Removal Of Pb Research Articles

Anchoring 0D ZnO on 1D cobalt molybdate support for selective removal of heavy metal ion

The health of people and the environmental ecosystem are severely threatened by pollutants. Photocatalysis a desirable and effective method for pollutants removal that is associated with the adsorption phenomenon. The CoMoO4/ZnO photocatalysts were fabricated by facile template free methods. 1D-0D of CoMoO4/ZnO was fully characterized by different techniques for investigation of Pb+2, Cd+2 and Zn+2 removal in aqueous medium. Although the support photocatalyst did not show proper activity, the formation of the heterostructure led to the significant removal of Pb+2 ion. Adequate adsorption of Pb+2 ion was accompanied by photocatalytic process of visible-light-driven n-n CoMoO4/ZnO heterojunction, caused to high performance. Effect of different parameters on photoactivity, and kinetics and thermodynamic were considered. The synergistic effect induced by formation of 1D CoMoO4 containing 0D ZnO particles drastically improve the charge carrier generation, transfer and separation. Consequently, the prepared CoMoO4/ZnO composites are considered good candidates for wastewater treatment.

Polyethyleneglycol-polyhydroxylbutyrate functionalized carbon nanotubes for industrial electroplating wastewater treatment

This study focuses on the production and purification of multi-walled carbon nanotubes (P-CNTs) via a catalytic chemical vapor deposition method and subsequent functionalization with amino polyethylene glycol (NH2-PEG) and its mixture with polyhydroxybutyrate (PHB) through a multi-step purification process to produce NH2-PEG-CNTs and NH2-PEG-PHB-CNTs, respectively. The developed nanoadsorbents were used to treat electroplating wastewater via batch adsorption to sorb potentially toxic metals and emerging pollutants. The nanoadsorbents were characterized before and after treatment with wastewater after thermal regeneration analyzed using HRSEM/EDS/SAED, DLS Nanozetasizer, BET, TGA/DTG, and FTIR. The nanoadsorbents showed a homogeneous distribution of clean and smooth crystalline interwoven tubular/cylindrical shapes and sizes, with broad polydispersed/high aspect ratio, large surface area, mesopores, and functional groups. The batch adsorption study showed simultaneous multi-capturing of toxic metals from industrial electroplating wastewater with a directly proportional relationship between contact time, adsorbent dosage andtemperature, and electrostatic activities via the positive surface charge of the nanoadsorbents (pH > pHzpc). The highest removal of Fe (15.86 %), Ni (79.82 %), Pb (79.82 %), and Cu (84.97 %) were obtained using NH2-PEG-PHB-CNTs. In addition, the ANOVA results show that the adsorption process depends on other parameters such as the concentration of toxic metals in the wastewater, its hydration energy, electronegativity, ionic mobility in the electrostatic activities, pH of the nanoadsorbents, water holding capacity of the polymer-functionalized nanoadsorbents, and synergistic effects of the bi-polymer. Moreover, the nanoadsorbents have a stable morphology after thermal regeneration for reusability purposes, and treated wastewater can be safely reused in the electroplating industry or for other purposes, such as agriculture.

Exploring the synergistic effects of calcium chloride modification on stem bark eucalyptus biochar for Cr(VI) and Pb(II) ions removal: Kinetics, isotherm, thermodynamic and optimization studies

In this study, stem bark eucalyptus was subjected to pyrolysis modification to produce modified biochar. The modified biochar (MSBEB) was characterized using Fourier Transform Infrared Spectroscopy (FTIR), Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray Diffraction (XRD), and Brunauer–Emmett–Teller (BET) techniques. The impact of adsorption process variables such as temperature, adsorbent dosage, pH and contact time on the metals ion removal efficiency were investigated. The optimum conditions for maximum removal of Cr(VI) and Pb(II) ions were determined as 45.20 °C, 0.12 g/L, and 120.5 min through optimization process. The excellent performance of the modified biochar can be attributed to its porous structure, surface area, surface chemistry and crystallinity as supported by SEM, BET, FTIR and XRD analysis. However, based on the high correlation coefficient (R2), low values of chi square (χ2) and sum of square error (SSE), the Freundlich isotherm and Pseudo-second order kinetics provided the best fit, suggesting chemisorption as the dominant mechanism. Thermodynamic analysis indicated an endothermic, spontaneous, and feasible reaction.

Composites of CoFe2O4/Graphene oxide/Kaolinite for adsorption of lead ion from aqueous solution

In this work, we established composites from kaolinite (K), CoFe2O4 (CF), and graphene oxide (GO) for the adsorption of the lead ion (Pb (II)). Initially, a composite of CF-GO was synthesized by hydrothermal method using cellulose bio-template extracted from false banana. The weight ratio of GO varied from 0.20 to 0.30, i.e., (1-x) CF/(x)GO (x = 0.20, 0.25, 0.30). The sample with x = 0.30, i.e., CF-0.3GO exhibited a better adsorption capacity of about 23.6 mg g−1 from the binary composite samples at the initial Pb concentration of 50 mg L−1. Then, the contact time and adsorbent dosage of CF-0.3GO were optimized with the corresponding results of 90 min and 1.2 g L−1, respectively. A ternary composite was formulated from the sample of CF-0.3GO and Kaolinite (K) with the nominal composition of (1-y)K/(y)(CF-0.3GO), where y = 0.30, 0.45, 0.60, and 0.75. Among the ternary composites, the sample with a composition of 0.25K/0.75(CF0-0.3GO) showed the best adsorption capacity of about 4.2 mg g−1 at the initial Pb concentration of 10 mg L−1, and this sample was subsequently selected for further studies. The synthesized composites were characterized using powder X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), and Differential thermogravimetric analysis (TGA-DTA), Brunauer-Emmett-Teller (BET), respectively, to determine phase purity, the particles morphology, functional groups, thermal stability, and surface area and pore volume of the of samples. Atomic absorption spectroscopy (AAS) was used to determine the adsorption capacity of samples. The effect of pH ranging from 2 to 10 was investigated for the present composite. At pH of 4, the adsorption capacity and removal efficiency changed significantly, with the corresponding results of 6.62 mg g−1 and 99 %, respectively, and becomes constant. Adsorption isotherms and kinetics were investigated for a composite with a composition of 0.25K/0.75 (CF-0.3GO). The Freundlich isotherm model best fits the adsorption isotherm, with a correlation coefficient of 0.93, and the kinetic behavior followed Pseudo-second-order adsorption kinetics. Finally, the synthesized composite was stable for three-round tests toward the Pb(II) removal. Therefore, the results of this study indicate that the composites of CoFe2O4/Graphene oxide/Kaolinite could be a potential candidate for the removal of Pb (II) ions.

Synergetic effect between zeolite 5 A and maghemite nanoparticles for fast lead uptake from the Peruvian river Cumbaza: Study of surface adsorption mechanism using X-ray photoelectron spectroscopy

A novel magnetic composite of zeolite 5A and maghemite nanoparticles has been synthesized at 300 K and its lead removal properties from the Peruvian river Cumbaza were systematically studied. Its kinetic adsorption properties were investigated, and a fast equilibrium time of 15 min was achieved with 97% of removal and an adsorbent dose of 0.5 g L−1. A 100% Pb removal efficiency was reached by increasing the adsorbent dose to 1.0 g L−1, which concomitantly also removed iron species from the river aliquots. During the kinetic tests, the optimum pH was from 6.5 to 7.5, showing that no chemical reactant alteration was required to achieve a remarkable efficiency for the magnetic composite. The kinetic adsorption behavior matched well with the pseudo-first and second-order models. Post-adsorption analysis confirmed the presence of lead in all the samples. The combined results also demonstrated a synergetic response between lead and both adsorbent phases. The adsorption mechanism was governed by three steps, including inner surface complexation between lead species and maghemite, followed by lead cationic exchange between calcium-bulk and sodium-surface from zeolite 5A. Hence, this novel magnetic adsorbent exhibits a high lead removal efficiency, and it is easy-to-handle separation properties in real effluents.

Insight into adsorption of Pb(II) with wild resistant bacteria TJ6 immobilized on biochar composite: Roles of bacterial cell and biochar

Microbial immobilization is a new strategy for bio-remediation of heavy metals. However, information regarding immobilization of wild resistant bacteria onto biochar for heavy metal separation is limited. This study proposed the use of wild-resistant bacteria TJ6 in combination with biochar produced from agricultural waste (BC-TJ6) for Pb removal and investigated the associated mechanisms using Fourier transform infrared spectroscopy (FT-IR), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Compared with the theoretical adsorption capacity according to the linear combination calculating by the mass ratio and adsorption capacity of individual component in the composite material, the actual adsorption capacity of BC-TJ6 for Pb(II) was increased by 73.54%. Specifically, the bridge between the bacteria and biochar of Pb(II) may explain the higher observed adsorption capacity of BC-TJ6 compared to theoretical values. EDS analysis based on electron micrograph showed that Pb(II) adsorbed onto TJ6 strain was 0.48%, while that onto biochar component was 0.14%. It indicated that the resistant bacteria contributed more to the adsorption of Pb(II) in BC-TJ6 composites. The FT-IR analysis suggested that the amide, carboxyl, and hydroxyl groups on the surface of the composite were involved in the adsorption of Pb(II). Further, XPS analysis demonstrated that Pb-O (42.12%) and Pb-OOC (27.6%) were the main Pb-molecular structures bound to the surface of the composite. This study is significant for improving the understanding of biochar-wild resistant bacterial combinations for heavy metal adsorption, and can provide guidance for the use of biochar-microbial remediation of heavy metal pollution.

Removal and emission characteristics of hazardous trace elements in total and graded particulate matters: A case study of a typical ultra-low emission coal-fired power plant

Particulate matters (PMs) and hazardous trace elements (HTEs) emitted from coal-fired power plants (CFPPs) have raised serious environmental and human issues. Herein, total PMs and graded PMs including PM<1, PM1–2.5 and PM2.5–10 at the inlet/outlet of air pollution control devices (APCDs) were collected from a representative ultra-low emission (ULE) CFPP in China. The removal efficiencies of total PMs by selective catalytic reduction (SCR), electrostatic precipitator (ESP), wet flue gas desulfurization (WFGD) and wet electrostatic precipitator (WESP) were 0.40 %, 99.9 %, 38.1 % and 85.3 %, respectively. PM2.5–10 was robustly removed by WFGD, while PM<1 and PM1–2.5 were readily removed by WESP. The removal efficiencies of As, Cd, Cr and Pb in total PMs by APCDs followed an order: ESP > WESP > WFGD > SCR. SCR significantly decreased Se concentration by 42.8 %, contrasting to the removal of As, Cd, Cr and Pb (10.8–20.8 %). As, Cd, Cr, Pb and Se concentrations in graded PMs at the outlets of ESP, WFGD and WESP decreased with particle size increasing. All As, Cd, Cr, and Pb contents in PM<1, PM1–2.5 and PM2.5–10 at WFGD outlet increased, surpassing their analogues at ESP and WESP outlets. However, the concentration of Se declined in PM<1 at WFGD outlet. The atmospheric emission factors (EFs) of As, Cd, Cr, Pb and Se in the studied ULE CFPP were respectively 7.32, 1.27, 6.05, 122.5 and 6.42 mg/t, in line with Monte Carlo simulations. This study would not only provide a basis for emission control of PMs and HTEs in CFPPs, but also promote the improvement of respective environmental policy.

Green and low-temperature synthesis of the magnetic modified biochar under the air atmosphere for the adsorptive removal of heavy metal ions from wastewater: CCD-RSM experimental design with isotherm, kinetic, and thermodynamic studies.

The accumulation of heavy metal ions in living cells leads to biological damage, which makes the necessity of using new methods to effectively remove heavy metal ions from the environment more vital. In this work, a magnetic modified biochar was prepared under regular air atmosphere and low temperature (220 ºC) and used as a low-cost and green adsorbent for efficient adsorptive removal of cobalt (Co(II)) and Lead (Pb(II)) ions from contaminated waters. The adsorption process was modeled and optimized using CCD-RSM to maximize the removal efficiency of heavy metal ions, as well as was monitored in detail by isotherm, kinetic, and thermodynamic studies. The results show that the Langmuir maximum adsorption capacity of the adsorbent reached 237.92mgg-1 (single) and 121.23mgg-1 (binary) for Co(II) and 207.21mgg-1 (single) and 106.56mgg-1 (binary) for Pb(II) under the short time of 25min and solution pH of 6.0. The kinetic studies revealed that the pseudo-first-order model was the best-fitted model to experimental data and indicated that the adsorption process was mostly through chemisorption. Also, thermodynamic studies showed that that adsorptive removal of Co(II)and Pb(II)ions followed an endothermic and spontaneous process. The reusability studies demonstrated that the adsorbent could be successfully regenerated with 5mL of 0.1mol L-1 HNO3 solution, and the adsorption efficiency was retaining about 90% after four adsorption-desorption cycles. Also, the results from using real water samples, including drinking water, groundwater, and river water, implied that the synthesized magnetic modified biochar was highly efficient for practical treatment processes. Overall, the results indicated that the proposed magnetic biochar can be considered as a cost-effective and efficient adsorbent for adsorptive removal of heavy metal ions from contaminated waters.

Pb2+ ion removal from contaminated aqueous solution by adsorption onto Graphene Oxide Sand Composite (GOSC) for efficient water purification

Lead is a heavy metal which affects all the systems of human body. An easy method for removal of lead contamination was developed by using graphene oxide coated sand particle (GOSC). In this study, GOSC was prepared using sand particle and sucrose solution under controlled heating program which shows efficient adsorption behavior compared to other adsorbents. GOSC offered very fast removal of Pb+2 with small amount of GOSC (0.09g) in 100 ppm adsorbate solution. Characterization of GOSC was done by using several advanced techniques like FTIR, XRD, SEM, EDX, TEM, DSC, and Zeta Potential measurements before and after adsorption of lead ion (Pb2+). Adsorption shows superiority over other methods because it involves effective and high removal efficiency adsorption (above 90%). Various parameters like the effect of time, pH, adsorbent, dose effect, concentration and temperature were studied. Various adsorption and kinetic models were also investigated using adsorption data and results showed that removal of lead (Pb2+) ion follows Langmuir isotherm (R2 = 99%), second order kinetics (R2 = 98%) and higher intraparticle diffusion (R2= 98%). The high percentage removal of metal ions with little quantity of GOSC confirmed that GOSC is an excellent, effective and economic adsorbent.

Removal of Pb(II) ions by cellulose modified-LaFeO3 sorbents from different biomasses

LaFeO3 perovskite is prepared by the cellulose-modified microwave-assisted citrate method using two different biomasses as a cellulose source; rice straw (RS) and banana peel (BP). The prepared samples are assigned as LaFeO3/cellulose-RS and as LaFeO3/cellulose-BP, respectively. Raman Spectra prove the presence of perovskite and cellulose phases, as well as biochar resulted from the thermal treatment of the cellulose. LaFeO3/cellulose-RS has a cauliflower morphology while, two phases are observed for LaFeO3/cellulose-BP, mesoporous cellulose phase and octahedral LaFeO3 nanoparticles as shown by scanning electron microscope (SEM) images. LaFeO3/cellulose-BP has higher porosity and larger BET surface area than LaFeO3/cellulose-RS. Both samples are applied for the removal of Pb(II) ions from aqueous solution by adsorption. The adsorption follows Langmuir isotherm, with maximum adsorption capacities of 524 and 730 mg/g for LaFeO3/cellulose-RS and LaFeO3/cellulose-BP, respectively. Cellulose precursors from different biomasses affect structural and morphological properties of LaFeO3/cellulose samples as well as the sorption performance for Pb(II) ions. BP is more recommended than RS, as a biomass, in the present study.

Efficient lead removal from aqueous solutions using a new sulfonated covalent organic framework: Synthesis, characterization, and adsorption performance

The aim of removing Pb(II) from water is to minimize the potential harm posed by toxic metals to both human health and the environment. To achieve this, a covalent organic framework adsorbent called TFPOTDB-SO3H was developed using a condensation process involving 2,5-diaminobenzenesulfonic acid and 2,4,6-tris-(4-formylphenoxy)-1,3,5-triazine. This adsorbent exhibited excellent properties such as high repeatability, selectivity, and easy solid–liquid separation. Under conditions of pH = 6.0 and 298 K, the TFPOTDB-SO3H demonstrated impressive capability of adsorbing Pb(II). In a brief span of 10 min, it attained a special elimination rate of 99.40 % and shown its capacity to adsorb up to 500.00 mg/g. The adsorbent presented effective removal of Pb(II) from a solution that had a mixture of various ions, showcasing its proficiency in capturing the contaminant, with a partition coefficient (Kd) of 3.99 × 106 mL/g and an adsorption efficiency of 99.75 % among six coexisting ions. The pseudo-second-order kinetic model was observed to govern the adsorption process kinetics, while the Langmuir isotherm model confirmed monolayer chemisorption as the mechanism for Pb(II) removal. Thermodynamic analysis indicated that the uptake process was both exothermic and spontaneous. Furthermore, the adsorbent maintained a significant adsorption efficiency of 89.63 % for Pb(II) even after undergoing four consecutive adsorption–desorption cycles. These findings collectively suggest that TFPOTDB-SO3H has excellent potential for effectively adsorbing and removing Pb(II) heavy metal ions from wastewater.

One-step synthesis of hollow and yolk-shell mesoporous organosilica nanospheres for efficient separation of lead ions

In this work, we demonstrate that monodispersed hollow mesoporous organosilica nanospheres (MONs) and yolk-shell MONs possessing controlled core cavity and mesoporous shell is successfully synthesized through a one-pot approach, which involves co-condensation of 3-aminopropyltriethoxysilane and 1,2-bis(triethoxysilyl)ethane templated by lauryl sulfonate betaine and sodium dodecyl benzenesulfonate. The MONs present an open mesoporosity, hollow cavity with a morphology tailored by the various core templates, and high surface area (328 m2/g). In addition, the composition of the hollow MONs could be further tuned through the same approach. The as-prepared hollow MONs as adsorbent deliver an enormous adsorption capacity (414 mg/g) towards the removal of Pb2+ from water solution. Importantly, the prepared hollow MONs present acceptable recycling and stability, since the performance in Pb2+ removal from water remains above 80 % even after 5 consecutive cycles. The adsorption of Pb2+ on hollow MONs follows the pseudo-second-order mechanics and Langmuir isotherm models. The results confirm hollow MONs exhibit considerable promise for the remarkably efficient separation of Pb2+ ions in water solution.

Pb(II) removal using calcium silicates synthesised from industrial wastes: process optimisation and kinetic modelling

ABSTRACT This study investigates the potential of calcium silicates (CS) synthesised from granite and marble waste as an adsorbent for sustainable waste management. A simple and chemical-free synthesis method was adopted in the preparation of CS. X-ray diffraction, scanning electron microscopy, zeta potential and particle size distribution techniques were used for the characterisation of CS. As Pb(II) and its derivatives from various industrial effluents exercise significant negative impact on the environment and human health, an attempt was made to remove Pb(II) by adsorption process. Batch experiments were conducted to evaluate the feasibility of removal of pb(II) using CS. The zeta potential value of −83.7 mV and the mean particle size of 916 nm for the prepared CS can enhance adsorption process. The analysis of various adsorption kinetic models reveals that pseudo second order kinetic model exhibited a favourable level of agreement with kinetic data (R2 = 0.999). Response surface methodology utilising central composite design was employed to evaluate various process parameters, such as initial Pb(II) concentration, pH, adsorbent dosage and sonication time on adsorption process. Results from 30 experimental runs performed in accordance with model recommendations concluded that the effect of selected parameters with an R2 value of 0.937 was adequate for the current study. In order to assess the goodness of fit and statistical significance of the model’s performance, ANOVA and Lack of Fit (LOF) tests were conducted. The findings show that Pb(II) can be easily removed from the aqueous solutions using CS as an adsorbent under optimal experimental conditions of 100 mg/l Pb(II) initial concentration, 2 g/l adsorbent dosage, pH of 8 and a sonication time of 45 min.

Adsorptive abatement of Pb2+ and crystal violet using chitosan-modified coal nanocomposites: A down flow column study

Every moment huge amounts of industrial wastewater are contaminating our surface/groundwater sources by discharging into the environment directly. This crude wastewater is the most problematic subject because it is the matrix of hazardous toxicants, which can drastically damage public health-safety. So, it is urgent to purify before discharging/reusing. This study focused on the recent improvement and latent implication of Activated Chitosan-Modified Coal(ACMC) bionanocomposite filter. Here, we briefly described how ACMC was produced and its potential application in the removal of Pb2+ and Crystal Violet (CV) effectively from wastewater. However, the influence of different parameters like initial concentration (20–40 ppm), volumetric flow rate (4–6 mL/min) and bed height (0.4–1.0 cm) were investigated appropriately meanwhile the adsorbent amount was (1.0–2.0 g). The adsorption efficiency and removal percent were strongly correlated with inlet concentration, flow rate, and bed height. The highest removal capacity and percentage were found nearly (243.08 and 238.51)mg/g additionally (78.48 and 82.50)% for Pb2+ and CV. Finally, three well-known column adsorption models namely Thomas, Yoon-Nelson and Adam-Bohart model were applied for the fitting of experimental data which exhibited a decent agreement with all three models that are also suitable for the description of breakthrough curve (BTC) and supports the Langmuir isotherm by following second-order reversible reaction kinetics. Thus this new class of ACMC nanoadsorbents could be beneficially used for the real-time bulk scale industrial wastewater treatment as a suitable replacement of hazardous fossil-based synthetic ones for sustainable environmental protection.

Single-Walled Carbon Nanotubes-Copper Metal-Organic Framework Composite for the Sensitive Detection of Lead Ions in Aqueous Solutions

Lead (Pb) is a hazardous heavy metal extensively employed in various industrial applications, often resulting in the presence of its ionic form (Pb2+) in water resources. Due to its profound toxicity to humans and the environment, the reliable detection and removal of Pb2+ ions from water are imperative. In this study, we have successfully synthesized a composite material consisting of single-walled carbon nanotubes (SWNTs) incorporated into a copper-based metal-organic framework (MOF) known as copper benzene tricarboxylate (CuBTC). This composite denoted as SWNTs@CuBTC, was synthesized via a solvothermal route. Comprehensive characterizations, including Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area analysis, and thermogravimetric analysis (TGA), were conducted to elucidate its structural and morphological properties. Electrochemical assessments, specifically cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were carried out to evaluate the electrochemical behaviour of the SWNTs@CuBTC composite. Subsequently, a sensor utilizing SWNTs@CuBTC was constructed by modifying glassy carbon electrodes (GCE) through a drop-casting technique. The sensing capabilities of this sensor were systematically examined using the differential pulse voltammetry (DPV) technique. Our sensor exhibited exceptional sensitivity towards Pb2+ ions, with a remarkable limit of detection (LOD) of 25 nM and a sensitivity of 0.1499 μA/nM, showcasing its potential for highly sensitive detection of Pb2+ ions in aqueous solutions.

Functionalized Ilmenite Ores for Improved Photocatalytic Removal of Pb(II) Ions in an Aqueous Solution by Visible Light Irradiation

Functionalized Ilmenite Ores for Improved Photocatalytic Removal of Pb(II) Ions in an Aqueous Solution by Visible Light Irradiation

Photocatalytic degradation of Rhodamine B and Removal of Pb2+ over an all-day-active carbon nitride

Solar energy-driven semiconductor photocatalysis has broad application prospect in the environmental governance field. However, vital problems that limits its application is that the discontinuity of nature sunlight. The ability of keeping catalytic activity in the dark could tackle these problems. Herein, a simple all-day-active photocatalytic system based on carbon nitride with electron storage property was carried out, which forms highly reductive radicals with lifetime exceeding diurnal cycle under sunlight irradiation. This carbon nitride system is capable to give off its trapped electrons to perform efficient Rhodamine B (RhB) degradation and Pb2+ reduction in the dark. The all-day-active photocatalyst system can still maintain catalytic activity even when it is cloudy or closer to night. Dramatically, this carbon nitride could hold the storage electrons for days under vacuum. The system above for storing sunlight as long-lived radicals will demonstrate a new approach for environmental protection, such as the remove of low-level pollutants in cloudy days and even the underground conditions.

Bentonite-Chitosan composites or beads for lead (Pb) adsorption: Design, preparation, and characterisation

This study investigated the efficiency of mixing bentonite with chitosan via different preparation methods, subsequently the different forms were investigated for their ability to remove Pb(II) ions from solution. The different forms of bentonite-chitosan (Bt-Ch), composites and beads, were prepared via solution blending and precipitation methods, respectively and in the weight ratios of 90%/10%, 70%/30% and 50%/50%. The beads were further subdivided, identified as “beads-A" and “beads-B", and were formed by adding either bentonite suspension or bentonite powder, respectively, to solubilised chitosan solution. The composites and beads were characterised by X-ray fluorescence (XRF), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and pH at zero point charge. XRF analysis showed a cation exchange mechanism occurred when chitosan was initially mixed with the bentonite. TGA results confirmed that beads contained more chitosan compared to their corresponding weight ratio equivalent composites. XRD results showed that chitosan was intercalated within the interlayer space of the bentonite for Bt-Ch composites and Bt-Ch beads-A and that the interlayer spacings increased with increasing chitosan loading. Though similar amounts of chitosan were present in both Bt-Ch beads-A and beads-B, there were fewer reflection shifts for beads B suggesting less intercalation of chitosan when the bentonite was added as a powder. FTIR spectra from the Bt-Ch composites and beads confirmed the presence of both chitosan and bentonite, and the NH bands of chitosan shifted to lower frequencies demonstrating their involvement in the bonding mechanism of chitosan with bentonite. The experimental adsorption data correlated well with both non-linear Langmuir and Freundlich isotherm models, and in which both chemisorption and physisorption processes played crucial roles. The Langmuir-maximum adsorption capacities of Pb(II) ions for all the analysed Bt-Ch composites and beads was found to range from 42.48 ± 4.22 to 94.60 ± 5.63 mg/g. The amount of chitosan present in the adsorbent and its distribution within or outside the interlayer space of the bentonite was shown to have pronounced effects on the Pb(II) uptake by the different Bt-Ch composites/beads, and although the chitosan greatly enhanced the adsorption of Pb(II) a cation exchange mechanism with the clay was still a dominant process. The adsorption of Pb(II) was also significantly affected by the presence of other multi-competing ions. Moreover, the developed Bt-Ch composites/beads exhibited good potential for re-use after five cycles of regeneration, thus, indicating their potential as cost-effective adsorbents for removal of Pb(II) ions from both drinking and wastewater.

Waste materials composited into an adsorbent for landfill leachate treatment.

The ability of a composite adsorbent composed primarily of various waste materials to adsorb heavy metals, NH3-N, and chemical oxygen demand (COD) from landfill leachate was investigated through batch sorption experiments. The study determined the optimal contact time and adsorbent dosage for the removal of Pb, Zn, Cu, Fe, NH3-N, and COD to be 15, 90, 30, 180, 30, and 30 min, respectively. The corresponding optimum adsorbent dosages were determined to be 5, 30, 5, 15, 5, and 30 g, respectively. The composite adsorbent exhibited high removal efficiencies, achieving the following maximum values: 96.4% for Pb, 92.7% for Zn, 60.3% for Cu, 87.1% for Fe, 75.0% for NH3-N, and 67.5% for COD. Pb and Fe showed the best fit with a Langmuir isotherm model, with corresponding adsorption capacities of 0.0165 and 1.14 mg/g, respectively. For Zn, Cu, NH3-N, and COD, the equilibrium data demonstrated the best fit with an Elovich isotherm model, with adsorption capacities of 0.004, 0.005, 0.016, and 4.29 mg/g, respectively. The kinetic data followed the pseudo-second-order kinetic model. It presented a potential solution for the disposal of the waste from which it was derived.

Radiation synthesis of IDAA functionalized loofah sponge for enhanced removal of Pb(II) and Cd(II): Behavior and mechanism investigation

Biomass has been deemed as the most promising adsorbent for metal ions capture due to its environment-friendly and easy functionalization. Within this work, we combined a green and powerful radiation grafting-ring opening method that yields high-density functional groups containing a large number of carboxylic acid groups with loofah sponge (LFs) to achieve a novel functionalized loofah sponge (LFs-PGMA-IDAA) as a Pb(II)/Cd(II) adsorbent. The as-prepared biosorbent could efficiently capture Pb(II) and Cd(II) ions in wastewater. Moreover, the biosorbent could quickly reach adsorption equilibrium within 80 min, and the kinetics data fit well with the pseudo-second-order model. The thermodynamic parameters reveal that the adsorbing process is both spontaneous and endothermic. Moreover, the biosorbent possessed excellent removal capacities towards Pb(II)/Cd(II), and the maximum uptake capacity of Pb(II) and Cd(II) were 237.85 and 169.81 mg/g at 318.15 K, pH = 5, respectively. Furthermore, the excellent Pb(II)/Cd(II) binding of LFs-PGMA-IDAA was primarily due to complexation, ion exchange, electrostatic interaction and pore adsorption. This research presents that iminodiacetic acid modified LFs could be utilized as a high-performance biosorbent for capturing heavy metal ions. It might serve as an eco-friendly adsorbent in practical wastewater treatment fields.