Adsorption Kinetics Of Pb Research Articles

Activated Nanocellulose from Corn Husk: Application to As and Pb Adsorption Kinetics in Batch Wastewater

The aim of this study was to evaluate the removal of Pb and As from an aqueous solution using corn residue cellulose nanocrystals (NCCs). The corn husk was subjected to alkaline digestion, followed by bleaching and esterification with 3% citric acid to obtain NCCs. A 10 ppm multimetal solution of Pb and As was prepared. The adsorption process was evaluated by adjusting the pH and NCC dosage, optimized through the nonlinear regression of empirical mathematical models. Based on the optimal parameters, the kinetics were evaluated using the PFO and PSO models. The NCCs displayed nanometer-level characteristics with a particle size less than 383.7 nm, a ζ potential in the range of −28–70 mV, pHZCP with an acidic tendency, a porous crystal structure as evaluated through SEM images, and the presence of functional groups with a high chelating capacity, as identified via FTIR. Optimum values of pH 8.0 and 20 mg/L of the NCC dose were found, from which it was observed that the PFO, PSO, and Elovich kinetics showed R2 > 0.974, with an adsorption capacity in the order Pb > As. The adsorbent-formulated NCCs presented a good capacity to remove heavy metals from aqueous media.

A magnetic macroporous α-Fe2O3/Mn2O3 nanocomposite as an efficient adsorbent for simple and rapid removal of Pb(II) from wastewater and electronic waste leachate.

A magnetic nanocomposite adsorbent, comprised of macroporous iron oxide/manganese oxide (α-Fe2O3/Mn2O3), is prepared, characterized, and used for lead(II) removal from both industrial wastewater and leachate of electronic waste. The synergistic interaction between iron oxide and manganese oxide significantly enhances the adsorption performance. The surface characteristics and structural composition of the nanocomposite are examined using high-resolution transmission microscopy, X-ray spectroscopy, and Brunauer-Emmett-Teller methods. Under optimized conditions, the present method offers a significantly high adsorption capacity (377.5 ± 8.9 mg.g-1), short contact time (10 min), and an excellent removal efficiency (98.0 ± 0.9%) compared with most of the previously suggested methods. The adsorption kinetics of Pb(II) on the nanocomposite surface follows pseudo-second-order kinetics and exhibits a good fit with the Dubinin-Radushkevich (D-R) model. These findings highlight the applicability of the α-Fe2O3/Mn2O3 magnetic nanocomposite as a promising efficient adsorbent for the rapid removal of lead(II) from hazardous wastewater. Moreover, the proposed nanocomposite adsorbent exhibits remarkable stability and can be easily isolated from the test sample solution for subsequent reuse. The efficacy of the developed adsorptive removal procedure is confirmed by achieving a complete lead(II) ion removal from some industrial wastewater discharged from lead battery factories and from the leachate of electronic waste.

Modification and Application Study of Activated Natural Zeolite for the Treatment of Liquid Waste from Chemical Laboratory

Natural zeolite from Malang Regency is a raw material that can be used as an adsorbent for heavy metal waste. However, this natural zeolite needs activation and optimization to be utilized maximally as an adsorbent. This study was conducted for both physical and chemical activation of natural zeolite. Characterization results of XRD indicated that the natural zeolite possesses crystalline phases and is of the mordenite type. Based on the XRF results, the Si/Al ratio increased from 5.768 to 6.119 after activation. Based on the characterization results using the BET method with SAA analysis, the surface area of non-activated natural zeolite was determined to be 20.8045 m²/g, while activated natural zeolite had a surface area of 137.8196 m²/g. Results of the adsorption study in treating liquid laboratory waste using simulated Pb and Cr metal wastes demonstrated that activated natural zeolite performed more effectively as an adsorbent than non-activated natural zeolite. The adsorbent’s optimum mass was 0.3 grams, resulting in an adsorption percentage of 97.43% for Pb and 97.56% for Cr, with a contact time of 30 minutes at pH 6. The adsorption kinetics of Pb and Cr metals were described using a pseudo-second-order rate equation. The adsorption of Pb and Cr was depicted using the Langmuir equation, indicating the monolayer formation on the homogenous adsorbent surface during the adsorption process. The activated natural zeolite has the potential to be employed as an independent adsorbent in the treatment of heavy metal waste.

New Approaches for Pb(II) Removal from Aqueous Media Using Nanopowder Sodium Titanosilicate: Kinetics Study and Thermodynamic Behavior.

Microporous sodium titanosilicate, Na2TiSiO5, has been successfully prepared using the sol-gel method. The structural and morphological characterization of synthesized product has been made via thermal analyses (TG-DTG), X-ray diffraction (XRD), and electron microscopy (SEM and TEM). Adsorption properties of the synthesized Na2TiSiO5 nanopowder for Pb(II) removal of aqueous media was investigated in different experimental conditions such as the contact time, the initial metal concentration, the pH, and the temperature. The Pb(II) adsorption on Na2TiSiO5 was discussed according to the kinetics and thermodynamics models. The adsorption kinetics of Pb(II) have been better described by the PS-order kinetic model which has the highest fitting correlation coefficients (R2: 0.996-0.999) out of all the other models. The adsorption results have been successfully fitted with the Langmuir and Redlich-Paterson models (R2: 0.9936-0.9996). The calculated thermodynamic parameters indicate that the Pb(II) adsorption is an endothermic process, with increased entropy, having a spontaneous reaction. The results have revealed a maximum adsorption capacity of 155.71 mg/g at 298 K and a very high adsorption rate at the beginning, more than 85% of the total amount of Pb(II) being removed within the first 120 min, depending on the initial concentration.

Potential of silica from water treatment sludge modified with chitosan for Pb(II) and color adsorption in sasirangan waste solution

Water treatment sludge (WTS) still contains a lot of silica oxide (SiO2) as much as 43.12-66.90% by weight and can act as an adsorbent to be applied to the treatment of Sasirangan wastewater. Silica extraction from WTS was carried out by microwave-assisted leaching, which - compared to conventional extraction - had several advantages including high extraction yields, fast, uniform, and more selective processing time. In addition, Sasirangan liquid waste is a by-product of the dyeing process of Sasirangan cloth, which still contains heavy metals in amounts exceeding the quality standard. This study aims to extract silica from WTS by microwave-assisted leaching process to synthesize silica modified by chitosan (Si-Kit) as an adsorbent to reduce Pb(II) from Sasirangan wastewater, and to obtain a kinetic model of the adsorption process. The silica from microwave-assisted leaching process (Si-MaL) and Si-Kit adsorbents were characterized using FTIR and SEM. The results showed that the dominant functional groups of Si-Kit included Si-O-Si, Si-O-C stretching vibrations, and stretching vibration of C=N showing that the condensation between aldehyde groups and amino groups occurred to form base after the addition of glutaraldehyde. The SEM images showed that Si-MaL and Si-Kit adsorbent obviously increased in particle size with the presence of visible particles of homogeneous granules and large pores. The removal efficiency percentage of Pb(II) and color occurred at 6% w/v adsorbent weight and 70 min was 87.20% and 61.87% respectively. Meanwhile, the adsorption kinetics of Pb(II) and color followed the zero order kinetics model at weight variation of 6%-w/v based on the value of R2 close to one and the adsorption capacity of Pb(II) ion and color were 12.01 mg g-1 and 467 mg g-1, respectively.

Iron-doped hydroxyapatite for the simultaneous remediation of lead-, cadmium- and arsenic-co-contaminated soil

Since lead, cadmium and arsenic have completely opposite chemical behaviors, it is very difficult to stabilize all these three heavy metals simultaneously. Herein, a novel iron-doped hydroxyapatite composite (Fe-HAP) was developed via an ultrasonic-assisted microwave hydrothermal method for the simultaneous remediation of lead-, cadmium-, and arsenic-co-contaminated soil in Hunan Province, South China. Using DTPA/sodium bicarbonate extractant to extract bioavailable Pb, Cd and As in soil after Fe-HAP remediation for 60 days, the immobilization efficiencies were 79.77%, 51.3% and 37.5% for Pb, Cd and As, respectively. The soil extractable and exchangeable fractions of Pb, Cd and As decreased significantly. In batch experiments, the adsorption kinetics of Pb, Cd and As on Fe-HAP were well described by pseudo-second-order models, indicating that the adsorption is controlled by chemisorption. In the Langmuir adsorption isotherm, the maximum adsorption capacities of Cd2+ and As(V) were 476.2 mg g−1 and 195.69 mg g−1, respectively, while Pb2+ fit the Freundlich model better. The XRD, SEM and XPS analyses indicated that Fe-HAP formed stable minerals of Pb5(PO4)3OH, Cd3(PO4)2·4H2O, Cd(OH)2 and Fe3(AsO4)2·6H2O with Pb, Cd and As. Overall, its facile and efficient immobilization performance indicate that Fe-HAP has potential for practical applications in integrative remediation of Pb-, Cd-, and As- co-contaminated soil.

Artificial humic acid synthesized from food wastes: An efficient and recyclable adsorbent of Pb (II) and Cd (II) from aqueous solution

Developing green, sustainable, and low-cost adsorbents for removing heavy metals from wastewater while recycling food wastes can avoid secondary environmental damage. In this work, artificial humic acid (A-HA) was prepared through biological fermentation using food wastes as raw materials with the goal to remove Pb (II) and Cd (II) from aqueous solution. The results showed that Pb (II) adsorption by A-HA was superior to that of Cd (II). Electrostatic interaction, surface complexation, ion exchange, and π – π interaction played key roles in the adsorption and desorption of A-HA for Pb (II) and Cd (II). The Langmuir isothermal adsorption model was more suitable for the adsorption of Pb (II) and Cd (II) by A-HA, and at 45 °C, maximum adsorption capacities were 37.6 mg/g and 3.33 mg/g, respectively. The adsorption kinetics of Pb (II) and Cd (II) by A-HA showed good fit with the pseudo-first-order kinetic model. The adsorption capacities of A-HA for Pb (II) and Cd (II) first increased gradually and finally stabilized with increasing initial concentration of adsorbate. In the pH range of 1–7, the adsorption capacities of A-HA for Pb (II) and Cd (II) first increased and remained stable. However, the adsorption capacities were inhibited by increasing ionic strength. Under optimal adsorption conditions, very little Pb (II) and Cd (II) were desorbed. In summary, A-HA might be a promising and effective adsorbent for metal removal because of its environmental friendliness, low cost, and its origin from food wastes as raw materials. • Food wastes as the rawmaterials of Artificial humic acid aligning to concepts of sustainable development of green chemistry. • Artificial humic acid showed an effective adsorption for Pb (II)/Cd (II). • Artificial humic acid had a better adsorption for Pb (II) than Cd(II). • Adsorption and desorption mechanism were electrostatic interaction, complexation, ion exchange and π – π interaction. • Adsorbate initial concentration, pH, and ionic strength had obvious effects on adsorption and desorption.

Effects of Chelating Surfactants on Competitive Adsorption of Lead and Zinc on Loess Soil

The study of competitive adsorption of heavy metals on soil is important for heavy metals contaminated soil remediation. However, there have been few studies on the impact of desorption reagents on heavy metal adsorption in soil. Batch adsorption studies were used to investigate the competitive adsorption mechanism of two heavy metals, Pb and Zn, on a loess soil in the presence of a new chelating surfactant, sodium N-lauroyl ethylenediamine triacetate (LED3A). Results showed that competitive adsorption equilibria of Pb and Zn were reached at 3 and 10 h, respectively. The maximum equilibrium adsorption capacities were 19.55 and 18.35 g.kg-1, respectively. LED3A affected the competitive adsorption kinetics of Pb and Zn by increasing the change in external mass transfer and reducing the change in internal mass transfer. LED3A reduced Pb and Zn adsorption capacities onto the soil through competitive chelation of the heavy metals. The heavy metal chelating ability of LED3A was higher for Zn than for Pb. When its concentration was larger than 5 g.L-1, LED3A showed a significant effect on the competitive adsorption of Pb and Zn. In the competitive system, the effect of Pb concentration on the Zn adsorption capacity was greater than the effect of Zn concentration on the Pb adsorption capacity. LED3A weakened the effect of Pb concentration and enhanced the effect of Zn concentration. LED3A showed a significant potential for efficiently leaching remediation of Pb and Zn co-contaminated soil.

Highly Effective Lead Ion Adsorption by Manganese-Dioxide-Supported Core-Shell Structured Magnetite

In this research, a magnetic core-shell composite, consisting of a Fe3O4 core and a silica shell (called Fe3O4@SiO2), was developed and then functionalized via MnO2 grafting at different MnO2 deposition levels (termed Fe3O4@SiO2-MnO2). The resulting materials were characterized by X-ray fluorescence, X-ray diffraction, a vibration sample magnetometer, transmission electron microscopy, N2 adsorption-desorption, zeta-potential studies and X-ray photoelectron spectroscopy. Visualizations showed that Fe3O4@SiO2-MnO2 had a magnetite core with size of 100 nm, overlaid by a rough silica shell and a relatively loose MnO2 deposition. The Pb(II) adsorption onto the composites was also assessed. It was found that MnO2 deposition on the Fe3O4@SiO2 surface enhanced Pb(II) adsorption, and the Pb(II) adsorption amount was highly correlated to the MnO2 deposition level. The adsorption kinetics of Pb(II) followed pseudo-second-order kinetics, and the adsorption rate could be decreased by increasing the initial concentration of Pb(II). A higher pH resulted in enhanced Pb(II) adsorption, which slightly increased with the coexistence of Na+ and Ca2+, along with the presence of dissolved humic acid. The adsorbent could easily be separated and recovered under the action of the external magnetic component and it displayed stable adsorption behaviour over four adsorption-desorption periods. The results emphasize the high potential of Fe3O4@SiO2-MnO2 materials for the adsorptive removal of Pb(II) in water.

Investigation of the adsorption behavior of Pb(II) onto natural-aged microplastics as affected by salt ions

In this study, the adsorption behavior of Pb(II) on natural-aged and virgin microplastics in different electrolyte solutions was investigated. The results demonstrated that natural-aged microplastics exhibited higher adsorption capacity for Pb(II) compared to virgin ones, and the addition of CaCl2 strongly inhibited the adsorption amount of Pb(II). The adsorption kinetics of Pb(II) adsorption were better fitted by the pseudo-second order model and Elovich equation, and were slowed down greatly at higher ionic strength. The rate-limiting steps of adsorption process were dominated by intra-particle diffusion. The adsorption isotherm of Pb(II) onto microplastics affected by salt ions can be well described by Freundlich model, the greater adsorption efficiency of natural-aged microplastics proved that adsorption process was multilayer and heterogeneous. In addition, pH significantly influenced the adsorption of Pb(II) due to the changes electrostatic interactions. The effect of fulvic acid in the electrolyte solutions was also revealed and attributed to the complexation with Na+ and Ca2+. Furthermore, the higher pH and ionic strength in different environmental water dramatically decreased adsorption capacity onto microplastics. Finally, it’s confirmed that the adsorption mechanisms affected by salt ions mainly involve electrostatic interaction, surface complexation, and ionic exchange. These findings indicate that salt ions exert an important influence on the adsorption of heavy metals for MPs, which should be further concerned.

Novel and Green Fe3O4@Sio2-L-Cys Magnetic Absorbent for Efficient Removal of Pb (II) from Aqueous Solution

In this study, Fe3O4@Sio2-NH2 was synthesized by the modification of Fe3O4 particles with tetraethyl orthosilicate(TEOS) and 3-aminopropyl-Triethoxysilane (APTES), and then the cysteine was grafted with glutaraldehyde as cross-linking agent.The material was characterized by XRD,FIIR and TEM. The effects of temperature, time, initial concentration of Pb(II) and pH value on the adsorption rate of Pb(II) were investigated, and the adsorption mechanism and the regeneration performance of the adsorbent were discussed.The results indicated that when the amount of adsorbent was 0.4g/L, the temperature was 303K, the adsorption time was 2.5h and the pH was 5.02, the adsorption rate of Pb(II) in water can reach up to 98.25%.The adsorption kinetics of Pb(II) on the material accorded with Lagergren quasi-second-order kinetic equation, which belonged to the chemisorption process.Adsorption isothermal curve studies showed that the adsorption of Pb(II) on the material complied with the Langmuir isothermal adsorption model and was a monolayer adsorption.The maximum adsorption capacity of Pb(II) is 120.77mg/g. Adsorption thermodynamics studies showed that the whole system was endothermic reaction,and warming was conducive to the adsorption,which happens spontaneously.After 4 times of the adsorption recycling,the adsorption rate can still reach 92.7%.

Adsorption of Pb(II) from Water onto ZnO, TiO2, and Al2O3: Process Study, Adsorption Behaviour, and Thermodynamics

This study is aimed at comparing the use of zinc oxide (ZnO), titanium dioxide (TiO2), and aluminium oxide (Al2O3) for removing lead ions from water through adsorption. The point of zero charge was obtained for ZnO, TiO2, and Al2O3 and was found to be 7.3, 7.1, and 9.0, respectively. The effect of pH, adsorbent dose, contact time, initial concentrations, and temperature was investigated in batch experiments. The optimal conditions obtained were 7, 2 g/L, 120 mins, 100 ppm, and 41°C, respectively, where the optimal removal efficiencies were 98.43%, 96.45%, and 85.50% for ZnO, TiO2, and Al2O3, respectively. In addition, analyses of adsorption kinetics, mechanisms, isotherms, and thermodynamics were performed. The adsorption kinetics of Pb(II) were compared to popular models, and it was found that the pseudo-second-order (PSO) model best fitted the Pb(II) uptake for all adsorbents at correlation coefficient ([Formula: see text]). The adsorption isotherms of Pb(II) were also compared to popular models, and it was found that the Pb(II) uptake by TiO2 and ZnO was well-described by the Langmuir model ([Formula: see text]) with maximum adsorption capacities of 55.04 and 58.88 mg/g, respectively. On the other hand, the behaviour of Al2O3 is described more accurately by the Dubinin-Radushkevich (D-R) model ([Formula: see text]), and the maximum adsorption capacity was 53.64 mg/g. The isotherm analysis proved that the limiting step of the adsorption process is the film diffusion mechanism. In addition, studying the heat of adsorption of Pb(II) implied that the adsorption is endothermic due to the positive values of enthalpy ([Formula: see text]) for all adsorbents. The absorbents were characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) to study the morphology of surfaces and the chemical characterization of the adsorbents to ensure that adsorption is achieved. ZnO showed better performance for the uptake of lead followed by TiO2 then Al2O3.

Plant extract mediated synthesis of Fe3O4-chitosan composite for the removal of lead ions from aqueous solution

Divalent lead ion contamination in drinking water pose adverse health effect, hence its removal using minute amount of chemical (Fe3O4) with the use of natural biopolymer (Chitosan) and green plant extracts Ricinus communis (Castor plant) for the synthesis of nanocomposites was determine in the present study. The phyto-magnetic nanomaterial was synthesized via co-precipitation method and characterized using Field Emission Scanning Electron Microscopy (FE-SEM), Fourier Transform-Infrared spectrometer (FTIR) and X-ray diffractometer (XRD) techniques. The application of the green synthesized (RC-Fe3O4-Chitosan) nanocomposites was determined in the adsorption of Pb(II) from aqueous solution. The experimental parameters such as contact time, pH range, adsorbent dosage, and effect of temperature were evaluated. The results showed that the maximum adsorption capacity of the divalent lead ions occurred at pH = 7.0, temperature = 323 K, contact time = 60 min and adsorbent dose = 0.3 g/L. The adsorption equilibrium was best fitted to the Freundlich isotherm. The maximum capacity determined from Freundlich isotherm was 50.72 mg/g at 323 K. Adsorption kinetics of Pb(II) was best described with pseudo-second-order kinetic model. Thermodynamics studies reveal that with an increase of solution temperature (303 K, 313 K and 323 K) the adsorption efficiency increases correspondingly to −4.35, −6.12, and −7.91 kJ/mol respectively, suggesting endothermic nature of the adsorption process. The reusability of the green synthesized adsorbent (RC-Fe3O4-chitosan) depicts seven successful sequential cycles. Therefore, the synthesized green magnetite chitosan composites can be used as a reliable and sustainable material for efficient removal of Pb(II)species from aqueous solution.

Composite of bentonite/CoFe2O4/hydroxyapatite for adsorption of Pb (II)

In this contribution, a composite from bentonite (B), CoFe2O4 (CF), and hydroxyapatite (HAP) was developed by chemical synthesis route for adsorption of a lead ion, Pb (II) from wastewater. Initially, a composite of B/CF was synthesized by varying the weight ratio of CF, i.e., (1–x)B/(x)CF (x = 0.05, 0.15, 0.25, 0.50), followed by ternary composite synthesis, which was formulated from the sample of (0.85B/0.15CF) and different weight ratios of HAP, i.e., (1–y)[(0.85B/0.15CF)]/yHAP where y = 0.25, 0.35 and 0.45 weight ratios of HAP. The sample of 0.85B/0.15CF was found to be optimal in its adsorption capacity of about 20 mg g−1 from the binary composite samples, while among the ternary composites, a sample with a composition of 0.65[(0.85B/0.15CF)]/0.35HAP revealed an optimum adsorption capacity of about 36 mg g−1, which was then selected for further studies. The adsorption kinetics of Pb (II) by the optimum 0.65[(0.85B/0.15CF)]/0.35HAP sample was studied at different contact times from 30–120 min, where the equilibrium was reached at around 90 min of contact time and the kinetic behavior adopted Pseudo-second order adsorption mechanism. The initial concentration of Pb (II) was also varied from 50–200 mg l−1 to study the adsorption isotherm, which resulted that adsorption capacity of 0.65[(0.85B/0.15CF)]/0.35HAP towards Pb (II) was increased to about 66 mg g−1 and the adsorption isotherm data best fitted with Langmuir adsorption isotherm model. Therefore, the result of this study pinpoints that the present composite material is a potential candidate for the adsorption of Pb (II) ion.

Poly(N-acryloyl-l-histidine)-modified wood sawdust as an efficient adsorbent for low-level heavy metal ions

An amphoteric metal adsorbent, poly(N-acryloyl-l-histidine)-modified sawdust (SD-g-P(A-His)), is prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization of N-acryloyl-l-histidine from modified sawdust. SD-g-P(A-His) possess imidazolyl and carboxyl groups and shows outstanding adsorption performance for heavy metals. The adsorption capacities of SD-g-P(A-His) are 241.8 and 95.7 mg/g for Pb(II) and Cu(II), respectively. Ten tested metal ions, e.g. Au(III), Cr(III), Cu(II), Fe(III), Ni(II), Pb(II), Pd(II), Hg(II), Mg(II) and Zn(II), can be effectively removed from the multi-metal solution at pH > 2.7, while Au(III) and Pd(II) can be selectively recycled from the multi-metal solution by lowering the pH to ≤ 1.0. The adsorption kinetics of Pb(II) and Cu(II) onto SD-g-P(A-His) fit well with the pseudo-second order model. SD-g-P(A-His) can treat the water with low concentration of metal ions down to sub-10 μg/L level to meet the Quality Standards for Drinking Water of China. Moreover, SD-g-P(A-His) can be recycled and maintain high adsorption efficiency (91.5%) even after 5 cycles.

Investigate the role of biofilm and water chemistry on lead deposition onto and release from polyethylene: An implication for potable water pipes

In this study, the influence of biofilm presence and water chemistry conditions on lead (Pb) deposition onto low density polyethylene (LDPE) surface was examined. The results demonstrated that biofilm presence on LDPE surfaces strongly and significantly enhanced Pb uptake, with the 13-fold greater equilibrium Pb surface loading when biofilm was present (1602 μg/m2) compared to the condition when it was absent (124 μg/m2). The kinetics of Pb adsorption onto LDPE surface when biofilm was present is best described by Pseudo 2nd order kinetic model. Pb adsorption onto new LDPE surfaces was significantly reduced from 1101 μg/m2 to 134 μg/m2 with increased aqueous solution’s ionic strength from 3 × 10−6 M to 0.0072 M. The presence of chlorine residual (2 mg/L) significantly reduced Pb adsorption onto LDPE surfaces by possible oxidation of Pb2+ to Pb4+ species. The kinetics of Pb release from LDPE surfaces was investigated under static and dynamic conditions through immediate exposure of Pb accumulated LDPE pellets to the synthetic water at pH 5.0 and 7.8. The results demonstrated a greater Pb release (86 %) at pH 5.0 compared to the pH 7.8 (58 %). An enhanced Pb release into the contact water was found under dynamic conditions compared to static conditions.

Adsorption of Pb(II) from Aqueous Solutions on Dithizone-Immobilized Coal Fly Ash

Adsorption of Pb(II) ions onto selective adsorbent of dithizone-immobilized coal fly ash (DCFA) from Holcim, Cilacap, Indonesia has been investigated in batch experiments. Prepared coal fly ash (CFA) modified by immobilization of dithizone previously were characterized by FT-IR and XRD. Several parameters influencing the adsorption of Pb(II) ions such as effect of pH, adsorbent dosage, contact time and initial concentration of ions on the efficiency of the adsorption were studied. The optimum condition of Pb(II) adsorption was found at pH 5, adsorbent dosage 0.1 g, contact time 60 min and initial Pb(II) ions concentration of 60 mg L–1. The adsorption kinetics of Pb(II) ions on DCFA was found to follow a pseudo-second-order kinetic model. The adsorption isotherm data were fitted to the Langmuir model. Kinetics and adsorption isotherm studies suggest that the capacity and affinity of the DCFA in adsorbing Pb(II) ions is significantly improved compared to those of non-immobilized activated coal fly ash (ACFA).

Removal of Pb(II) from Aqueous Solutions by Periclase/Calcite Nanocomposites

Periclase/calcite nanocomposites (PCN) were synthesized via calcination and carbonation treatment of dolomite. The surface and structural properties of PCN were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption-desorption isotherm, thermogravimetry (TG), and transmission electron microscopy (TEM). The potential of PCN to remove Pb(II) from aqueous solutions was examined by batch experiments. The effects of solid-liquid ratio (0.1–1 g L−1), initial solution pH (2–7), reaction time (0–60 min), temperature (303–323 K), and initial Pb(II) concentration (100–500 mg·L−1) on lead removal were investigated. The results showed that the removal rate of Pb(II) firstly increased and then kept stable with the increasing initial pH from 2 to 7, and the optimal solid-liquid ratio was determined as 0.2 g L−1. The adsorption kinetics of Pb(II) on PCN was well fitted to pseudo-second-order model. The adsorption equilibrium isotherm of Pb(II) over PCN could be well fitted by Langmuir model, and the maximum removal capacity was 1150.06 mg g−1 at 323 K. The thermodynamic parameters indicated that the adsorption of Pb(II) was an endothermic and spontaneous process. According to the mechanism study, the gradual release of OH− and CO32− from the dissociation of periclase and calcite can react with Pb(II) to form hydrocerussite (Pb3(CO3)2(OH)2) on PCN surface.

Synthesis of clay-cellulose biocomposite for the removal of toxic metal ions from aqueous medium

Clay-cellulose biocomposite (CCB) was synthesized in the present study. Spin and pressure-induced heating was applied to aggregate exfoliated clay tubules and cellulose using polyethylene glycol as an intermediate. The synthesized CCB was modified in the presence of NaOH at high temperature to obtain negative surface charge on the adsorbent. Physico-chemical properties of CCB were evaluated using different characterization techniques including Fourier transform infrared (FT-IR) and X-ray photoelectron (XPS) spectroscopy. The efficiency of the synthesized biocomposite for Pb(II) and Cd(II) removal from water was studied via laboratory scale experiments. The adsorption kinetics of Pb(II) and Cd(II) onto CCB was well described by the pseudo-second-order kinetic model. The maximum Langmuir adsorption capacity of CCB was found to be 389.78 and 115.96 mg g−1 for Pb(II) and Cd(II), respectively. Fixed-bed column studies were conducted for the adsorption system to compare the adsorption performance of CCB in continuous mode.

Comparison of the lead and copper adsorption capacities of plant source materials and their biochars

Lead (Pb) and Cu are the most common pollutants found in industrial effluents which affect ecosystem and human health. To remove Pb and Cu from aquatic system, cost-effective and environmentally friendly adsorbents are required. Therefore, the study evaluated the adsorption of Pb and Cu by waste plant materials and their biochars. The adsorption kinetics and isotherms were applied to compare the Pb and Cu adsorption capacities using the gingko (Spiraea blumei) leaf (GL), peanut shell (PS), and Metasequoia leaf (ML), and their derived biochars (GB, PB, and MB, respectively). The GB showed a significantly higher Pb adsorption capacity than the other adsorbents. Maximum Pb adsorption by GB was 138.9 mg/g followed by GL (117.6 mg/g). The highest Cu adsorption (59.9 mg/g) was also achieved by GB followed by GL (57.8 mg/g). The carbonates and the phosphate functional groups in the GB and higher affinity of Pb to the functional groups contributed to higher Pb adsorption. The Pb adsorption kinetics on the plant source materials and their biochars followed a pseudo-second order model. The Pb and Cu adsorption capacities, with the exception of the GL, ML, and GB, are better explained by Langmuir-isotherm models. The carbonization did not always lead to better heavy metal adsorption. The Pb and Cu adsorption significantly reduced with carbonization of ML because of disappearance of oxygen containing functional groups. Therefore, appropriate method to prepare metal adsorbent should be selected depending on feedstocks and metal removal mechanisms. The GL is the most-abundant fallen leaf in the streets of the Republic of Korea; therefore, the use of the GL biochar for heavy-metal adsorption will also reduce the cost for waste disposal.