Removal of Lead in a Fixed-Bed Column Packed with Activated Carbon and Crab Shell

ABSTRACT

Crab shell particles (Protunus trituberculatus) and activated carbon (Norit 0,8 SUPRA) were used as packing materials in a fixed-bed column. When 1 g crab shell was added in a column packed with 10 g activated carbon, breakthrough occurred at 1500 bed volumes as compared to 380 bed volumes for 10 g activated carbon only. The addition of crab shell particles into an activated carbon column resulted in an increased uptake of lead. The dramatic improvement might be attributed to an increase in and OH^? available for binding lead. From the results of SEM, XRD, and FT-IR analyses, the major mechanism of lead removal was based on dissolution of CaCO₃ in the crab shell followed by precipitation of Pb₃(CO₃)₂(OH)2(s) on the surface of activated carbon. The lead uptake increased twofold when the influent lead concentration was increased from 10 to 50 mg/L.     

Effects of co-ion initial concentration ratio on removal of Pb<Superscript>2+</Superscript> from aqueous solution by modified sugarcane bagasse

A modified sugarcane bagasse (SCB) fixed bed column was used to remove Pb²⁺ from aqueous solution. To determine the optimal condition for Pb²⁺ separation, Ca²⁺ was chosen as the model interfering ion, and effects of Ca²⁺ and Pb²⁺ initial concentration ratio (C ₀ ^Ca : C ₀ ^Pb ) on the adsorption of Pb²⁺ were investigated. Results showed that adsorption amount ratio of Ca²⁺ and Pb²⁺ (q _e ^Ca : q _e ^Pb ) had a good linear relationship with C ₀ ^Ca : C ₀ ^Pb . Mass ratio of Pb²⁺ absorbed on the modified SCB was higher than 95% at C ₀ ^Ca : C ₀ ^Pb <1.95, illustrating that Pb²⁺ could be selectively removed from aqueous solution. To verify that, simulated waste water containing co-ions of K⁺, Na⁺, Cd²⁺ and Ca²⁺ was treated, and results showed that the equilibrium amount of Pb²⁺, K⁺, Na⁺, Cd²⁺ and Ca²⁺ adsorbed was 134.14, 0.083, 0.058, 1.28, and 1.28mg g^?1, respectively, demonstrating that the modified SCB could be used to remove Pb²⁺ from aqueous solution in the investigated range.     

REMOVAL OF TOXIC Pb2+ IONS BY SYNTHETIC HYDROXYAPATITES

The removal behavior of toxic Pb²⁺ ions from aqueous and nonaqueous solutions by two synthetic hydroxyapatites (S-1 and S-2) has been investigated by using both batch and column methods.

It was found that Pb²⁺ ions in the both solutions were easily removed to the apatite samples mainly by cation-exchange reactions between the Pb²⁺ ions in the solutions and Ca²⁺ ions of the samples at room temperature. Further, in the system of aqueous PbF₂ solutions, anion-exchange reactions between F^? ions in the solutions and OH ^? ions of the samples occurred simultaneously and the liberated OH ^? and Ca²⁺ ions influenced removal behavior of Pb²⁺ and F^? ions. The maximum removal amount of Pb²⁺ ions from the aqueous solutions was 400?mg per g of S-1. Pb^? ions in the waste water from lead plating factories were completely removed to the apatite samples. In this manner, it was found that the apatites, especially S-1 can be employed as a new removal agent for the treatment of poisonous Pb²⁺ ions in waste water.     

Tuning of conductive type and magnetic properties of Ca3Co2O6 ceramics through Pb‐doping

The effect of Pb doping on structural, electrical, magnetic, and thermal transport properties of Ca_3?xPb_xCo₂O₆ (x=0‐0.3) ceramics has been investigated systemically. It is found that the substituted Pb‐ions have a mixed valence state of +2 and +4, and a small amount of Co³⁺ ions will transfer into Co²⁺ due to the substitution of Pb⁴⁺ for Ca²⁺. The resistivity decreases monotonically with increasing Pb content, which is related to the variation in carrier concentration and the enhanced grain connectivity. The signs of both Hall coefficient and thermopower changed from positive to negative by a proper Pb doping, indicating the conductive type of Ca₃Co₂O₆ can be effectively tuned from p to n through the doping. The low‐temperature magnetization, the magnetic exchange coupling constant J and Weiss temperature θ decrease monotonically with the increase in Pb‐doping content, indicating the strength of the ferromagnetic interaction between adjacent high spin Co³⁺ ions has been weakened due to the reduced magnetic correlation length in these Pb‐doped samples.     

Ethylenediamine tetraacetic acid modification of crosslinked chitosan designed for a novel metal‐ion adsorbent

Novel chitosan‐based adsorbent materials were synthesized with a higher fatty diacid diglycidyl as a crosslinking agent, and the adsorption ability of the resulting polymers for several metal ions was evaluated. Selective adsorption for Cu²⁺ in comparison with other divalent metal ions, such as Ni²⁺, Pb²⁺, Cd²⁺, and Ca²⁺, was observed with the crosslinked chitosan sorbent at pH 6; however, the adsorption power decreased abruptly as the pH value of the solution decreased. The addition of ethylenediamine tetraacetic acid (EDTA) residues to crosslinked chitosan significantly enhanced the adsorption power for metal ions, especially for Ca²⁺. The adsorptivity of Ca²⁺ was dramatically improved with the introduction of EDTA residues, and the value was greater than that obtained with a commercial chelate resin (CR11). Although the adsorption power of the EDTA‐derivatized sorbent for other metal ions was just comparable to that of the CR11 material, the newly synthesized adsorbent could be used for the recovery of metal ions from industrial waste solutions with a relatively wide range of pHs, from 4.0 to 6.0. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2758–2764, 2004     

CaCO3 crystallization controlled by (2-hydroxypropyl-3-butoxy) propylsuccinyl chitosan

Calcium carbonate (CaCO₃) was crystallized in (2-hydroxypropyl-3-butoxy) propyl-succinyl chitosan (HBP-SCCHS) solutions by a slow vapor diffusion method. The CaCO₃ crystals were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetry analysis (TGA) and N₂ adsorption–desorption methods. By varying the concentrations of HBP-SCCHS and Ca²⁺, temperature and initial pH, the CaCO₃ crystals with different morphologies were obtained. Based on the analysis of CaCO₃ crystals obtained under different conditions, the mechanisms of the CaCO₃ crystallization in the presence of HBP-SCCHS were proposed. It was found that the adsorption of HBP-SCCHS molecules on CaCO₃ surfaces played a key role in the formation of CaCO₃.     

Continuous biosorption of heavy metal ions by Ca-loadedlaminaria japonica in fixed bed column

Continuous biosorption process for removal of lead and copper by laboratory scale fixed-bed reactor was carried out using Ca-loadedLaminaria japonica. All biosorption processes were observed as cation exchange such as Pb²⁺ vs. Ca²⁺, Cu²⁺ vs. Ca²⁺, and Pb²⁺ vs. Cu²⁺. The affinity of lead ions towardsL. japonica was stronger than that of copper ions because the initial amount of desorbed Cu²⁺ in Cu-Pb system was higher than that of eluted Pb²⁺ in Pb-Cu system.     

Microwave preparation and adsorption properties of EDTA‐modified cross‐linked chitosan

A novel chitosan‐based adsorbent (CCTE) was synthesized by the reaction between epichlorohydrin O‐cross‐linked chitosan and EDTA dianhydride under microwave irradiation (MW). The chemical structure of this new polymer was characterized by infrared spectra analysis, thermogravimetric analysis, and X‐ray diffraction analysis. The results were in agreement with the expectations. The static adsorption properties of the polymer for Pb²⁺, Cu²⁺, Cd²⁺, Ni²⁺, and Co²⁺ were investigated. Experimental results demonstrated that the CCTE had higher adsorption capacity for the same metal ion than the parent chitosan and cross‐linked chitosan. In particular, the adsorption capacities for Pb²⁺ and Cd²⁺ were 1.28 mmol/g and 1.29 mmol/g, respectively, in contrast to only 0.372 mmol/g for Pb²⁺ and 0.503 mmol/g for Cd²⁺ on chitosan. Kinetic experiments indicated that the adsorption of CCTE for the above metal ions achieved the equilibrium within 4 h. The desorption efficiencies of the metal ions on CCTE were over 93%. Therefore, CCTE is an effective adsorbent for the removal and recovery of heavy metal ions from industrial waste solutions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of CaCO3 coated corundum aggregates by dip-coating and heat treatment and its effects on the properties and microstructures of Al2O3–MgO castables

The CaCO₃ coated corundum aggregates were prepared by impregnating tabular corundum aggregates with sizes of 1–5 mm in calcium hydrogen citrate solution and heat treatment at 430 °C, which were also used in Al₂O₃–MgO castables. The effects of Ca²⁺/Cit^3? mole ratio in precursor solution on coating characteristics of CaCO₃ coated corundum aggregates as well as the effects of CaCO₃ coatings on properties and microstructure of castables were investigated. It is found that the thickness and continuity of CaCO₃ coating is increased and the size of CaCO₃ particles in coatings decreases first and then increases as Ca²⁺/Cit^3? mole ratio is decreased. High-temperature properties of castables are improved by in-situ formation of calcium hexaaluminate (CA₆) layer at aggregate/matrix interface after sintering at 1600 °C. The Al₂O₃–MgO castables exhibit the best thermal shock resistance when Ca²⁺/Cit^3? mole ratio is 1/3. It is contributed by deflections of cracks and consumptions of fracture energy in a continuous platelet CA₆ layer with thickness of 10 μm, which is in-situ formed through reaction between Al₂O₃ and CaO derived from CaCO₃ coatings. The present investigation provides a novel approach to enhance thermal shock resistance of the Al₂O₃–MgO castables.     

Effects of magnetic field on calcium carbonate precipitation: Ionic and particle mechanisms

There are two most widely reported mechanisms to study the effect of magnetic fields on calcium carbonate (CaCO₃) precipitate, namely ionic and particle mechanisms. The effects are most debatable because they are contrary to each other. This study explored the effects of both mechanisms in CaCO₃ deposit and total CaCO₃ precipitation using ionic and particle methods. The ionic method showed reductions in CaCO₃ deposit and total precipitation rate of CaCO₃, whereas the particle method showed the opposite results. The particle number decreased and the average particle diameter of CaCO₃ deposit increased in the ionic method. Meanwhile in the particle method, the particle number increased, average particle diameter decreased and particle aggregation of CaCO₃ was observed. XRD measurement on all deposits showed that the crystal deposit was mostly of calcite and the traces of vaterite. However, the amount of the crystal in the particle method was observed to be less than that in the ionic method, indicating that CaCO₃ deposit was more amorphous. Particle mechanism decreased the Ca²⁺ ion concentration in solution during magnetization, and ionic mechanism reduced scale (CaCO₃) formation after magnetization and separation processes. This method could be applied for decreasing water hardness and prevent the formation of scaling.     

Selective and Efficient Liquid Membrane Transport of Thallium (III) Ion by Potassium‐dicyclohexyl‐18‐crown‐6 as Specific Carrier

Abstract

Potassium‐dicyclohexyl‐18‐crown‐6 was used as a selective and efficient carrier for the uphill transport of thallium (III) ion as [TlCl₄]^? complex ion through a chloroform bulk liquid membrane. By using oxalate anion as a metal ion acceptor in the receiving phase, the amount of thallium (III) transported across the liquid membrane after 120 min was 96±2%. The selectivity and efficiencies of thallium transport from aqueous solutions containing Cu²⁺, Zn²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Co³⁺, Mn²⁺ _, Cr³⁺, Mg²⁺, Ca²⁺, K⁺, Na⁺, and Fe³⁺ ions were investigated. In the presence of Na₃PO₄ (0.01 M) at pH=3 as a suitable precipitation agent in the source phase, the interfering effect of Pb²⁺ ion were diminished drastically.     

Development of a fixed‐bed column with cellulose/chitin beads to remove heavy‐metal ions

Environmental friendly cellulose/chitin beads, having relatively high mechanical properties, were successfully prepared from a blend of cellulose and chitin in 6 wt % NaOH/5 wt % thiourea aqueous solution by coagulating with 5% H₂SO₄ aqueous solution. The ability of the beads to adsorb Pb²⁺ in an aqueous solution was measured with a fixed‐bed column. The effects of important parameters, to design an adsorption column of the cellulose/chitin beads for fixed‐bed columns, were investigated. The breakthrough curves for the adsorption behavior indicated that the column performance was improved with decreasing initial lead concentration, ionic strength, flow velocity or bead size, as well as increasing pH dependence and bed height. Column studies showed that constants, calculated from the experimental data, and the Bed Depth Service Time (BDST) model had a good correlation. The columns were easily regenerated by treating with 0.1 mol/L HCl aqueous solution after the adsorption of metals, providing a simple and economical method for removal and recovery of heavy metals. After four adsorption–desorption cycles, the efficiency of column for the removal of lead was not significantly reduced (not more than 5%). It is shown that heavy‐metal biosorption processes in fixed‐bed columns could give a broad range of potential industrial applications. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 684–691, 2004     

The competitive heavy metal removal by hydroxyethyl cellulose-g-poly(acrylic acid) copolymer and its sodium salt: The effect of copper content on the adsorption capacity

Summary Crosslinked hydroxyethyl cellulose-g-poly(acrylic acid) (HEC-g-pAA) graft copolymer was prepared by grafting of acrylic acid (AA) onto hydroxyethyl cellulose (HEC) using [Ce(NH₄)₂(NO₃)₆]/HNO₃ initiator system in the presence of poly(ethyleneglycol diacrylate) (PEGDA) crosslinking agent in 1:1 (v/v) mixture of methanol and water at 30 °C. Carboxyl content of copolymer was determined by neutralization of –COOH groups with NaOH solution and sodium salt of copolymer (HEC-g-pAANa) was swelled in distilled water in order to determine the equilibrium swelling value of copolymer. Both dry HEC-g-pAA and swollen HEC-g-pAANa copolymers were used in the heavy metal ion removal from three different aqueous ion solutions as follows: a binary ion solution with equal molar contents of Pb²⁺and Cd²⁺, a triple ion solution with equal molar contents of Pb²⁺, Cu²⁺ and Cd²⁺, and a triple ion solution with twice Cu²⁺molar contents of Pb²⁺and Cd²⁺. Higher removal values on swollen HEC-g-pAANa were observed in comparison to those on dry polymer. The presence of Cu²⁺decreased the adsorption values for Pb²⁺ and Cd²⁺ ions on both types of HEC copolymer. However, with further increase in Cu²⁺ content both dry and swollen copolymers became apparently selective to Cu²⁺ removal and Cu²⁺ removal values exceeded the sum of adsorption values for Pb²⁺ and Cd²⁺. Maximum metal ion removal capacities were 1.79 and 0.85 mmol Me²⁺/g_polymer on swollen HEC-g-pAANa and dry HEC-g-pAA, respectively.     

High energy storage performance in Ca-doped PbZrO3 antiferroelectric films

In this work, antiferroelectric Pb_1-xCa_xZrO₃ (PCZ) thin films with different concentrations of Ca²⁺ were prepared by chemical solution deposition, and the effects of Ca²⁺ concentration on the antiferroelectric properties and energy storage performance were investigated. The results show that the optimal Ca²⁺ concentration in the PCZ thin films is x = 0.12 for electric properties and energy storage performance. The recoverable energy storage density and energy storage efficiency is 50.2 J/cm³ and 83.1 % at 2800 kV/cm, which is 261 % and 44.8 % higher than those of the PbZrO₃ (PZ) films. These effects are attributed to the enhancement of stability of antiferroelectric phase, diffuseness in the field-induced phase transition and electric breakdown strength by Ca²⁺-doping in the PZ films. Our results demonstrate that doping an appropriate amount of Ca²⁺ ions in antiferroelectric thin films is an effective way to improve their energy storage performance.     

Novel composite biopolymers of sodium alginate/natural rubber/coconut waste for adsorption of Pb(II) ions

A novel composite adsorbent in the form of beads for removal of Pb²⁺ from wastewater was prepared by blending a sodium alginate (NaAlg) solution, natural rubber (NR) latex, and coconut waste (cofiber). After being crosslinked by calcium chloride, the beads were highly stable, flexible, and easily used in the environment. The optimum composition of the beads with an average size of 1.1–1.2 mm was 4% NaAlg:NR latex (60% dry rubber content):cofiber at 50:1:0.72 and a 2%w/w CaCl₂ solution used for cross linking. The physico‐chemical properties of the beads were examined by the swelling ratio measurement, ATR‐FTIR, and SEM. The effects of the amount of cofiber, NR, and initial Pb²⁺ ions, the pH of the medium, the bead content, and the contact time, on the adsorption of Pb²⁺ were investigated. NR improved the water resistance and, hence, the stability of the beads. The cofiber increased the porosity and contact area and, hence, the efficiency of the composite beads to adsorb the Pb²⁺ up to 99.6%. The prepared beads are promising material to use for the effective and economical removal of Pb²⁺ from water. POLYM. COMPOS., 35:1013–1021, 2014. © 2013 Society of Plastics Engineers     

Determination of the efficiency and removal mechanism of cobalt by crab shell particles

The effects of contact time, solution pH and ionic strength on interactions between cobalt (⁵⁹Co) ions in synthetic liquid waste and particles of raw crab shell, Portunus trituberculatus, in batch reactions were studied. Approximately 19.5 mg dm^?3 Co was removed within 6 h after contact with 1.0 g dm^?3 crab shell at an initial concentration of 20 mg dm^?3 Co. Due to the dissolution of calcium carbonate in the crab shell, the solution pH changed spontaneously to 10, leading to precipitation of cobalt ions. The efficiency of cobalt removal depended on solution pH, but was less pH sensitive than for controls without crab shell. The maximum uptake of Co at an initial pH value of 5.0 was 510 mg g^?1 crab shell. The removal efficiency was affected slightly by ionic strength up to 2.0 mol dm^?3 of NaCl. Scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) indicated that the removal mechanism of Co by crab shell resulted primarily from the dissolution of calcium carbonate followed by precipitation of cobalt on the surface of the shell. Compared with commonly used ion‐exchange resins such as natural zeolite, Durasil 70, and Durasil 230, the efficiency of Co removal by a column of mixture of crab shell and activated carbon was at least three‐fold greater, indicating that crab shell is a suitable biosorbent for the removal of cobalt from liquid waste. Copyright © 2004 Society of Chemical Industry     

Coupled transport of Pb2+ through tri‐n‐octylamine‐xylene‐polypropylene supported liquid membranes

Transport of Pb²⁺ was carried from acidic solution into alkaline stripping phase through tri‐n‐octylamine‐xylene‐polypropylene supported liquid membrane. The transport of Pb²⁺ through the membrane was studied by varying the concentration of Pb²⁺ and HNO₃ in feed solution, NaOH concentration in strip solution and TOA concentration in membrane phase. The flux data obtained has been used to study the stoichiometry of complex Pb(NO₃)_n+2(HNR₃)_n. The supported liquid membrane (SLM) has been found stable for 10 runs with 24 h between each run. This SLM has been used effectively to extract lead ions along with chromium, copper and zinc ions from aqueous acidic leached solution of paint and industrial effluents. © 2012 Canadian Society for Chemical Engineering     

Synthesis and adsorption properties for metal ions of crosslinked chitosan acetate crown ethers

Two novel chitosan derivatives—crosslinked chitosan dibenzo‐16‐c‐5 acetate crown ether (CCTS‐1) and crosslinked chitosan 3,5‐di‐tert‐butyl dibenzo‐14‐c‐4 diacetate crown ether (CCTS‐2)—were synthesized by the reaction of crosslinked chitosan with dibenzo‐16‐c‐5 chloracetate crown ether and 3,5‐di‐tert‐butyl dibenzo‐14‐c‐4 dichloracetate crown ether with the intent of forming polymers that could be used in hazardous waste remediation as toxic metal‐binding agents in aqueous environments. Their structures were confirmed with elemental analysis, infrared spectral analysis, and X‐ray diffraction analysis. In the infrared spectra of CCTS‐1 and CCTS‐2, the characteristic peaks of aromatic backbone vibration appeared at 1595 cm⁻¹ and 1500 cm⁻¹; the intensity of the N H and O H stretching vibration in the region of 3150–3200 cm⁻¹ decreased greatly. The X‐ray diffraction analysis showed that the peak at 2θ = 20° decreased greatly in CCTS‐1 and CCTS‐2. The adsorption and selectivity properties of CCTS‐1 and CCTS‐2 for Pb²⁺, Cu²⁺, Cr³⁺, and Ni²⁺ were studied. Experimental results showed that the two crosslinked chitosan derivatives had not only good adsorption capacities for Pb²⁺, Cu²⁺, but also high selectivity for Pb²⁺, Cu²⁺ in the coexistence of Ni²⁺. For aqueous systems containing Pb²⁺, Ni²⁺, or Cu²⁺, Ni²⁺, CCTS‐1 only adsorbed Pb²⁺ or Cu²⁺. For aqueous systems containing Pb²⁺, Cr²⁺ and Ni²⁺, CCTS‐2 had high adsorption and selectivity properties for Pb²⁺. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2069–2074, 1999     

Dissolution of alumina ceramics in HCl aqueous solution

Dissolution of a cold isostatically pressed high purity alumina ceramics in aqueous HCl solutions was studied as a function of immersion time and acid concentration. From the amounts of Al³⁺, Mg²⁺, Ca²⁺, Na⁺, Si⁴⁺ and Fe³⁺ ions released in the corrosive solution, a degree of dissolution χ_i for each component was calculated according to the equation χ_i = A/B, where A and B are respectively the amount of the element released in the corrosive solution and the amount of the element in the untreated material. The determination of the amounts of ions released in the corrosive solutions was carried out by means of atomic absorption spectrometry (AAS). The corrosion of alumina ceramics in the HCl aqueous solution is determined by the solubility of alumina and the solubility of grain-boundary impurities. Very low dissolution values of Al³⁺, Mg²⁺, Ca²⁺, Na⁺, Si⁴⁺ and Fe³⁺ ions after the corrosion test of alumina ceramics showed a very good corrosion resistance in the HCl aqueous solution.     

Ion migration law in flotation pulp and its influence on the separation of smithsonite and quartz

This study investigated the migration law of ion release and adsorption in the flotation pulp of oxide zinc ore, and found that numerous different ions existed in the pulp. The total concentrations and major sources of various ions (Pb²⁺, Zn²⁺, Fe³⁺, Ca²⁺, Mg²⁺, SO₄^2-, etc.), released from the minerals after grinding, were determined. The zeta potential tests indicated that a mixed-ion solution strongly influences the surface charge of the minerals. The flotation tests show that the migration law of ions is detrimental to the separation and concentration of minerals.