[Effects of Modified Distillers' Grains Biochar on Cadmium Forms in Purple Soil and Cadmium Uptake by Rice].

Biochar and modified biochar have been widely used as remediation materials in heavy metal-contaminated agricultural soils. In order to explore economical and effective materials for the remediation of cadmium (Cd)-contaminated acidic purple soil, distillers 'grains were converted into distillers' grains biochar (DGBC) and modified using nano-titanium dioxide (Nano-TiO2) to produce two types of modified DGBCs:TiO2/DGBC and Fe-TiO2/DGBC. A rice pot experiment was used to investigate the effects of different biochar types and application rates (1%, 3%, and 5%) on soil properties, nutrient content, Cd bioavailability, Cd forms, rice growth, and Cd accumulation. The results showed that:① DGBC application significantly increased soil pH, cation exchange capacity (CEC), and nutrient content, with TiO2/DGBC and Fe-TiO2/DGBC exhibiting better effects. ② DGBC and modified DGBCs transformed Cd from soluble to insoluble forms, increasing residual Cd by 1.22% to 18.46% compared to that in the control. Cd bioavailability in soil decreased significantly, with available cadmium being reduced by 11.81% to 23.67% for DGBC, 7.64% to 43.85% for TiO2/DGBC, and 19.75% to 55.82% for Fe-TiO2/DGBC. ③ DGBC and modified DGBCs increased rice grain yield, with the highest yields observed at a 3% application rate:30.60 g·pot-1 for DGBC, 37.85 g·pot-1 for TiO2/DGBC, and 39.10 g·pot-1 for Fe-TiO2/DGBC, representing 1.13, 1.40, and 1.44 times the control yield, respectively. Cd content in rice was significantly reduced, with grain Cd content ranging from 0.24 to 0.30 mg·kg-1 for DGBC, 0.16 to 0.26 mg·kg-1 for TiO2/DGBC, and 0.14 to 0.24 mg·kg-1 for Fe-TiO2/DGBC. Notably, Cd content in rice grains fell below the food safety limit of 0.2 mg·kg-1 (GB2762-2022) at 5% for TiO2/DGBC and 3% and 5% for Fe-TiO2/DGBC. In conclusion, Nano-TiO2 modified DGBC effectively reduced the bioavailability of soil Cd through its own adsorption and influence on soil Cd forms distribution, thus reducing the absorption of Cd by rice and simultaneously promoting rice growth and improving rice yield. It is a type of Cd-contaminated soil remediation material with a potential application prospect. The results can provide scientific basis for farmland restoration and agricultural safety production of Cd-contaminated acidic purple soil.

Spectral characterization of the impact of modifiers and different prepare temperatures on snow lotus medicinal residue-biochar and dissolved organic matter.

This study involved the production of 20 biochar samples derived from secondary medicinal residues of Snow Lotus Oral Liquid, processed within the temperature range of 200-600 °C. Additionally, four medicinal residues, including dissolved organic matter (DOM), from 24 samples obtained using the shaking method, served as the primary source material. The investigation focused on two key factors: the modifier and preparation temperature. These factors were examined to elucidate the spectral characteristics and chemical properties of the pharmaceutical residues, biochar, and DOM. To analyze the alterations in the spectral attributes of biochar and medicinal residues, we employed near-infrared spectroscopy (NIR) in conjunction with Fourier-infrared one-dimensional and two-dimensional correlation spectroscopy. These findings revealed that modifiers enhanced the aromaticity of biochar, and the influence of preparation temperature on biochar was diminished. This observation indicates the stability of the aromatic functional group structure. Comparative analysis indicated that Na2CO3 had a more pronounced structural effect on biochar, which is consistent with its adsorption properties. Furthermore, we utilized the fluorescence indices from UV-visible spectroscopy and excitation-emission-matrix spectra with the PARAFAC model to elucidate the characteristics of the fluorescence components in the DOM released from the samples. The results demonstrated that the DOM released from biochar primarily originated externally. Aromaticity reduction and increased decay will enhance the ability of the biochar to bind pollutants. Those results confirmed the link between the substantial increase in the adsorption performance of the high-temperature modified charcoal in the previous study and the structural changes in the biochar. We investigated the structural changes of biochar and derivative DOM in the presence of two perturbing factors, modifier and preparation temperature. Suitable modifiers were selected. Preparation for the study of adsorption properties of snow lotus medicinal residues.

Synthesis of struvite-enriched slow-release fertilizer using magnesium-modified biochar: Desorption and leaching mechanisms.

To improve the retention and slow-release abilities of nitrogen (N) and phosphorus (P), an 82 %-purity struvite fertilizer (MAP-BC) was synthesized using magnesium-modified biochar and a solution with a 2:1 concentration ratio of NH4+ to PO43- at a pH of 8. Batch microscopic characterizations and soil column leaching experiments were conducted to study the retention and slow-release mechanisms and desorption kinetics of MAP-BC. The slow-release mechanism revealed that the dissolution rate of high-purity struvite was the dominant factor of NP slow release. The re-adsorption of NH4+ and PO43- by biochar and unconsumed MgO prolonged slow release. Mg2+ ionized by MgO could react with PO43- released from struvite to form Mg3(PO4)2. The internal biochar exhibited electrostatic attraction and pore restriction towards NH4+, while magnesium modification and nutrient loading formed a physical antioxidant barrier that ensured long-term release. The water diffusion experiment showed a higher cumulative release rate for PO43- compared to NH4+, whereas in soil column leaching, the trend was reversed, suggesting that soil's competitive adsorption facilitated the desorption of NH4+ from MAP-BC. During soil leaching, cumulative release rates of NH4+ and PO43- from chemical fertilizers were 3.55-3.62 times faster than those from MAP-BC. The dynamic test data for NH4+ and PO43- in MAP-BC fitted the Ritger-Peppas model best, predicting release periods of 163 days and 166 days, respectively. The leaching performances showed that MAP-BC reduced leaching solution volume by 5.58 % and significantly increased soil large aggregates content larger than 0.25 mm by 24.25 %. The soil nutrients retention and pH regulation by MAP-BC reduced leaching concentrations of NP. Furthermore, MAP-BC significantly enhanced plant growth, and it is more suitable as a NP source for long-term crops. Therefore, MAP-BC is expected to function as a long-term and slow-release fertilizer with the potential to minimize NP nutrient loss and replace part of quick-acting fertilizer.

Novel mint-stalks derived biochar for the adsorption of methylene blue dye: Effect of operating parameters, adsorption mechanism, kinetics, isotherms, and thermodynamics.

The pyrolysis of mint stalks and lemon peels was performed to synthesize mint-stalks (MBC) and lemon-peels (LBC) derived biochars for adsorbing methylene blue (MB). The preparation, characterization, and application of MBC in adsorption have not been reported in the literature. MBC showed higher surface area and carbon content than that of LBC. The removal ratios of MB were 87.5% and 60% within 90 min for MBC and LBC, respectively at pH 7, temperature of 30oC, adsorbent dose of 0.5 g/L, and MB concentration of 5 mg/L. The optimal MBC dose was 1 g/L achieving a removal efficiency of 93.6% at pH 7, temperature of 30oC, contact time of 90 min, and initial dye concentration of 5.0 mg/L. The adsorption efficiency decreased from 98.6% to 31.33% by raising the dye concentration from 3.0 mg/L to 30 mg/L. Further, the increase of adsorbent dose to 10 g/L could achieve 94.2%, 90.3%, 87.6%, and 84.1% removal efficiencies of MB in the case of initial concentrations of 200 mg/L, 300 mg/L, 400 mg/L, and 500 mg/L, respectively. MBC showed high stability in adsorbing MB under five cycles, and the performed analyses after adsorption reaffirmed the stability of MBC. The adsorption mechanism indicated that the adsorption of MB molecules on the biochar's surface was mainly because of the electrostatic interaction, hydrogen bonding, and π-π stacking. Pseudo-second-order and Langmuir models could efficiently describe the adsorption of MB on the prepared biochar. The adsorption process is endothermic and spontaneous based on the adsorption thermodynamics. The proposed adsorption system is promising and can be implemented on a bigger scale. Moreover, the prepared biochar can be implemented in other applications such as photocatalysis, periodate, and persulfate activation-based advanced oxidation processes.

A new strategy for improving the energy efficiency of electro-Fenton: Using N-doped activated carbon cathode with strong Fe(III) adsorption capacity to promote Fe(II) regeneration.

Fe(II) regeneration plays a crucial role in the electro-Fenton process, significantly influencing the rate of ·OH formation. In this study, a method is proposed to improve Fe(II) regeneration through N-doping aimed at enhancing the adsorption capacity of the activated carbon cathode for Fe(III). N-doping not only enriched the pore structure on the surface of activated carbon, providing numerous adsorption sites, but also significantly increased the adsorption energy for Fe(III). Among the types of nitrogen introduced, pyridine-N exhibited the most substantial enhancement effect, followed by pyrrole-N, while graphite-N showed a certain degree of inhibition. Furthermore, N-doping facilitated the adsorption of all forms of Fe(III) by activated carbon. The adsorption and electrosorption rates of the NAC-900 electrode for Fe(III) were 30.33% and 42.36%, respectively. Such modification markedly enhanced the Fe3+/Fe2+ cycle within the electro-Fenton system. The NAC-900 system demonstrated an impressive phenol degradation efficiency of 93.67%, alongside the lowest electricity consumption attributed to the effective "adsorption-reduction" synergy for Fe(III) on the NAC-900 electrode. Compared to the AC cathode electro-Fenton system, the degradation efficiency of the NAC-900 cathode electro-Fenton system at pH = levels ranging from 3 to 5 exceeded 90%; thus, extending the pH applicability of the electro-Fenton process. The degradation efficiency of phenol using the NAC-900 cathode electro-Fenton system in various water matrices approached 90%, indicating robust performance in real wastewater treatment scenarios. This research elucidates the impact of cathodic Fe(III) adsorption on Fe(II) regeneration within the electro-Fenton system, and clarifies the influence of different N- doping types on the cathodic adsorption of Fe(III).

Biochar aided priming of carbon and nutrient availability in three soil orders of India.

In recent years biochar (BC) has gained importance for its huge carbon (C) sequestration potential and positive effects on various soil functions. However, there is a paucity of information on the long-term impact of BC on the priming effect and nutrient availability in soil with different properties. This study investigates the effects of BC prepared from rice husk (RBC4, RBC6), sugarcane bagasse (SBC4, SBC6) and mustard stalk (MBC4, MBC6) at 400 and 600 °C on soil C priming and nitrogen (N), phosphorus (P), and potassium (K) availability in an Alfisol, Inceptisol, and Mollisol. BC properties were analyzed, and its decomposition in three soil orders was studied for 290 days in an incubation experiment. Post-incubation, available N, P, and K in soil were estimated. CO2 evolution from BC and soil alone was also studied to determine the direction of priming effect on native soil C. Increasing pyrolysis temperature enhanced pH and EC of most of the BC. The pyrolysis temperature did not show clear trend with respect to priming effect and nutrient availability across feedstock and soil type. MBC6 increased C mineralization in all the soil orders while RBC6 in Alfisol and SBC6 in both Inceptisol and Mollisol demonstrated high negative priming, making them potential amendments for preserving native soil C. Most of the BC showed negative priming of native SOC in long run (290 days) but all these BC enhanced the available N, P, and K in soil. SBC4 enhanced N availability in Alfisol and Inceptisol, RBC4 improved N and P availability in Mollisol and P in Alfisol and MBC6 increased K availability in all the soils. Thus, based on management goals, tailored BC or blending different BC can efficiently improve C sequestration and boost soil fertility.

Does livestock-Manure-Derived Biochar Suitable for the Stabilization of Cadmium and Zinc in Contaminated Soil?

Both livestock-manure and livestock-manure-derived biochar have been used to remediate heavy metal-contaminated soil. However, direct comparisons of the heavy metal stabilization efficiency of livestock-manure and EQC-manure-biochar (derived from an equal quantity of corresponding livestock-manure) are limited. In the present study, the effect of livestock-manures and EQC-manure-biochars on soil properties and heavy metal bioavailability and leachability were compared using two contrasting soils (Ferralsols and Fluvisols). The results showed that both the livestock-manures and EQC-manure-biochars significantly changed soil pH, available phosphorus, available potassium, alkaline nitrogen and organic matter content (p < 0.05), but the trends were variable. In Ferralsols, the DTPA-extractable Cd and Zn decreased by -0.38%~5.70% and - 3.79%~9.98% with livestock-manure application and by -7.99%~7.23% and - 5.67%~7.17% with EQC-manure-biochars application. In Fluvisols, the DTPA-extractable Cd and Zn decreased by 13.39%~17.41% and - 45.26%~14.24% with livestock-manure application and by 10.76%~16.90% and - 36.38%~16.37% with EQC-manure-biochar application. Furthermore, the change in TCLP-extractable Cd and Zn in both soils was similar to that of DTPA-extractable Cd and Zn. Notably, the Cd and Zn stabilization efficiency of the EQC-manure-biochars was no better than that of the corresponding livestock-manures. These results suggest that the use of livestock-manure-derived biochar is not cost-effective for the remediation of heavy metal-contaminated soil.

Effect of Deashing Treatment on Ash Fusion Characteristics of Biochar from Bamboo Shoot Shells.

To investigate the influence of deashing on fusion characteristics, a combined method of water and acid washing with different sequences (water washing followed by acid washing, and acid washing followed by water washing) was used to treat the biochar of bamboo shoot shells (BBSSs). The results show that deashing decreased the K content of the biochar from 50.3% to 1.08% but increased the Si content from 33.48% to 89.15%. The formation of silicates and aluminosilicates from alkali metal oxides with silicon was an inevitable result of ash phase transformation at the high temperatures used to improve the fusion temperature (>1450 °C). The thermochemical behavior of ash mainly occurs at 1000 °C. The deashing treatment significantly reduced the reaction intensity during the high-temperature process. This significantly increased the thermal stability of the ash. The adjustment of the washing sequence had a slight impact on the chemical compositions, but the differences in ash micromorphology were obvious. Deashing treatments with different washing sequences can significantly improve ash fusion properties effectively and reduce the risk of scaling, slagging, and corrosion. This study provides a new and reasonable strategy for the deashing of biochar to commercially utilize bamboo shoot shell resources.

In-situ synthesis of ZIF-8 on magnetic pineapple leaf biochar as an efficient and reusable adsorbent for methylene blue removal from wastewater.

The presence of organic dyes in aquatic systems poses a significant threat to ecosystems and human well-being. Due to recycling challenges, traditional commercial activated carbon is not cost-effective. To address this, an imidazolate acid zeolite framework-8 (ZIF-8)-modified magnetic adsorbent (ZMPLB-800) was synthesized through the in-situ formation of ZIF-8 and subsequent carbonization at 800 °C, using magnetic pineapple leaf biochar (MPLB) as a carrier. The porous structure of ZMPLB-800 facilitates the rapid passage of dye molecules, enhancing adsorption performance. ZMPLB-800 exhibited remarkable adsorption capacity for methylene blue (MB) across a pH range of 3-13, with a maximum adsorption capacity of 455.98 mg g-1. Adsorption kinetics and thermodynamics followed the pseudo-second-order kinetic model and Langmuir isotherm model. Mechanisms of MB adsorption included pore filling, hydrogen bonding, electrostatic interactions, π-π interactions, and complexation through surface functional groups. Additionally, ZMPLB-800 demonstrated excellent regeneration performance, recording a removal efficiency exceeding 87% even after five adsorption/desorption cycles. This study provides a novel strategy for treating dye wastewater with MOF composites, laying the foundation for waste biomass utilization.

The spatiotemporal heterogeneity of fertosphere hotspots impacted by biochar addition and the implications for NH3 and N2O emissions.

The fertosphere, as the interfaces between fertilizer granular and soil particles, represents a key hotspot for nitrogen transformation processes, particularly for ammonia (NH3) and nitrous oxide (N2O) emissions. Understanding the heterogeneity of the fertosphere, especially when incorporating organic amendments like biochars, is crucial for predicting NH3 and N2O emissions after soil fertilization. In this study, we investigated the effects of three types of biochar (pristine, aged, and acid-washed biochar) on heterogeneity of fertosphere induced by localized urea application. pH-specific planar optodes were employed to visualize pH gradients in fertosphere hotspots with high spatial and temporal resolution. In addition, we conducted thorough measurements of the gradient distribution of electric conductivity (EC), mineral N, aqueous NH3 in soil and enzyme activities relevant to nitrification. Concurrently, NH3 and N2O emissions from the soil were continuously monitored at a high temporal resolution. Initially, urea-induced fertosphere exhibited significant NH3 emissions, primarily attributed to the pH elevation resulting from urea hydrolysis. However, after 6 days, NH3 emissions subsided, and there was a notable sharp increase in N2O emissions. Importantly, compared to urea application alone, the inclusion of pristine biochar led to a delay in soil pH decline with a 19% rise in NH3 emission. Aged biochar, characterized by a higher content of oxygen functional groups, demonstrated increased NH4+/NH3 adsorption capacity and enhanced ammonia monooxygenase (AMO) activity in soil, resulting in an 18% reduction in NH3 emission. While a slight decrease of 5% in NH3 cumulative emission was observed in the acid-washed biochar treatment. Notably, biochar could potentially promote nitrification-derived N2O emissions due to the accumulation of NH3 oxidation products (NH2OH). These findings could contribute to refining N transformation models for fertilized soils, and optimizing N fertilizer application strategies.

Using the benzenepolycarboxylic acid (BPCA) method to assess activated biochars and their PFAS sorption abilities.

Activated carbon (AC) has important industrial and environmental applications as it has excellent abilities to sorb contaminants such as per- and polyfluoroalkyl substances (PFAS). Current research aims to develop activated biochars (AB) from renewable biomass to replace AC that is produced from fossil feedstock. Both AC and AB are primarily comprised of condensed aromatic carbon (ConAC), the component that is the focus of this study. ConAC is characterized to determine its relationship with biochar activation conditions and PFAS sorption, which are understudied at present. Benzenepolycarboxylic acid (BPCA) markers for ConAC were quantified in steam-activated biochars (AB-Steam) and carbon dioxide-activated biochars (AB-CO2) prepared from waste timber at different temperatures (800, 850, 900 °C) and molar ratios of feedstock-carbon:steam (0.50 - 1.25). A non-activated biochar was also included as a reference. ConAC relative to total organic carbon content was higher in AB-Steam than in AB-CO2 (92 ± 2 % vs. 81 ± 11%). The ratio of benzenehexa- (B6CA) to benzenepentacarboxylic (B5CA) acids revealed that AB-Steam also had larger ConAC clusters than AB-CO2. These findings provide novel evidence that steam activation is more effective than CO2 activation in creating ConAC. To assess how ConAC impacts AB sorption abilities, AB-Steam were used to remediate PFAS from contaminated soils. The observed strong correlations between ConAC content and sorption of long-chain PFAS suggest the importance of hydrophobic interactions between PFAS tails and ConAC. Poor correlations for short-chain PFAS, on the other hand, indicated the existence of electrostatic repulsion interactions between PFAS head groups and ConAC. Collectively, these results explain the great ability of AB-Steam to sorb PFAS from contaminated soils (up to 100% remediation). More broadly, this work demonstrates that the BPCA method can be a valuable tool to assess the quality of biochars and other carbonaceous sorbents in relation to their production conditions or contaminant sorption abilities.

Prediction and optimizing of methylene blue sequestration to activated charcoal/magnetic nanocomposites using artificial neutral network and response surface methodology.

Green synthesized magnetic nanoparticles (MNPs) linked with activated charcoal (AC) (AC/Fe3O4 NCs) were exploited for methylene blue (MB) confiscation in this study. The AC/Fe3O4 NCs produced were characterized using TEM, FTIR, UV/Vis and XRD spectrometry. The Response-Surface-Methodology (RSM) was utilized to improve the experimental data for the MB sorption to AC/Fe3O4 NCs, with 20 experimental runs implemented through a central composite design (CCD) to assess the effect of sorption factors-initial MB concentration, pH and sorbent dosage effects on the response (removal-effectiveness). The quadratic model was discovered to ideally describe the sorption process, with an R2 value of 0.9857. The theoretical prediction of the experimental data using the Artificial-Neural-Network (ANN) model showed that the Levenberg-Marquardt (LM) had a better performance criterion. Comparison between the modelled experimental and predicted data showed also that the LM algorithm had a high R2 of 0.9922, which showed NN model applicability for defining the sorption of MB to AC/Fe3O4 NCs with practical precision. The results of the non-linear fitting (NLF) of both isotherm and kinetic models, showed that the sorption of MB to AC/Fe3O4 NCs was perfectly described using the pseudo-second-order (PSOM) and Freundlich (FRHM) models. The estimated optimum sorption capacity was 455 mg g-1. Thermodynamically, the sorption of MB to AC/Fe3O4 NCs was shown to be non-spontaneous and endothermic.

Sustainable removal of caffeine and acetaminophen from water using biomass waste-derived activated carbon: Synthesis, characterization, and modelling.

The removal of caffeine (CFN) and acetaminophen (ACT) from water using low-cost activated carbons prepared from artichoke leaves (AAC) and pomegranate peels (PAC) was reported in this paper. These activated carbons were characterized using various analytical techniques. The results showed that AAC and PAC had surface areas of 1203 and 1095 m2 g-1, respectively. The prepared adsorbents were tested for the adsorption of these pharmaceuticals in single and binary solutions. These experiments were performed under different operating conditions to evaluate the adsorption properties of these adsorbents to remove CFN and ACT. AAC and PAC showed maximum adsorption capacities of 290.86 and 258.98 mg g-1 for CFN removal, 281.18 and 154.99 mg g-1 for the ACT removal over a wide pH range. The experimental equilibrium adsorption data fitted to the Langmuir model and the kinetic data were correlated with the pseudo-second order model. AAC showed the best adsorption capacities for the removal of these pharmaceuticals in single systems and, consequently, it was tested for the simultaneous removal of these pollutants in binary solutions. The simultaneous adsorption of these compounds on AAC was improved using the central composite design and response surface methodology. The results indicated an antagonistic effect of CFN on the ACT adsorption. AAC regeneration was also analyzed and discussed. A statistical physics model was applied to describe the adsorption orientation of the tested pollutants on both activated carbon samples. It was concluded that AAC is a promising adsorbent for the removal of emerging pollutants due to its low cost and reusability properties.

A systematic review on enhancement strategies in biochar-based remediation of polycyclic aromatic hydrocarbons.

Polycyclic aromatic hydrocarbons (PAHs) are pervasive ecological pollutants produced essentially during the inadequate burning of organic materials. PAHs are a group of different organic compounds that are made out of various aromatic rings. PAHs pose a serious risk to humans and aquatic ecosystems because of their mutagenic and carcinogenic properties. In this way, there is a critical prerequisite to utilizing successful remediation strategies and methods to limit the dangerous effect of these pollutants on the ecosystem. Biochar has believed of intriguing properties such as simple manufacturing operations and more affordable and more productive materials. Biochar is a sustainable carbonaceous material that has an enormous surface area with bountiful functional groups and pore structure, which has huge potential for the remediation of toxic pollutants. This review emphasizes the occurrence, development, and fate of toxic PAHs in the environment. In the present review, the properties and role of biochar in the removal of PAHs were illustrated, and the influencing factors and an efficient key mechanism of biochar for the remediation of PAHs were discussed in detail. Various surface modification methods can be utilized to improve the biochar properties with the magnetization process; the advancements of modified biochar are pointed out in this review. Finally, the constraints and prospects for the large-scale application of biochar in the remediation of toxic pollutants are highlighted.

Pyrolysis of biomass harvested from heavy-metal contaminated area: Characteristics of bio-oils and biochars from batch-wise one-stage and continuous two-stage pyrolysis.

This study evaluates pyrolysis products obtained from biomasses (silver grass, pine, and acacia) harvested from heavy-metal-contaminated soil. To do so, we utilized two methods: a batch one-stage pyrolysis, and a continuous two-stage pyrolysis. The study results show that the yields and characteristics of bio-oils and biochars varied depending on the pyrolysis process and the type of biomass. The two-stage pyrolysis having two reactors (auger and fluidized bed reactors) appeared to be very suitable for specific chemicals production such as acetic acid, acetol, catechol, and levoglucosan. The biochar obtained from the fluidized-bed reactor of two-stage pyrolysis had high thermal stability, high crystallinity, high inorganic content, and a small number of functional groups. In contrast, the biochar obtained from the one-stage pyrolysis had low thermal stability, low crystallinity, a high carbon content, and a large number of functional groups. The biochar obtained from the two-stage pyrolysis appeared to be suitable as a material for catalyst support and as an adsorbent. The biochar obtained from one-stage pyrolysis appeared to be a suitable as a soil amendment, as an adsorbent, and as a precursor of activated carbon. All biochars showed a negative carbon footprint. In the end, this study, which was conducted using two different processes, was able to obtain the fact that products of pyrolysis biomass contaminated with heavy metals have different characteristics depending on the process characteristics and that their utilization plans are different accordingly. If the optimal utilization method proposed through this study is found, pyrolysis will be able to gain importance as an effective treatment method for biomass contaminated with heavy metals.

Machine learning application for predicting key properties of activated carbon produced from lignocellulosic biomass waste with chemical activation.

The successful application of gradient boosting regression (GBR) in machine learning to forecast surface area, pore volume, and yield in biomass-derived activated carbon (AC) production underscores its potential for enhancing manufacturing processes. The GBR model, collecting 17 independent variables for two-step activation (2-SA) and 14 for one-step activation (1-SA), demonstrates effectiveness across three datasets-1-SA, 2-SA, and a combined dataset. Notably, in 1-SA, the GBR model yields R2 values of 0.76, 0.90, and 0.83 for TPV, yield, and SSA respectively, and records R2 of 0.90 and 0.91 for yield in 2-SA and combined datasets. The model highlights the significance of the soaking procedure alongside activation temperature in shaping AC properties with 1-SA or 2-SA, illustrating machine learning's potential in optimizing AC production processes.

[Adsorption Properties of Magnetic Phosphorous Camellia Oleifera Shells Biochar to Sulfamethoxazole in Water].

Magnetic phosphorous biochar （MPBC） was prepared from Camellia oleifera shells using phosphoric acid activation and iron co-deposition. The materials were characterized and analyzed through scanning electron microscopy （SEM）， X-ray diffractometry （XRD）， specific surface area and pore size analysis （BET）， Fourier infrared spectroscopy （FT-IR）， and X-ray photoelectron spectroscopy （XPS）. MPBC had a high surface area （1 139.28 m2·g-1） and abundant surface functional groups， and it could achieve fast solid-liquid separation under the action of an external magnetic field. The adsorption behavior and influencing factors of sulfamethoxazole （SMX） in water were investigated. The adsorbent showed excellent adsorption properties for SMX under acidic and neutral conditions， and alkaline conditions and the presence of CO32- had obvious inhibition on adsorption. The adsorption process conformed to the quasi-second-order kinetics and Langmuir model. The adsorption rate was fast， and the maximum adsorption capacity reached 356.49 mg·g-1. The adsorption process was a spontaneous exothermic reaction， and low temperature was beneficial to the adsorption. The adsorption mechanism was mainly the chemisorption of pyrophosphate surface functional groups （C-O-P bond） between the SMX molecule and MPBC and also included hydrogen bonding， π-π electron donor-acceptor （π-πEDA） interaction， and a pore filling effect. The development of MPBC adsorbent provides an effective way for resource utilization of waste Camellia oleifera shells and treatment of sulfamethoxazole wastewater.

[Safe Utilization Effect of Passivator on Mild to Moderate Cadmium Contaminated Farmland].

In order to study the safe utilization of acid cadmium （Cd） contaminated soil， light and moderate Cd-contaminated farmland in Shangluo， Shaanxi Province was taken as the research object， and lime， biochar， and calcium magnesium phosphate fertilizer were applied. Through the wheat-maize rotation experiment， the safe utilization effect of different amounts of passivator on Cd-contaminated soil was explored， and the best ratio of passivator was selected. The results showed that： ① the soil quality could be improved to varying degrees by applying the passivator. ② After the application of amendments， the grain yield of wheat and maize increased to different degrees. ③ The lime 2 340 kg·hm-2 （C3） treatment had the best effect， which increased the soil pH of wheat and corn by 1.453 and 1.717 units， respectively， and reduced the available Cd content by 34.38% and 30.20%， respectively. ④ The application of biochar 1 800 kg·hm-2 （B2） treatment had the best effect on reducing the Cd contents in wheat roots， straws， and grains， which were significantly reduced by 53.60%， 38.86%， and 52.96%， respectively， compared with that in CK. The Cd content in wheat grains was reduced to 0.09 mg·kg-1， which was lower than the limit value of wheat Cd （0.1 mg·kg-1） specified in the "National food safety standard food pollutant limit" （GB 2762-2017）. The application of the biochar 1 260 kg·hm-2 （B1） treatment had the best comprehensive effect on reducing the Cd contents of maize roots， straws， and grains， which were significantly reduced by 43.74%， 53.20%， and 94.57%， respectively， compared with that in CK. The Cd content of maize grains was reduced to 0.001 9 mg·kg-1， which was far lower than the limit value of maize Cd （0.1 mg·kg-1） specified in the "National food safety standard food pollutant limit" （GB 2762-2017）. Therefore， under the conditions of the field experiment， considering the influence of various indexes， biochar had the best effect on farmland soil in the wheat-maize rotation area with mild to moderate Cd pollution.

Efficient Adsorption of Nitrogen and Phosphorus in Wastewater by Biochar.

Nitrogen and phosphorus play essential roles in ecosystems and organisms. However, with the development of industry and agriculture in recent years, excessive N and P have flowed into water bodies, leading to eutrophication, algal proliferation, and red tides, which are harmful to aquatic organisms. Biochar has a high specific surface area, abundant functional groups, and porous structure, which can effectively adsorb nitrogen and phosphorus in water, thus reducing environmental pollution, achieving the reusability of elements. This article provides an overview of the preparation of biochar, modification methods of biochar, advancements in the adsorption of nitrogen and phosphorus by biochar, factors influencing the adsorption of nitrogen and phosphorus in water by biochar, as well as reusability and adsorption mechanisms. Furthermore, the difficulties encountered and future research directions regarding the adsorption of nitrogen and phosphorus by biochar were proposed, providing references for the future application of biochar in nitrogen and phosphorus adsorption.

Efficient Cr(VI) removal by pyrite/porous biochar: Critical role of potassium salt and sulphur.

The excessive accumulation of hexavalent chromium (Cr(VI)) in the environment poses a risk to environment and human health. In the present study, a potassium bicarbonate-modified pyrite/porous biochar composite (PKBC) was prepared in a one-step process and applied for the efficient removal of Cr(VI) in wastewater. The results showed that PKBC can significantly remove Cr(VI) within 4 h over a wide range of pH (2-11). Meanwhile, the PKBC demonstrated remarkable resistance towards interference from complex ions. The addition of potassium bicarbonate increased the pore structure of the material and promoted the release of Fe2+. The reduction of Cr(VI) in aqueous solution was primarily attributed to the Fe(II)/Fe(III) redox cycle. The sulphur species achieved Fe(II)/Fe(III) cycle through electron transfer with iron, thus ensuring the continuous reduction capacity of PKBC. Besides, the removal rate was also maintained at more than 85% in the actual water samples treatment process. This work provides a new way to remove hexavalent chromium from wastewater and demonstrates the potential critical role of potassium bicarbonate and sulphur.