7th International YWP conference, Taipei Chinese Taiwan Adsorption of heavy metals by an iron coated natural Australian zeolite Thuy Chung Nguyen Paripurnanda Loganathan, Tien Vinh Nguyen, Jaya Kandasamy, Ravi Naidu, Saravanamuthu Vigneswaran Good afternoon 7th International YWP conference, Taipei Chinese Taiwan

content Objectives Introduction Materials and methods Results and discussion Conclusions Here we say that for a few events: they have to sign up. Someone from the SC will be in charge.

OBJECTIVES Determine the adsorptive removal of heavy metals (Zn, Cd, Cu, Pb and Cr) from synthetic water using zeolite and iron- coated zeolite (ICZ) Model equilibrium adsorption Model kinetic adsorption Determine the breakthrough adsorption capacity in fixed-bed columns Model fixed-bed column adsorption Here we say that for a few events: they have to sign up. Someone from the SC will be in charge.

Introduction Heavy metals may enter natural water bodies (lakes, rivers) from industries, roads, and agricultural activities At elevated concentrations, many heavy metals can be toxic to aquatic organisms and humans Therefore, they should be removed from the water Here we say that for a few events: they have to sign up. Someone from the SC will be in charge.

Introduction HM removal technology Membrane filtration Oxidation reduction Ion exchange Electro-dialysis Adsorption Reverse osmosis Several methods are available for the removal of heavy metals. Of these, adsorption is an attractive method because it is a simple, environmentally friendly and effective method Low cost and locally available absorbents are attractive Zeolite is one of the popular adsorbent used to remove heavy metals. However, its effectiveness can be increased by chemical modification such as coating with metal oxides Here we say that for a few events: they have to sign up. Someone from the SC will be in charge.

Introduction Zeolites exist in large amounts in Australia and many other countries. It has large cation-exchange capacity and is capable of removing large quantities of heavy metals from contaminated water. The modifications of zeolites such as coating of hydrous ferric oxide (HFO) or manganese oxide on zeolite can enhance the ligand sorption capacity of heavy metal ions. Here we say that for a few events: they have to sign up. Someone from the SC will be in charge.

Method of preparation of Iron-coated zeolite (Doula 2009) MATERIALS AND Method Method of preparation of Iron-coated zeolite (Doula 2009) Structure of Zeolite Zeolites (natural and synthetic) are materials in which (SiO4)4 and (AlO4)5 tetrahedra are linked by sharing oxygen atoms to give ring structures, which, in turn, are linked to give an overall three-dimensional structure which contains regular channels and cavities (like honeycomb) of sizes similar to those of small to medium-sized molecules.

MATERIALS AND Method Batch equilibrium adsorption Single metals and mixed metals (pH 6.5) Langmuir adsorption isotherm model Batch kinetic adsorption Pseudo-first and pseudo-second order models Column adsorption Single metals and mixed metals (pH 5.0), column height 10 cm, flow rate 0.52 m/h, duration of experiments (for single 30-40 hrs, for mixed metals ~ 24hrs) Thomas model

MATERIALS AND Method Model Equation Graphical method used to calculate model constant Langmuir q e = q max K L C e 1+ K L C e C e q e = 1 q max K L + C e q max C e = equilibrium concentration of HM (mg/L), q e = amount of HM, C e = equilibrium concentration of HM (mg/L), q e = amount of HM adsorbed (mg/g), q max = maximum amount of HM adsorbed (mg/g); KL = Langmuir constant related to the energy of adsorption (L/mg) Pseudo-first order kinetic dq t dt = k 1 ( q e − q t ) ln ( q e − q t) =ln q e − k 1 t q e = amount of HM adsorbed at equilibrium (mg/g); q t = amount of HM adsorbed at time, t (min) (mg/g) and k 1 = equilibrium rate constant of pseudo-first order sorption (1/min) Pseudo-second order kinetic dq t dt = k 2 ( q e − q t ) 2 t q t = 1 k 2 q e 2 + t q e q e = amount of HM adsorbed at equilibrium (mg/g); q t = amount of HM adsorbed at time, t (min) (mg/g) and k 2 = equilibrium rate constant of pseudo-second order (1/min) Thomas 𝒍𝒏 ( 𝑪 𝒐 / 𝑪 𝒕 −𝟏)= 𝒌 𝑻𝒉 𝒒 𝒐 𝐌/𝐐−𝒌 𝑻𝒉 𝑪 𝒐 𝐭 𝒌 𝑻𝒉 = Thomas rate constant (mL/min mg), 𝒒 𝒐 = equilibrium HM uptake per g of zeolite (mg/g), 𝑪 𝟎 = inlet HM concentration (mg/L), 𝑪 𝒕 = outlet HM concentration at time t (mg/L), M = mass of zeolite (g), Q = filtration velocity (mL/min) and t = filtration time (min)

Fixed bed column experimental set-up MATERIALS AND Method Flow rate: 0.52 m/h, height 10 cm Up flow Mass of zeolite and ICZ: 40 grams pH 6.0 (for single) and pH 5.0 (for mixture) Fixed bed column experimental set-up

results FTIR XRD SEM EDS Surface area (BET) Similar XRD and FTIR between zeolite and ICZ EDS: Zeolite Fe content 3.42% ICZ Fe content 8.79% Surface area: Zeolite 12.24 m2/g ICZ 7.68 m2/g SEM: Iron coated on the surface of zeolite FTIR XRD SEM EDS Surface area (BET) Zeolite 40.000 X ICZ 40.000 X

Isotherm adsorption experiment for single and mixed metals results Zeolite ICZ Isotherm adsorption experiment for single and mixed metals

results Adsorption capacity for all HMs: ICZ > Zeolite Pb > Cu > Cd > Zn > Cr Mixed metals competition for adsorption at high concentrations Single metal adsorption higher than mixed metals Zero point of charge: Zeolite pH < 3.0; ICZ pH 5.8 Zeta potential values Langmuir model parameters for HM adsorption on zeolite and ICZ at pH 6.5 Qmax Pb Cu Cd Zn Cr Langmuir Zeolite Sinlge 9.97 8.53 6.72 5.83 5.03 Mixture 6.54 4.34 4.20 3.72 4.01 ICZ 11.16 9.33 7.24 6.22 5.47 7.63 6.11 4.42 4.61 3.89

results Kinetic experiment (single) Qe (mg/g) Pb Cd Cu Zn Cr Zeo Qe exp. 4.70 3.90 4.40 4.00 2.50 Qe 6.17 5.32 4.61 4.54 4.04 ICZ 5.29 4.13 4.92 3.96 2.56 5.20 4.50 4.10 3.70 The kinetic adsorption data fitted satisfactorily to both pseudo 1st and pseudo 2nd order models for both single and mixed metals system but 2nd order is better than 1st order Better fit of pseudo second-order suggested that chemical process may be the rate-limiting step in the adsorption Kinetic experiment (mixture) Pb Cd Cu Zn Cr Zeo Qe exp. 5.57 4.30 3.61 3.96 2.42 Qe 4.70 3.70 3.50 3.30 2.40 ICZ 6.03 4.81 4.18 5.36 3.55 5.10 4.10 3.80 3.20

results Zeolite ICZ Shoud be opposite side: metal order should be in the order of adsorption capacity Kinetic experiments for single and mixed metals at pH 6.5

Breakthrough adsorption capacities and Thomas model parameters results Column experiment Breakthrough adsorption capacities and Thomas model parameters HM Individual metal Metal mixture Qe Qo R2 Zeolite Pb 1.67 1.61 0.924 0.63 0.61 0.899 Cd 1.32 1.29 0.894 0.52 0.876 Cu 1.15 1.14 0.949 0.48 0.49 0.879 Zn 1.19 1.10 0.959 0.45 0.41 0.917 Cr 0.81 0.74 0.945 0.35 0.32 ICZ 2.28 2.03 1.03 0.95 0.954 1.89 1.82 0.933 0.93 0.86 0.940 1.70 0.948 0.89 0.83 0.946 1.66 0.919 0.75 1.17 1.08 0.76 0.67 0.957 Qe: Breakthrough adsorption capacity (mg/g) Qo: Thomas adsorption capacity

results Single adsorption for all metals Adsorption capacity : ICZ > Zeolite: Pb > Cd > Cu > Zn > Cr

results Mixed HMs Adsorption capacity : Breakthrough time for ICZ longer than for zeolite For both zeolite and ICZ, HMs adsorption order: Pb > Cd > Cu > Zn > Cr

Mechanism of heavy metal adsorption on adsorbents results Mechanism of heavy metal adsorption on adsorbents Ligand exchange M(OH)2: precipitation Low pH High pH Electrostatic induction is a redistribution of electrical charge in an object, caused by the influence of nearby charges Precipitation

CONCLUSIONs Equilibrium adsorption data sastisfactorily fitted to Langmuir model for all single and mixed HMs Langmuir adsorption capacities of HMs: Pb > Cu > Cd > Zn, Cr for single metal (5.0-11.2 mg/g) and for mixed metals solution (3.7-7.6 mg/g). The kinetic adsorption data fitted reasonably well to the pseudo-second-order Batch adsorption shows better for zeolite and ICZ

CONCLUSIONs Breakthrough adsorption capacity for single and mixed HMs in zeolite and ICZ column Pb > Cd > Cu > Zn > Cr Langmuir > Freudlich Pseudo first-order > Pseudo second-order All column breakthrough data fitted satisfactorily by Thomas model Both the batch and column adsorption data showed that ICZ had higher metal adsorption capacity than zeolite ICZ is a potential adsorbent for removing heavy metals from water

ACKNOWLEDGEMENT Thanks so much my supervisors Prof. Vigneswaran, Dr Loganathan and Dr Tien Vinh Nguyen for their great academic supports We would like to thank the Faculty of Engineering and IT, and Faculty of Science, UTS for technical support This study was funded by Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) (project number 02-050-07)

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