Removal Efficiency Of Pb Research Articles

Fe doped bimetallic HKUST-1 MOF with enhanced water stability for trapping Pb(II) with high adsorption capacity

• Fe doped HKUST-1 MOF was synthesised with varying concentrations of Fe. • Increased metal-ligand bonding in presence of Fe improved the structural stability. • Improved hydrolytic stability for Fe 0.05 HKUST-1 MOF for up to 10 hrs. • Fe 0.05 HKUST-1 MOF exhibited a Pb(II) adsorption performance of > 550 mg g −1. HKUST-1 Metal-Organic Framework (MOF), due to its coordinatively unsaturated metal sites, high surface area and microporosity, is one the most prominent MOF candidates. Our study investigates the consequence of doping iron into HKUST-1 MOF on its hydrostability, and demonstrates its usability for Pb(II) removal. A simple one-pot solvothermal process was used to synthesize Fe doped HKUST-1 MOF with varying dopant concentrations of Fe (5–20 mol%). Through various characterisation techniques (XPS, XRD, FTIR, ICP-OES) and MD simulations we demonstrated the incorporation of Fe into the HKUST-1 framework, which happened through Fe substituting the Cu(II) sites. Water stability studies using experimental and modelling approaches demonstrated that partial substituted Fe-HKUST-1 MOFs have a greater surface area retention with very little loss in crystallinity as compared to pristine HKUST-1 MOF. Fe substitution of as low as 5 mol% yielded a significant enhancement in the hydrostability of HKUST-1 MOFs, wherein the structure was intact for up to 10 hrs of water treatment. Similarly, 5 mol% Fe doping had a 53% reduction in the amount of Cu being leached out from the HKUST-1 MOF framework. Fe doped HKUST-1 MOFs showed exceptionally high Pb(II) selectivity, Pb(II) removal efficiency of > 90%, and a high Pb(II) adsorption capacity of 565 mg g −1 . This study opens up the possibility of using doping as a strategy to enhance the hydrostability of HKUST-1 MOF and in the process improve its applicability for environmental remediation applications.

Enhanced Cr (VI) removal with Pb (II) presence by Fe2+-activated persulfate and zero-valent iron system

ABSTRACT Combined heavy metals such as chromium (Cr (VI)) and lead (Pb (II)) in natural water have globally posed severe environmental and public health risk. Here the removal of Cr (VI) and Pb (II) mixed pollutants using Fe2+-activated persulfate (PS) with extra zero-valent iron (ZVI), which was not only a supplementary Fe2+ source, but also a high-efficiency absorbent, was investigated. During removal, pivotal factors of initial pollutant concentration, dosages of ZVI and PS, initial pH and temperatures were examined. Interestingly, generating a lot of H+ in the process of Fe (II) activating persulfate were helpful to the corrosion of ZVI over a large range of pH (1–9). Under the optimum condition, removal efficiency of Pb (II) and Cr (VI) have reached 100% and 94.26% respectively. The removal mechanism was suggested as a three-step reaction that the Pb (II) boosted the removal of Cr (VI) by co-precipitated in wastewater, and the Pb (II) and Cr (VI) were adsorbed and subsequently reduced to Pb0 and Cr3+ as Cr(OH)3 or Cr3+-Fe3+ hydroxides on ZVI surface. Cr (VI) and Pb (II) adsorption kinetics agreed with the pseudo-second-order reaction rate expression. In addition, we were surprised to found that the contribution effect of chromium and lead co-precipitation for their removal by Fe (II) – PS-ZVI has strong dependence on initial pH and concentration ratio of Cr (VI) and Pb (II). The result indicated that Fe (II)-PS-ZVI system should be a favourable removal technology for Cr (VI) and Pb (II).

Surface migration of Pb(II) from water and soil using an aerogel/graphite felt primary cell system

To develop a zero energy consumption electrokinetic remediation method of Pb(II) in water and soil, a primary cell system was constructed via synergistic effects of the electromigration, ion exchange, precipitation and hydrogen bond. The primary cell system used cathode of calcium alginate aerogel/graphite felt (CAA/GF) and another piece of CAA/GF was placed on the top of the water and soil. Thus the electric field in the system could drive positively charged Pb(II) towards the top of and thus Pb(II) was surface migrated, promoting removal of Pb(II). This system achieved Pb(II) removal efficiency of 97.8% and maximum power density of 32.1 mW m−2. Additionally, the CAA/GF presented a good reusability. This work provides a promising and facile method to remove heavy metals from water and soil, which might have a huge application prospect.

Removal behavior and mechanisms of cadmium and lead by coupled ethylenediaminetetraacetic acid washing and electrochemical reduction: influence of current conditions.

Ethylenediaminetetraacetic acid (EDTA) washing has been used extensively to remediate heavy metal-contaminated soils. Electrochemical reduction treatment of spent washing solution is an effective method of EDTA regeneration. However, at present, these two technologies are usually regarded as two independent treatment processes. This research raised a new heavy metal-contaminated soil treatment strategy-a combination technique of coupled EDTA washing and electrochemical reduction. We speculated that the combination of EDTA washing and electroreduction treatment could improve the efficiency of Cd and Pb removal from contaminated soil. In this study, the removal performance and mechanisms of Cd and Pb under different current conditions were investigated based on a coupling of EDTA washing and electrochemical reduction. The combination technique can increase Cd and Pb removal efficiencies by 13.37-15.24% and 14.91-27.05%, respectively, compared with EDTA washing alone. Sequential extraction analysis showed that the reducible fraction improved metal removal efficiency. The percentage of metal removed increased with an increased current value and EDTA concentration. In addition, pulse current mode removed more Cd and Pb than continuous current, although the difference was not significant (p > 0.05). However, pulse current could effectively eliminate the cathodic hydrogen evolution reaction, resulting in a further heavy metal deposition at the cathode. The combination technique exhibited enhanced removal efficiency due to EDTA regeneration in the suspension and the cathodic reduction reaction. The most cost-effective treatment in 48h was a pulse current mode of 32min on/16min off-32mA-EDTA-10mM, where 47.56% of Cd and 77.00% of Pb were removed from the soil with an electric energy consumption of 8.24 Wh.

Immobilization of Pb and Cd by two strains and their bioremediation effect to an iron tailings soil

Soil quality of the iron tailings mining was worrying and there are many kinds of heavy metals exceeding the standard. For tailing soil remediation, two strains (C2-Z and P2-Z) were isolated from iron tailing soil in Northwest China based on their Cd and Pb immobilizing potential, respectively. Biosorption capacity of the two strains were 51.90 mg/g and 109.73 mg/g, respectively. Changes of surface morphology and functional groups of C2-Z and P2-Z cells were observed after exposed to Cd2+ and Pb2+ by SEM-EDS and FTIR. Strain C2-Z and P2-Z achieved the immobilization of Cd and Pb respectively through bioprecipitation (25.9 %, 47.07 %), extracellular biosorption (24.5 %, 46.98 %) and intracellular accumulation (1.4 %, 1.95 %). Medium-scale ecosystem experiments revealed that the bacterial consortia CP could reduce acid-soluble Pb (5.72 %) and Cd (16.72 %) in the tailing soil, and increased urease activities (from 0.11–28.5 ng NH4-N/g), acid phosphatase activities (from 0.001–64.02 ug pNP/g) and sucrase activities (from 0.001–50.99 mg Glc/g). Thus, the isolated strain C2-Z and P2-Z could serve as potential candidate for the remediation of Cd and Pb contaminated soil due to their significant Cd and Pb removal efficiency and immobilizing capability.

Understanding the microstructure, mineralogical and adsorption characteristics of guar gum blended soil as a liner material.

Guar gum blended soil (GGBS) offers potentially advantageous engineering characteristics of hydraulic conductivity and strength for a soil to be used as a liner material. Characterization techniques such as X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy and scanning electron microscope were used to examine the mineral composition, functional groups and morphological changes in the unblended soil (UBS) and GGBS. These characterization approaches are used to understand adsorption-associated mechanisms of Pb(II) removal. Batch adsorption tests were performed to evaluate the adsorption capacity of UBS and the GGBS with various proportions (0.5%, 1.0%, 1.5% and 2.0%) of guar gum (GG) towards the removal of Pb(II) ions. Batch adsorption experiments were conducted by varying the pH, dosage of adsorbent, concentration of metal ions and contact time. The experimental results showed that the optimum removal of Pb(II) ions was high at a pH of 3.0 for all blends, and adsorption tests beyond 3.0 pH demonstrated a decline in adsorption performance. The maximum Pb(II) removal efficiency of 95% was obtained using the 2.0% GGBS. The isotherm model assessment for adsorption experimental data of Pb(II) showed the best fit for the Langmuir model on using GG. The present research demonstrated that the guar gum-treated blends exhibited potential Pb(II) ion adsorption properties and therefore can be used as sustainable liner material in sanitary landfills.

Robust MOF film of self-rearranged UiO-66-NO2 anchored on gelatin hydrogel via simple thermal-treatment for efficient Pb(II) removal in water and apple juice

Pb(II), a highly toxic heavy metals that targets the human nervous system, has contaminated water and food in recent years. The nanomaterial of Metal–organic frameworks (MOFs) possesses superior removal performances. However, their practical application is limited by their nature of fine powdery. Herein, we developed robust MOFs film without the adding of polymer in MOFs ink and the modification of the substrate, which was achieved by choosing appropriate substrate of gelatin hydrogel with functional groups and simple thermal-treatment after coating UiO-66-NO 2 onto gelatin hydrogel. The volatilization of the UiO-66-NO 2 dispersant ethyl acetate promotes the rearrangement and dense accumulation of UiO-66-NO 2 crystals to form a dense UiO-66-NO 2 film. During the following thermal-treatment process, –COOH of UiO-66-NO 2 and –NH 2 of gelatin chemically reacted to establish the stable composites of UiO-66-NO 2 film and gelatin hydrogel. The results of batch adsorption experiments demonstrate that adsorption behaviors of the as-synthesized gelatin/UiO-66-NO 2 film composite hydrogels can be explained by the pseudo-second-order kinetic model and the Langmuir isotherm model, stating that this adsorption process involves with a chemical monolayer adsorption. Besides, gelatin/UiO-66-NO 2 film composite hydrogels own satisfactory removal efficiency for Pb(II) in apple juice, and the adsorption process has little impairment on the quality of apple juice. These results suggest that MOFs film is suitable for water decontamination and food safety control fields. • Developing uniform UiO-66-NO 2 film grown on gelatin hydrogel substrate. • UiO-66-NO 2 crystals rearranged during the volatilization of ethyl acetate. • –COOH of UiO-66-NO 2 reacted with –NH 2 of gelatin during drying process. • Pb(II) chelates with –COOH and –NH 2 of as-synthesized adsorbent. • Adsorption process has little effect on the quality of apple juice.

Role of heavy metal tolerant rhizosphere bacteria in the phytoremediation of Cu and Pb using Eichhornia crassipes (Mart.) Solms

The role of multi-heavy metal tolerant bacteria isolated from the rhizosphere of Eichhornia crassipes in the phytoremediation of Cu and Pb under laboratory conditions was investigated. The heavy metal tolerant rhizosphere bacteria were identified as Bacillus cereus, Paenibacillus alvei, Aeromonas caviae, Paenibacillus taiwanensis, and Achromobacter spanius. Results showed a significant variation in wet weight, Heterotrophic Plate Count (HPC) of the rhizosphere, HPC of water, removal and uptake of Cu and Pb by E. crassipes, either alone or in association with the rhizosphere bacteria. The removal of Cu by E. crassipes in different experimental conditions showed that OTC (Oxytetracycline) untreated E. crassipes with rhizosphere bacteria has maximum removal with 95%, followed by E. crassipes alone with 84%. The OTC treated E. crassipes with rhizosphere bacteria could remove 81% of Cu. The maximum Pb removal efficiency of 93.4% was shown by OTC untreated E. crassipes with rhizosphere bacteria, followed by E. crassipes alone with 86.8%. The OTC treated E. crassipes with rhizosphere bacteria showed the least removal efficiency with 82.32%. The translocation factor (TF) values for Cu and Pb were lower than 1 indicated that the absorption was mainly accomplished in the roots of E. crassipes. The order of accumulation of Cu and Pb in E. crassipes was noted as root > leaf > petiole.

Halloysite and coconut shell biochar magnetic composites for the sorption of Pb(II) in wastewater: Synthesis, characterization and mechanism investigation

Halloysite/biochar was prepared by co-pyrolysis at different temperatures using coconut shell and halloysite as raw materials. Magnetic adsorbents were prepared through ball-mill extrusion with Fe3O4 and the halloysite/biochar and the capacity of the adsorbents to adsorb Pb(II) from water was evaluated and compared. The effects of pH, contact time, and initial Pb(II) concentration on the adsorption capacity of the magnetic adsorbents for Pb(II) were investigated. The pseudo-second-order (R2 =0.9999) and Langmuir isothermal models (R2 =0.9906) fit the experimental data well. The prepared samples denotes as MBM-HBC700 exhibited the highest Pb(II) adsorption capacity (833.33 ± 16.71 mg·g-1), and the removal efficiency of Pb(II) by the magnetic adsorbents was above 90% after four adsorption–desorption cycles. Complexation, cation exchange, cation–π interaction, precipitation, pore filling and electrostatic adsorption have been proposed as the main removal mechanisms. After applying MBM-HBCs to simulated electroplating wastewater, the contents of Pb(II), Cu(II), Zn(II), and Cr(VI) were significantly lower than the discharge standard of China. The magnetic adsorbents prepared in this study have wide application prospects in the treatment of Pb(II) in wastewater, thus providing a new approach for promoting waste recycling and utilization.

Heavy metals removal from landfill leachate by coagulation/flocculation process combined with continuous adsorption using eggshell waste materials.

The use of agricultural waste materials to remove heavy metals from wastewater is attractive due to its simplicity and economic efficiency. In this study, the applicability of calcined eggshell waste materials (CES) for heavy metals removal from real wastewater were examined via transport column experiment preceded by coagulation/flocculation process.A column packed with granular activated carbon (GAC) is operated in parallel to CES column to evaluate the adsorptive attributes of CES. The findings are assessed from another set of column experiments consisting of sand followed by CES column to evaluate the effect of particulate matter (PM) on CES performance toward heavy metals removal. In coagulation experiment, alum addition at an optimum dose (3.0 g/L) reduced the total suspended solids (TSS) by 80%, whereas the Fe, Pb, Zn, Cu, Ni, and Cr were reduced by 80%, 77%, 76%, 73%, 56%, and 49%, respectively. Under the current applied hydrodynamic conditions, using sand column before CES column improved the removal efficiencies of Fe, Pb, Cu, Zn, Ni, and Cr from 50% to 92%, 55% to 93%, 60% to 87%, 53% to 76%, 45% to 65%, and 41% to 60%, respectively. The whole results illustrate that CES can be competitive to GAC for heavy metals removal from landfill leachate, mainly if applied after PM removal by sand filtration.

Investigations on lignite use for lead removal from aqueous solutions under static and dynamic conditions: adsorption properties and mechanism exploration

Lignite, as an abundant and low-cost material, was tested for lead (Pb(II)) removal from aqueous solutions under various experimental conditions for both static (batch) and dynamic (column) experiments. Static assays showed that Pb(II) removal efficiency increases with rising in its initial concentration, aqueous pH, and adsorbent dosage values. Adsorption kinetic and isothermal data were well fitted with the pseudo-second-order and Freundlich models, respectively, suggesting that lead removal by lignite is mainly governed by chemical processes and occurs heterogeneously on multilayer surfaces. The maximum Langmuir’s adsorption capacity was equal to 61.4 mg·g -1 , which is high in comparison to various natural materials. The laboratory column experiments showed that Pb(II) breakthrough curves and subsequent lignite adsorption efficiency is highly dependent on the bed height. Due to the short time contact between Pb(II) and lignite particles inside the column, the highest adsorption capacity was about 21%, which is lower than the one found in the batch mode. Even under dynamic conditions, lignite exhibits a high adsorption capacity compared to other adsorbents, which promotes its use as a low-cost and efficient material for Pb(II) and the removal of other heavy metals from wastewaters.

Removal of lead (II) ions from water using chitosan/polyester crosslinked spheres derived from chitosan and glycerol-based polyester

The present study reports development of eco-friendly polymeric spheres derived from crosslinking of chitosan (CTS) with different polyesters. The polyesters were synthesized via polycondensation reaction of maleic anhydride with 1,4-butadiol and glycerol, potential renewable chemical, as hydroxyl sources. The structures of the prepared polyesters and the crosslinking of CTS/polyester spheres were confirmed by Fourier transform infrared spectroscopy. Crosslinking of CTS with polyesters enhances the structure and the stability of CTS-based spheres in aqueous media, but decreases its hydrophilicity. The obtained spheres were employed for adsorption of lead ions (Pb2+) from aqueous solutions. The batch adsorption experiments were evaluated to investigate the effect of glycerol-loading on adsorption of Pb2+ ions. The results indicated that the amount of adsorbed (Pb2+) ions was increased with time and operating temperature. The maximum 83.5% removal efficiency of Pb2+ ions from aqueous solution was achieved at pH= 5.0. The experimental data was described with the Langmuir and Freundlich isotherm models, whereas the Freundlich model showed the best fit of the data.

Synthesis and application of graphene oxide as a nanoadsorbent to remove Cd (II) and Pb (II) from water: adsorption equilibrium, kinetics, and regeneration.

In this work, graphene oxide (GO) was synthesized by the modified Hummers method. The nanomaterial was characterized by FTIR and Raman spectroscopy, SEM, and pH at the point of zero charge. GO exhibited typical characteristics of graphene-based materials, indicating that graphite oxidation and exfoliation occurred successfully. Cd (II) and Pb (II) adsorption onto GO was carried out in batch systems, in which the effect of adsorbent dosage, contact time, and initial adsorbate concentration were evaluated. Langmuir, Freundlich, and Sips isotherm models, as well as pseudo order models and Elovich kinetic equation were applied to adsorption experimental data. Results indicated that increasing adsorbent mass, the removal efficiency of Cd (II) and Pb (II) increased. Freundlich isotherm better described Pb (II) adsorption (R2 = 0.96), while Cd (II) isotherm showed linear behavior. From the Akaike's AIC parameter, kinetic data were satisfactorily described by pseudo-first order (Cd (II)) and pseudo-n order (Pb (II)) models. GO was successfully subjected to five regeneration cycles, maintaining high efficiency (> 90%) in all cycles. GO showed high potential for the adsorption of Cd (II) and Pb (II) from aqueous solution, due to its high adsorption capacity, rapid Cd (II) and Pb (II) intakes, and great regeneration performance.

Indonesian Kaolin supported nZVI (IK-nZVI) used for the an efficient removal of Pb(II) from aqueous solutions: Kinetics, thermodynamics and mechanism

A remarkably efficient Indonesian Kaolin (IK) supported nano zerovalent iron composite (IK-nZVI) has been synthesized, and subjected to the elimination Pb(II) from the wastewater. The results were authenticate the nZVI nanoparticles have a chain shape and establish as separable nanospheres with an average size (29.95 nm) on the surface of IK. The FTIR spectra demonstrate the presence of Al-O as well as Si-O bonds. XRD results demonstrate the presence of zerovalent iron. SEM confirmed less agglomeration of Fe(0) nanoparticles which improves the mechanical strength. The weak signals of Fe and O confirm the establishment of zerovalent iron in nanocomposite. TEM demonstrates that the nanocomposite has a chain like structure. Pb(II)percentage removal was improved by rise in the IK-nZVI amount which results in rising the adsorption site. The nanocomposite had on optimum Pb(II) sorption at pH range of 4.5–6.5. The amount adsorbent increasing with the Pb(II) removal percentage was decreased. Kinetics study demonstrated that Pb(II) sorption was accomplished through more than one processes. IK was proved active support to progress the dispersion, and steadiness of IK-nZVI nanocomposite. The sorption processes pollutant was estimated through the kinetics models, and different sorption isotherm equations like Langmuir (LM), Langmuir-Freundlich (L-F), and Freundlich (FL) isotherms. The IK-nZVI typically accompanies outstanding Pb(II) removal efficiency of 98% and 96.05% with a span of 5 and 10 min for low and high concentrations, respectively. Significantly, the results reveal the maximum adsorption capability of the IK-nZVI is 192.0 mg/g. The thermodynamic study shown endothermic and spontaneous adsorption onto the IK-nZVI surface. Specifically, the IK-nZVI nanocomposite possesses key advantages in terms of simple method, nature friendly, cost-effectiveness, and decent adsorption efficiency for the potential elimination of toxic metal ion (Pb(II)) in the aqueous phase.

Novel Zn-Fe engineered kiwi branch biochar for the removal of Pb(II) from aqueous solution

In this study, a novel adsorbent made from kiwi branch biochar modified with Zn-Fe (KB/Zn-Fe) was compared with original biochar to the Pb(II)'s adsorptivity from waste water. The adsorbent was synthetized by liquid-phase deposition. Batches of sorption tests were performed, and the biochars' representative properties were tested. Characterizations revealed the physicochemical properties of biochars and showed that the KB/Zn-Fe composites were successfully synthesized. The Langmuir model and pseudo-second-order kinetic model were proven to satisfactorily fit the original biochar and KB/Zn-Fe. The KB/Zn-Fe showed Langmuir maximum adsorption ability to Pb (II) in aqueous solution of 161.29 mg g-1, compared with 36.76 mg g-1 for original biochar. The adsorption ability of Pb(II) decreased and the Pb(II) removal efficiency increased with increasing biochar dose. The effect of co-existence of NO3- to the absorptive capacity of KB/Zn-Fe on Pb(II) was unremarkable, but Cl- could increase the absorptive capacity. Multiple Pb(II) adsorption mechanisms by KB/Zn-Fe include surface precipitation of metal hydroxides, complexation with active functional groups and ion-exchange. This work provides guidance for future production of biochar with efficient adsorption ability, which could be used to remove Pb(II) ions from wastewater.

Preparation of zeolite A by inorganic complex precursor route for efficient elimination of heavy metal cations from aqueous solutions

In the present study, zeolite A was synthesized via inorganic complex precursor as an efficient novel route by using tris(acetylacetonato)aluminum(III), [Al(C5H7O2)3], and tris(acetylacetonato)silicon(IV) chloride hydrochloride, [Si(C5H7O2)3]Cl.HCl. The physicochemical properties of the zeolite A were characterized by FT-IR, XRD, SEM/EDX, BJH, and BET techniques. The performance of the synthesized zeolite A was evaluated for the elimination of heavy metal cations (Co2+, Cu2+, Zn2+, Cr3+ and Pb2+) from aqueous solutions. The results revealed that removal efficiencies of the synthesized zeolite A toward all investigated heavy metal cations were obtained to be more than 95% and the maximum removal efficiency was observed for Pb2+. The influence of parameters such as pH, contact time and adsorbent amount was surveyed on the removal efficiency of Pb2+ by the zeolite A. The most desirable conditions for Pb2+ removal was attained at pH 6.5, the zeolite amount of 0.5 g, 400 mgL−1 initial concentration of Pb2+ and the contact time of 30 min. The adsorption process followed second- order kinetics model and the pseudo-second-order adsorption rate constant (k 2) was obtained to be 4.32 × 10−4 g mg−1min−1.

Removal of zinc, lead and nickel from contaminated soil by electro-kinetic technology under the influence of washing and buoyance forces with different purging solutions

ABSTRACT The effects of the washing process, purging solution, and buoyance force (inclined topography action) on the effectivity of the electro-kinetic method used to remediate of a silty clay loam and natural soils contaminated with Zn, Pb and/or Ni were investigated by applying 12 different experiments. The results revealed that the washing process and buoyance force can cause a small increase in the Zn removal efficiency (≤ 31%) when compared with non-washing approach using distilled water purging solution. Using 0.1 M of EDTA solution for the soil contaminated with listed metals in combination with washing can lead to significant increase in the removal efficiencies with percentages not greater than 58.4, 60.68 or 42.8%, respectively. In the presence of EDTA, however, the majority of metals passed through the soil media to the anode area. In contrast, these metals are accumulated near the cathodic region in the presence of distilled water. The results demonstrated that the buoyance force (resulted from inclination angle of 30°) with EDTA had adverse influence on the metal profile along the treated soil. Finally, the results certified that EDTA in electro-kinetic process coupled with soil washing is a new hybrid technique which achieved Pb removal efficiency from natural soil reached to 58% by improving the solubilization and transport of metal ions.

Chemically Modified Sago Fly Ash for Pb(II) Removal from Water

The use of agricultural by-products has been widely studied to develop effective and inexpensive adsorbent for heavy metal removal. In this study, sago (M.sagu) fly ash (FA) was chemically modified to afford an operational adsorbent for Pb (II) elimination from water. Chemical modification was carried out via acid-base treatment using NaOH and HCl. The chemically modified fly ash (MFA) was characterized via proximate, surface morphology, and functional groups' surface area analyses. The effects of adsorption parameters, namely, Pb (II) initial concentration, sorbent dosage and contact time on the eradication of Pb (II) by MFA was analyzed in batch experiments with Langmuir and Freundlich isotherms. Optimization of Pb (II) removal by MFA was studied via response surface methodology (RSM) approach. Results revealed that chemical modification has successfully enhanced the adsorptive properties of MFA (BET surface area: 231.4 m2/g, fixed carbon: 55.83%). MFA exhibits better Pb (II) removal efficiency (90.8%) compared to FA (63.6%) at the following adsorption condition: Pb (II) initial concentration (5 ppm), contact time (30 min) and agitation speed (150 rpm). The adsorption of Pb (II) by FA and MFA fitted well with Freundlich isotherm (R2>0.9). RSM study suggested that the optimum Pb (II) removal was 99.4% at the following conditions: Pb (II) initial concentration (20 ppm), contact time (2 h) and sorbent dosage (0.6 g/50 mL). The results concluded the potential optimum operational condition for Pb (II) removal from aqueous environment by MFA as a low cost adsorbent, at larger scale.

Inoculation of Bacillus cereus enhance phytoremediation efficiency of Pistia stratiotes and Eichhornia crassipes in removing heavy metal Pb

This study investigates the effects of inoculation rhizhosperic microbes namely Bacillus cereus-NMeHI-Cr2 towards the roots of two locally aquatic macrophytes in removing heavy metals Pb from simulated wastewater. Water lettuce (Pistia stratiotes) and water hyacinth (Eichhornia crassipes) were selected in this study due to their absorption capability and acts as biological filters by accumulating heavy metals in their tissue’s bodies. The inoculation of B. cereus-NMeHI-Cr2 onto the roots of P. stratiotes and E. crassipes was conducted in non-continuous horizontal flow (NCHF) reactor with addition of 1.5mg/L of Pb comprising of T2: treatment with inoculation of B. cereus-NMeHI-Cr2, T4: Non inoculation of B. cereus-NMeHI-Cr2 and T6: no plant growth in NCHF reactor (control). After 15 days of cultivation, the treatment integrated with inoculation of B. cereus-NMeHI-Cr2 resulted 83.7% removal efficiency of Pb followed by T4 (70.4%) and T6 (2%) respectively. Furthermore, 63.8 ug/g of Pb was observed in T2 treatment with similar distribution pattern as roots > leaves > stalks in E. crassipes and roots> leaves in P. stratiotes. The physical changes of both plants were also monitored to show any toxicity symptoms experienced as a result of heavy metal Pb. This study validates that the removal of Pb was done via rhizofiltration mechanism as the value of enrichment factor was found below than 1000. The identified plants species with inoculation of Bacillus cereus-NMeHI-Cr2 provides a simple and cost-effective method for application of metal polluted water.

Carbon nanotube filter for heavy metal ion adsorption

This study investigated carbon nanotube filtration technology using catalyst particles supported on silicalite-1–biomorphic carbon materials (BCMs). Aqueous solutions of Mn(II), Cu(II), Cr(III), Cd(II), and Pb(II) were used to test the efficiency of heavy metal ions removal. Carbon nanotubes (CNTs) were synthesized and grown on BCMs by the chemical vapor deposition method catalyzed with the catalyst (Co, Fe, and Ni). The synthesized CNTs with Co– and Fe– nanoparticles were typically multi-walled carbon nanotubes, and they showed good crystallinity (ID/IG = 1.05) and yield of (11.10 and 8.86) %. The removal efficiency of Mn(II), Cu(II), Cr(III), Cd(II), and Pb(II) ions using Co-catalyzed CNT filter was 97.57%, 98.01%, 97.89%, 97.42%, and 99.99%, respectively.