyrolysis of PET plastics facilitates the migration of N toward solid and liquid-phase products, S and Cl to the gas-phase products via pyrolysis. Oxygenated compounds of pyrolytic volatiles decreased from 38.18% to 28.43%, concurrently promoting the formation of phenolic compounds. The co-pyrolysis improved the quality of biochar and the ability to adsorb Pb and Cu. This systematic study can provide some support for the further improvement of SS pyrolysis technology, and will also be beneficial for subsequent applications.

5.
Nanomaterials (Basel) ; 14(12)2024 Jun 16.
Article de Anglais | MEDLINE | ID: mdl-38921913

RÉSUMÉ

With the processes of industrialization and urbanization, heavy metal ion pollution has become a thorny problem in water systems. Among the various technologies developed for the removal of heavy metal ions, the adsorption method is widely studied by researchers and various nanomaterials with good adsorption performances have been prepared during the past decades. In this paper, a variety of novel nanomaterials with excellent adsorption performances for Pb(II) and Cu(II) reported in recent years are reviewed, such as carbon-based materials, clay mineral materials, zero-valent iron and their derivatives, MOFs, nanocomposites, etc. The novel nanomaterials with extremely high adsorption capacity, selectivity and particular nanostructures are summarized and introduced, along with their advantages and disadvantages. And, some future research priorities for the treatment of wastewater are also prospected.

6.
J Hazard Mater ; 475: 134923, 2024 Aug 15.
Article de Anglais | MEDLINE | ID: mdl-38889469

RÉSUMÉ

This study investigates the co-precipitation of calcium and barium ions in hypersaline wastewater under the action of Bacillus licheniformis using microbially induced carbonate precipitation (MICP) technology, as well as the bactericidal properties of the biomineralized product vaterite. The changes in carbonic anhydrase activity, pH, carbonate and bicarbonate concentrations in different biomineralization systems were negatively correlated with variations in metal ion concentrations, while the changes in polysaccharides and protein contents in bacterial extracellular polymers were positively correlated with variations in barium concentrations. In the mixed calcium and barium systems, the harvested minerals were vaterite containing barium. The increasing concentrations of calcium promoted the incorporation and adsorption of barium onto vaterite. The presence of barium significantly increased the contents of O-CO, N-CO, and Ba-O in vaterite. Calcium promoted barium precipitation, but barium inhibited calcium precipitation. After being treated by immobilized bacteria, the concentrations of calcium and barium ions decreased from 400 and 274 to 1.72 and 0 mg/L (GB/T15454-2009 and GB8978-1996). Intracellular minerals were also vaterite containing barium. Extracellular vaterite exhibited bactericidal properties. This research presents a promising technique for simultaneously removing and recycling hazardous heavy metals and calcium in hypersaline wastewater.


Sujet(s)
Baryum , Calcium , Précipitation chimique , Eaux usées , Eaux usées/composition chimique , Baryum/composition chimique , Calcium/composition chimique , Calcium/métabolisme , Bacillus/métabolisme , Carbonate de calcium/composition chimique , Carbonate de calcium/métabolisme , Polluants chimiques de l'eau/métabolisme , Polluants chimiques de l'eau/composition chimique , Recyclage , Carbonates/composition chimique , Carbonic anhydrases/métabolisme , Purification de l'eau/méthodes
7.
J Environ Health Sci Eng ; 22(1): 271-279, 2024 Jun.
Article de Anglais | MEDLINE | ID: mdl-38887755

RÉSUMÉ

Adsorption of heavy metals on stream sediments has important implications for the fate and transport of contaminants in subsurface ecosystems. Lead (Pb) is a potentially hazardous heavy metal that is found in high amounts in anthropogenic environments, especially aquatic ecosystems. The key mechanisms for distributing this metal in the environment are adsorption and desorption in stream to sediment, and vice versa. Therefore, this work is mainly focused on the study of the influence of amorphous Fe/Al-oxyhydroxides and soil organic matter (SOM) on the adsorption of Pb onto natural stream sediment. Spiking adsorption experiments were carried out with four types of samples namely, untreated dried sediment, Fe/Al-oxyhydroxides depleted sediment, SOM depleted sediment and both Fe/Al as well as SOM depleted sediment in the pH range of 3.0 to 8.0. The results showed that Pb adsorption was reduced by up to 45% in amorphous Fe/Al-oxyhydroxide depleted sediment at pH 4.0 to 6.0, whereas a similar adsorption reduction was observed in SOM depleted sediment at pH 6.5 to 7.5. Maximum Pb adsorption was reduced by up to 75% in both amorphous Fe/Al-oxyhydroxides and SOM depleted sediment samples at pH ranges ranging from 3.0 to 7.0. Furthermore, it was shown that SOM was most significant at pH 6.5, while Fe/Al-oxyhydroxides were more important when pH was > 6.5 for the Pb adsorption in natural stream sediment.

8.
Environ Sci Pollut Res Int ; 31(25): 36551-36576, 2024 May.
Article de Anglais | MEDLINE | ID: mdl-38755474

RÉSUMÉ

Among the many heavy metal pollution treatment agents, carbonate materials show strong flexibility and versatility by virtue of their high adsorption capacity for heavy metals and the characteristics of multiple and simple modification methods. It shows good potential for development. This review summarizes the application of carbonate materials in the treatment of heavy metal pollution according to the research of other scholars. It mainly relates to the application of surface-modified, activated, and nano-sized carbonate materials in the treatment of heavy metal pollution in water. Natural carbonate minerals and composite carbonate minerals solidify and stabilize heavy metals in soil. Solidification of heavy metals in hazardous waste solids is by MICP. There are four aspects of calcium carbonate oligomers curing heavy metals in fly ash from waste incineration. The mechanism of treating heavy metals by carbonate in different media was discussed. However, in the complex environment where multiple types of pollutants coexist, questions on how to maintain the efficient processing capacity of carbonate materials and how to use MICP to integrate heavy metal fixation and seepage prevention in solid waste base under complex and changeable natural environment deserve our further consideration. In addition, the use of carbonate materials for the purification of trace radioactive wastewater and the safe treatment of trace radioactive solid waste are also worthy of further exploration.


Sujet(s)
Carbonates , Métaux lourds , Carbonates/composition chimique , Adsorption
9.
Bioresour Technol ; 402: 130762, 2024 Jun.
Article de Anglais | MEDLINE | ID: mdl-38692371

RÉSUMÉ

Ionic cadmium (Cd (II)) in water is a significant threat to ecosystems, the environment, and human health. Research is currently focused on developing efficient adsorption materials to combat Cd (II) pollution in water. One promising solution involves co-pyrolyzing solid residue from anaerobic digestion of food waste with oil-based drill cuttings pyrolysis residue to create a biochar with high organic matter content. This biochar has a lower heavy metal content and leaching toxicity compared to China's national standards, making it both safe and resourceful. It exhibits a high adsorption capacity for Cd (II) in water, reaching up to 47.80 ± 0.37 mg/g. Raising the pyrolysis temperature above 600 °C and increasing the amount of pyrolysis residue beyond 30 % enhances the biochar's adsorption capacity. The adsorption process is primarily driven by mineral precipitation, offering a promising approach for dual waste resource management and reducing heavy metal pollution.


Sujet(s)
Cadmium , Charbon de bois , Déchets solides , Cadmium/composition chimique , Charbon de bois/composition chimique , Adsorption , Pyrolyse , Polluants chimiques de l'eau/composition chimique , Minéraux/composition chimique , Précipitation chimique , Purification de l'eau/méthodes
10.
Polymers (Basel) ; 16(9)2024 May 05.
Article de Anglais | MEDLINE | ID: mdl-38732760

RÉSUMÉ

The rapid worldwide industrial growth in recent years has made water contamination by heavy metals a problem that requires an immediate solution. Several strategies have been proposed for the decontamination of wastewater in terms of heavy metal ions. Among these, methods utilizing adsorbent materials are preferred due to their cost-effectiveness, simplicity, effectiveness, and scalability for treating large volumes of contaminated water. In this context, heavy metal removal by hydrogels based on naturally occurring polymers is an attractive approach for industrial wastewater remediation as they offer significant advantages, such as an optimal safety profile, good biodegradability, and simple and low-cost procedures for their preparation. Hydrogels have the ability to absorb significant volumes of water, allowing for the effective removal of the dissolved pollutants. Furthermore, they can undergo surface chemical modifications which can further improve their ability to retain different environmental pollutants. This review aims to summarize recent advances in the application of hydrogels in the treatment of heavy metal-contaminated wastewater, particularly focusing on hydrogels based on cellulose and cellulose derivatives. The reported studies highlight how the adsorption properties of these materials can be widely modified, with a wide range of adsorption capacity for different heavy metal ions varying between 2.3 and 2240 mg/g. The possibility of developing new hydrogels with improved sorption performances is also discussed in the review, with the aim of improving their effective application in real scenarios, indicating future directions in the field.

11.
Int J Biol Macromol ; 266(Pt 2): 131110, 2024 May.
Article de Anglais | MEDLINE | ID: mdl-38522694

RÉSUMÉ

Chitosan (CS) and sodium alginate (SA)-based biocomposites (CSA) were prepared with the in-situ generation of Calcium Carbonate (CSAX_Ca) through a simple, straightforward, economical, and eco-friendly procedure. Different drying conditions (X) were tested to achieve suitable structural and surface characteristics to enhance adsorption capacity: freeze-dried (L), vacuum-dried with methanol (M), and freeze-dried + vacuum-dried with methanol (LM). Temperature and adsorbent dosage effects on the adsorption capacity of Cu2+ or Pb2+ were examined. Results showed that the higher-yielding biocomposite (CSALM_Ca) exhibited rapid adsorption and good diffusion properties, achieving removal above 90 % within contaminant initial concentration ranges of 10-100 mg/L. At 35 °C, a pseudo-second-order kinetic and the Langmuir model effectively described kinetics and isotherms, revealing maximum adsorption (qe, max) of 429 mgCu2+/L and 1742 mgPb2+/g. Characterization through FTIR, XRD, and SEM of the as-prepared adsorbents confirmed the presence of CaCO3 in vaterite and calcite forms and the influence of drying conditions on the material morphology. Post-adsorption material characterization, in combination with adsorption findings, revealed chemisorption processes involving Ca2+ ion exchange for Cu2+ or Pb2+, resulting in surface-insoluble compounds. The best-performing material showed that after three reuse cycles, the removal of Cu2+ and Pb2+ decreased to 75 % and 62 %, respectively.


Sujet(s)
Alginates , Carbonate de calcium , Chitosane , Cuivre , Plomb , Polluants chimiques de l'eau , Purification de l'eau , Chitosane/composition chimique , Cuivre/composition chimique , Alginates/composition chimique , Plomb/composition chimique , Adsorption , Carbonate de calcium/composition chimique , Polluants chimiques de l'eau/composition chimique , Cinétique , Purification de l'eau/méthodes , Eau/composition chimique , Propriétés de surface , Température
12.
Nanomaterials (Basel) ; 14(6)2024 Mar 11.
Article de Anglais | MEDLINE | ID: mdl-38535653

RÉSUMÉ

Three Fe3O4 magnetic solvent-free nanofluids with different amine-based coronal layer structures are synthesized and characterized by using magnetic Fe3O4 as the core, silane coupling agent as the corona, and polyether amines with different graft densities and chain lengths as the canopy. The concentration of heavy metal ions after adsorption is measured by atomic absorption spectrometry (AAS) to study the effect of Fe3O4 magnetic solvent-free nanofluids on the adsorption performance of the heavy metal ions lead (Pb(II)) and copper (Cu(II)) in water. The adsorption of Fe3O4 magnetic solvent-free nanofluid was explored by changing external condition factors such as adsorption contact time and pH. Additionally, the adsorption model is established. The magnetic solvent-free nanofluid is separated from water by applying an external magnetic field to the system, and desorption and cyclic adsorption tests are carried out. Based on the adsorption mechanism, the structure design of Fe3O4 magnetic solvent-free nanofluid was optimized to achieve optimal adsorption performance.

13.
Bioresour Technol ; 397: 130440, 2024 Apr.
Article de Anglais | MEDLINE | ID: mdl-38346594

RÉSUMÉ

The non-homogeneous structure and high-density ash composition of biochar matrix pose significant challenges in characterizing the dynamic changes of heavy metal adsorption onto biochar with micro-computed tomography (Micro-CT). A novel in-situ registration subtraction image segmentation method (IRS) was developed to enhance micro-CT characterization accuracy. The kinetics of Cu(II) adsorption onto pellet biochar derived from corn stalks were tested. Respectively, the IRS and traditional K-means algorithms were used for image segmentation to the in-situ three-dimensional (3D) visual characterization of the Cu(II) adsorption onto biochar. The results indicated that the IRS algorithm reduced interference from high-density biochar composition, and thus achieved more precise results (R2 = 0.95) than that of K-means (R2 = 0.72). The visualized dynamic migration of Cu(II) from surface adsorption to intraparticle diffusion reflexed the complex mechanism of heavy metal adsorption. The developed Micro-CT method with high generalizability has great potential for studying the process and mechanism of biochar heavy metal adsorption.


Sujet(s)
Métaux lourds , Polluants chimiques de l'eau , Cuivre/composition chimique , Microtomographie aux rayons X , Zea mays , Adsorption , Charbon de bois/composition chimique , Métaux lourds/composition chimique , Cinétique , Polluants chimiques de l'eau/composition chimique
14.
Materials (Basel) ; 17(4)2024 Feb 17.
Article de Anglais | MEDLINE | ID: mdl-38399173

RÉSUMÉ

Red mud (RM) and Yellow River sediment (YRS) are challenging to handle as waste materials. In this study, RM with geopolymer and heavy metal adsorption characteristics was combined with YRS and ground granulated blast furnace slag (GGBS) to develop a porous geopolymer with high strength and high adsorption performance. A geopolymer cementitious material with high strength was prepared using high temperature water bath curing of 90 °C and different dosages of YRS, and a porous geopolymer concrete was further prepared. The compressive strength, fluidity and setting time of geopolymer cementitious materials were tested, and the compressive strength, porosity and permeability of porous geopolymer concrete were also tested. The environmental impact assessment of geopolymer cementitious materials was further conducted. The hydration products and microstructure of geopolymer gel materials were analyzed by XRD, SEM and FT-IR tests. The results show that the addition of YRS can effectively prolong the setting time of the geopolymer cementitious material, and the enhancement rate is as high as 150% compared with the geopolymer cementitious materials without the addition of YRS. An appropriate amount of YRS can improve the compressive strength of the geopolymer cementitious materials, and its early compressive strength can be further improved under the high temperature water bath curing of 90 °C, and the compressive strength at an age of 3 d can be up to 86.7 MPa. Meanwhile, the compressive strength of porous geopolymer concrete at an age of 28 d is up to 28.1 MPa. YRS can participate in geopolymer reactions, and high temperature water bath curing can promote the reaction degree. Curing method and YRS dosages have little effect on the porosity and permeability of the porous geopolymer concrete. The porous geopolymer has a good heavy metal adsorption effect, and the alkaline pH values can be gradually diluted to neutral.

15.
J Colloid Interface Sci ; 660: 859-868, 2024 Apr 15.
Article de Anglais | MEDLINE | ID: mdl-38277842

RÉSUMÉ

The issue of heavy metal contamination in water is a global concern, and the development of highly efficient adsorbent materials is crucial for the removal and detoxification of heavy metals. Polymer-based materials have emerged as a promising class of adsorbents due to their ability to capture heavy metal pollutants and reduce them to less toxic forms. The limited surface area of conventional polymer adsorbents makes them less effective for high-capacity adsorption. Herein, we present a low-temperature steam activation approach to address this challenge. This activation approach leads to a remarkable increase of over 20 times in the surface area of concave aminophenol-formaldehyde (APF) polymer nanospheres (from 45 to 961 m2/g) while preserving their reductive functional groups. The activated concave APF nanospheres were evaluated for their adsorption capabilities towards two typical heavy metal ions (i.e., Cr(VI) and Cd(II)) in aqueous solutions. The maximum adsorption capacities achieved were 1054 mg g-1 for Cr(VI) and 342 mg g-1 for Cd(II), which are among the highest performances reported in the literature and are much higher than the capacities of the non-activated APF nanospheres. Additionally, approximately 71.5 % of Cr(VI) was simultaneously reduced to Cr(III) through the benzenoid amine pathway during adsorption, highlighting the crucial role of the steam activation strategy in enhancing the capability of polymer adsorbents.

16.
J Hazard Mater ; 466: 133442, 2024 Mar 15.
Article de Anglais | MEDLINE | ID: mdl-38244458

RÉSUMÉ

Due to the broad interest in using biochar from biomass pyrolysis for the adsorption of heavy metals (HMs) in wastewater, machine learning (ML) has recently been adopted by many researchers to predict the adsorption capacity (η) of HMs on biochar. However, previous studies focused mainly on developing different ML algorithms to increase predictive performance, and no study shed light on engineering features to enhance predictive performance and improve model interpretability and generalizability. Here, based on a dataset widely used in previous ML studies, features of biochar were engineered-elemental compositions of biochar were calculated on mole basis-to improve predictive performance, achieving test R2 of 0.997 for the gradient boosting regression (GBR) model. The elemental ratio feature (H-O-2N)/C, representing the H site links to C (non-active site to HMs), was proposed for the first time to help interpret the GBR model. The (H-O-2N)/C and pH of biochar played essential roles in replacing cation exchange capacity (CEC) for predicting η. Moreover, expanding the coverages of variables by adding cases from references improved the generalizability of the model, and further validation using cases without CEC and specific surface area (R2 0.78) and adsorption experimental results (R2 0.72) proved the ML model desirable. Future studies in this area may take into account algorithm innovation, better description of variables, and higher coverage of variables to further increase the model's generalizability.


Sujet(s)
Métaux lourds , Adsorption , Métaux lourds/composition chimique , Charbon de bois/composition chimique , Apprentissage machine
17.
Environ Technol ; : 1-13, 2024 Jan 29.
Article de Anglais | MEDLINE | ID: mdl-38286341

RÉSUMÉ

Eradication of heavy metal pollution has become the prime priority over the conservation of water resources in the upcoming era. Herein, the study involved the halophilic fungal melanin from Curvularia lunata showed a promising biosorbent for the removal of toxic heavy metals which shows eco-friendly, cost-effective, high stability, and adsorbent efficiency. Polyurethane blended with fungal melanin polymers, makes polymeric nanofibrous membranes through electrospinning techniques. BET isotherms revealed the raw fungal melanin holds a surface area of 3.54 m2/g exhibiting type IV isotherms. BJH results in a total pore volume of 5.79 cc/g with a pore diameter of 6.54 ± 1 nm for pores smaller than 4544.8 Å. Exhibits Eumelanin properties were characterized by FE - SEM and FTIR functional elements. ICPMS confirmed the metal adsorption proficiency on both raw and melanized membranes before and after treatments. Over 17 heavy metals, Ni2+ were adsorbed with 100% efficiency by raw melanin alone with 42.48 µg/L of Ni2+ concentration in the water sample, whereas, Cu2+, Zn2+, Co2+, Cr2+, Pb2+, Mn2+, Al3+, Mo6+, Sb3+, Ba2+, Fe2+, and Mg2+ stands next with 99%. In this study, gentle/simple application of raw fungal melanin (without PUR tailored) can detoxify the maximum concentration of heavy metals present in the water bodies which are further used for irrigation and even drinking purposes. This mycoremediation approach can be easily adapted to industrial production than other high-performance membrane materials with minimal process modification, making it a promising strategy for improving the adsorption properties used in various applications after still furthermore investigation.

18.
Polymers (Basel) ; 15(18)2023 Sep 07.
Article de Anglais | MEDLINE | ID: mdl-37765537

RÉSUMÉ

Bacterial cellulose (BC) is a highly crystalline nanosized material with a high number of active groups. This study focuses on the synthesis of BC membranes through fermentation, their characterization and application to remove Ni(II) and Pb(II) from wastewater by adsorption under different conditions. Four-day-grown BC membranes form three-dimensional nanofibril networks with a pH of 6.3 and a high cationic demand (52.5 µeq·g-1). The pseudo-second-order kinetic model and the Sips isotherm model best describe the adsorption of both metals. The intraparticle diffusion model of Ni(II) revealed a three-step mechanism of adsorption-plateau-adsorption, while Pb(II) adsorption followed a typical reducing-slope trend up to saturation. The highest removal of Ni(II) and Pb(II) was obtained at pH 4 with a BC dosage of 400 mg·L-1. The maximum adsorption capacities were 28.18 mg·g-1 and 8.49 mg·g-1 for Ni(II) and Pb(II), respectively, involving the total coverage of the material active sites. Thermodynamically, Ni(II) adsorption was exothermic, and Pb(II) was endothermic. The obtained values of sorption heat, activation and Gibbs' energy depicted a physisorption process. Ni(II) removal mechanism was ruled by crystallization on the metals adsorbed on the BC active groups, while Pb(II) was driven by the adsorption process, as shown by TEM images of the spent material.

19.
Chemosphere ; 343: 140216, 2023 Dec.
Article de Anglais | MEDLINE | ID: mdl-37748655

RÉSUMÉ

We previously reported that monoalkyl dithiocarbamate-modified cellulose (DMC) exhibited excellent adsorption performance for arsenite (AsIII), cadmium (CdII), lead (PbII), gold (AuIII), silver (AgI), platinum (PtIV), and palladium (PdII). However, its adsorption capability for AsIII decreased by 96.4% after two weeks of storage at 40 °C under an air atmosphere. This decrease in adsorption ability could occur for other metals that dithiocarbamates can extract. In this study, we investigated the adsorption performance of DMC for various metals before and after storage and proposed a possible mechanism for this decrease. We found significant decreases in the adsorption abilities of PbII (11.4%), AgI (39.5%), PtIV (65.5%), and PdII (69.6%), whereas AuIII and CdII adsorption was largely retained, with decreases of 1.1% and 4.0%, respectively. FTIR analysis of the stored DMC revealed the formation of S-S bonds and the retention of dithiocarbamate peaks, indicating the formation of dithiocarbamate dimers (thiuram disulfides). To further support thiuram disulfide formation, dialkyl thiuram disulfides were tested for the adsorption of the seven employed metals. The metal adsorption behavior of dialkyl thiuram disulfides was almost identical to that of the stored adsorbent, ensuring thiuram disulfide formation. In conclusion, the loss of adsorption capability can be mainly attributable to the formation of thiuram disulfide.

20.
Int J Biol Macromol ; 253(Pt 2): 126416, 2023 Dec 31.
Article de Anglais | MEDLINE | ID: mdl-37633556

RÉSUMÉ

Nowadays, wastewater treatment is a critical concern, particularly regarding the removal of heavy metals through adsorption methods. Extensive research has been conducted on obtaining high-yield and environmentally friendly adsorbents. Natural polymer adsorbents especially have shown promise in ion and organic molecule adsorption. To enhance the practical applicability of adsorbents, the combination of biopolymers to form biocomposites is a promising alternative. In this study, adsorbents based on a 1:1 wt./wt. of chitosan (CS) and alginate (SA) were prepared. The influence of the regeneration route and drying conditions on the copper adsorption capacity was investigated, along with reaction parameters such as contact time, adsorbent particle size, and pH. The highest adsorption capacity was observed in the composite material obtained through a one-pot regeneration process and freeze-dried. The CSAR3L sample exhibited a remarkable adsorption capacity of 288 mg Cu(II)/g after 360 min at 25 °C. The synergistic effect between the CS and SA precursors was confirmed by analyzing the individual precursors and their mechanical mixture. The initial adsorption rates at pH 6 followed the order: CSAR3-L > Bk-CSR3L > Bk-SAR3L + Bk-CSR3L > Bk-SAR3L. The physicochemical and morphological properties of the materials were studied by FTIR, XRD, DLS, XPS, optical microscopy, EDS-SEM, elemental chemical analysis, and TGA-DTG. The utilization of different drying methods resulted in the formation of calcium carbonate crystalline phases in the as-prepared materials, thus creating substantial adsorption active sites. After the adsorption process, hydroxylated copper sulfate phases and a significant decrease in calcium concentration were observed, indicating that an ion exchange adsorption mechanism occurred. The analysis of adsorption kinetics and the shape of the adsorption isotherms, in agreement with the characterization results, suggested the presence of multiple active sites and the formation of a chemisorption monolayer.


Sujet(s)
Chitosane , Métaux lourds , Polluants chimiques de l'eau , Cuivre/composition chimique , Chitosane/composition chimique , Alginates/composition chimique , Polluants chimiques de l'eau/composition chimique , Adsorption , Cinétique , Concentration en ions d'hydrogène
SÉLECTION CITATIONS
DÉTAIL DE RECHERCHE