Novel fibrous Ag(NP) decorated clay-polymer composite: Implications in water purification contaminated with predominant micro-pollutants and bacteria.

Due to the potential harm caused by emerging micro-pollutants to living organisms, contaminating water supplies by micro-pollutants like EDCs, pharmaceuticals, and microorganisms has become a concern in many countries. Considering both microbiological and micro-pollutant exposure risks associated with water use for agricultural/or household purposes, it is imperative to create a strategy for improving pollutant removal from treated wastewater that is both effective and affordable. Natural clay minerals efficiently remove contaminants from wastewater, though the pristine clay has less affinity to several organic pollutants. Hydrophilic polymers, viz., poly(ethylene glycol) (PEG), improve the dispersion of particles, flocculation processes, and surface properties. In this study, PEG grafted with attapulgite, thereby providing a high-specific surface-area, mesoporous materials for the adsorption of micro-pollutants like ciprofloxacin (CIP) and 17α-ethinylestradiol (EE2) at high rates. A gentle washing process regenerates the clay-polymer material several times with no performance loss, and the natural water implications show fair applicability of solid in decontaminating the CIP and EE2 in an aqueous medium. Further, greenly synthesized silver nanoparticles in situ disperse with the clay polymer efficiently remove the gram-positive and gram-negative bacterium viz., Bacillus subtilis, and Pseudomonas aeruginosa, which are commonly persistent in aquatic environments. The clay polymer outperformed a modified clay composite to eliminate microorganisms and organic micro-pollutants in significant quantities quickly. These results clearly show the importance of fibrous clay-polymer composite for water purification technologies.

Highly efficient hydrophobic nanocomposite in the decontamination of micropollutants and bacteria from aqueous wastes: A sustainable approach.

Micro-pollutants (specifically antibiotics and personal care products) and potential bacterial contamination pose a severe threat to human health and marine life. The study derives indigenous novel fibrous hydrophobic nanocomposite, efficient in decontaminating the micro-pollutants (tetracycline (TC) and bisphenol A (BPA)) and potential pathogens (S. pyogenes and E. coli) from aqueous wastes. A facile method synthesizes the fibrous attapulgite (ATP)- poly(4-vinylpyridine-co-styrene) (PVP) framework decorated in situ with the Ag0 nanoparticles (ATP@PVP/Ag0). A greener method using the Artocarpus heterophyllus leaf extract derives the Ag0(NPs). Various analytical methods extensively characterize the materials. A comprehensive study that includes pH, concentration, background electrolytes, and ionic strength reveals the sorptive removal insights of TC and BPA utilizing the ATP@PVP solid. The elimination of tetracycline (TC) and bisphenol A (BPA) agrees well with the pseudo-second-order kinetics. The pH 3.07 and 6.06 favor removing TC and BPA with the capacity of 10.86 mg/g and 17.36 mg/g at 25 °C. The hydrogen bonding and hydrophobic interactions predominate the sorption mechanism, and the material shows remarkable stability and reusability in repeated sorption/desorption operations. Similarly, the natural water implications and flow-bed system show fair applicability of solid in decontaminating the TC and BPA in an aqueous medium. Further, the material ATP@PVP/Ag0 exhibits very high inhibition of potential pathogens S. pyogenes and E. coli and optimizes the solid dose and solution pH.

Novel nanocomposite thin film in the efficient removal of antibiotics using visible light: Insights of photocatalytic reactions and stability of thin film in real water implications.

Novel clay (bentonite) supported Ag0 nanoparticles (NPs) doped TiO2 nanocomposite (Clay/TiO2/Ag0(NPs)) thin film was obtained by using template synthesis method. The nanocomposite material is decorated with cubical Ag0(NPs) and utilised successfully in the photocatalytic degradation of tetracycline (TC) and sulfamethazine (SMZ) from aqueous solutions utilizing visible light and UV-A radiations. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) analyses were used to characterise the nanocomposite materials. Diffusion reflectance spectroscopy (DRS) was utilised to determine the bandgap energies of the materials and also to confirm that Ag0(NPs) was successfully doped with TiO2. The nanocomposite material showed highly efficient photocatalytic activity for the breaking down of TC/SMZ under visible light irradiation by the enhanced electron-hole separation and adsorption of antibiotics at the vicinity of the catalyst. The oxidative degradation of TC/SMZ were shown to be highly dependent on the pH, initial concentration of TC/SMZ, and various co-existing ions. Reusability test of Clay/Ag0(NPs)/TiO2 nanocomposite revealed that the activity did not decline with repeated use. Treatment of TC and SMZ in real water system further enhanced the application potential of the novel catalysts for the treatment of full-scale wastewater polluted with these antibiotics.

Novel cubical Ag(NP) decorated titanium dioxide supported bentonite thin film in the efficient removal of bisphenol A using visible light.

The persistent endocrine-disrupting chemical bisphenol A is posing serious health concerns; hence, it is known to be an emerging and potential water contaminant. The present investigation aims to synthesize novel cubical Ag(NP) decorated titanium dioxide-supported bentonite (Ag/TiO2@Clay) nanocomposite using a novel synthetic process. The nanocomposite materials were characterized by several analytical methods viz., transmission electron microscopy (TEM), X-ray diffraction (XRD) analyses, energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) and diffuse reflectance spectroscopy (DRS). Further, the photocatalytic removal of bisphenol A was conducted utilizing the thin film catalyst under the LED (light emitting diode; visible light) and UV-A (ultra violet-A) light sources. The parametric studies solution pH (6.0-12.0), pollutant concentrations (1.0-20.0 mg/L), and the interaction of several scavengers and co-existing ions are studied extensively to demonstrate the insights of the removal mechanism. The mineralization of bisphenol A and repeated use of the thin film catalyst showed the potential usage of photocatalysts in the devised large-scale operations. Similarly, the natural matrix treatment was performed to evaluate the suitability of the process for real implications.

Efficient and selective use of functionalized material in the decontamination of water: removal of emerging micro-pollutants from aqueous wastes.

The contamination of the aquatic environment with emerging micro-pollutants is a serious global concern. The aim of this investigation was to synthesize novel functionalized material (BNAPTES) precursor to natural bentonite in a single pot facile synthetic route. The material was utilized for efficient and selective removal of tetracycline (TC) and triclosan (TCS) in aqueous wastes. The grafting of silane was confirmed with the FT-IR (Fourier Transform Infra-Red) analysis and the EDX (Energy Dispersive X-ray) analysis showed the incorporation of amino group with the bentonite. The structural changes of clay due to silane grafting were studied with the help of XRD (X-ray Diffraction) and BET (Brunner-Emmett-Teller) surface area analyses. Batch adsorption studies showed that functionalized clay significantly increased the selectivity and adsorption capacity of bentonite for TC and TCS. The Langmuir monolayer adsorption capacity was found to be 15.36 and 17.15 mg/g for TC and TCS, respectively. The rapid uptake of TC and TCS by functionalized material followed pseudo-second-rate kinetics. Further, a total of 78% of TC and 73% of TCS were removed within 5 min of contact and the adsorption equilibrium was achieved within 120  min. The influence of background electrolytes and co-existing ions indicated that TC and TCS were selective towards BNAPTES. The loading capacities of the column packed with BNAPTES were found to be 56.00 and 44.42 mg/g for TC and TCS, respectively. Further, BNAPTES was found efficient even in real water treatment since the attenuation of TC and TCS was not affected significantly in the real water matrix.

Gum Hydrocolloids Reinforced Silver Nanoparticle Sponge for Catalytic Degradation of Water Pollutants.

The accumulation of organic contaminants including dyes in aquatic systems is of significant environmental concern, necessitating the development of affordable and sustainable materials for the treatment/elimination of these hazardous pollutants. Here, a green synthesis strategy has been used to develop a self-assembled gum kondagogu-sodium alginate bioconjugate sponge adorned with silver nanoparticles, for the first time. The properties of the nanocomposite sponge were then analyzed using FTIR, TGA, SEM, and MicroCT. The ensued biobased sponge exhibited hierarchical microstructure, open cellular pores, good shape memory, and mechanical properties. It merges the attributes of an open cellular porous structure with metal nanoparticles and are envisaged to be deployed as a sustainable catalytic system for reducing contaminants in the aqueous environment. This nanocomposite sponge showed enhanced catalytic effectiveness (km values up to 37 min-1 g-1 and 44 min-1 g-1 for methylene blue and 4-nitrophenol, respectively), antibacterial properties, reusability, and biodegradability (65% biodegradation in 28 days).

Noble metal-doped TiO2 thin films in the efficient removal of Mordant Orange-1: insights of degradation process.

Nanocomposite Ag0(NPs)/TiO2 is synthesised in a facile template method enabling nanoparticles of reduced Ag evenly distributed within the titania network. The morphological studies of nanocomposites were extensively performed employing SEM/EDX (scanning electron microscopy/energy dispersive X-ray), TEM (transmission electron microscopy) and AFM (atomic force microscopy). Moreover, the bandgap energies of materials were obtained using the diffuse reflectance spectrometer (DRS). The newer insights in the photocatalytic elimination of Mordant Orange-1 (MO1) was obtained using the nanocomposite thin film for various parametric studies utilising the UV-A and LED illuminations. The kinetics of degradation of MO1 was performed, and the rate constant was favoured at lower concentrations of MO1. Moreover, the elimination efficiency of MO1 was favoured with a decrease in solution pH. The NPOC results inferred that a fairly good extent of MO1 was mineralised using a thin-film catalyst for both the UV-A and LED illuminations. The minimal effect of several co-ions demonstrated the applicability of thin films in the elimination of MO1, and the stability of the thin film has shown the potential applicability of thin-film catalysts. Further, the mechanism of photocatalytic degradation was demonstrated with the radical scavenger studies and ascertained the reaction pathways.

Photocatalytic degradation of amoxicillin and tetracycline by template synthesized nano-structured Ce3+@TiO2 thin film catalyst.

Contamination of the aquatic environment with pharmaceutical compounds is a serious environmental concern. The present investigation aims to utilize the Ce3+/TiO2 thin film catalyst to remove of potential antibiotics (amoxicillin and tetracycline) using the less harmful UV-A radiations. Reduced cerium ion-doped TiO2 is obtained by a simple one-step facile template method using polyethylene glycol as the templating agent. The synthesized catalysts Ce3+@TiO2 (non-template) and Ce3+@TiO2(T) (template) were characterized by spectroscopic methods. The XPS reaffirms the reduced Ce3+ dispersed within the titania network, and the AFM showed the surface roughness of the thin films. Detailed physicochemical analyses were conducted to deduce the degradation mechanism, and repeated use of the thin film photocatalyst showed enhanced stability. Significant mineralization of the antibiotics indicates the potential applicability of the photocatalytic catalyst. Furthermore, the presence of Ce3+ significantly restricted the recombination of electron/hole pairs in the photo-excited TiO2 semiconductor and showed enhanced photocatalytic degradation of the antibiotics proceeded predominantly through the •OH.

New insights in photocatalytic removal of Alizarin Yellow using reduced Ce3+/TiO2 catalyst.

The present communication aims to obtain a novel Ce3+/TiO2 thin film in a single step facile method using the in situ template process. The material was characterized by the XRD (X-ray diffraction), XPS (X-ray photoelectron spectroscopy), TEM (transmission electron microscope), and AFM (atomic force microscope) analyses. The thin film catalyst was intended to introduce in the degradation of one of potential dye Alizarin Yellow from aqueous solutions using the UV-A radiations. The mechanisms of degradation along with the physicochemical parametric studies were conducted extensively. The mineralization of pollutant and the replicate use of catalysts further enhance the applicability of present communication. Additionally, the real matrix treatment was conducted to simulate the treatment process.

Synthesis and characterization of Ag0(NPs)/TiO2 nanocomposite: insight studies of triclosan removal from aqueous solutions.

Nanocomposite mesoporous Ag0(NPs)/TiO2 thin film materials were synthesized and assessed for its efficient application in the elimination of potentially important drug triclosan from aqueous solutions. A template synthesis using the polyethylene glycol was enabled to obtain Ag0(NPs)/TiO2 nanocomposite materials where zerovalent Ag was in situ doped to the titania network. The nanocomposite materials were characterized by the scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), EDX elemental mapping, X-ray diffraction (XRD) analyses and Brunauer-Emmett-Teller (BET) methods. Further, the diffuse reflectance spectroscopy (DRS) was introduced to estimate the band gap of these solids. The thin film materials were subjected to the remediation of water contaminated with triclosan using the UV-A light. The oxidative elimination of triclosan was demonstrated as a function of pH, concentration of triclosan and presence of several co-existing ions. Increase in pH (4.0-10.0) and triclosan concentrations (0.5-15.0 mg/L) had decreased significantly the percentage degradation of triclosan. The pseudo-first-order kinetics was shown in the degradation of triclosan and rate constant was significantly decreased with the increase in pollutant concentration (0.5-15.0 mg/L) and pH (4.0-10.0). The 1000 times presence of scavengers showed that •OH were, predominantly, caused the oxidation of triclosan. Moreover, multiple application of nanocomposite Ag0(NPs)/TiO2(B) revealed that the thin film was fairly intact since the photocatalytic efficiency of triclosan removal was almost unaffected.

Nanocomposite thin films Ag0(NP)/TiO2 in the efficient removal of micro-pollutants from aqueous solutions: A case study of tetracycline and sulfamethoxazole removal.

The aim of this communication is to synthesize novel Nanocomposite thin film materials (Ag0(NP)/TiO2) using the template process. Surface morphology of materials was obtained by the Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analyses. The presence of doped Ag-nanoparticles was confirmed by the TEM images along with the SEM-EDX analyses. The Atomic Force Microscopic images were demonstrated the surface roughness and thickness of Nanocomposite thin films. X-ray diffraction analysis confirmed that TiO2 was predominantly present to its anatase mineral phase. The Fourier Transform Infra-red analysis conducted to obtain the functional groups present with the solid. The specific surface area and pore sizes of Nanocomposites were obtained by the BET (Brunauer, Emmett, and Teller) analysis. Further, the Nanocomposite thin film photocatalysts were successfully employed in the degradation of emerging micro-pollutants viz., the antibiotics tetracycline and sulfamethoxazole from aqueous solutions using less harmful UV-A light (λmax 330 nm). The effect of solution pH (pH 4.0-8.0) and pollutant concentrations (1.0 mg/L-20.0 mg/L (for tetracycline) and (0.5 mg/L-15.0 mg/L (for sulfamethoxazole)) was extensively studied in the photocatalytic removal of these antibiotics. A significant decrease in percentage of non-purgeable organic carbon removal indicated that the micro-pollutants was substantially mineralized by the photocatalytic treatment. The stability of thin film was assessed by the repeated use of Nanocomposite thin films and results were indicated that the degradation of tetracycline or sulfamethoxazole was almost unaffected at least for six cycles of photocatalytic operations. The presence of several cations and anions in the degradation of these antibiotics was studied. Additionally, the presence of 2-propanol and EDTA inhibited significantly the degradation of these micro-pollutants i.e., the percentage of degradation was decreased by 31.8 and 24.2% (for tetracycline) and 42.8 and 39.9% (for sulfamethoxazole), respectively. This indicated that the degradation of tetracycline or sulfamethoxazole was predominantly proceeded by the OH radicals; generated at the valance and conduction band of semiconductor. Similarly, the presence of sodium azide inhibited the percentage removal of these antibiotics.

Nanocomposite Au NP/TiO2 thin film in the efficient remediation of aqueous solutions contaminated with emerging micro-pollutants.

The present communication specifically aims to synthesize novel nanocomposite material Au NPs/TiO2 in a simple template process using the polyethylene glycol as filler media. The thin film of the nanocomposite material was characterized by the advanced analytical tools. The surface morphology was obtained by the scanning electron microscopic (SEM) and transmission electron microscopic (TEM) images of solids. Similarly, the surface topography and roughness of solid were obtained by the atomic force microscopic (AFM) image of thin film. X-ray diffraction (XRD) data enabled to confirm that the TiO2 was predominantly present with its anatase phase. The specific surface area and pore size of the solid were obtained using the N2 adsorption/desorption data. Nanocomposite Au NP/TiO2 thin film was employed in the photocatalytic removal of sulfamethoxazole and triclosan from aqueous solutions using less harmful UV-A light (λmax = 330 nm). Various physicochemical parametric studies enabled to deduce the mechanism involved in the degradation process. The degradation kinetics as a function of pH (pH 4.0-10.0) and micro-pollutant concentrations (0.5-15.0 mg/L) was extensively studied. The mineralization of these pollutants was obtained using the non-purgeable organic carbon (NPOC) data. The stability of thin film was assessed by the repeated operations, and presence of several co-existing ions simulates the studies to real matrix treatment. Further, the presence of scavengers enabled to pin point the radical-induced degradation of sulfamethoxazole and triclosan from aqueous solutions.

Silane grafted chitosan for the efficient remediation of aquatic environment contaminated with arsenic(V).

HYPOTHESIS: Chitosan, naturally abundant biomaterial showed an insignificant affinity toward arsenate. The incorporation of organosilane could improve the physical and chemical properties of chitosan for the efficient removal of arsenate from aquatic environment. EXPERIMENT: The hybrid materials were obtained by grafting the natural biopolymer chitosan with 3-mercaptopropyl trimethoxysilane (CHMS) and trimethoxy-octylsilane (CHTS). The hybrid materials along with bare chitosan were characterized with SEM-EDX, FT-IR and BET specific surface area analyses and the solid materials were further employed in the efficient remediation of aqueous solutions contaminated with As(V) under batch and column reactor operations. FINDINGS: The hybrid materials showed an extremely high percentage of As(V) removal compared to bare chitosan within a wide range of pH. As(V) was aggregated rapidly onto the solid surfaces and relatively high percent removal of As(V) was achieved in a wide range of As(V) initial concentrations. Moreover, As(V) was bound with, relatively, weaker forces and forming an 'outer sphere complexes' at the surface of solids. The presence of co-existing ions could not significantly affect the removal of As(V) from aqueous solutions. Furthermore, breakthrough data confirmed that these two hybrid materials possessed significantly high loading capacity of As(V) even under dynamic conditions.

Physico-chemical studies in the removal of Sr(II) from aqueous solutions using activated sericite.

Sericite, a mica based natural clay, was annealed at 800 °C for 4 h followed by acid activation using 3.0 mol/L of HCl at 100 °C in order to obtain activated sericite (AS). The activation of sericite causes a significant increase in specific surface area. Further, SEM images of the AS showed a disordered and heterogeneous surface structure with mesopores on its surface whereas the pristine sericite possessed a compact layered structure. The materials were further employed in the removal of Sr(II) from aqueous solutions in a batch reactor system. Removal of Sr(II) was studied as a function of pH, concentration of adsorbate, contact time, background electrolyte concentrations and dose of adsorbents using pristine sericite and AS. The removal of Sr(II) was favoured increasing the pH of the solution and the extent of Sr(II) removal was increased with increasing the sorbate concentration. Equilibrium sorption data obtained with pristine sericite were fitted well to Langmuir adsorption isotherm whereas the sorption data collected using AS better fitted to the Freundlich adsorption isotherm. The time dependence sorption data showed that the uptake of Sr(II) was very rapid and an apparent sorption equilibrium was achieved within 30 min and 60 min of contact for sericite and AS, respectively. The kinetic data were modelled to the pseudo-first order and pseudo-second order rate kinetics and sorption capacities as well as rate constants were evaluated. Increase in background electrolyte concentrations NaNO3 (0.001-0.1 mol/L) indicated that the presence of NaNO3 caused to decrease the percent removal of Sr(II) by sericite and AS. Furthermore, fixed-bed column reactor operations were performed to obtain the breakthrough data. The breakthrough data were fitted well to the non-linear Thomas equation. Therefore, the present study suggested that AS can be adequately applied for the removal of Sr(II) from the aquatic environment.

Sericite in the remediation of Cd(II)- and Mn(II)-contaminated waters: batch and column studies.

Sericite, a mica-based natural clay was employed in the remediation of waters contaminated with two important heavy metal toxic ions, viz. Cd(II) and Mn(II), under batch and column experimentation. The batch reactor studies were intended to study various physicochemical parameters, viz. effect of sorptive pH, concentration, contact time, and background electrolyte concentrations which helped to deduce the mechanism involved at the solid/solution interface. The percent uptake of Cd(II) and Mn(II) was increased with increasing of the sorptive pH, and almost 100 % of these cations were removed at pH 10. Equilibrium-state sorption data was modeled and fitted well to the Langmuir and Freundlich adsorption isotherms. The kinetic data followed the pseudo-first-order and pseudo-second-order kinetic models. Increasing the background electrolyte concentrations by 100 times caused significant decrease of the uptake of Cd(II) and Mn(II) ions, which inferred that these metal cations were less adsorbed specifically and predominantly attached with relatively weak electrostatic attraction onto the solid surface. Additionally, the fixed-bed column reactor operations were also performed to assess the suitability of sericite in the attenuation of Cd(II) and Mn(II) from aqueous solutions under dynamic conditions. The breakthrough data obtained were successfully utilized to fit into a nonlinear fitting of Thomas equation. The results showed that the naturally and abundantly available sericite could be a potential natural material in the remediation of aquatic environment contaminated with Cd(II) and Mn(II).

Organo-modified sericite in the remediation of an aquatic environment contaminated with As(III) or As(V).

The aim of this investigation was to obtain the hybrid material precursor to the naturally and abundantly available sericite, a mica-based clay; the materials were further employed in the remediation of arsenic from aqueous solutions. The study was intended to provide a cost-effective and environmentally benign treatment technology. The hybrid organo-modified sericite was obtained using hexadecyltrimethylammonium bromide (HDTMA) and alkyldimethylbenzylammonium chloride (AMBA) organic surfactants by introducing regulated doses of HDTMA or AMBA. The materials were characterized using infrared and X-ray diffraction analytical data, whereas the surface morphology was discussed by taking its SEM images. These materials were employed to assess the pre-concentration and speciation of As(III) and As(V) from aqueous solutions. The batch reactor data showed that increasing the sorptive concentration (from 1.0 to 15.0 mg/L) and pH (i.e., pH 2.0 to 10.0) caused the percent uptake of As(III) and As(V) to decrease significantly. The kinetic data showed that a sharp initial uptake of arsenic reached its equilibrium state within about 50 min of contact time, and the sorption kinetics followed a pseudo-second-order rate law both for As(III) and As(V) sorption. A 1,000 times increase in the background electrolyte concentration, i.e., NaNO3, caused a significant decrease in As(III) removal, whereas As(V) was almost unaffected, which inferred that As(III) was adsorbed, mainly by the van der Waals or even by the electrostatic attraction, whereas As(V) was adsorbed chemically and formed "inner-sphere" complexes at the solid/solution interface. The equilibrium state modeling studies indicated that the sorption data fitted well the Freundlich and Langmuir adsorption isotherms. Henceforth, the removal capacity was calculated under these equilibrium conditions. It was noted that organo-modified sericite possessed a significantly higher removal capacity compared to its virgin sericite. Between these two organo-modified sericite, the HDTMA-modified sericite possessed a higher removal capacity compared to the AMBA-modified sericite.

Manganese and iron oxide immobilized activated carbons precursor to dead biomasses in the remediation of cadmium-contaminated waters.

The aim of the present investigation was to exploit the high specific surface area of activated carbons in immobilizing the manganese and iron oxides as to obtain a suitable, efficient and cost effective and environment benign wastewater treatment process in the remediation of cadmium-contaminated waters. The manganese and iron oxides were impregnated in situ onto the surface and pores of the activated carbons precursors to the rice hulls and areca nut wastes. The solids were characterized with the help of Fourier transform infrared spectroscopy and X-ray diffraction analytical data, and the BET specific surface area as obtained. The surface morphology of these solids was discussed with the help of scanning electron microscopic images. The activated carbon samples along with the manganese and iron immobilized activated carbons were further employed in the batch and column reactor operations in the remediation of cadmium-contaminated waters. The batch data showed that an increase in sorptive pH from 2.0 to 10.0 and concentration from 1.0 to 20 mg/L favoured the uptake of cadmium by these solids. Moreover, the 1,000 times increase in background electrolyte concentrations NaNO3 caused an insignificant decrease in cadmium uptake by these solids, which inferred that sorbing ions/species were sorbed specifically and forming 'inner-sphere' complexes onto the solid surface. The concentration dependence data were utilized to model various adsorption isotherms and indicated that Freundlich adsorption isotherm was reasonably fitted well. The kinetic data was fitted well to the pseudo-second-order rate equations; hence, the equilibrium sorption capacity was estimated. Furthermore, the dynamic experiments carried out by the column experiments and the breakthrough data were fitted well to the non-linear Thomas equations; accordingly, the loading capacity of the column was estimated. Iron or manganese immobilized activated carbons showed relatively higher loading capacity compared to its precursor activated carbons hence showing its possible implication in the remediation processes. Moreover, among these modified ACs, IIAC showed higher removal capacity than the MIAC solid.

Biomass-derived materials in the remediation of heavy-metal contaminated water: removal of Cadmium(II) and copper(II) from aqueous solutions.

Manganese-coated activated carbon (MCAC) and activated carbon were used in batch experiments for the removal of cadmium(II) and copper(II). Results showed that uptake of Cd(II) and Cu(II) was unaffected by increases in pH (3.0 to 8.5) or concentration (1 to 20 mg/L). Increased ionic strength (from 0.001 to 1 M NaNO3), however, significantly affected the uptake of Cd(II); adsorption of Cu(II) was not affected. Freundlich adsorption isotherm results indicated that MCAC possessed higher sorption capacity than activated carbon. Second-order rate constants were found to be 0.0386 for activated carbon and 0.0633 g/mg x min for MCAC for Cd(II) and 0.0774 for AC and 0.1223 g/mg x min for MCAC for Cu(II). Column experiments showed that maximum sorption capacity of MCAC was 39.48 mg/g for Cu(II) and 12.21 mg/g for Cd(II).

Sorption behaviour of manganese-coated calcined-starfish and manganese-coated sand for Mn(II).

The objective of the present investigation was to explore the sorption behaviour of manganese-coated samples of calcined starfish (MCCSF) (i.e. the impregnation of calcined starfish with manganese) for the removal of low levels of an important heavy metal toxic ion, Mn(II), from aqueous solutions. The suitability of this solid was further compared with two different samples of manganese-coated sands (MCS): MCS4 and MCS9 impregnated at pH 4.0 and pH 9.0, respectively. These comparative studies were performed in both batch and column experiments. Batch data indicated that a fairly good stability of the coating was obtained for these three samples in the pH region 2.5 to 10.0. The removal efficiency of MCCSF was fairly good in comparison with the MCS4 and MCS9 samples. These last two samples possessed similar Mn(II) removal capacities. Moreover, a small dose of sodium hypochlorite further enhanced the uptake of Mn(II) by these solids. The sorbate concentration dependence data fitted reasonably well to the Freundlich adsorption isotherm. The column data indicated that MCCSF possessed a relatively higher adsorption capacity compared with the MCS4 and MCS9 samples. The breakthrough curves obtained were then used to evaluate the apparent removal capacity of these solids under the dynamic conditions using the Thomas equation. The SEM images obtained for these manganese-coated solids along with the virgin base materials, i.e. sand and calcined starfish, showed that manganese oxides occupied the surfaces or pores of the base materials and formed clusters on the base surface.

Application of ferrate(VI) in the treatment of industrial wastes containing metal-complexed cyanides : a green treatment.

Ferrate(VI) was employed for the oxidation of cyanide (CN) and simultaneous removal of copper or nickel in the mixed/complexed systems of CN-Cu, CN-Ni, or CN-Cu-Ni. The degradation of CN (1.00 mmol/L) and removal of Cu (0.095 mmol/L) were investigated as a function of Fe(VI) doses from 0.3-2.00 mmol/L at pH 10.0. It was found that Fe(VI) could readily oxidize CN and the reduction of Fe(VI) into Fe(III) might serve efficiently for the removal of free copper ions. The increase in Fe(VI) dose apparently favoured the CN oxidation as well as Cu removal. Moreover, the pH dependence study (pH 10.0-13.0) revealed that the oxidation of CN was almost unaffected in the studied pH range (10.0-13.0), however, the maximum removal efficiency of Cu was obtained at pH 13.0. Similarly, treatment was carried out for CN-Ni system having the initial Ni concentration of 0.170 mmol/L and CN concentration of 1.00 mmol with Fe(VI) dose 2.00 mmol at various pH values (10.0-12.0). Results showed a partial oxidation of CN and partial removal of Ni. It can be observed that Fe(VI) can partially degrade the CN-Ni complex in this pH range. Further, Fe(VI) was applied for the treatment of simulated industrial waste/effluent waters treatment containing CN, Cu, and Ni.