Adsorption Of Pb Research Articles

Characteristics and Influence Factors of Pb(II) Adsorption by Graphene Oxide-Montmorillonite Composite.

This study presents the fabrication of a novel porous composite of graphene oxide-montmorillonite (GO-MMT) through the modification of montmorillonite using the freeze-drying method for the purpose of Pb removal. The characterization of the GO-MMT composite was conducted using scanning electron microscopy, Fourier transform infrared spectrometry, and X-ray diffraction. The results from batch adsorption experiments revealed that the GO-MMT composite exhibited a superior capacity for Pb removal compared to MMT. Furthermore, a single factor experiment confirmed that the dosage of the GO-MMT composite or GO, pH, temperature, and reaction time all significantly influenced the adsorption of Pb by the GO-MMT composite, MMT, or GO. This superiority can be attributed to the presence of oxygen-containing functional groups, the site-blocking effect, and the ion exchange mechanism exhibited by the GO-MMT composite.

Adsorption of Lead Metal Ions in Solution with Diphenylcarbazide Modified Silica Gel

Silica gel is one of the adsorbents whose surface is easy to modify and can be used in the adsorption of heavy metal ions. This study aims to modify silica gel with diphenylcarbazide and use it as an adsorbent for Pb2+ metal ions. The modification was carried out by impregnation of silica gel with diphenylcarbazide solution at a ratio of 1 gram of silica gel and 1 mmol of diphenylcarbazide. Characterization with IR spectrophotometry to analyze the functional groups formed on the modified silica gel and the initial silica gel, acid-base titration to determine the surface acidity, and methylene blue method to determine the surface area of ??the two silica gels. . The results showed that the modification of silica gel with diphenylcarbazide had been successfully made, indicated by the appearance of the absorption band of the N-H group at ±3375.43 cm-1, aromatic C-H at ±3032.10 cm-1 and C=O at 1658.78 cm-1. , which are groups derived from diphenylcarbazide, and the absorption band of the Si-O-Si group at ±1203.58 cm-1, the Si-OH group at 912.33 cm-1, and the –OH group in the wave number range of 3600 -3400 cm-1, which is the main group of silica gel. Diphenylcarbazide-modified silica gel experienced an increase in surface acidity from 0.5205 to 0.8133 mmol/g, and a slight increase in surface area from 46.1057 to 46.1613 m2/g. Adsorption of diphenylcarbazide modified silica gel on Pb2+ metal ions in optimum solution occurred at pH 3, contact time 10 minutes, and initial concentration of Pb2+ 300 mg/L, with an adsorption capacity of 52.6264 mg/g. The adsorption that occurs follows the Langmuir isotherm.

Removal of Pb(II), Cu(II), and Ag(I) from aqueous solutions using biochar derived by P-enriched water hyacinth

ABSTRACT A new synthesis was developed to prepare engineered biochar derived from phosphorous-rich water hyacinth. The statistical analysis indicated a significant correlation between P content and the removal rates of Pb (II), Cu (II), and Ag (I), revealing the pivotal role of enrich P in the biochar for heavy metals (HM) removal. SEM-EDX, XRD and FTIR analyses validated the presence of P functional groups on the surface of P-biochar. Batch experiments showed that the strong acidic initial solution negatively affected the adsorption of HM ions, and a similar negative impact was observed during Cu (II) adsorption under the high ionic strength conditions. Competitive adsorption experiment confirmed P-biochar’s resilience against competing metal ions during the adsorption of HM ions. Pb (II) and Ag (I) adsorption were primarily governed by precipitation/reduction, along with complexation reactions involving P functional groups. Cu (II) adsorption was dominated by complexation between Cu (II) and P functional groups.

Removal of lead from aqueous solution by magnetic modified dendrimer (Fe3O4@SiO2/(3-aminopropyl) triethoxysilane@dendrimer/benzaldehyde)

Synthesis of a magnetite nanoadsorbent was reported in the study. In this regard, poly(amidoamine) (PAMAM) dendrimer (with generation 10)-functionalized Fe3O4@SiO2/APTES ((3-aminopropyl) triethoxysilane) was prepared, modified by benzaldehyde (BZ), and characterized by fourier-transfer-infrared (FTIR), vibrating-sample-magnetometer (VSM), field-emission-scanning-electron-microscope (FE-SEM), X-Ray-diffraction (XRD), thermal-gravimetric-analysis (TGA), and elemental analysis. The nanoadsorbent with VSM value of 35.3 emu/g was used to investigate adsorption of Pb(II) ions from aqueous solutions and this process relied on the solution pH, lead concentration, nanoadsorbent dose, contact time, and temperature. The results revealed the maximum adsorption efficiency of 97.56% in pH = 6, initial lead concentration = 160 mg L−1, adsorbent dose of 15 mg, contact time = 60 min, and temperature = 45 °C. The adsorption isotherm and kinetic models of Pb(II) removal followed the Freundlich model and pseudo-second-order, respectively. The adsorption was endothermic and spontaneous, which was exhibited by the thermodynamic parameters. This research suggests that the nanoadsorbent can be considered for the other metal ions removal from wastewater treatment.

Synthesis, characterization and application of steel waste-based iron oxide nanoparticles for removal of heavy metals from industrial wastewaters

Water treatment and reuse can avail more clean and safe water for human use. In this study, iron oxide waste powder generated from the steel pickling process was used to develop iron oxide nanoparticles (IONPs) using solution gelation synthesis process. The powder and developed IONPs were characterized by X-ray fluorescence and diffraction (XRF, XRD), scanning electron microscopy, Fourier-transform infrared spectroscopy, and Brunauer-Emmett-Teller (BET) analyses. Adsorption experiments were carried out on synthetic water with lead and chromium metal ions. The adsorption data were analysed with Langmuir and Freundlich models. Adsorption kinetics were also analysed with Pseudo-First-Order and Pseudo-Second-Order models using non-linear regression. The synthesized IONPs were porous with active surface functional groups of hydroxyl bonds, with BET specific surface area of 325.02 m2/g. XRD results confirmed the cubic spinel structure of IONPs with particle sizes of 20–30 nm. The nanoparticles at a dosage of 0.35 g in 10 mL for 50 min effectively removed Pb(II) and Cr(VI) metal ions up to 99.9% from both synthetic water and industrial wastewater. The adsorption capacity (qmax) of IONPs was found to be 417 and 326.80 for Pb(II) and Cr(VI) respectively. Freundlich isotherm model data fitted best for the removal of both metal ions. The regression values for kinetic models confirmed that pseudo-second-order best fit the adsorption of both Pb(II) and Cr(VI) confirming chemisorption processes. This study contributes to elucidating alternative application of pickling waste from the steel rolling mills for the benefit of heavy metal removal in industrial wastewater.

Sodium alginate/ diatom -based blotting hydrogel material for Pb(II) removal: Effect of crosslinker optimization on its composition, selectivity, and desorption rate

In this study, we report a novel adsorption material (SAD-IIP), which is used for the directional adsorption of Pb (II), the polymerization time, the amount of crosslinking agent and the crosslinking time were optimized by response surface design, and the effect of the amount of crosslinking agent on the adsorption of lead on SAD-IIP was analyzed. The numerical control of cross-linking agent directly determines the number of effective imprinting sites, which affects the orientation selectivity of target ions and the desorption rate of the adsorbent. The results showed that the best adsorption performance was obtained when the polymerization temperature was 59.14 ° C, the amount of glutaraldehyde was 1.20 ml, and the crosslinking time was 92.55 min. The adsorption amount and imprinting factor were 244.09 mg/G and 9.90, respectively, the self-polymerization and self-crosslinking of the adsorbent in the imprinting process are effectively avoided. The adsorption mechanism of SAD-IIP is ion exchange with Ca2+ and chelation coordination of sulfhydryl, hydroxy, carboxyl with lead ion. After 10 cycles, the removal rate of Pb (II) and desorption rate of SAD-IIP were 92.75% and 70.43%, respectively. These results indicate that the rational control of the introduction conditions of cross-linking agent is of theoretical and practical value for the preparation of new hydrogel imprinting materials for selective adsorption of target ions and efficient recovery of Pb (II).

Highly nanocrystalline Mg doped ZnFe2O4 powders for rapid and simultaneous adsorption of Lead, Copper, and Cadmium heavy metals ions in synthetic / sea waters

This research aims to investigate the effect of Mg doping on individual and simultaneous adsorption of Pb+2, Cu+2, and Cd+2 heavy metals in aqueous solution and in seawater samples, by Zinc ferrite nanoparticles. The Mg-doped Zinc ferrite nanoparticles are synthesized successfully by the sol-gel route and varying Mg concentrations. TEM, XRD, FTIR, Raman, and XPS characterizations confirm the cubic spinel structure of Zinc ferrite with a semi-spherical shaped nanosized particles (10-15nm) irrespective of Mg doping content. The BET surface area manifests a significant increase within Mg doping (39.3 m2/g) compared with the pure zinc ferrite (28.4 m2/g). Accordingly, Mg-doped Zinc ferrite powders demonstrate considerable adsorption capacities for Pb+2 (143.5mg/g), Cu+2 (117mg/g), and Cd+2 (77mg/g) within 2h under optimized experimental conditions. The prepared nanopowders exhibit high selectivity towards Pb+2 in simultaneous adsorption in aqueous solutions (85mg/g) and real seawater samples. Nonetheless, the selectivity of Pb+2 ions drops dramatically to 25mg/g within real seawater samples due to the strong ionic strength of high-salinity seawater. This study provides insights into the importance of doped spinel ferrite nanoparticles in highly efficient, rapid, and simultaneous adsorption of heavy metals. Besides, it reveals the challenge of performing the adsorption process in real seawater.

Biotransformation of Pb and As from sewage sludge and food waste by black soldier fly larvae: Migration mechanism of bacterial community and metalloregulatory protein scales

The accumulation and transformation of lead (Pb) and arsenic (As) during the digestion of sewage sludge (SS) by black soldier fly larvae (BSFL) remain unclear. In this study, we used 16 s rRNA and metagenomic sequencing techniques to investigate the correlation between the microbial community, metalloregulatory proteins (MRPs), and Pb and As migration and transformation. During the 15-day test period, BSFL were able to absorb 34–48 % of Pb and 32–45 % of As into their body. Changes in bacterial community abundance, upregulation of MRPs, and redundancy analysis (RDA) results confirmed that ZntA, EfeO, CadC, ArsR, ArsB, ArsD, and ArsA play major roles in the adsorption and stabilization of Pb and As, which is mainly due to the high contribution rates of Lactobacillus (48–59 %) and Enterococcus (21–23 %). Owing to the redox reaction, the regulation of the MRPs, and the change in pH, the Pb and As in the BSFL residue were mainly the residual fraction (F4). The RDA results showed that Lactobacillus and L.koreensis could significantly (P < 0.01) reduce the reducible fraction (F2) and F4 of Pb, whereas Firmicutes and L.fermentum can significantly (P < 0.05) promote the transformation of As to F4, thus realizing the passivation Pb and As. This study contributes to the understanding of Pb and As in SS adsorbed by BSFL and provides important insights into the factors that arise during the BSFL-mediated migration of Pb and As.

Harnessing Agricultural Byproducts: Rice Husk-Derived Adsorbents for Heavy Metal Remediation in Water

This study investigates the removal of heavy metals Pb(II), Cr(VI) and Ni(II) from water using rice husk-derived materials. The adsorption effectiveness of rice husk charcoal and its refined forms, including carbon-silica, silica, and carbon, was assessed after activation with HCl. The results revealed that activation improves the adsorption of Pb(II) and Cr(VI), particularly at lower concentrations, due to increased surface area and active sites. However, the influence of activation on Ni(II) is less significant. This research highlights the potential of using eco-friendly, cost-effective rice husk-derived adsorbents for water purification, offering a sustainable solution to heavy metal contamination and agricultural waste management.

Alginate-encapsulated biochar as an effective soil ameliorant for reducing Pb phytoavailability to lettuce (Lactuca sativa L.).

The alginate-biochar formulation for metal removal from aquatic environments has been widely tried but its use for lowering phytoavailability of metals in the soil-crop continuum is limited. Biochar has been increasingly used as a soil amendment due to its potential for soil carbon sequestration and sorption capacity. Handling of powdery biochar as a soil top-dressing material is, however, cumbersome and vulnerable to loss by water and wind. In this experiment, biochar powder, which was pyrolyzed from oak trees, was encapsulated into beads with alginate, which is a naturally occurring polysaccharide found in brown algae. Both batch and pot experiments were conducted to examine the effects of the alginate-encapsulated biochar beads (BB), as compared to its original biochar powdery form (BP), on the Pb adsorption capacity and phytoavailability of soil Pb to lettuce (Lactuca sativa L.). The BB treatment improved reactivity about six times due to a higher surface area (287 m2g-1) and five times due to a higher cation exchange capacity (50 cmolc kg-1) as compared to the BP treatment. The maximum sorption capacity of Pb was increased to 152 from 81mgg-1 because of surface chemosorption. Adsorption of Pb onto BB followed multiple first-order kinetics and comprised fast and slow steps. More than 60% of the Pb was adsorbed in the fast step, i.e., within 3h. Also, the BB treatment, up to the 5% level (w/w), increased soil pH from 5.4 to 6.5 and lowered the phytoavailable fraction of Pb in soil from 5.7 to 0.3mgkg-1. The Pb concentrations in lettuce cultivated at 5% for the BP and BB treatments were similar but 63 and 66% lower, respectively, than those of the control soil. The results showed that the encapsulation of biochar with alginate enhanced adsorption by the biochar.

Interferometric fiber sensor for lead ion detection based on MoS2 hydrogel coating

A fiber optic sensor coated with molybdenum disulfide (MoS2) hydrogel is firstly proposed for the detection of lead ion (Pb2+). By splicing a dispersion-compensating fiber (DCF) between two single-mode fibers (SMFs) to form a Mach-Zehnder interferometer (MZI), and using a fusion splicer to discharge the SMF input and output to form a thick waist cone to act as a coupler. A portion of the DCF cladding is etched to excite higher order cladding patterns and a hydrogel sensing film is applied to the etched area, the sulfur atoms in the sensing film form coordination bonds with Pb2+ and change the refractive index (RI) of the sensing film, which further leads to the wavelength shift of the resonant dip. The production process is simple and environmentally friendly. By monitoring the wavelength shift, the adsorption of Pb2+ is continuously monitored, and the sensor has a sensitivity of 3.25 × 108 nm/(mol/L) in the range of 0–1.1 × 10−8 mol/L Pb2+ in aqueous solution. The theoretical detection limit of Pb2+ concentration is 6.15 × 10−11 mol/L at a spectrometer resolution of 0.02 nm. In addition, the experimental results show that the sensor has good repeatability, selectivity and stability, and has a broad application prospect in the field of Pb2+ detection in industry and agriculture.

Treatment of Waters Having Different Ionic Composition and pH with Natural Zeolites from Bulgaria

The migration of 32 elements from natural zeolitized tuffs from the Beli Plast and Golobradovo deposits (Bulgaria) was determined in ultrapure, tap, mineral, and coal mine waters in order to evaluate their desorption and adsorption properties. The tuffs are Ca-K-Na and contain clinoptilolite (90 and 78wt.%, respectively), plagioclase, sanidine, opal-CT, mica, quartz, montmorillonite, goethite, calcite, ankerite, apatite, and monazite. The desorption properties are best revealed during the treatment of ultrapure, tap, and mineral water, whereas the adsorption properties are best manifested in coal mine water treatment. The concentrations of Al, Si, Fe, Na, Mn, F, K, Pb, and U increase in the treated ultrapure, tap, and mineral water, while the content of K, Be, Pb, and F increase in the treated mine water. The tuffs show selective partial or complete adsorption of Na, Mg, Sr, Li, Be, Mn, Fe, Co, Ni, Cu, Zn, Al, Pb, U, and SO42−. They demonstrate the ability to neutralize acidic and alkaline pH. Sources of F are presumed to be clinoptilolite and montmorillonite. The usage of zeolitized tuffs for at-home drinking water treatment has to be performed with caution due to the migration of potentially toxic and toxic elements.

Preparation of magnetic DTPA-modified chitosan composite microspheres for enhanced adsorption of Pb(II) from aqueous solution

In this study, magnetic DTPA-modified chitosan composite microspheres (MDCM) were prepared by reverse emulsion-double crosslinking method (carbodiimide followed by glutaraldehyde) for removal of Pb(II) from aqueous solution. The obtained magnetic adsorbents were characterized by FTIR, SEM, XRD, VSM, BET, and 13C NMR. The effects of the pH, contact time, initial concentration, and competitive metal cations (Na(I), Ca(II), or Mg(II)) on Pb(II) adsorption were investigated. The results revealed that MDCM exhibited high removal performance over a wide pH range and in the presence of competitive metal cations. The maximum adsorption capacity of MDCM for Pb(II) is 214.63 mg g−1 at pH 3, which is higher than most recently reported magnetic adsorbents. Adsorption kinetics and isotherms can be described by the pseudo-second-order model and Langmuir model, respectively. In addition, MDCM is easy to regenerate and can be reused five cycles with high adsorption capacity. Finally, the adsorption mechanism was further revealed by FTIR and XPS analysis. Overall, MDCM has practical application potential in removing Pb(II) from contaminated wastewater due to its high adsorption efficiency, good reusability, and convenient magnetic separation.

A novel oyster shell biocomposite for the efficient adsorptive removal of cadmium and lead from aqueous solution: Synthesis, process optimization, modelling and mechanism studies.

This study highlights the effectiveness of oyster shell biocomposite for the biosorption of Cd(II) and Pb(II) ions from an aqueous solution. The aim of this work was to modify a novel biocomposite derived from oyster shell for the adsorption of Cd(II) and Pb(II) ions from aqueous solution. The studied revealed the specific surface BET surface area was 9.1476 m2/g. The elemental dispersive x-ray analysis (EDS) indicated that C, O, Ag, Ca were the predominant elements on the surface of the biocomposite after which metals ions of Cd and Pb were noticed after adsorption. The Fourier transform Irradiation (FT-IR) revealed the presence of carboxyl and hydroxyl groups on the surface. The effect of process variables on the adsorption capacity of the modified biocomposite was examined using the central composite design (CCD) of the response surface methodology (RSM). The process variables which include pH, adsorbent dose, the initial concentration and temperature were the most effective parameters influencing the uptake capacity. The optimal process conditions of these parameters were found to be pH, 5.57, adsorbent dose, 2.53 g/L, initial concentration, 46.76 mg/L and temperature 28.48°C for the biosorption of Cd(II) and Pb(II) ions from aqueous solution at a desirability coefficient of 1. The analysis of variance (ANOVA) revealed a high coefficient of determination (R2 > 0.91) and low probability coefficients for the responses (P < 0.05) which indicated the validity and aptness of the model for the biosorption of the metal ions. Experimental isotherm data fitted better to the Langmuir model and the kinetic data fitted better to the pseudo-second-order model. Maximun Cd(II) and Pb(II) adsorption capacities of the oyster shell biocomposite were 97.54 and 78.99 mg/g respectively and was obtained at pH 5.56 and 28.48°C. This investigation has provided the possibility of the utilization of alternative biocomposite as a sustainable approach for the biosorption of heavy metal ions from the wastewater stream.

Adsorption Kinetics and Mechanism of Pb(II) and Cd(II) Adsorption in Water through Oxidized Multiwalled Carbon Nanotubes

Toxic heavy metals are ubiquitous in the aquatic environment and show a significant danger to human health. Carbon nanotubes have been extensively used in treating the contamination of groundwater due to their porous multi-layer nature. Batch tests revealed that oxidized multiwalled carbon nanotubes (O-MWCNTS) offer better removal of Pb(II). The removal rate of Pb(II) was 90.15% at pH 6 within 24 h, which was ~58% more than that of Cd(II). The removal rate decreased to 55.59% for Pb(II) and to 16.68% for Cd(II) when the initial concentration of Pb(II)/Cd(II) ranged from 5 to 15 mg·g−1. The removal rate in the competitive tests was about 60.46% for Pb(II) and 9.70% for Cd(II). The Langmuir model offered better description of the adsorptive data for both ions. And the Qm of Pb(II) was 5.73 mg·g−1, which was 2.39 mg·g−1 more than that of Cd(II) in a single-icon system, while Qm was 7.11 mg·g−1 with Pb(II) and 0.78 mg·g−1 with Cd(II) in competitive water. And thermodynamic tests further indicated that the activating energy of Pb(II) and Cd(II) was 83.68 and 172.88 kJ·mol−1, respectively. Lead and cadmium adsorbed on the surface of O-MWCNTS are antagonistic in the competitive system. Based on XPS analyses, it was concluded that the absorbed lead/cadmium species on O-MWCNTS were (-COO)2Pb, (-COO)Pb(-O)/(-COO)2Cd, and (-COO)Cd(-O). Additionally, they offered theoretical evidence supporting the practicality of using nanocomposite membranes as a means to remove cadmium and lead.

Synergistic effects of aluminum doping and amino functionalization to enhance adsorption capacity of ultrathin-nanosheet-assembled calcium silicate hydrate architectures for effective removal of Pb2+ and Cu2+ from aqueous solution

This study demonstrates for the first time the potential of the novel combination of aluminum (Al) doping and amino functionalization to drastically enhance the adsorption capacity of nanosheet-assembled hierarchical calcium silicate hydrate (CSH) architectures for heavy metal Pb2+ and Cu2+ ions in aqueous solution. The designed and prepared amino-functionalized Al-doped CSH (CASH-NH2) exhibits excellent adsorption capability to adsorb Pb2+ and Cu2+ ions. The maximum adsorption capacity of Pb2+ and Cu2+ ions is 911 and 509 mg g−1, respectively, which is much higher than that of pure CSH and other relative CSH-based adsorbents. The experimental measurements of cation exchange capacity (CEC) and surface composition discover that the adsorption of Pb2+ and Cu2+ ions on CASH-NH2 is preponderantly achieved by the cation exchange and surface complexation, in which Al doping substantially enhances the exchange capacity between Ca2+ of CSH and Pb2+ or Cu2+, and the functional amino groups chelate Pb2+ or Cu2+ to realize surface complexation of CASH architectures. Thereby the excellent adsorption performance of CASH-NH2 is attributed to the significant enhancement in the CEC between Ca2+ of CASH and Pb2+ or Cu2+, and the amino functionalization-induced surface complexation of the CASH, which are achieved by the synergistic effect of Al doping and amino functionalization. This work opens a new way for simultaneously exploiting metal doping and amino functionalization to boost the adsorption performance of other adsorbents to achieve highly efficient removal of toxic cationic species from polluted water.

Green synthesis of phillipsite from natural microcline for use as an adsorbent for Cu(II), Cd(II), Pb(II), and methylene blue dye from polluted water

Green synthesis of phillipsite from natural microcline for use as an adsorbent for Cu(II), Cd(II), Pb(II), and methylene blue dye from polluted water

Kinetics and mechanism of Pb(II), Cd(II) and Cu(II) adsorption on ferrochrome ash from aqueous solutions

ABSTRACT There has been significant interest in the development of novel approaches and techniques that can effectively ensure the supply of safe and uncontaminated water to human communities. Among the several treatment strategies available, adsorption is particularly favourable due to its inherent versatility in terms of design and operation. Additionally, a diverse selection of cost-effective adsorbents has been successfully employed for the purpose of remediating heavy metal-contaminated wastewater. The current study employed an industrial waste ferrochrome ash (FCA), as a novel adsorbent to eliminate Pb(II) and Cd(II) ions from aqueous solutions. To accomplish this goal, the FCA underwent characterisation by XRF, XRD, and SEM-EDS analyses. Afterwards, batch adsorption experiments were carried out and the maximum adsorption capacities were obtained as 1519 and 84.5 for Pb(II) and Cd(II) mg/g, respectively which makes the FCA an applicable adsorbent for their removal from wastewater. Furthermore, it was found out that the adsorption of Pb(II) and Cd(II) on FCA fits the pseudo-second order (PSO) kinetics and Langmuir isotherm models. Based on the findings, it can be inferred that the adsorption mechanism of Pb(II) and Cd(II) followed a monolayer chemisorption process, characterised by the valency forces between the metal ions and the surface of the adsorbent. Furthermore, adsorption capacity of the WGFCA was examined at different temperatures and it was found out that the adsorption of Pb(II) and Cd(II) on WGFCA is an exothermic and spontaneous process. Additionally, an examination was conducted on the desorption characteristics and the structural integrity of the WGFCA, revealing that it may be successfully restored under acidic conditions for subsequent utilisation. Finally, competitive adsorption characteristics of Pb(II), Cd(II) and Cu(II) ions were investigated and the sequence of adsorption capacity in such multi-cationic systems was found to be Pb(II)>Cu(II)>Cd(II).

Cd(II) and Pb(II) adsorption in karst soils amended with litter extract from Ficus virens

In this study, different proportions of Le were used to amend purple, yellow, and yellow–brown soils of karst areas to investigate the effect of litter extract (Le) from Ficus virens on Cd(II) and Pb(II) adsorption in karst soils. The basic physicochemical properties of Le-amended karst soils were determined, and the microscopic morphology of Le-amended karst soils was detected. The batch method was used to study the isothermal adsorption characteristics of Cd(II) and Pb(II) adsorption on different Le-amended karst soils. Physicochemical properties and microscopic morphology results showed that Le was amended on the karst soil surface and changed the surface properties of the karst soil. The maximum adsorption capacity range of Cd(II) and Pb(II) by Le-amended karst soils was 92.10–241.61 and 108.91–262.12 mmol/kg, respectively, and the peak value was reached when the karst soils were amended with 20 % of Le. Increasing the pH and temperature were beneficial to Cd(II) and Pb(II) adsorption in each Le-amended karst soil. The adsorption amount of Cd(II) and Pb(II) initially increased and thendecreased with the increase in ionic strength. Cd(II) and Pb(II) adsorption was a spontaneous, endothermic, and entropy-increasing process, and electrostatic attraction, precipitation, complexation, and ion exchange were the main adsorption mechanisms. The adsorption amount of Cd(II) and Pb(II) by Le-amended yellow–brown soil maintained approximately 85 % of original sample after three rounds of regeneration.

Effectiveness of cork and pine bark powders as biosorbents for potentially toxic elements present in aqueous solution

Cork oak and pine bark, two of the most prolific byproducts of the European forestry sector, were assessed as biosorbents for eliminating potentially toxic elements (PTEs) from water-based solutions. Our research suggests that bioadsorption stands out as a viable and environmental eco-friendly technology, presenting a sustainable method for the extraction of PTEs from polluted water sources. This study aimed to evaluate and compare the efficiency of cork powder and pine bark powder as biosorbents. Specifically, the adsorption of Fe, Cu, Zn, Cd, Ni, Pb and Sn at equilibrium were studied through batch experiments by varying PTEs concentrations, pH, and ionic strength. Results from adsorption-desorption experiments demonstrate the remarkable capacity of both materials to retain the studied PTE. Cork powder and pine bark powder exhibited the maximum retention capacity for Fe and Cd, while they performed poorly for Pb and Sn, respectively. Nevertheless, pine bark showed a slightly lower retention capacity than cork. Increasing the pH resulted in cork showing the highest adsorption for Zn and the lowest for Sn, while for pine bark, Cd was the most adsorbed, and Sn was the least adsorbed, respectively. The highest adsorption of both materials occurred at pH 3.5–5, depending on the PTE tested. The ionic strength also influenced the adsorption of the various PTEs for both materials, with decreased adsorption as ionic strength increased. The findings suggest that both materials could be effective for capturing and eliminating the examined PTEs, albeit with different efficiencies. Remarkably, pine bark demonstrated superior adsorption capabilities, which were observed to vary based on the specific element and the experimental conditions. These findings contribute to elucidating the bio-adsorption potential of these natural materials, specifically their suitability in mitigating PTEs pollution, and favoring the recycling and revalorization of byproducts that might otherwise be considered residue.