Removal Efficiency Of Pb Research Articles

Application of Iron Powder Reduction Method to Remove Heavy Metals in Waste Pickling Acid

The removal of heavy metals in waste pickling acid by iron powder reduction was studied. The effects of reaction time, reaction temperature and dosage of iron powder on the removal efficiency of Zn, Cr, Ni and Pb in waste pickling acid were investigated. The results showed that, the removal rate of Cr tended to be stable after 2 h of reaction under magnetic stirring. After 4 hours, the removal rate of Zn,Ni and Pb tended to be stable. The temperature was increased from 20°C to 90 °C, the removal rates of Ni and Pb could be increased by 9.09% and 11.6%, while the removal rates of Zn and Cr were only increased by 1.15% and 2.85%; Increasing the dosage of iron powder was beneficial to the removal of heavy metals in waste pickling acid, and the combined amount of free acid in the waste acid would affect the removal efficiency of heavy metals. The research results had important guiding significance for the practical application of iron powder reduction method in the heavy metal purification project of waste pickling acid.

Removal of Pb(II) Ions from Aqueous Solutions by Spherical Nanocomposites Synthesized Through Immobilization of Paecilomyces lilacinus in Silica Nanoparticles Coated with Ca-Alginate

In the present study, a novel microbial nanocomposite "Paecilomyces lilacinus-silica nanoparticlescalcium-alginate beads" (P. lilacinus-SN-Cal-Alg) were synthesized and their high efficiency for removing Pb(II) ions was demonstrated in aqueous solution. P. lilacinus-SN-Cal-Alg beads before and after the adsorption of Pb(II) were characterized by FT-IR, SEM-EDS, and XPS analyses. The adsorption capacity of Pb(II) by P. lilacinus-SN-Cal-Alg beads was analyzed in aqueous solution. For comparison, the adsorption capacity of Pb(II) by another type of microbial composites, namely, P. lilacinus-Cal-Alg beads, without addition of silica nanoparticles, was also studied in parallel. Lastly, the equilibrium data in adsorption process were examined by both Langmuir and Freundlich isotherm models to evaluate adsorption mechanism. The results showed that an excellent removal efficiency of Pb(II) in aqueous solution (85.54%) was obtained at initial concentration of 200 mg/L by using the P. lilacinus-SN-Cal-Alg beads. Meanwhile, they exhibited the better adsorption capacity for Pb(II) than P. lilacinus-Cal-Alg beads. The adsorption process by P. lilacinus-SN-Cal-Alg beads was best described by the Langmuir model indicating that monolayer adsorption of Pb(II) ions takes place on the beads surfaces and showed that its maximum adsorption capacity was 282.49 mg/g.

Adsorption study of Heavy Metals from Aqueous Solutions using Magnetite Nanoparticles

Contamination of heavy metals in wastewater is a significant worldwide problem, which is causing to detrimental effect on human health and environment. In present work, magnetite nanoparticles were used for the expulsion of Pb(II) and Cd(II) ions from aqueous solutions at varying pH conditions, contact time and adsorbent amounts. Magnetite nanoparticles were synthesized by co-precipitation method. Synthesized nanoparticles were characterized by XRD, FTIR, UV-Vis, VSM and SEM techniques for structural, optical, magnetic and morphological properties. The crystalline nature of magnetite nanoparticles with crystallite size 10.16 nm was confirmed by XRD. Optical properties and functional group identification of magnetite nanoparticles were revealed by UV-Vis and FTIR spectroscopy respectively. VSM measurements showed that the saturation magnetization of magnetite nanoparticles was 56.42 emu/g. This indicates that after adsorption, an easy separation of metal loaded magnetite nanoparticles from aqueous solutions can be achieved by applying the external magnetic field. Adsorption experiments results showed that the adsorption capacity of magnetite nanoparticles is higher for Pb(II) ions. At optimum conditions, the maximum removal efficiencies for Pb(II) and Cd(II) ions were 98.6% and 93% respectively. Langmuir and Freundlich adsorption isotherms were found suitable for adsorption processes. The adsorption kinetic data for both the metal ions were best fitted by pseudo second order reaction. Surface images of bare and metal loaded magnetite nanoparticles supported the confirmation of adsorption of metal ions on nanoparticles surface. Thus, it is concluded that magnetite nanoparticles can be effectively used as an adsorbent for expulsion of heavy metals from aqueous solutions.

Adsorptive removal of Pb(II) ions from aqueous solutions by thiourea-functionalized magnetic ZnO/nanocellulose composite: Optimization by response surface methodology (RSM)

Removal of pollutants by bio-superadsorbent is currently in the limelight due to their low cost and biocompatibility with the environment. In this research, the thiourea-modified magnetic ZnO/nanocellulose composite (TZFNC) with high adsorption capacity and separation efficiency for Pb(II) was prepared successfully, and its physicochemical properties were characterized via XRD, SEM, TEM, AFM, BET, FTIR, XPS, EDAX, Zeta-potential and VSM, respectively. Response surface methodology (RSM) has been applied in order to study the influence of operational parameters (pH, lead ions concentration, adsorbent dosage and contact time) on the removal efficiency of lead ions with TZFNC as a novel adsorbent. The results indicated that the efficiency of Pb(II) removal is 99.99% under the optimum conditions of experimental factors (pH = 6.5, the amount of adsorbent = 40 mg, Pb(II) concentration = 60 mg L−1, and contact time = 14.5 min). The equilibrium, and kinetic studies suggested that the adsorption process followed the Langmuir isotherm and Pseudo-Second-Order model. Thermodynamic data showed that the sorption process was feasible, spontaneous, and endothermic. The maximum adsorption capacity was found to be 554.4 mg/g. The good adsorption performance, recyclability and easy magnetic separation ability made sure that the TZFNC has great potential for purification of Pb(II) contaminated wastewater.

Activating CaCO3 to enhance lead removal from lead-zinc solution to serve as green technology for the purification of mine tailings

Efficient lead removal from metal-containing wastewater, such as acid mine drainage (AMD), is an important step in environmental purification and secondary resources recovery. In this paper, a novel approach by mechanochemically activating CaCO3 through simply wet ball milling in metal-containing solution was developed, where selective Pb2+ precipitation in the form of PbCO3 was achieved based on its reaction with the CO32− from the activated CaCO3. By such milling operation, the removal efficiency of Pb2+ from aqueous solution could reach over 99%, while more than 99% Zn2+ (as well as Mn, Ni and Cd) was remaining in the solutions, demonstrating the feasibility and high effectiveness of precipitating Pb2+ and serving the purpose of recovering other metals without Pb impurity. The solubility differences between Pb carbonate and other carbonates of Zn, Mn, Ni or Cd were understood to be the main pathway and using CaCO3 would offer an easy operation and environmental friendly process to purify the metals-containing wastewater by precipitating Pb, compared with the difficulties when using alkaline neutralization to treat them. In addition, basic zinc carbonate (a zinc-containing ore waste) as an alternative precipitant to CaCO3 in the separation process was also confirmed to increase the zinc recovery in the solution while maintaining high Pb2+ removal efficiency.

Reduction of radioactive impurities from the liquid scintillator by using a Metal scavenger

The KamLAND2-Zen experiment is a future plan to perform the search for neutrinoless double-beta decay (0vββ) by using a large liquid-scintillator (LS) based detector, i.e., KamLAND2. The KamLAND detector will be upgraded by increasing the light yield of scintillation. One of the upgrade plans consists of using a new linear alkylbenzene (LAB) based LS. We have developed the LAB-LS radio-purification method by using a metal scavenger. The scavenging process resulted in a Pb-removal efficiency of 90.1±1.0% at most, and LS performance parametrics, such as light yield, light transparency, amount of radioactive impurities remaining, and the concentration of components were observed to be stable after scavenging. Therefore, it can be asserted that scavenging is a useful method for LS purification.

Synthesis and application of magnetized nanoparticles to remove lead from drinking water: Taguchi design of experiment

Abstract Contamination in drinking water from heavy metals like Pb2+ has severe effects on health. In this study, potato peel (PP) was used as the substrate and magnetic iron nanoparticles (MI) were deposited on PP using a co-precipitated method. Fourier transformation infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the deposition of MI on PP. The L16 (4^4) method of Taguchi design of experiment (DOE) was used for the optimization of adsorption condition, i.e., at 6 pH, 10 min of contact time, and a dose of 15 g/L can give more than 90% removal efficiency of Pb2+ using PP-MI. Contour maps, Taguchi response analysis, and analysis of variance (ANOVA) suggested that pH has a dominant contribution in the removal of Pb2+. The adsorption process was favorable, spontaneous, and exothermic in nature and was followed by pseudo second order kinetics. A comparison of the sorption capacity of PP-MI for Pb2+ with literature values suggested that PP-MI has good potential for the removal of Pb2+. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

Aqueous Lead Removal under Optimized Conditions Using Phosphoric Acid Activated Coconut Coir Activated Carbon

The global burden of heavy metal environmental pollution remains one of the most challenging issues to be addressed urgently. Lead (Pb) has been well recognized as a toxic environmental pollutant. The main objective of this study was to examine the adsorption efficiency of phosphoric activated coconut coir activated carbon for lead (II) removal from an aqueous solution. Synthesized activated carbon was characterized before and after the adsorption of Pb(II) by powder X-Ray diffraction, Fourier transforms infrared spectroscopy and scanning electron microscopy coupled with energy dispersive X-Ray. Furthermore, the removal efficiency of Pb(II) of synthesized activated carbon was tested with different concentrations of Pb(II) solutions, pH levels, adsorbent dosages, and contact time. Atomic absorption spectroscopy was used to analyze the Pb(II) concentrations in water samples. The maximum Pb(II) removal percentage of 100% was obtained with 50 mL of 5 mg/L Pd(II) ion solution and 0.20 g of the synthesized activated carbon. Adsorption data were well fitted with the Freundlich adsorption isotherm model, and adsorption kinetics were fitted with the pseudo-second-order kinetic model with R2 of 0.99. These results conclude that the synthesized activated carbon can be used as a potential sorbent for the removal of lead from wastewaters.

Enhancement of tartaric acid modified washing solutions for lead decontamination of tropical soils

Abstract Tartaric acid is generally not an effective soil washing solution, hence this study focuses on enhancing its usage for soil-Pb decontamination. Three tropical soil types (sandy, clay and loamy) with different lead concentrations were subjected to single batch washing using 0.01, 0.1, 0.5 and 1 M tartaric acid with 5% and 10% KCl modification at 3% soil-pulp-density for 2, 6, 12 and 24 h washing time. The optimum washing conditions were 1 M tartaric acid at 24 h washing time, with Pb removal efficiency: sandy- 94.3%, clay-67.6% and loamy-36.8%. Modification of tartaric acid with 5% and 10% KCl brought about some degree of enhancement of Pb removal efficiency especially for clay and loamy soils. Removal efficiency for 5% KCl modification were: sandy-97.9%, clay-96.2% with 1 M tartaric acid at 24 h washing time, loamy-76.7% for 0.5 M tartaric acid. Similarly, 10% KCl modification were: sandy-96.7%, clay-97.2% for 1 M tartaric acid at 24 h, loamy-82.1% for 0.5 M tartaric acid. Removal efficiency was soil concentration dependent. Generally, removal efficiency increased with increasing tartaric acid concentrations and washing time. Tartaric acid washing is promising and recommended in events of moderate contamination and 10% KCl modification in event of high level contamination. Further study is needed on enhancing very low concentrations of tartaric acid for large scale applications.

Simultaneous removal of multiple heavy metals from soil by washing with citric acid and ferric chloride.

The remediation of soil contaminated with multiple heavy metals is a matter of great concern due to its serious threat to the ecosystem and human health. Batch and slurry reactor soil washing experiments were conducted to explore the removal of Cd, Cr, Pb and Zn using 7 agents. Citric acid (CA) and ferric chloride (FeCl3) exhibited an obvious synergistic effect on the removal of heavy metals. Furthermore, the concentration of heavy metals in different soil particle size fractions was closely related to the soil element concentrations. Fine sand (0.05–0.25 mm) had a strong adsorption capacity for Cr and Pb because of the high Mn concentration. Notably, heavy metals in smaller-size soil particles could be efficiently removed by CA and FeCl3. After remediation, the bioavailability of heavy metals in soil decreased. The potential ecological risk of heavy metals in soil reduced from an extremely high level to a low level. Moreover, some elements (e.g. Al, Mn and Fe) and organic matter in soil were dissolved by CA and FeCl3, which accelerated the desorption of heavy metals from the soil. In a slurry reactor experiment, the removal efficiencies of Cd, Cr, Pb and Zn were 94.8%, 79.5%, 92.7% and 97.2%, respectively. The combination of CA and FeCl3 is a feasible practice to remediate soil contaminated by multiple heavy metals.

Removal of Pb (II) from Synthetic Solution and Paint Industry Wastewater Using Activated Carbon Derived from African Arrowroot (Canna indica) Stem

This study aimed to investigate the potential of Canna indica stem‐based activated carbon (CISAC) for the removal of Pb (II) ions from synthetic solution and paint industry wastewater. The effects of pH, initial Pb (II) ion concentration, and adsorbent dose were studied using an aqueous solution prepared using pure lead nitrate (Pb(NO₃)₂) on a batch mode. Dried Canna indica stem (CIS) was carbonized in a rectangular furnace at 500°C for 2 h and treated with phosphoric acid (H3PO4) at a ratio of 1 : 1 (w/v). Results showed that the CISAC had 5.4% of moisture, 5.0% of ash, 26.7% of volatile matter, 62.9% of fixed carbon, and 797.5 mg/g of iodine number. The Fourier Transform Infrared (FTIR) results showed that the hydroxyl, carboxyl, and phenolic functional groups were dominant in the CISAC surface. Physicochemical characteristics revealed that raw wastewater had a concentration of 4.6 mg/L Pb (II), 3 mg/L Cu (II), 171 mg/L BOD5, 2402 mg/L COD, and 619 mg/L TSS. Better removal of Pb (II) ion from aqueous solution was achieved at a pH of 5.5, initial Pb (II) concentration of 102.4 mg/L, and an adsorbent dose of 1.4 g using response surface methodology. The highest removal efficiencies of Pb (II) which was achieved from aqueous solution and paint wastewater were 98% and 70%, respectively. The experimental data are fitted with Langmuir and Freundlich isothermic models. The results suggested CISAC as a promising adsorbent to remove Pb (II) ion from paint industry wastewater.

Activated hydrochar from palm leaves as efficient lead adsorbent

A carbon-rich hydrochar HTC-PL was prepared by hydrothermal carbonization of Phoenix dactylifera palm leaves. HTC-PL was chemically modified with H2O2 to give activated AHTC-PL. High-resolution transmission electron microscope HRTEM of AHTC-PL indicated sponge-like cubic mesoporous nanostructures. Thermal analysis of HTC-PL and AHTC-PL shows two degradation steps around 330 and 400 °C. The physico-chemical properties and energy generation capability of hydrochar HTC-PL were evaluated. The hydrochar has higher heating value of 20.95 MJ/kg. Langmuir isotherm and pseudo-second-order kinetic provided the best fit to the adsorption data of lead by HTC-PL materials. Removal of lead by AHTC-PL at 25 °C resulted in an adsorption capacity of 74.5 mg/g while that of HTC-PL biochar is 17.8 mg/g. The adsorption data using a fixed-column technique were best fitted by Thomas model. The % removal efficiency of Pb2+ ions by AHTC-PL column was almost unchanged for three cycles.

Removal of Heavy Metals and Nutrients from Municipal Wastewater using Salvinia molesta and Lemna gibba

The present study was focused on the investigation of the abilities and efficiencies of Salvinia molesta and Lemna gibba to remove selected heavy metals (Cr, Cu, Fe, Ni and Pb) and excess nutrients from wastewater taken from the Moratuwa-Ratmalana municipal wastewater treatment plant. The wastewater samples were analysed for pH, Temperature, for N-Nitrates, N-Nitrites, ammonia Nitrogen, Phosphates, and selected heavy metals, Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and Total Kjeldhal Nitrogen. Then, the wastewater samples were treated with S. molesta and L. gibba separately for a period of 7 days and analysed for N-Nitrates, N-Nitrites, Ammonia Nitrogen, Phosphates and five selected heavy metals at 24 hour intervals. BOD, COD and Total Kjeldhal Nitrogen were analysed at 7 days intervals. The average Total Nitrogen removal efficiencies of S. molesta and L. gibba were 73.3% and 62.1% whereas the average Total Phosphate removal efficiencies of S. molesta and L. gibba were 72.6% and 77.2% respectively. The average Cr, Cu, Fe, Ni and Pb removal efficiencies of S. molesta were 81.6%, 69.8%, 65.2%, 66.3% and 74.8% respectively. The average Cr, Cu, Fe, Ni and Pb removal efficiencies shown by L. gibba were 86.9%, 69.7%, 73.1%, 61.8% and 85.7% respectively. The Bio Concentration factors of S. molesta for Cr, Cu, Fe, Pb and Ni were 823, 698, 652, 663 and 748 respectively and the Bio Concentration factors of S. molesta for Cr, Cu, Fe, Pb and Ni were 870, 698, 731, 618 and 857 respectively. According to the obtained results in the present study S. molesta and L. gibba can be considered as suitable candidates for the polishing of municipal wastewater.

Antibacterial dynamic membranes loaded by cephalexin/amine-functionalized SBA_15 for Pb(II) ions removal

Novel antibacterial dynamic membranes loaded by cephalexin/amine fiinctionalized SBA_15 were fabricated for heavy metal removal from aqueous solution. The mesoporous CPX/NH2-SBA_15 nanocomposite was formed as a uniform adsorptive and hydrophilic layer on the ultrafiltration polymeric membrane (PVDF). The modified adsorbent and membranes were characterized by SEM, XRD, N2 adsorption-desorption analysis, FT-IR, TGA, DSC and contact angle. A number of qualitative (well diffusion, disk diffusion) antibacterial assays were conducted against grampositive S. aureus and gram-negative E. coli. In addition, to evaluate its anti-biofouling performance, the model concentrated bacteria suspension in liquid medium was used as a feed solution. 100% bacteria mortality for certain concentration and suitable inhibition zones up to 3.5 cm were attained. An increment in the flux recovery from 55% (for UF) to 87% (for self-forming dynamic membrane (DM)) and 91% (for pre-coated DM) indicated that the dynamic layer improved the anti-biofouling property of the support membrane. High Pb(II) removal efficiency (99.8%) was achieved for the modified membrane during dynamic filtration test. CPX/NH2/SBA-15 dynamic membrane showed higher Pb2+ rejection than SBA-15 dynamic membrane because of amine groups located on the adsorbent surface. In general, membranes provide good performance like better flux and rejection besides antibacterial and anti-biofouling behavior.

Effective coating of crosslinked polyethyleneimine on elastic spongy monolith for highly efficient batch and continuous flow adsorption of Pb(II) and acidic red 18

Adsorption using monolithic adsorbents is an attractive emerging technology for water treatment, but it still remains a great challenge to facilely combine microscopically a well-developed surface functionality with a macroscopic architecture. In this work, we reported a simple, low-cost, and effective method for constructing uniform coating of crosslinked polyethyleneimine (PEI) on monolithic melamine sponge (MS) through pre-modification with polydopamine (PDA), followed by a rotary evaporation-driven “crosslinking–surface deposition” process. Due to the amine groups-rich surface and highly open porous structure, the resulting monolithic adsorbent ([email protected]/MS) exhibited high adsorption capacities and fast adsorption kinetics toward Pb(II) (231.81 mg g−1; < 100 min) and acid red 18 (AR18, 464.53 mg g−1; < 180 min). Moreover, [email protected]/MS possessed excellent shape memory property and could be manually collected with tweezers, indicating its great operational convenience in recycling. Cyclic adsorption/desorption experiments confirmed its satisfying reusability. Continuous flow adsorption behaviors of the [email protected]/MS monolith were further investigated by directly using it as stationary phase, which also exhibited high removal efficiencies for Pb(II) and AR18. Besides, adsorption mechanisms based on the characterization analyses were also proposed. Our study provides an effective strategy for fabricating high-quality PEI-based monolithic adsorbents with great potential to be used in environmental remediation.

Removal of lead (II) ions from aqueous solution by Hydroxyapatite biosorbent extracted from Ostrich bone

Hydroxyapatite (HAp) is a broadly studied bioceramic for biomedical implant and bone tissue regeneration. Despite this, it is a good adsorbent of heavy metal ions. Its chemical formula is Ca10 (PO4)6(OH) 2. It was extracted by the calcination process from Ostrich bone. The obtained HAp was characterized by X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) spectroscopy and was used for removal of lead (II) ion from aqueous solutions. A series of experiments were conducted in order to determine the effects of pH, contact time and sorbent dosage in a optimize condition for maximum adsorption. The results showed that the removal efficiency of Pb (II) ions reached 99.04% with an initial concentration of 50 mgL1 , pH range; 3 to7 and 1 hour contact time. The adsorption rate of Pb (II) ions onto the HAp was found incredibly fast and equilibrium was reached within 5 minute. Within this time 72.32% of lead (II) ions were removed. The equilibrium removal process of Pb (II) ions at pH range 4.5-5.5 were well described by the Langmuir isotherm model, with a maximum adsorption capacity of 430.7 mg/g. Key words: Ostrich bone, hydroxyapatite, calcinations, adsorption, Pb (II) ion, pH.

Remediation of industrial wastewater using four hydrophyte species: A comparison of individual (pot experiments) and mix plants (constructed wetland)

Remediation and management of industrial wastewater (IWW) using hydrophytes act as one of the cost effective and environmentally friendly technologies. The present study was conducted to assess the role and efficiency of selected four hydrophyte species through constructed wetland (CW) for the removal of heavy metals (HMs) from IWW. Samples of wastewater (WW) were collected from the main drain of Hayatabad Industrial Estate (Peshawar, Pakistan) and analysed for HMs like cadmium (Cd), copper (Cu) and lead (Pb) along with basic physicochemical parameters like pH, electric conductivity (EC), total suspended solids (TSS), total dissolved solids (TDS), dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), dissolved organic carbon (DOC) through standard analytical methods. Four hydrophytes species such as Typha latifolia (cattail), Eichhornia crassipes (water hyacinth), Lemna gibba (duck weed) and Pistia stratiotes (water cabbage) were transplanted into CW (mix cultivation). Each selected species was also cultivated in individual pots for investigating their efficiency to remove HMs. The Cd, Cu and Pb removal efficiency of CW was recorded as 39.5%, 80.3% and 85.5%, respectively. The removal efficacy of hydrophyte species including cattail, water hyacinth, duck weed and water cabbage was 96.2%, 72.2%, 60.4% and 93.3%, respectively for Cd, while 83.6%, 82.3%, 90.0% and 81.7% for Cu and 95.9%, 78.0%, 91.3% and 97.1% for Pb, respectively. Findings of T-Test and One-Way ANOVA showed that the concentrations of Cd, Cu and Pb in IWW were significantly (P ≤ 0.01) reduced by the treatment of hydrophytes revealing the higher efficiency of CW and selected species used in this study. The HMs were removed in order of Pb > Cu > Cd. Most efficient removal for Cd was found by water cabbage, Cu by duck weed and Pb by water hyacinth. It was concluded that CW is one of the environmentally friendly and cost-effective technologies that can be used for the treatment of IWW due to the efficiency of hydrophytes species in terms of HMs removal.

Assessment of the Cu(II) and Pb(II) removal efficiency of aqueous solutions by the dry biomass Aguapé: kinetics of adsorption.

Plant-based materials are promising adsorbents for treating liquid effluents. This study describes the kinetic and equilibrium parameters that best represent the copper(II) and lead(II) removal process by Eichhornia crassipes (Aguapé) dry biomass from aqueous solution, using a batch adsorption system. The plants were washed, dried, and reduced to small particles. The adsorption kinetics were assessed by varying the metal concentrations in 5, 10, and 20 mg L-1 and a control treatment (without metals) with a mixture contact time of between 5 and 720 min. Equilibrium data were fitted to the Langmuir and Freundlich models. Kinetic assay revealed fast adsorption: kinetic equilibrium was attained within 2 h with a removal efficiency of ~ 60%. The results demonstrated a fast recovery cycle of metals using the biosorbent. The biomass of E. crassipes is low cost with potential for use as a biosorbent to remove metals from solutions.

Adsorption characteristics of Pb(II) using biochar derived from spent mushroom substrate

As a multifunctional material, biochar is considered a potential adsorbent for removing heavy metals from wastewater. Most biochars with high adsorption capacities have been modified, but this modification is uneconomical, and modifying biochar may cause secondary pollution. Thus, it is necessary to develop an efficient biochar without modification. In this study, spent P. ostreatus substrate and spent shiitake substrate were used as the raw materials to prepare biochar. Then, the physicochemical properties of the biochars and their removal efficiencies for Pb(II) were investigated. The results showed that the physicochemical properties (e.g., large BET surface area, small pore structure and abundant functional groups) contributed to the large adsorption capacity for Pb(II); the maximum adsorption capacities were 326 mg g−1 (spent P. ostreatus substrate-derived biochar) and 398 mg g−1 (spent shiitake substrate-derived biochar), which are 1.6–10 times larger than those of other modified biochars. The Pb(II) adsorption data could be well described by the pseudo-second-order kinetic model and the Langmuir model. This study provides a new method to comprehensively utilize spent mushroom substrates for the sustainable development of the edible mushroom industry.

Remediation of heavy metal Pb (II) in aqueous solution using Kaolin-supported nano iron

In this experiment, liquid phase reduction method was used to synthesize and prepare the Kaolin supported nanoscale zero-valent iron (K-nZVI). By methods of x-ray techniques (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Lorentz-Transmission Electron Microscope (L-TEM), BET, etc, we researched the physical and chemical properties of the synthesized materials, like chemical component, microstructure and so on. The synthesized iron was in its Fe0 state (α-Fe) and was of nano scale. Both the characterization of TEM and SEM indicated that Kaolin could scattered the iron nanoparticles and prevent aggregation of iron particles. The removal experiments indicated that the 40% iron content synthesized K-nZVI showed the best removal efficiency for Pb (II). After contacting for 16 h, the removal efficiency of Pb (II) by 40%K-nZVI reached 93%, which is higher than that of other K-nZVI of different iron content. K-nZVI lost its excellent efficacy for removing metals in acidic solution, removing less than 10% Pb (II) from the water. 0.5 g adsorbent dose of 30%K-nZVI could remove nearly 100% Pb (II) from the aqueous solution after reaction for 11 h.