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Folic acid (VB9) was used as an eco-friendly sequestering chemical compound to modify and develop a novel nanocomposite via surface immobilization and chemical bonding with nanosilica (Nano-SiO2) in the chloride form to generate Nano-SiO2@VB9. The synthesized materials were investigated and characterized by several means of SEM, HR-TEM, TGA, FT-IR, XRD and surface area determination. The tendency of Nano-SiO2@VB9 nanocomposite to extract and remove bivalent lead, cadmium and copper ions was studied and optimized under various variables including pH of contact medium, nanocomposite dose, contact time, effect of metal ion concentration and interfering cations-anions. The highest determined capacity values were 562.1, 973.8 and 152.1 mg g−1 for Cd(II), Pb(ІІ) and Cu(II), respectively. The optimum contact time for sorption of metal ions was identified as 25 min, while 10.0 mg of Nano-SiO2@VB9 nanocomposite was the optimum dosage to establish the maximum capacity values. The adsorbed ions were arranged in a multilayer surface and the equilibrium up-take of metal ions by Nano-SiO2@VB9 nanocomposite was favorably characterized by the Freundlich adsorption isotherm model. The potential applications of Nano-SiO2@VB9 for removal and preconcentration of Cu(II), Pb(II) and Cd(II) from real water samples using multistage microcolumn were also studied to confirm excellent percentage extraction values 94–100%, 100% and 57–81%, respectively.

The present study is aimed to examine the adsorption characteristics of Cu(II) by using the novel cellulose acetate composite and to apply it for the removal of Cu(II) from real wastewater samples. In order to achieve this objective, ethylenediamine, diethylenetriamine, triethylenetetramine and te-traethylenepentanene were used for immobilization of grafted cellulose acetate-nanoscale manganese dioxide. Cellulose was extracted from mangrove species Avicennia marina and converted to cellulose acetate then it was formed composite with nano-manganese dioxide via precipitation of nano-manganese dioxide on it. The composite was grafted with acrylamide monomer before immobilization. The synthesized compounds were used for adsorption of Cu(II) and characterized by FT-IR, TGA and SEM. The adsorption characteristics of synthesized sorbents were optimized. Langmuir and Freundlich models were used to establish sorption equilibria. The analytical applications of these modified materials were applied successfully for the removal of Cu(II).

Zirconium (Zr) decorated with manganese dioxide (MnO2) nanoparticles-functionalized reduced graphene oxide (RGO); (Zr-MnO2@RGO) tertiary nanocomposite was fabricated by a facile chemical route. The bi-functionality of the novel nanocomposite by Zr and MnO2 nanoparticles has greatly enhanced the efficiency and kinetics of its adsorptivity towards arsenic As(V). The physicochemical properties of the fabricated nanocomposite were characterized extensively by using XRD, Raman spectroscopy, TGA, HR-TEM, FT-IR, SEM, and EDX techniques. The effects of medium pH, mass dosage, kinetics, initial arsenate concentration were investigated via batch-adsorption experiments. Contact time study revealed that pseudo-second-order equation fitted well the kinetic data indicated a fast and feasible sorption process. The reusability and stability performance of the nanocomposite was evaluated and confirmed after five adsorption-desorption cycles. The efficacy of the potential novel nanocomposite towards the simultaneous removal of As(V) from industrial and groundwater samples has been examined.

Hexavalent chromium, Cr(VI), is a highly toxic species, while trivalent chromium, Cr(III), is an essential trace element for humans and other organisms. In the present work, a simple, rapid, and efficient procedure for water treatment of Cr(VI) is described. Active carbon (AC) was chemically treated with HCl and NaOH for the formation of surface modified Acidic-AC and Basic-AC sorbents, respectively. In addition, AC sorbent was treated with HNO$_{3}$ as an oxidizing agent and sodium sulfite as a reducing agent for the formation of Ox-AC and Rd-AC sorbents, respectively. The modified AC sorbents were tested to identify their potential applications in removal of Cr(VI) under various controlling factors using the batch technique. The results indicated that these sorbents can be used in water treatment due to their excellent and efficient reduction of Cr(VI) into Cr(III) with percentage transformation values in the range of 90%-100%. Acidic-AC was found to be the superior sorbent in the reduction process of Cr(VI). The produced Cr(III) was removed from aqueous solutions via adsorption on the surface of these sorbents. The reduction and adsorption processes of Cr(VI)-Cr(III) were evaluated and optimized under different experimental parameters. The potential applications of these sorbents in real water treatment were also explored.

The aluminon functionalized MNPs (Fe 3 O 4 @aluminon) as a novel magnetic nano-sorbent have been synthesized by a simple hydro-thermal method for the removal of Cr(VI) and Cr(III) from aqueous solution. Fe 3 O 4 @aluminon MNPs were characterized using SEM, HRTEM, FTIR, VSM and TGA techniques. The Fe 3 O 4 @aluminon nano-sorbent has good dispersibility and valuable magnetic property. The effects of pH, equilibration time, mass of nano-sorbent and initial concentration of adsorbate on the percentage recovery of Cr(VI) and Cr(III) by Fe 3 O 4 @aluminon were investigated. The adsorption equilibrium was attained in 20 min at 25 °C and the adsorption kinetics obeyed the pseudo-second order model. The experimental data for the adsorption of Cr(VI) and Cr(III) better fitted the Langmuir isotherm and the maximum adsorption capacities were 263.2 mg/g for Cr(VI) at pH 1.0 and 400.0 mg/g for Cr(III) at pH 7.0. The adsorption–desorption cycles revealed that Fe 3 O 4 @aluminon nanoparticles had high stability and appropriate reusability. The removal efficiencies of chromium ions from different water samples were successfully accomplished (∼ 95.0–96.7 ± 1.4–2.1%).

Baker’s yeast (Saccharomyces cerevisiae) was immobilized on mango (Mangifera indica L.) leaves to prepare a novel, low cost, and eco-friendly biosorbent Mi-yeast. The fabricated biosorbent was characterized by FTIR and SEM and applied to remove Co(II) and Ni(II) ions from aqueous solutions via batch mode technique. The biosorption equilibria were established in 30 min and the experimental data were applied to Freundlich, Langmuir, and Dubinin–Radushkevich isotherm models. The maximum biosorption capacities were found to be 526 mg g−1 for Co(II) at pH 6 and 250 mg g−1 Ni(II) at pH 7. Among four kinetic models, the experimental data were best described by the second-order expression. Different foreign ions were found to have a negligible interfering effect on the biosorption capacities. Mi-yeast could be regenerated using 0.2 M HCl during repeated biosorption–desorption cycles with 4–7% loss in metal efficiency after five cycles. The potential applications of Mi-yeast for selective removal of Co(II)...

Biosorption and water treatment of Mg(II) and Ca(II) hardness was designed via surface loading of heat inactivated Fusarium verticillioides fungus (Fus) on nano-silica (NSi) for developing the (NSi–Fus) as a novel biosorbent. Surface characterization was confirmed by FT-IR and SEM analysis. The (NSi), (Fus) and (NSi–Fus) sorbents were investigated for removal of Mg(II) and Ca(II) by using the batch equilibrium technique under the influence of solution pH, contact time, sorbent dosage, initial metal concentration and interfering ion. The maximum magnesium capacity values were identified as 600.0, 933.3 and 1000.0 μmole g −1 while, the maximum calcium values were 1066.7, 1800.0 and 1333.3 μmole g −1 for (NSi), (Fus) and (NSi–Fus), respectively. Sorption equilibria were established in ∼20 min and the data were well described by both Langmuir and Freundlich models. The potential applications of these biosorbents for water-softening and extraction of magnesium and calcium from sea water samples were successfully accomplished.

Heat inactivated Aspergillus ustus (Asp), silicon dioxide-nano-powder (N―Si), and silicon dioxide nano-powder-combined-heat inactivated Aspergillus ustus (N―Si―Asp) were used to study the biosorption of Cd(II) from aqueous solutions via batch equilibrium technique. Surface characterization and immobilization of the fungal cells on silicon dioxide-nano-powder were examined and confirmed by using FT-IR and ESM analysis. Cadmium biosorption processes were investigated under the effect of pH, contact time, sorbent dosage and initial metal concentration. The three examined sorbents were found to exhibit maximum μmol g-1 capacity values in pH 7.0. The maximum determined cadmium capacity by silicon dioxide-nano-powder (N―Si) (600 μmol g− 1) was found higher than that exhibited by the heat inactivated fungal cells (Asp) (400 μmol g− 1). However, (N―Si―Asp) exhibited the highest sorption cadmium capacity (1000 μmol g− 1) as a combined behavior of both silicon dioxide nano-powder and Aspergillus ustus units. Sorption equilibria were established in 20 min and their data were well described by both Langmuir and Freundlich models. The potential applications of these sorbents for biosorptive removal of Cd(II) from real samples contaminated with cadmium, were successfully accomplished via a micro-column under constant flow rate.

Dowex anion exchanger-immobilized-baker’s yeast [Dae-yeast] were synthesized and potentially applied as environmental friendly biosorbents to evaluate the up-take process of anionic and cationic mercury(II) species as well as other metal ions. Optimization of mass ratio of Dowex anion exchanger versus yeast (1:1–1:10) in presence of various interacting buffer solutions (pH 4.0–9.0) was performed and evaluated. Surface modification of [Dae-yeast] was characterized by scanning electron microscopy (SEM) and infrared spectroscopy. The maximum metal biosorption capacity values of [Dae-yeast] towards mercury(II) were found in the range of 0.800–0.960, 0.840–0.950 and 0.730–0.900 mmol g−1 in presence of buffer solutions pH 2.0, 4.0 and 7.0, respectively. Three possible and different mechanisms are proposed to account for the biosorption of mercury and mercuric species under these three buffering conditions based on ion exchange, ion pair and chelation interaction processes. Factors affecting biosorption of mercury from aqueous medium including the pH effect of aqueous solutions (1.0–7.0), shaking time (1–30 min) and interfering ions were searched. The potential applications of modified biosorbents for selective biosorption and extraction of mercury from different real matrices including dental filling waste materials, industrial waste water samples and mercury lamp waste materials were also explored. The results denote to excellent percentage extraction values, from nitric acid as the dissolution solvent with a pH 2.0, as determined in the range of 90.77–97.91 ± 3.00–5.00%, 90.00–93.40 ± 4.00–5.00% and 92.31–100.00 ± 3.00–4.00% for the three tested samples, respectively.

A method is proposed and explored for speciation of Cr(III) and Cr(VI), selective extraction and preconcentration in various water samples based on dynamic and static techniques. Three newly designed alumina phases-physically adsorbed-2-pyridenecarboxyladehyde-thiosemicarbazone [Al-2PC-TSC (I–III)] were synthesised and characterised. Stability tests and application of [Al-2PC-TSC (I–III)] as inorganic ion exchangers and chelating solid sorbents for various metal ions were studied and evaluated. The distribution coefficient and separation factors of chromium species versus other interfering metal ions were determined to examine the incorporated selectivity into these alumina phases. Quantitative recovery of Cr(VI) was accomplished by [Al-2PC-TSC (I–III)] at pH = 1.0 while Cr(III) was found to be quantitatively recovered on these sorbents at pH = 7.0 with minimal or no interference between these two species under the studied buffering conditions. Selective solid phase speciation and preconcentration of Cr(I...

A method is presented and described for speciation, extraction and preconcentration of Cr(III) and Cr(VI) based on dynamic and static solid phase extraction techniques. Three newly designed alumina phases-physically adsorbed-isatin-thiosemicarbazone (I-III) were synthesized, characterized, tested for stability and applied as inorganic ion exchangers and chelating solid sorbents for various metal ions. The selectivity characteristics incorporated into these alumina phases were studied and evaluated via determination of the distribution coefficients and separation factors of chromium species versus other interacting metal ions. Quantitative recovery of Cr(VI) was accomplished by alumina phases (I-III) in pH 1.0 giving percentage extraction values of approximately 99.9-100.0%, while Cr(III) was found to be quantitatively recovered by these sorbents in pH 7.0 leading to percentage extraction values approximately 100.0% with minimal or no interference between these two species under the studied buffering conditions. Selective solid phase speciation and preconcentration of Cr(III) and Cr(VI) in various real water samples were successfully performed and accomplished by newly designed alumina phases (I-III) via a preconcentration micro-column.

A speciation method is developed for Cr(III) and Cr(VI) at selected medium pH range via solid phase extraction on three designed and synthesized chelating inorganic solid sorbents based on adsorption of thiosemicarbazide, as the nitrogen and sulfur containing chelating compound, on alumina surface [Al-TSC (I–III)]. The influence of various parameters including medium pH, time of contact, and interference of matrix and coexistent elements on the speciation and selective extraction processes of chromium species are studied and evaluated on the basis of determination of the metal adsorption capacity, distribution coefficient, and separation factor. Quantitative recovery of Cr(VI) was accomplished by [Al-TSC (I–III)] at pH = 1.0, while Cr(III) was found to be recovered on these sorbents at pH = 7.0 with minimal or no interference between these two species under the studied buffering conditions. The proposed method has been successfully applied for speciation, selective extraction, and preconcentratio...

Chromium is one of the most toxic and carcinogenic heavy metals. Conventional techniques which are commonly applied for removal of chromium ions from aqueous matrices have several drawbacks whereas biosorption has a high performance for metal extraction. Three fungal strains, i.e., (1) Aspergillus ustus (Asp), (2) Fusarium verticillioides (Fus), and (3) Pencillium funiculosum (Pen), have been immobilized on nanosilica (NSi) surface to develop highly effective three biosorbents, i.e., (1) NSi-Asp, (2) NSi-Fus, and (3) NSi-Pen. They are used for solid phase extraction and selective removal of Cr(III) and Cr(VI) ions. Surface characterization and immobilization of fungal cells on nanosilica were examined and confirmed by using scanning electron imaging and Fourier-transform infrared analysis. Biosorption and removal of chromium ions were followed up via batch experiment under the influence of pH, contact time, biosorbent dosage, and initial metal ion concentration. The maximum biosorption capacity va...

Metal pollution is well recognized as one of the major environmental problems that must be imperatively addressed and solved. In this study, three types of alumina adsorbents (I-III) were physically immobilized with purporogallin as a chelating ion exchangers. These were found to exhibit strong capability and selectivity characters for a series of heavy metal ions. Surface modification of hybrid alumina was characterized and identified from the determination of surface coverage and infrared analysis. Hybrid alumina adsorbents were identified for their strong resistivity to acid leaching in pH>2-7 as well as their high thermal stability up to 350 degrees C. The ability of newly synthesized hybrid inorganic/organic alumina adsorbents (I-III) to bind and extract various metal ions was examined and evaluated in various buffer solutions (pH 1.0-7.0) via determination of the metal adsorption capacity values. These were identified as high as 420-560, 500-580 and 500-590 micromol g(-1) for alumina adsorbents (I), (II) and (III), respectively in the case of high concentration levels of Cr(III), Fe(III) and Cu(II). The influence of alumina matrices were highly characterized when low concentration levels (microg ml(-1) and ng ml(-1)) of metal ions were used. Hybrid alumina adsorbents were successfully applied for selective extraction, removal and preconcentration of various heavy metals from underground water samples with percentage recovery values of 92-100+/-1-3%.