Characterization and Pb(II) removal potential of corn straw- and municipal sludge-derived biochars

Optimization of Fermented Maize Stover for the Fattening Phase of Geese: Effect on Production Performance and Gut Microflora

To optimize the utilization of fermented maize stover (FMS) feed during the fattening phase of Xianghai flying geese (XFG), a total of 300 XFG at 125 days of age were randomly assigned to four dietary treatment groups with three replicates of 25 in each set. Group A was fed the basal fattening diet, while the B, C, and D groups were fed the basic fattening diet and diets supplemented with 5%, 10% or 15% FMS, respectively. The findings indicate that the production performance indicators (especially the dressed, eviscerated and breast muscle yield) of Group D closely resembled Group A more than Groups B and C. Intestinal morphometry found that the jejunal villus height and the villus height/crypt depth were significantly increased in Group D compared to Group A. Next, 16S rRNA amplicon sequencing of the extracted DNA revealed that beneficial microbiota (Coprococcus and Victivallis) showed increased abundance in Group D. Cecal flora function analysis further revealed that some amino acid and glycerol biosynthesis were found to be associated with growth performance in geese. These findings suggest that incorporating 15% FMS as a substitute for a portion of the feed during the fattening phase of XFG can effectively sustain their production performance, optimize the gut microbial community and morphometrical traits, provide new insight into using non-conventional feed resources to reduce feed cost and improve economic benefits in the breeding industry.

Performance evaluation of a lab-scale subsurface flow-constructed wetland system for textile industry wastewater treatment

This study compares biochar (BCW) systems' pollutant removal effectiveness to conventional subsurface flow (CCW) in constructed wetland systems to treat textile wastewater. The two systems were identical in construction, but the biochar was 0.1 m thick over gravel and sand (maximum flow rate of 0.021 m3 h-1) as the primary medium over CCW (flow rate of 0.02 m3 h-1). The results revealed that the BCW approach was more efficient than the CCW system (pebble over sand and gravels) in removing and lowering heavy metals below thresh hold limits such as Cr, Cd, Cu, Pb, Ni, and Zn. The alkaline nature of textile water achieves neutrality in both CCW and BCW. However, BCW is more efficient due to a larger active surface area and the ability to filter out more metal and organic ions. TDS reduction efficiency in BCW was 53.07%, compared to 40.04% in CCW. Heavy metal removal was 100% in BCW at 3 to 12 h, whereas it takes 6 to 24 h in CCW (82% for Cr to 93% for Cu). The quick removal of Na from textile wastewater by BCW was reversed and achieved equilibrium in 24 h in contrast to the CCW system (> 24 h). The findings obtained at the lab scale level demonstrated that the BCW system was more effective in reducing TDS, neutralizing the alkalinity of textile wastewater, and removing heavy metals. This study strongly supports the potential application of biochar-constructed wetlands for textile wastewater treatment.

Comparison of 17β-Estradiol Adsorption on Corn Straw- and Dewatered Sludge-Biochar in Aqueous Solutions

Removal of steroid hormones from aqueous environment is of prevailing concern because of their adverse impact on organisms. Using biochar derived from biomass as adsorbent to remove pollutants has become more popular due to its low cost, effectiveness, and sustainability. This study evaluated the feasibility of applying corn straw biochar (CSB) and dewatered sludge biochar (DSB) to reduce 17β-estradiol (E2) from aquatic solutions by adsorption. The experimental results showed that the adsorption kinetics and isotherm behavior of E2 on the two biochars were well described by the pseudo-second-order (R2 > 0.93) and Langmuir models (R2 > 0.97). CSB has higher E2 adsorption capacity than DSB, and the maximum adsorption capacity was 99.8 mg/g obtained from Langmuir model at 298 K, which can be attributed to the higher surface area, porosity, and hydrophobicity of this adsorbent. Higher pH levels (>10.2) decreased the adsorption capacities of biochar for E2, while the ionic strength did not significantly affect the adsorption process. The regeneration ability of CSB was slightly better than that of DSB. The possible adsorption mechanism for E2 on biochar is suggested as π−π interactions, H−bonding, and micropores filling. These results indicated that CSB has more potential and application value than DSB on reducing E2 from aqueous solutions when considering economy and removal performance.

Removal of pharmaceuticals from water using sewage sludge-derived biochar: A review

In recent years, considerable attention has been paid to the beneficial utilization of sewage sludge to reduce the risks associated with sludge disposal. Besides other applications of sludge, biochar produced from sludge has also been employed for the elimination of various pollutants from water. This review critically evaluates the recent progress in applications of sludge-based biochar for the adsorption of pharmaceuticals from water. The synthesis techniques of biochar production from sludge and their effects on physicochemical characteristics of produced biochar are discussed. The removal of various pharmaceuticals by sludge-based biochar are described in detail, with the emphasis on the adsorption mechanism and their reusability potential. It is evident from the literature that sludge-based biochar has demonstrated excellent potential for the adsorption of numerous pharmaceuticals from the aqueous phase. The major hurdles and issues related to the synthesis of sludge-based biochar and applications are highlighted, with reference to the adsorption of pharmaceuticals. Finally, a roadmap is suggested along with future research directions to ensure the sustainable production of biochar from sludge and its applications in water treatment.

Removal of lead from aqueous solutions using three biosorbents of aquatic origin with the emphasis on the affective factors

The biosorptive potentials of three aquatics-based biosorbents, including shells of a bivalve mollusk and scales of two fish species for Pb removal from aqueous solutions were evaluated, for the first time. A Box-Behnken design with the response surface methodology was used to investigate the effects of the seven important variables (contact time, temperature, initial concentration, dosage, size, salinity and pH) on the sorption capacity of the sorbents. Among the seven studied factors, the effects of biosorbent dosage, initial concentration and pH were significant for all the response variables, while biosorbent size was not significant for any of the responses. The initial concentration was the most influential factor. The presence of Pb ions on the surfaces of the biosorbents after the adsorption was clearly confirmed by the SEM-EDX and XRF analyses. The maximum sorption capacities of the biosorbents were comparable to the literature and the descending order was as follows: scales of Rutilus kutum and Oncorhynchus mykiss and the shells of Cerastoderma glaucum. The isotherm studies revealed Langmuir model applicability for the Pb adsorption by R. kutum and O. mykiss scales, while Freundlich model was fitted to the adsorption C. glaucum shells.

High capacity Pb(II) adsorption characteristics onto raw- and chemically activated waste activated sludge

The Pb(II) adsorption characteristics of chemically activated waste activated sewage sludge (WAS) were compared to raw WAS. Adsorption kinetics and equilibrium isotherm parameters were fit using classic adsorption models. HCl and H₂SO₄ activation terminated any significant sludge-based adsorption. Raw and ZnCl₂ activated WAS displayed Langmuir adsorption capacities of 307 mg/g and 274 mg/g, respectively. Surface characterization revealed that chemical activation with ZnCl₂ increased the BET surface area for raw WAS from 0.97 m²/g to 1.78 m²/g, but did not significantly change the surface structure. FTIR analyzes and XPS were used to further investigate the nature of lead binding. The relationships between equilibrium ion concentration and Pb(II) adsorption suggest cationic exchange with hydrogen, calcium, and zinc as a significant mechanism of Pb(II) removal alongside electrostatic attraction. The pH_PZC was determined as 2.58 and 2.30 for ZnCl₂ activated WAS and raw WAS respectively. HNO₃ and Ca(NO₃)₂ demonstrated sufficient elution properties for WAS recovery. For authentic industrial effluent both raw and ZnCl₂ activated WAS displayed Pb(II) removal behavior comparable to simulated Pb(II) solutions. In comparison with modified and unmodified sludges from literature, this study demonstrates the auspicious potential of raw WAS as an effective Pb(II) adsorbent independent of pyrolytic or chemical activation.

Performance of wild plants-derived biochar in the remediation of water contaminated with lead: sorption optimization, kinetics, equilibrium, thermodynamics and reusability studies

This study aims to investigate the sorptive performance of Pb(II) from water of a novel biochar (WPC) produced by fast pyrolysis under anoxic conditions of wild plants (WP). The maximum Pb(II) sorption capacity of WPC is 50.25 mg/g under determined optimum conditions, which are solution pH 5.0, WPC dose 50 mg, contact time 180 min and solution temperature 50 °C. The sorption kinetics and isotherm data were observed to fit well with the Ho-McKay and Langmuir models, respectively. The thermodynamic parameters (ΔG^o, ΔH^o and ΔS^o) calculated for the WPC-Pb(II) sorption system showed that the process was spontaneous and endothermic. The Pb(II) desorption and regeneration studies of WPC with different desorbent agents was also performed. The findings in this study showed that WP can be used as an abundant precursor in the production of very low cost and eco-friendly biochar, and also that its biochar can be used as an environmentally-friendly sorbent in wastewater treatment. Novelty statementWith increasing population and developing industry in the world, agriculture and industrial wastes are increasing. These wastes create environmental and water pollution and adversely affect the health of living things. Efforts to eliminate these negativities have a negative impact on the world economy. For this purpose, various improvement methods are applied. However, the adsorption method is widely used due to its ease of application, efficiency and economic. In order to make this method more economical, many researchers have carried out researches on the preparation of low-cost adsorbents, especially from vegetable wastes.The novelty of this study is the first reporting to use wild plants as a sustainable precursor to produce a low-cost biochar using the traditional pyrolysis method and to examine its adsorption performance for Pb(II) ion removal from water. I believe that if this study is published, it will create a paradigm in environmental improvement studies on wild plants evaluation.

Preparation and characterization of cornstalk microspheric hydrochar and adsorption mechanism of mesotrione

In this study, cornstalk was pyrolysed to obtain hydrochar (HC), which was used to remove mesotrione from aqueous solutions. HC characterization and batch experiments were conducted to investigate mesotrione adsorption and the underlying mechanism. The characterization revealed microspheres on the HC surface. FT-IR spectra showed that the HC contained a large number of -OH groups, C=C bonds of aromatic rings, C-H groups in aromatic rings and phenolic C-O bonds. The adsorption results showed that the mesotrione adsorption ability gradually increased as the HC preparation temperature increased. The quasi-second-order kinetic equation (R² ≥ 0.9860, p < 0.05) agreed well with the mesotrione adsorption process. The maximum monolayer adsorption capacity, which was obtained at pH 7 and 45°C with HC prepared at 240°C, was 3181.7 mg kg^-1 with the Langmuir isotherm model (R² ≥ 0.9491, p < 0.05). Van der Waals and dipole forces and hydrogen bonds were inferred as the main adsorption mechanisms. HC has potential as an effective and energy-saving adsorbent for mesotrione to reduce environmental pollution.

Conversion of sewage sludge into biochar: A potential resource in water and wastewater treatment

Production of biochar from sewage sludge (SS) is consistent with the goal of sustainable resource recovery and promotes a wastewater-based circular economy. Thermochemical conversion of SS to biochar resolves two major issues simultaneously as it minimizes the cost of disposal and acts as a resource to eliminate the toxic contaminants from water and wastewater. The reusability and ready availability of the biochar, irrespective of the season, makes it an economically viable material for wastewater treatment. In this review, explicit insights into the production, modification and usage of SS derived biochar are provided including (i) the production yield, (ii) characteristic features such as physical, chemical, electrochemical and morphological aspects, and (iii) impact on contaminant removal through adsorption, catalytic and electrochemical processes. Particular attention is given to the use of SS derived biochar as an adsorbent for contaminants present in wastewaters, the potential use of biochar as a catalyst and support material in advanced oxidation processes and the use of biochars as an electrode material. The effect of pyrolysis conditions and co-pyrolysis with other materials on biochar properties is explored and insight is provided into the toxicity of biochar components present at different process conditions.

Chemical structure and mechanism of polysaccharide on Pb2+ tolerance of Cordyceps militaris after Pb2+ domestication

In this study, the purified polysaccharide (DCP-I) was extracted from Cordyceps militaris domesticated with Pb²⁺. After that, the structural feature and mechanism of lead resistance of DCP-I were investigated using novel approaches. The results showed that the average molecular weight of DCP-I was 1.206 × 10³ kDa and mainly consist of Rhamnose, Galactose, Glucose, Galacturonic acid and Glucuronic acid in a molar ratio of 0.130:47.687:40.784:1.795:0.48. Besides, the main chain of DCP-I was composed by →6)-Galp-(1→, →4)-Glcp-(1→ and →1,4)-Glcp-(6→, while the side chain was →1)-Rhaf-(2→ and D-Glcp-(1→, and the DCP-I contained Alacturonic acid and Glucuronic acid. In addition, the result of Congo red test showed that DCP-I did not exist triple-helical structures. SEM, EDX and XPS analyses results showed that the functional groups of DCP-I related to C, H and O (-OH, -COOH and -C=O) could combined with Pb²⁺effectively. The adsorption processes were described by the Pseudo-second-order kinetic model (R² = 0.9978) and Langmuir isotherm (R² = 0.9979) for Pb²⁺ indicating that adsorption process of DCP-I to Pb²⁺ was a kind of single molecular layer chemical adsorption.

The characteristics of oestrone mobility in water and soil by the addition of Ca-biochar and Fe-Mn-biochar derived from Litchi chinensis Sonn

In this study, the effect of biochar (BC) derived from Litchi chinensis Sonn. and its modification, including Ca-biochar (Ca-BC) and Fe-Mn-biochar (Fe-Mn-BC), on the transportation of oestrone (E1) in water and soil was investigated. Fe-Mn-BC showed better adsorption ability than other types of biochar (BC, Ca-BC) under different conditions (humic acid, pH, ionic strength) in an aqueous environment. The maximum mass of sorbent at 298 K increased from 1.12 mg g^-1 (BC) to 4.18 mg g^-1 (Fe-Mn-BC). Humic acid had a greater impact on aqueous E1 adsorption on these biochars than did the pH and ionic strength. Fe-Mn-BC as a soil amendment had a great control of E1 transport in soil, and no leachate of E1 was observed in the column experiment. E1 mobility showed strong retardation in amended soil with Ca-BC (R_f = 11.2) compared with raw soil (R_f = 7.1). These results suggested that Fe-Mn-BC was more effective in controlling E1 transportation, and Fe-Mn-BC could be used as an alternative and inexpensive adsorbent to reduce E1 contaminants from water and soil.

Removal of Aquatic Cadmium Ions Using Thiourea Modified Poplar Biochar

Removal of aquatic cadmium ions using biochar is a low-cost method, but the results are usually not satisfactory. Modified biochar, which can be a low-cost and efficient material, is urgently required for Cd-polluted water and soil remediation. Herein, poplar bark (SB) and poplar sawdust (MB) were used as raw materials to prepare modified biochar, which is rich in N- and S- containing groups, i.e., TSBC-600 and TMBC-600, using a co-pyrolysis method with thiourea. The adsorption characteristics of Cd2+ in simulated wastewater were explored. The results indicated that the modification optimized the surface structure of biochar, Cd2+ adsorption process by both TSBC-600 and TMBC-600 was mainly influenced by the initial pH, biochar dosage, and contact time, sthe TSBC-600 showed a higher adsorption capacity compared to TMBC-600 under different conditions. The Langmuir adsorption isotherm model and pseudo-second-order kinetic model were more consistent with the adsorption behavior of TSBC-600 and TMBC-600 to Cd2+, the maximum adsorption capacity of TSBC-600 and TMBC-600 calculated by the Langmuir adsorption isotherm model was 19.998 mg/g and 9.631 mg/g, respectively. The modification method for introducing N and S into biochar by the co-pyrolysis of biomass and thiourea enhanced the removal rate of aquatic cadmium ions by biochar.

Biochar surface complexation and Ni(II), Cu(II), and Cd(II) adsorption in aqueous solutions depend on feedstock type

Biochar is a promising material for efficient removal of toxic metals from wastewater to meet standards for discharge into surface water. We characterized adsorption behaviour of willow (Salix alba) wood (WW) and cattle manure (CM) and their biochars, willow wood biochar (WWB) and cattle manure biochar (CMB), and elucidated the mechanisms for the removal of Ni(II), Cu(II) and Cd(II) from aqueous solutions. The kinetic adsorption suggests that the adsorption of Ni(II), Cu(II) and Cd(II) by feedstock and their biochars was controlled by mass transport, and chemisorption also played a role in the adsorption process. The Elovich model also well described the adsorption kinetics for WW and CM (R² > 0.92), indicating that heterogeneous diffusion was the mechanism. The Sips isotherm model fitted best (R² > 0.98) for Ni(II), Cu(II) and Cd(II) adsorption by the feedstocks and their biochars, indicating that both monolayer and multilayer adsorption played roles on the heterogeneous surfaces of the four adsorbents. The WWB had a higher while the CMB had a lower adsorption capacity than their respective feedstock due to the presence of abundant -COOH functional group on WWB surface to interact with Ni(II), Cu(II) and Cd(II) to form surface complexes. The higher specific surface area and lower pH of point of zero charge (PZC) of WWB were other contributing factors for its greater removal capacity. Therefore, we conclude that proper feedstocks need to be selected to produce biochars that are efficient for the removal of toxic metals from wastewater.

Preparation and application of magnetic biochar in water treatment: A critical review

In recent years, magnetic biochar has been widely used in removal of pollutants from water. In this paper, the preparation technologies of magnetic biochar are analyzed, and the performance and application of magnetic biochar in removal of inorganic pollutants such as heavy metals, and organic pollutants are investigated. Moreover, the adsorption behaviors, the key influencing factors and the adsorption mechanisms of magnetic biochars are summarized in this paper. Compared with common biochar, magnetic biochar is more effective in removal of water pollutants, including Cd(II), Pb(II), Zn(II), Cu(II), methylene blue, tetracycline, pesticide and phosphate. Langmuir and Freundlich models are adopted as the mainly adsorption isotherms, while pseudo-second-order model is employed as Kinetic model of heavy metal ions and organic contaminants in water. This study also investigates degradation of organic contaminants in water using magnetic biochar as catalyst. Results showed that encapsulated γ-Fe₂O₃ nanoparticles enhanced the catalytic ability of persulfate activator. Further researches on preparation and application of magnetic biochar in water treatment are prospected in this review.

Crayfish shell biochar modified with magnesium chloride and its effect on lead removal in aqueous solution

In this study, crayfish shell was pyrolyzed at 600 °C to obtain an unmodified biochar (CS600). MgCl₂ was used as a modifier to pretreat crayfish shell to produce a modified biochar (CS600-MgCl₂) under the same pyrolysis conditions. The two biochars were characterized for physicochemical properties and evaluated for lead (Pb²⁺) sorption ability to determine the modification mechanism. Mono-element batch adsorption experiments were conducted to compare the sorption performances of CS600 and CS600-MgCl₂ to Pb²⁺ in aqueous solutions. All the experiments were carried out at pH of 7. According to the Freundlich-Langmuir model, CS600-MgCl₂ had a higher adsorption capacity (152.3 mg/g) than CS600 (134.3 mg/g). FTIR, SEM, XRD, BET, and ICP analyses were applied to inform the interpretation of the mechanism. CS600 was calcium-rich and mainly removed Pb²⁺ through the ion exchange mechanism by replacing Ca²⁺ in the biochar. The increased Pb²⁺ adsorption capacity of CS600-MgCl₂ was mainly due to the enlarged specific surface area and the formation of Mg₃(OH)₅Cl·4H₂O on the modified biochar. Findings of this study suggest that both CS600 and CS600-MgCl₂ can be used to remove heavy metal ions from wastewater and MgCl₂ can improve the sorption performance of biochar.

Adsorption characteristics and mechanism of Pb(II) by agricultural waste-derived biochars produced from a pilot-scale pyrolysis system

The objective of this study was to investigate the feasibility of removing Pb²⁺ by pilot-scale fluidized bed biochar, and then to put forward an industrial-scale fluidized bed pyrolysis progress of cogeneration of biochar and high-temperature gas. Corn stalk biochars (CSBs) were prepared at 400-600 °C, in which the maximum Pb²⁺adsorption capacity (Q_m) of CSB450 is 49.70 mg⋅g^-1 at the optimal condition. Adsorption isotherms, kinetics, and thermodynamics were determined, and Pb²⁺-loaded biochar was analyzed by fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD) and scanning electron microscope with energy dispersive spectrometer (SEM-EDS). Ion exchange, complexation and mineral precipitation together contributed to Pb²⁺ adsorption on CSBs. For high-temperature CSBs with fewer oxygen functional groups (OFGs) and stronger aromatization, Pb²⁺ adsorption by ion exchange and functional group complexation was reduced. The mineral precipitationwas formed during the adsorption process. Using the pilot-scale fluidized bed in this study, the carbon yield per year would achieve 31.79 t, and about 1.58 t of Pb²⁺ would be adsorbed according to the adsorption capacity at the pyrolytic temperature of 450 °C.The results are beneficial to screen for effective biochar as a cost-effective industrial adsorbent to remove Pb²⁺ in contaminated water.

Effect of corn straw biochar application to sediments on the adsorption of 17α-ethinyl estradiol and perfluorooctane sulfonate at sediment-water interface

The immobilization of organic contaminants in sediment-water systems is of growing concern. Using biochar as sorbent amendment to reduce the mobility of pollutants in the sediment-water interface is becoming increasingly popular as a low-cost and environmentally friendly option. In this study, we mixed sediment from the Weishan Lake with biochar (0%, 2%, and 5% (w/w)) derived from corn straw to investigate the adsorption of perfluorooctane sulfonate (PFOS) and 17α-ethinyl estradiol (EE2). Biochar addition significantly improved the adsorption rates and capacities of EE2 and PFOS on sediments by the factors 1.7-3.5; the organic carbon concentration in the sediment was the main factor influencing this process. The sorption of EE2 and PFOS to sediment was near-linear (Freundlich exponent 1/n of 0.799-0.805), but non-linear for biochar (0.430-0.476) and sediment+biochar (0.370-0.421). The mobility of PFOS in the water-sediment system after biochar addition was significantly reduced, with a considerable increase (about three times) in the sediment-water distribution coefficient K_d. Compared to EE2, PFOS is anionic compound and contains hydrophobic C-F chains and hydrophilic S-O groups, making it more susceptible pH influences and resulting in interactions with-OH, -C=O, Si-O-Si, -O-Si, and -Al-O-Al groups via hydrogen bonding, ligand exchange, and surface complexation. We suggest that biochar amendment at ～5% is a viable approach to immobilize EE2 and PFOS at the sediment-water interface.

Soil lead immobilization by biochars in short-term laboratory incubation studies

Exchangeable lead (Pb) extracted by ammonium acetate from three independent incubation studies was assessed to understand the influence of feedstock, pyrolysis temperatures, and production conditions on Pb immobilization capacities of different biochars. Vegetable waste biochar, pine cone, wood bark, cocopeat, red pepper stalk, and palm kernel shell were used as feedstocks (food supply and agricultural wastes) to produce biochars at 200-650 °C with and without N₂/CO₂. Biochars were applied at 5 and 2.5% (w w^-1) to a Pb contaminated (i.e., 1445 mg kg^-1) agricultural soil collected near an old mine. Lead immobilization in biochar treated soils at the end of incubation period was normalized per gram of biochar applied. Biochar produced from vegetable waste at 500 °C showed the highest Pb immobilization (87%) and highest total exchangeable cations (13.5 cmol₍₊₎ kg^-1) at the end of the 45 d incubation period. However, on the basis of Pb immobilization per gram of biochar, red pepper stalk biochar produced in CO₂ at 650 °C was the best in Pb immobilization (0.09 mg kg^-1 g^-1 biochar) compared to the other biochars. The enhanced ability to immobilize Pb by biochar produced in CO₂ could be due to the presence of siloxanes (SiOSi) on biochar surface. Pearson correlation analysis revealed that alkaline pH, ash%, and N% of biochars influence in Pb immobilization and exchangeable cation availability in soil. Biochar production atmosphere considerably change its properties that influence Pb immobilization. Further studies are needed on the modification of properties and Pb immobilization by biochars produced from various feedstocks in CO₂.

Effect of Fe-functionalized biochar on toxicity of a technosol contaminated by Pb and As: sorption and phytotoxicity tests

Biochar, produced by the pyrolysis of biomass under low oxygen conditions, has gathered attention in the last few years due to its capability to reduce metal(loid)s bioavailability and mobility in soils, as well as its beneficial effects on soil fertility. Indeed, biochar amendment to polluted soil induced usually an increase of pH, water holding capacity, and nutrient contents, associated with a decrease of metal(loid)s concentrations in soil pore water, through sorption. However, biochar has been shown efficient in sorbing cation pollutants, like Pb, but present a low sorption capacity towards anions like As. This contrasted behavior poses a problem, as most polluted soils are multi-contaminated, with both cation and anion pollutants. One of the solutions to overcome such problem is to functionalize biochar, by modifying its surface. However, most studies actually focused on functionalization effect on metal(loid)s sorption towards batch experiments, and only a few dealt with modified biochar incorporation to the soil. Therefore, this study aimed (i) to assess the sorption capacity of hardwood biochars, harboring different particle sizes, towards Pb and As; (ii) to evaluate the effect of a Fe-functionalization on Pb and As sorption; and (iii) to validate the results, in a phytotoxicity test using Phaseolus vulgaris as bioindicator plant. The batch experiments showed that all four biochars were able to efficiently sorb Pb, the fine biochars showing higher sorption values than the coarse biochars. As sorption was very low. Fe-coating increased As sorption value, while having no effect on Pb sorption. However, when incorporated in the soil, Fe-coated biochar did not improve soil physico-chemical properties compared to the pristine biochar; especially, it did not reduce As soil pore water concentrations. Finally, bean plant did not show differences in terms of biomass production between the two biochars incorporated into polluted soil, demonstrating that Fe-functionalization did not improve biochar capacity to decrease soil toxicity.

Lead and uranium sorptive removal from aqueous solution using magnetic and nonmagnetic fast pyrolysis rice husk biochars

This paper discusses the sorption characteristics of Pb(ii) and U(vi) on magnetic and nonmagnetic rice husk biochars.