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A simple and economical method for modifying chitosan based on non-catalytic direct condensation reaction between chitosan and phenolic acids “Gallic and Caffeic acids” has been developed to produce condensation adduct resins RI and RII. The resins structure and morphology were confirmed by physical and chemical tools such as FTIR, SEM, EDX, XRD elemental analysis, TGA, water regain, dissociation in acidic medium, and point of zero charge. The new resins were evaluated as silver ions adsorbents. Factors affecting adsorption, as well as kinetics, equilibrium, and thermal properties of adsorption, were studied using conventional equations. The new resins showed more efficient removal of toxic silver ions from the aqueous medium than parent chitosan polymer. The maximum adsorption capacity amounted to 67.5, 300, and 278 mg/g with removal efficiency reaching 22.5%, 100%, and 92.66% for chitosan, RI, and RII; respectively at pH 6.5 and initial silver concentration 300 mg/L. The new resins showed spontaneous chemisorption toward silver ions with exothermic nature for RI, and endothermic nature for RII. The new condensation adduct resins showed good re-use ability reaching 83% and 67% for RI and RII; respectively, by using 0.01 M nitric acid solution.

Though abundant studies have targeted the sorption of Cr(VI) and As(V) anions by organic polymers or magnetic metal oxides, there is no research literature on the sorption characteristics of Cr(VI) and As(V) by thiourea-formaldehyde resin (TF) and its magnetic derivative (MTF). TF resin is a strong chelating agent, which has several practical applications. This paper reports on the removal of Cr(VI) and As(V) oxoanions by TF and MTF sorbents. The sorbents were characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, zetametry, Brunauer-Emmett-Teller (BET) analysis, and differential light scattering (DLS). The synergistic influence of magnetite incorporation and ultrasonic power on sorption kinetics, isotherms, and oxoanion desorption were investigated, including the analysis of the uncertainty in the study results. The relationship between kinetic and equilibrium constants of the two sorbents under normal shaking and ultrasound shaking was analysed. Ultrasound power improved the mass transfer and makes the sorption ultra-fast while magnetite enhanced the sorption capacity. The MTF particles sorbed 4.28 and 1.97 mmol g−1 of Cr(VI) and As(V), respectively, under optimum conditions. Further, desorption kinetics and efficiency of Cr(VI) and As(V) were estimated using normal shaking and ultrasonic agitation. Ultrasound power reduced the time and the concentration of NaCl required for the stabilization of desorption efficiency.

International audience; Chitosan functionalized with 2-mercaptobenzimidazole (2-MBI) (i.e. 2-MBI@Chit) shows high sorption capacity (i.e., 1.28 mmol MB g-1) for methylene blue (MB) at pH close to 9.3). Sorption is weakly decreased (by less than 25%) by high NaCl concentration (up to 45 g L-1). The sorption (slightly endothermic) is fitted by the Langmuir equation. The kinetic profile is fitted by the pseudo-first order rate equation (PFORE): equilibrium reached within 90 min of contact. The resistance to film diffusion is minimized when setting agitation speed at 200 rpm. Dye desorption is successfully achieved (up to 94.5%) using 0.8 M; desorption kinetics is little slower than the sorption step. The loss in sorption capacity at the fifth sorption/desorption cycle does not exceed 5%. Yoon-Nelson, Bohart-Adams, and bed-depth service time equations are used for analyzing the breakthrough in fixed-bed columns. At the exhaustion of the column, the sorption capacity approaches the maximum sorption capacity in batch: all the reactive groups remain accessible in dynamic sorption mode. The dye is efficiently recovered from spiked seawater and the sorption performance is depreciated by less than 16% while comparing tap water and seawater under selected experimental conditions.

A new sorbent based on Sepia shells (cuttlefish bones) has been synthesized (SSBC) and tested for the sorption of cationic dye (crystal violet, CV) and an anionic dye (congo red, CR). SSBC was produced by reaction of sepia shells powder with urea in the presence of formaldehyde. In the first part of the work, the sorbent was characterized using scanning electron microscopy, energy dispersive X-ray analysis, Fourier-transform infra-red spectrometry and titration (for determining pH(PZC)). In a second step, sorption properties were tested on the two dyes through the study of pH effect, sorbent dosage, temperature and ionic strength; the sorption isotherms and uptake kinetics were analyzed at the optimum pH: Langmuir equation fits isotherm profiles while the kinetic profile can be described by the pseudo-second order rate equation. Maximum sorption capacities reach up to 0.536 mmol g(−1) for CV and 0.359 mmol g(−1) for CR, at pH 10.6 and 2.4, respectively. The comparison of sorption properties at different temperatures shows that the sorption is endothermic. Processing to the sorption under microwave irradiation (microwaved enforced sorption, MES) increases mass transfer and a contact time as low as 1 min is sufficient under optimized conditions (exposure time and power) reaching the equilibrium, while 2–3 h were necessary for “simple” sorption. Dye desorption was successfully tested using 0.5 M solutions of NaOH and HCl for the removal of CR and CV, respectively. The sorbent can be re-used for a minimum of four cycles of sorption/desorption. Finally, the sorbent was successfully tested on spiked tap water and real industrial wastewater. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s40201-019-00435-1) contains supplementary material, which is available to authorized users.

Metal/mineral-incorporating materials have received significant attention over the last decades given the outstanding adsorption behavior towards various pollutants, especially Cr(VI), in aqueous solutions. Here, the pattern of sorption of some pollutants with special focus on Cr(VI) removal over metal/mineral-incorporating materials has been compiled. Furthermore, the key influencing adsorption variables, i.e., pH, concentration at the beginning, contact time, and dosage of sorbent, were discussed while considering different material classifications. Different isothermal and kinetic models were elaborated. Langmuir and Freundlich's models are adopted as the main sorption isotherms, while the pseudo-second-order kinetic model is the most fitted heavy metal ion and Cr(VI) kinetic model in aqueous systems. The results revealed that metal/mineral-incorporating materials are quite effective for heavy metal (especially Cr(VI)) recovery from water and confirmed that these materials are affordable and reliable for contaminated water remediation. Also, several methods are available for the modification of these materials in order to increase their sorption efficiency. However, to establish the use of metal/mineral-incorporating materials for water purification compared with other established methods, more investigations are required to determine the best modification method and investigate the release of metals from these materials during sorption.

Owing to its availability, low cost and strong reducibility capacity, chitosan can be widely used for Cr(VI) recovery, in this study the removal of Cr(VI) from aqueous solution was investigated using composite adsorbents derived from chitosan (obtained from shrimp peels) and Cu(OH)2 or CuO (prepared by alkaline precipitation of Cu(II) ions) to manufacture ChiCu(OH)2 and ChiCuO, respectively. The adsorbents were characterized by using SEM, BET surface area and zeta potential measurements. Adsorption uptake was highly dependent on pH, temperature, Cr(VI) concentration and sorbent mass: The optimum pH for Cr(VI) removal being close to 4. The adsorption isotherm can be described by Langmuir adsorption isotherm while the uptake kinetics was highly fitted with the pseudo-second order rate equation. The effect of temperature was also evaluated, verifying the endothermic nature of the adsorption process. Chromium desorption was performed using alkaline saline solution (20 g L−1 NaCl with the pH set to 12 with NaOH). The recycling of the sorbent was tested, maintaining a removal efficiency and a metal recovery over 90% for three successive adsorption/desorption cycles. The results showed that, the fabricated nanocomposites are promising adsorbents for Cr(VI) from aqueous solution.

International audience; Alginate-PEI beads are functionalized by phosphorylation and applied for the sorption of Nd(III) and Mo(VI). The successful grafting of phosphoryl groups (as tributyl phosphate derivative) is characterized by FTIR and XPS analysis, elemental analysis, titration (pHPZC), TGA, BET and SEM-EDX analyses. The multi-functional characteristics of the sorbent (i.e., carboxylic, hydroxyl, amine and phosphate groups) contribute in the binding of metal ions having different physicochemical behaviors. The sorption of Nd(III) is strongly increased by phosphorylation, while for Mo(VI) the enhancement is rather limited. Optimum sorption occurs at pH 3–4: maximum sorption capacity reaches up to 1.46 mmol Nd(III) g−1 and 2.09 mmol Mo(VI) g−1; sorption isotherms are fitted by the Langmuir equation. The equilibrium is reached within 30–40 min and the kinetic profiles are simulated by the pseudo-first order rate equation. The coefficients of the effective diffusivity are close to the self-diffusivity of Nd(III) and Mo(VI) in water; as a confirmation of the limited impact of resistance to intraparticle diffusion in the kinetic control. The sorbent is selective for Nd(III) over Mo(VI) and other alkali-earth or base metals (at pH close to 2.5–3). Metals can be readily desorbed using 0.2 M HCl/0.5 M CaCl2 as the eluent. The loss in sorption does not exceed 5% at the fifth cycle, while desorption remains complete. A series of treatments (including acidic leachate, cementation, precipitation, sorption and elution) is successfully applied for the recovery of rare earths from Egyptian ore; with enrichment in the oxalate precipitate of Nd(III), Gd(III), Sm(III) and Eu(III).

International audience; The valorization of algal biomass and bi-valve shells allows synthesizing, in the presence of urea, a sorbent highly efficient for methylene blue (MB) sorption (sorption capacity: 1.5 mmol MB g−1 at pH 5.8). The dye-functionalized sorbent shows enhanced sorption properties for Cr(VI) recovery at pH 3. The sorption isotherm is fitted by the Langmuir equation: maximum sorption capacity reaches 8.53 mmol Cr g−1 (for MB-loading: 1.5 mmol g−1). Different mechanisms may be involved such as the electrostatic attraction of anionic species, chelation on reactive groups, reduction of Cr(VI) into Cr(III). Under selected experimental conditions, the sorption is achieved within less than 60 m. The kinetic profiles are controlled by the pseudo-second order rate equation. Alkaline NaCl solutions effciently desorb chromate while maintaining a good stability of the dye (negligible release). Therefore, the sorption and desorption performances are maintained remarkably stable for at least 5 sorption/desorption cycles. The sorbent is successfully applied for chromate recovery from Cr(VI)–spiked solutions (tap water and wastewater from petrochemical unit) with limited loss in sorption performances. The sorbent is characterized by BET, TGA, FTIR, SEM, EDX and zetametry to help in the understanding of binding mechanisms and sorption performances.

With the target of recovering rare earth elements (REEs) from acidic leachates, a new functionalized hydrogel was designed, based on the phosphorylation of algal/polyethyleneimine beads. The functionalization strongly increased the sorption efficiency of the raw material for Pr(III) and Tm(III). Diverse techniques were used for characterizing this new material and correlating the sorption performances and mechanisms to the physicochemical structure of the sorbent. First, the work characterized the sorption properties from synthetic solutions with the usual procedures (study of pH effect, uptake kinetics, sorption isotherms, metal desorption and sorbent recycling, and selectivity from multi-element solutions). Optimum pH was found close to 5, sorption isotherms were fitted by the Langmuir equation (maximum sorption capacities close to 2.14 mmol Pr g-1 and 1.57 mmol Tm g-1). Fast uptake kinetics were modeled by the pseudo-second order rate equation. The sorbent was highly selective for REEs against alkali-earth and base metals. The sorbent was remarkably stable for sorption and desorption operation (using 0.2 M HCl/0.5 M CaCl2 solutions). The sorbent was successfully applied to the leachates of Egyptian ore (pug leaching) after a series of pre-treatments (precipitation steps), sorption, and elution. The selective precipitation of REEs using oxalic acid allows for the recovery of a pure REE precipitate.

International audience; The recycling of precious and strategic metals from secondary resources (including E-wastes) is of critical importance for the recovery of scarce metals widely used in High-Tech devices. Therefore, the development of efficient and selective sorbents is of great importance. The grafting of 2-mercaptobenzimidazole onto chitosan microparticles allows developing highly selective sorbents. The incorporation of magnetite particles is also a strategic aspect for facilitating the use and recovery of microparticles. Sonication (at two different frequencies: 37 kHz and 80 kHz) shows high potential for improving both kinetic and thermodynamic aspects associated with silver uptake on 2-MBI-chitosan materials. Sorption capacities as high as 3 mmol Ag g−1 can be obtained with contact times as low as 20–30 min. The sorption isotherms are successfully fitted by the Langmuir and the Sips equations, while the kinetic profiles are modeled using the pseudo-second order rate equation and the resistance to intraparticle diffusion. The sorption process is exothermic: the sonication (and the frequency of sonic generator) strongly changes the thermodynamic parameters. The sonication also speeds up metal desorption, which is highly efficient using acidic thiourea solutions: the sonication allows also reducing the concentration of thiourea in the eluent required for complete silver elution. The sorbent shows remarkable stability is terms or sorption and desorption for five successive recycling runs. The acid leachates of printed circuit board are efficiently treated with the 2-MBI-chitosan sorbent for the recovery, enrichment and separation of precious metals (Ag, Au and Pd) from base metals (major elements: iron copper, aluminum, tin).

Ligand-functionalized nanomaterials exhibit great potential for the removal of hazardous substances from the environment and industrial wastewater. In this work, a composite nanosphere material was fabricated using mesoporous silica and organic ligand, and employed for the efficient detection and subsequent removal of toxic sulfanilamide (SNA) from waste samples. The organic ligand 2-naphthol was successfully conjugated onto the mesoporous nanospheres, which then captured SNA under suitable conditions. A naked-eye color change was observed even when a trace amount of SNA interacted with the material, which is the most promising advantage of the fabricated material. A low limit of detection and quantification limit were also determined, and the new nanosphere material revealed the ultra-trace detection performance of 0.27 μg L−1 of SNA in aqueous media. The effect of solution pH, competing ions, color optimization and initial concentration of SNA on the nanosphere material was investigated under the optimum conditions. The nanosphere material exhibited rapid adsorption properties, and its maximum adsorption capability approached 79.20 mg g−1. Several compounds were examined as common interfering substances including vanillin, glucose, lactose, starch and sucrose, which did not adversely interfere in both the detection and adsorption systems using the proposed nanosphere material. The data emphasized that the proposed material is highly suitable for the capture of SNA from contaminated water based on its selectivity, sensitivity, cost-effectiveness and eco-friendly approach. The results also indicate that this nanosphere material will attract attention from researchers for the efficient and selective capture of the toxic SNA.

Lauryl sulfate is utilized to functionalize magnetic graphene oxide (MGOLS) for fast removal of methylene blue (MB) using batch sorption experiments. The effects of different analytical parameters including medium pH, equilibration time, MGOLS dosage, initial MB concentration and temperature on the % MB removal are investigated. Among different isotherm and kinetic models, the experimental data were best fitted to the Langmuir and pseudo-second-order rate equations. The maximum Langmuir loading capacity reaches 624.42 mg g−1 for MGOLS under optimal conditions. Sorption kinetic of MGOLS is very fast: Approximately 96% of dye extraction was recorded within the first 2 minutes of this sorption process. The sorption mechanism is proposed and the feasibility, thermic and entropic characteristics were evaluated. Sorption and desorption performances of MGOLS are maintained almost constant over five cycles of sorption/desorption. The results concluded MGOLS as an efficient extractor for fast and feasible recovery of MB from aqueous matrices.

Magnetic disinfectants were achieved through the polymerization of thiourea and formaldahyde in the presence of magnetite nano particles (MTUF), the as-prepared MTUF was loaded with Ag(I) or Au(III). The obtained disinfectants (MTUF-Ag and MTUF-Au) were test for some selected pathogenic strains deactivation. The toxicity of MTUF before and after Ag(I) or Au(II) loading was estimated. The antimicrobial activity tests of MTUF-Ag and MTUF-Au were carried out against Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa as examples of Gram negative bacteria; Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, and Bacillus subtilis as examples of Gram positive bacteria; Candida albicans as representative for fungi. The results showed that the minimum inhibitory concentration (MIC) of MTF-Ag against Escherichia coli, Salmonella typhimurium, Listeria monocytogenes, Staphylococcus aureus and Candida albicans were 1.5, 2.0, 1.5, 1.0 and 2.5 mg mL−1, respectively after 40 min of contact time. While MTUF-Au showed higher MIC concentrations: 6.0, 4.0, 4.0, 4.0 and 6 mg mL−1 for the mentioned strains, respectively. The studied MTUF-Ag and MTUF-Au were successfully tested for deactivation of the studied pathogenic microorganism’s water and wastewater samples. It can be concluded that, MTUF-Ag and MTUF-Au are good candidates for water disinfection.

One-pot synthesis of a new magnetic disinfectant was achieved through the polymerization of thiourea and formaldehyde in the presence of magnetite nanoparticles (MTUF). The obtained magnetic chelating resin was loaded with Ag(I) ions. This material was tested as a disinfectant for water pathogenic microorganism's deactivation. The toxicity of MTUF before and after Ag(I) loading was estimated. The antimicrobial activity tests of MTUF-Ag were carried out against Escherichia coli, Salmonella Typhimurium, and Pseudomonas aeruginosa as examples of Gram-negative bacteria; Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, and Bacillus subtilis as examples of Gram-positive bacteria; and Candida albicans as representative for fungi. The results showed that the minimum inhibitory dosage (MID) of MTF-Ag against Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes, Staphylococcus aureus, and mixed culture were 1.5, 2.0, 1.0, 1.5, and 1.5 mg/mL, respectively, after 40 min of contact time. While C. albicans was more resistant to the magnetic disinfectant, only three log reductions were done at 2.5 mg/mL. The studied MTUF-Ag was successfully tested for water and wastewater pathogenic microorganism's deactivation. It can be concluded that MTUF-Ag could be a good candidate for water disinfection.

In this study, chitosan and bio-based activated carbon obtained from sugarcane bagasse biowaste were used for the synthesis of efficient sorbent for Cu(II) and Cd(II) ion via precipitation method. The prepared material was enriched with amino groups through grafting tetraethylenepentamine and tested for heavy metal remediation from water samples. The influence of pH was investigated showing optimum sorption at pH 6 for Cu(II) and Cd(II). Sorption tests, explained by means of the most common sorption models, evidenced that the best performances were reached pointing out the promising application of the prepared sorbent for water purification treatments: Uptake kinetics are relatively fast: the equilibrium was reached within 140 min; and the kinetic profiles were preferentially fitted by the pseudo-second order rate equation. Sorption isotherms are fitted by Langmuir equation. The sorbent showed high metal ion sorption capacity with negligible influence of ion strength. The maximum sorption capacities reached 3.44 and 2.38 mmol g− 1 for Cu(II) and Cd(II), respectively at 298 K. Thermodynamic parameters were evaluated through variation of temperature. The sorption is unfavorable at elevated temperatures. Metal ions were successfully desorbed using 1 M HNO3 solution.

The necessity of decontaminating effluents for the dual purpose of environmental beneficiation and valorization of low-grade resources is driving the development of new sorbents. The functionalization of biopolymers is a promising strategy for improving sorption performance. Incorporating magnetic micro-particles offers an opportunity for the facilitated recovery of spent micron-size sorbent. Combining magnetic facilities and biopolymer functionalization represents a winning strategy. Magnetic glycine-grafted chitosan (G@MChs) was synthesized for the sorption of Ni(II), Zn(II), and Hg(II) before being applied to the removal of hazardous and strategic metals from tailing leachates. The sorbent was characterized using Fourier transform infrared spectroscopy and scanning electron microscopy, before and after metal sorption. The acid–base properties of functionalized sorbent were also determined (pHPZC). Uptake kinetics were studied in mono- and multi-component solutions using different equations for kinetic modeling at optimized pH (i.e., pH0: 5.5). Langmuir and Sips equations were applied to model sorption isotherms in single-component solutions. In addition, sorption isotherms in multi-component solutions were used to evaluate the preference for selected metals. Maximum sorption capacities were 0.35 mmol Hg g−1, 0.47 mmol Zn g−1, and 0.50 mmol Ni g−1. Acidified urea solution (pH 2.7) successfully desorbs metal ions from G@MChs (desorption &gt, 90%). The sorbent was tested for the recovery of hazardous and strategic metal ions from acidic leachates of tailings. This study demonstrates the promising performance of G@MChs for the treatment of complex metal-bearing solutions.

Magnetic chitosan grafted with Schiff’s base polymer (M-Schiff’s-Chit) was prepared as a green sorbent starting from shrimp peels for the effective removal of hexavalent chromium. Chitosan extraction involved three main stages as preconditioning, demineralization deproteinization and deacetylation. The grafting process is confirmed by elemental analysis, Fourier transform infrared spectroscopy. Adsorption experiments were carried out in batch sorption mode to investigate the effect of pH, contact time, sorbent dose, concentration of Cr(VI) and evaluating the thermodynamics. Sorption kinetics are effectively modeled using the pseudo-second order rate equation while Langmuir equation successfully fits sorption isotherms. The sorption is endothermic, spontaneous and entropic. Chromate desorption can be successfully performed with 2 M of NaCl in 0.5 M NaOH and the sorbent can be recycled for at least three sorption/desorption cycles without significant loss in sorption/desorption performances. Furthermore, the environmentally friendly and low-cost M-Schiff’s-Chit could be applied as an effective sorbent to remediate Cr(VI) contamination from tannery effluent.

The adsorption of crystal violet (CV) dye onto magnetic alginate (MAlg) composite from aqueous solutions was studied. Experiments were carried out as function of contact time, dosage, temperature, pH, and CV concentration in the solutions. Optimum CV uptake was observed at equilibrium pH 7 and most of the CV was sorbed within 30 min. The equilibrium adsorption data were analyzed using two common adsorption models: Langmuir and Freundlich. The results revealed that Langmuir isotherm fit the experimental results well. The maximum adsorption capacity obtained from Langmuir isotherm equation was 0.113 mmol g−1at 298 ± 1 K. The kinetics adsorption of CV onto MAlg composite was investigated using the pseudo first-order and pseudo second-order kinetic models. The results showed that the adsorption of CV onto MAlg composite followed pseudo second-order kinetic model. Thermodynamic data indicated that the adsorption process is an endothermic and spontaneous reaction. Due to its outstanding adsorption capacities, MAlg composite is an excellent adsorbent for the removal of CV. The composite regeneration was greater than 98.6% with 0.01 mol/L HCl, and MAlg composite could be repeatedly utilized for CV removal with negligible loss in sorption capacity.

The adsorption of Cu(II), Cd(II) and Pb(II) from aqueous solution onto methyl methacrylate-Na-Y-Zeolite (MMA-Na-Y-Zeolite) composite was analyzed in a batch system with respect to pH, contact time, initial metal ion concentration, adsorbent dosage and temperature. The sorbent was characterized by FT-IR spectrometry, SEM analysis and X-ray diffraction (XRD). Kinetic profiles are successfully modeled with the pseudo-second order rate equation. The Langmuir, the Dubinin–Radushkevich and Temkin equations fit well-adsorption isotherms of Cu(II) and Cd(II), while the distribution of Pb(II) at equilibrium did not fit any of the studied adsorption isotherms. The change of free energy (ΔG o ), enthalpy (ΔH o ) and entropy (ΔS o ) of adsorption were also evaluated. The thermodynamics of the adsorption Cu(II) and Cd(II) indicated endothermic nature, on the other side exothermic adsorption was recorded for Pb(II). The regeneration efficiency of MMA-Na-Y-Zeolite reached 96.6%, 98.18% and 98.4% for Cu(II), Cd(II) and Pb(II), respectively. The results indicate that MMA-Na-Y-Zeolite composite could be employed as low-cost material for the removal of heavy metals from real water samples.

Bivalve shells of Anadara uropigimelana were firstly tested as a potential biosorbent for methylene blue (MB) recovery from an aqueous solution, Scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDX), Fourier-transform infrared (FTIR) and zeta potential measurements were used to characterize bivalve shells sorbent. The influence of variables including pH, amount of sorbent, contact time, concentration of the dye and temperature on MB sorption has been investigated. Percentage removal of 93.6% were obtained under optimum conditions of variables (initial pH of 10.4, sorbent dose of 1 g L−1, initial MB concentration of 20 mg L−1, and temperature of 25 ± 1 °C). The sorption of MB dye onto the sorbent could reach equilibrium after 10 min. Equilibrium data were well fitted to the Langmuir model. Sorption isotherm results showed that the maximum sorption capacity of MB by bivalve shells was 1000 μg g−1. Thermodynamic analysis showed that the sorption of MB onto bivalve shells increased with increasing temperature from 25 to 55 °C, indicating the endothermic nature of the sorption process. Meanwhile, the positive values of ΔSo suggest the increased randomness at the solid/solution interface during the MB sorption. The sorbent was successfully tested for color removal from dyeing facility. This work shows that the bivalve shells hold promises acting as effective sorbent to remove dyes in the wastewater.

International audience; Magnetic chitosan nanoparticles, activated by glycidyl methacrylate, can be functionalized by grafting diethylenetriamine (DETA) and dithizone for improving U(VI) sorption at pH around 5. The physicochemical properties of the materials have been characterized by a wide variety of analytical techniques. Uranyl sorption increases with the pH (progressive deprotonation of amine and sulfur groups). Uptake kinetics are controlled by the agitation mode: the equilibrium time is reduced while using ultrasonic treatment (especially at highest frequency: 80 kHz): the cavitation effect improves the accessibility to internal reactive groups (sorption capacity is increased). The diffusivity coefficient is increased by 4–5 times. In the case of microwave, the sorption capacity is significantly reduced (especially for R-Dithizone, down to 0.8 mmol U g−1) because of temperature increase, which limits the sorption (exothermic mechanism). Mass transfer is tremendously enhanced: equilibrium time is less than 60 s (30 min for ultrasonic treatment and 120 min with mechanical agitation). Sorption capacity at monolayer saturation (Langmuir) decreases with increasing the temperature from 2.20 to 1.74 mmol U g−1 for R-Amine (from 1.77 to 1.22 mmol U g−1 for R-Dithizone). The sorption enthalpy is close to −19.7 kJ mol−1 for R-Amine (with positive entropy change, ΔS°) and −34.2 kJ mol−1 for R-Dithizone (negative ΔS°). Metal desorption is highly efficient using 0.3 M Na2CO3 /0.1 M H2O2 solution. Metal desorption is instantaneous (less than 1 min) and complete when using microwave treatment. The ultrasonic treatment allows improving desorption efficiency and decreasing the concentration of the eluent compared with mechanical agitation. The process is successfully applied for uranyl separation from the leachates of marine sediments, especially in the presence of Complexon III (masking agent).

The development of new materials is needed to address the environmental challenges of wastewater treatment. The phosphorylation of guar gum combined with its association to chitosan allows preparing an efficient sorbent for the removal of U(VI) from slightly acidic solutions. The incorporation of magnetite nanoparticles enhances solid/liquid. Functional groups are characterized by FTIR spectroscopy while textural properties are qualified by N2 adsorption. The optimum pH is close to 4 (deprotonation of amine and phosphonate groups). Uptake kinetics are fast (60 min of contact), fitted by a pseudo-first order rate equation. Maximum sorption capacities are close to 1.28 and 1.16 mmol U g−1 (non-magnetic and magnetic, respectively), while the sorption isotherms are fitted by Langmuir equation. Uranyl desorption (using 0.2 M HCl solutions) is achieved within 20–30 min, the sorbents can be recycled for at least five cycles (5–6% loss in sorption performance, complete desorption). In multi-component solutions, the sorbents show marked preference for U(VI) and Nd(III) over alkali-earth metals and Si(IV). The zone of exclusion method shows that magnetic sorbent has antibacterial effects against both Gram+ and Gram- bacteria, contrary to non-magnetic material (only Gram+ bacteria). The magnetic composite is highly promising as antimicrobial support and for recovery of valuable metals.

A new composite material was obtained by in situ polymerization of thiourea and formaldehyde in the presence bentonite microgranules as a support. This material was characterized by Scanning electron microscope (SEM), Energy Dispersive X-Ray Analysis (EDX), X-ray diffraction (XRD). SEM and EDX analyses confirm the homogeneity of the sorbent in term of composition. The composite sorbent was used for the removal of Pb(II), Mn(VII) and Cr(VI) from their aqueous solution. Sorption uptake was highly dependent on pH, initial metal ion concentration and the mass of the adsorbent. The optimum pH is being close to 4 for Mn(VII) and Pb(II) sorption, while maximum Cr(VI) sorption was at pH 2. Kinetic experiments were carried out and different models were applied in order to elucidate the rate-controlling mechanism, the uptake kinetics was modeled using the pseudo-second order rate equation. The sorption isotherm can be best described by the Langmuir sorption isotherm and the maximum sorption capacities are 13.38, 14.81 and 4.20 mg g −1 for Pb(II), Mn(VII), and Cr(VI), respectively. The sorbent was successfully tested for Pb(II) and Cr(VI) removal from industrial effluents, while Mn(VII) was not detected the studied samples. Pb(II) desorption was performed using an aqueous solution of 0.1 M HCl, while Mn(VII) and Cr(VI) desorption was done using an aqueous solution of 0.1 M NaOH. The recycling of the sorbent was tested, maintaining a removal efficiency and a metal recovery over 90% for four successive sorption/desorption cycles. The effect of temperature was also evaluated, verifying the endothermic nature of the sorption process.

Magnetic alginate beads are potential biosorbent for sorption of lanthanum(III) from an aqueous medium. Batch experiments were carried out to study the equilibrium, kinetics, and thermodynamics of lanthanum sorption. The effects of initial solution pH, initial lanthanum concentration, and temperature on lanthanum sorption were investigated. The optimum pH value was defined to be 4. Kinetic and isotherm experiments were carried out at the optimum pH. It was enough to reach the adsorption equilibrium at 4 hours, and the maximum uptake capacity was (1.8 mmol g−1) at 25°C. Uptake kinetics and sorption isotherms were obtained and modeled using conventional and simple equations: best results were respectively obtained with the pseudo-second-order rate equation and the Langmuir equation. The La(III) loaded magnetic alginate beads were regenerated using 0.1 M CaCl2 without activity loss.

Magnetic chitosan was prepared by co-precipitation with polymeric Schiff’s base resulting from the reaction of thiourea with glutaraldehyde. This material has great potential as high-effective sorbent for Remazol Brilliant Blue R (RBBR): maximum sorption capacity reached 0.441 mmol g−1 at pH 1.6 and at 25°C. Kinetic plots, pH dependence, isotherm data, and influences of ionic strength were reported. The data from equilibrium sorption experiments are well fitted to the Langmuir isotherm and the pseudo-second-order sorption kinetics indicates that chemisorption controls the process. The distribution coefficient was calculated at different temperatures and the thermodynamic parameters have been calculated: the sorption reaction is endothermic, spontaneous, and increases the entropy of the system. Alkaline solution (0.5 M NaOH) was used for desorbing RBBR from loaded sorbent. The sorbent exhibited good regenerability over several repeated adsorption/desorption cycles.

Chitosan was modified through four different modification routes. First, epichlorohydrine cross-linked Chitosan was grafted with 3-Amino-1,2,4 triazole,5-thiol and melamine to produce RI and RII, respectively. Second, glutaraldehyde cross-linked chitosan was chemically modified using ammonium hydroxide then grafted with 3-Amino-1,2,4 triazole,5-thiol and melamine to produce RIII and RIV, respectively. The prepared polymers were characterized via FTIR, TGA, elemental analysis, water regain and surface area. RIII and RIV shows higher thermal stability, bigger surface area, and lower water regain, than RI and RII. Removal of Reactive Black 5 (RB5) anions from their aqueous solutions were studied using the modified chitosan adsorbents under various parameters such as pH, agitation time, and temperature. The maximum adsorption capacities are 0.492, 0.330, 0.622 and 0.698 mmol g −1 for RI, RII, RIII, and RIV, respectively, at pH 3 and 25 °C. The nature of interaction of RB5 with the adsorbents was identified. Uptake kinetics and adsorption isotherms were modeled using conventional and simple equations: best results were respectively obtained with the pseudo-second order rate equation and the Langmuir equation. The thermodynamic parameters have been calculated: the adsorption is endothermic, spontaneous and contributes to increase the entropy (randomness) of the system. RI and RII gives higher desorption yield than RIII and RIV, this probably due to the presence of the quaternary ammonium moiety in the last two sorbents.

Herein, a novel eco-friendly urea calcium alginate xerogel beads chemically functionalized with Congo red dye (U-CAB-CR1.43) was fabricated on the basis of commercial valorization of two copious waste biomass; Padina boergesenii brown alga and Anadara uropigimelana bivalve shells. The synthesized sorbent was characterized via FT-TR, BET surface area, TGA, SEM and EDX analyses. Sequential sorption capability of as-prepared biosorbent was investigated by appraising its efficiency to capture Cu(II) metal ion under variable operational parameters. Varying of sorbent doses form 0.5 g L−1 to 5 g L−1 was studied. Sorption isotherms, uptake kinetics and thermodynamic studies as prerequisite tools for plausible apprehension of sorption mechanism were also analyzed under optimized pH value (i.e. pH = 6.5). The results revealed that the isotherm profile of U-CAB-CR1.43 fits Langmuir equation with maximum sorption capacity of 6.94 mmol g-1 (441 mg g-1). Kinetic profile was accurately conformed to pseudo-second order rate equation. Thermodynamic function parameters emphasized the endothermic nature of sorption process. Successful desorption scenario using 0.5 mol L−1 of HCl has considerably promoted the spent sorbent to be further used up to four consequent sorption/desorption cycles. Feasibility of productive sorbent to expel Cu(II) from miscellaneous wastewater was successfully researched. To sum up, this study presents an efficient strategy for capturing Cu(II) from miscellaneous wastewater.

International audience; Thiourea-formaldehyde (TF) resin is prepared by polycondensation of its two precursors; the incorporation of pre-formed magnetite particles allows synthesizing a magnetic derivative of TF (MTF). These materials are applied to the sorption of two dyes (titan yellow, TY, and rose bengal, RB). Ultrasonic treatment (UT) is tested as an alternative to mechanical agitation (MA). The two sorbents are characterized by scanning electron microscopy, vibrating-sample magnetometry, BET surface area analysis, thermogravimetric analysis, Fourier-transform infrared and NMR spectroscopy, zetametry. Sorption properties are compared for TF and MTF under both MA and UT; considering pH effect, uptake kinetics (modeled using the pseudo-second order rate equation, and resistance to intraparticle diffusion), sorption isotherms (fitted by the Langmuir and Sips equations), the effect of competitor ions, and the desorption efficiency. Optimum sorption occurs at pH 3 (balance between (a) the electrostatic interactions between protonated groups (sorbent) and anionic forms of the dyes, and (b) the competitor effects of counter anions). UT strongly decreases the contact time required for reaching equilibrium (from 240 min to 30 min). UT increases the sorption capacities: in the range 0.3–0.6 mmol dye g−1 (MA) up to 0.9–1 mmol dye g−1. The magnetic core does not change kinetics, while it increases TF sorption capacities for both TY and RB. Under UT, the maximum sorption capacities are comparable for TF and MTF; however, the affinity of MTF remains higher than TF for the two dyes. Alkaline NaCl solutions completely desorb the dyes; UT decreases both the contact time and the NaCl concentration required for achieving the complete desorption of loaded dyes. The sorbents are recycled with high stability in sorption performance for at least five cycles.

Chitosan (natural polymer), glycidyl methacrylate (synthetic polymer) and magnetite are combined to produce novel magnetic macro-reticular hybrid synthetic–natural materials. The amino group concentration in the obtained materials was enriched through two different modification routes to generate effective sorbents for Remazol Brilliant Blue R (RBBR) ions. These materials showed a higher affinity towards the uptake of RBBR ions from aqueous media: maximum sorption capacity reached 0.153 mmol g−1 at pH 2.0 and at 25 °C. The nature of the interaction of RBBR with the sorbents was identified. The uptake kinetics and sorption isotherms were best described by the pseudo-second order rate equation and the Langmuir equation, respectively. The distribution coefficient was calculated at different temperatures and the thermodynamic parameters have been calculated: the sorption reaction is endothermic, spontaneous and increases the entropy of the system. Alkaline solution (0.5 M NaOH) was used for desorbing RBBR from loaded sorbents: a regeneration efficiency as high as 90–99% was obtained.

Magnetic sorbent microgranules with magnetite (Fe3O4) core and glycidyl methacrylate/N,N′-methylenebisacrylamide shell were prepared (MGMA). Diethylenetriamine (DETA) was successfully grafted (through a relatively simple solution reaction) onto the magnetic microgranules to obtain a sorbent (MGMA–DETA) with a very high content of amine groups. The obtained sorbent (MGMA–DETA) was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and thermogravimetric analysis (TGA). This material showed high affinity for Acid Yellow 99 dye (AY99) uptake from aqueous solutions: the maximum sorption capacity reached 0.25 mmol g−1 at pH 3.0 and ambient temperature (i.e., 25 ± 1 °C). Uptake kinetics and sorption isotherms were obtained and modeled using conventional and simple equations: the best results were respectively obtained with the pseudo-second order rate equation and the Langmuir equation. The distribution coefficient was obtained at different temperatures and the thermodynamic parameters have been calculated: the sorption is endothermic, spontaneous (especially at high relative temperature) and contributes to increase the entropy (randomness) of the system. NaOH solution (1.0 M) was used for AY99 desorption from loaded sorbents, and the sorbent could be efficiently recycled for a minimum of three sorption/desorption cycles. Therefore, MGMA–DETA could serve as a promising adsorbent for AY99 removal from industrial wastewater.

International audience; A composite material (PAN-Na-Y-zeolite) was prepared by polymerization of acrylonitrile in the presence of Na-Y zeolite. The A composite was functionalized by amidoximation through the reaction of hydroxylamine on nitrile groups of the composite. The sorbent (APNa-Y-zeolite) was fully characterized by FTIR spectrometry, XRD diffraction, thermogravimetric analysis, scanning electron microscopy, zetametry and BET analysis. The sorption properties of APNa-Y-zeolite were investigated for the recovery of Cu(II), Cd(II) and Pb(II) from synthetic solutions before being tested for the purification of local tap water. Sorption properties were characterized through the study of pH effect, uptake kinetics, sorption isotherms. The pseudo-second order rate equation fitted well kinetic profiles. Sorption isotherms were modeled using the Langmuir, the Freundlich and the Sips equations. Thermodynamic parameters were evaluated through variation of temperature. While the sorption of Cu(II) and Cd(II) was endothermic, Pb(II) recovery was exothermic. Metal ions were successfully desorbed using 5 M HCl solutions. High concentrations of NaCl hardly alter sorption performance, contrary to humic acid that slightly reduces metal binding.

Magnetic Schiff's base chitosan composite has been prepared starting from shrimp peels as a raw material. Chitosan extraction involved three main stages as preconditioning, demineralization deproteinization and deacetylation. Chitosan modification process took place through the reaction between chitosan and polymeric Schiff's base of thiourea/glutaraldehyde in the presence of magnetite. The synthetic hybrid composite was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy-energy dispersive X-ray analyses and tested as sorbent for Cr(VI) recovery from aqueous solution. The performance of the sorbent was systematically evaluated by batch sorption experiments, followed by equilibrium and kinetic studies with different mathematical models. The isotherm study demonstrate that the sorbent achieved 99.1% (sorption capacity; 252.45 mg g−1) removal efficiency in Cr(VI) solution with concentrations up to 400 mg/L. Experimental data gave better mathematical fitting towards pseudo-second-order kinetic model and Langmuir isotherm model. The distribution coefficient was obtained at different temperatures and the thermodynamic parameters have been calculated: the sorption is endothermic, spontaneous and contributes to increase the randomness of the system. The sorbent could be recycled for three cycles of sorption/desorption.

The immobilization of Mo(VI) on magnetic poly p-phenylenediamine-thiourea-formaldehyde composite polymer (MpPDTF) (through an intermediary adsorption step) increased sorption of As(V) ions: retention capacity increased from 35.15 mg As g−1 for MpPDTF to 99.04 mg As g−1 for MpPDTF immobilized Mo(VI) at 298 ± 1 K. The impact of temperature and Mo(VI) immobilization on the kinetic and equilibrium constants of As(V) sorption on MpPDTF was evaluated. The thermodynamic study shows that Mo(VI) immobilization on MpPDTF changes the sorption process of As(V) on MpPDTF from exothermic associated with entropy decrease to endothermic associated with entropy increase. Also the impact of phosphate competition was studied. MpPDTF immobilized Mo(VI) was successfully tested for As(V) removal from the industrial effluents of insecticides manufacturing industry. NaHCO3 solution (0.5 M) can be efficiently used for sorbent regeneration for at least 3 cycles with limited decrease in sorption performance.

International audience; A composite sorbent (MGMA) was synthesized by coating a magnetite core with glycidyl methacrylate-based polymer, further grafted with diethylenetriamine (DETA). The absence of coercivity and remanence in VSM analysis confirms that the material has super paramagnetic properties that make it readily separable from the liquid phase applying external magnetic field. The sorbent (MGMA-DETA) was tested for Hg(II) recovery from aqueous solutions (of increasing complexity). The separation of Hg(II) from multi-metal solutions was tested at different pH values. The impact of counter ions on metal sorption was also tested at different pHs. Sorption mechanisms explained the different effects of counter ions (in relation with metal speciation) and also the relative selectivity of the sorbent for Hg(II) over other base metals. Uptake kinetics and sorption isotherms were modeled with the pseudo-second order rate equation and the Langmuir equation, respectively. The thermodynamic parameters have been calculated. The sorbent was successfully tested for Hg(II) removal from two industrial effluents (from chlor-alkali industry and from mercury-oxide manufacturing). The sorbent could be recycled for at least 4 cycles of sorption/desorption. This means that the magnetic sorbent is a promising material for the efficient and selective removal of mercury from complex solutions.

International audience; A new hybrid material was prepared using chitosan, glycidyl methacrylate and magnetite microparticles. The concentration of amine groups on the sorbent was increased by grafting diethylenetriamine. These materials were tested for the sorption of Hg(II) metal ions. These materials showed high affinity and selectivity for Hg(II) uptake from aqueous solutions: maximum sorption capacity reached 2.6 mmol g(-1) at pH 4.0. The influence of pH was tested on the selective separation of Hg(II) from a mixture of Hg(II), Co(II), Cu(II), Fe(II), Ni(II), Zn(II) and Mg(II). The effect of counter anions was also studied at different pH values. Sorption may occur by chelation of cationic mercury species on amino groups or by ion exchange of chloroanionic mercury species on protonated amino groups. Uptake kinetics and sorption isotherms were modeled using the pseudo-second order rate equation and the Langmuir equation, respectively. The distribution coefficient was obtained at different temperatures and the thermodynamic parameters have been calculated: the sorption is endothermic, spontaneous and contributes to increase the entropy of the system. Potassium iodide was used for Hg(II) desorption from loaded sorbents: desorption yields 99%, and the sorbent could be efficiently recycled for a minimum of three sorption/desorption cycles.

International audience; The removal of As(V) ions from aqueous solution was carried out using composite sorbents based on chitosan (as the encapsulating material) and Cu(OH)(2) or CuO. The sorbents were characterized using SEM, EDX and Zeta potential analysis. Sorption uptake was highly dependent on pH, temperature, initial As(V) concentration and sorbent dosage (SD): the optimum initial pH for arsenic removal was found close to 4. The sorption isotherm was described by the Langmuir equation. The metal ion can be bound through two different sorption sites: one having a strong affinity for As(V) (probably Cu(OH)2 or CuO) and the other having a lower affinity (probably the encapsulating material). The uptake kinetics was well fitted by the pseudo-second order rate equation. The effect of temperature was also evaluated, verifying the endothermic nature of the sorption process. Arsenic elution was performed using a saline solution (30 g L-1 NaCl) at pH 12. The recycling of the sorbent was tested, maintaining a removal efficiency and a metal recovery over 95% for five successive sorption/desorption cycles.