101. 题目: Spatial distribution and driving factors of soil organic carbon in the Northeast China Plain: Insights from latest monitoring data
Soil organic carbon (SOC) is a critical component of soil fertility and plays a crucial role in the global carbon cycle. Despite the widespread reports of a decrease in SOC content and stock in the Northeast China Plain in recent decades, the current status and driving factors of its content and distribution are unclear. In this study, the surface soil (0–20 cm) SOC content data of 1920 sampling points within the Northeast China Plain covering an area of 2.6 × 105 km2 were obtained based on the Land Quality Geochemical Monitoring Network established in 2018. Random forest model and correlation analysis were used to identify the main driving factors of SOC distribution. The results showed that the SOC content, soil organic carbon density (SOCD), and soil organic carbon storage (SOCS) in the Northeast China Plain were 13.48 g·kg−1, 3.71 kg·C·m−2, and 961.44 Tg, respectively. SOC content in paddy land was the highest among different land use types, which reached 18.77 g·kg−1. SOC content showed strong spatial dependence and gradually increased from southwest to northeast in the monitoring area. The results of the random forest analysis showed that the SiO2, mean annual temperature, and Fe2O3 explained 38.2 %, 18.8 %, and 13.3 % of the spatial variation of SOC, respectively. Although the SOCS (0–20 cm) in the Northeast China Plain has decreased by 10.05 % in the last 40 years compared to the Second National Soil Survey (1980), it's important to note that the SOCS has transitioned from a decreasing trend between 1980 and 2006 to an increasing trend from 2006 to 2018.This study provides important information for decision-makers on the spatiotemporal changes of SOC and its driving factors in the Northeast China Plain, which has a great significance for soil carbon sequestration and the development of management strategies to maintain soil fertility.
102. 题目: Divergence in soil particulate and mineral-associated organic carbon reshapes carbon stabilization along an elevational gradient
Variations in climates and vegetation types along elevations in mountain ecosystems strongly reshape soil organic matter (SOM) stabilization. However, soil carbon (C) stabilization pathways from litter to SOM and potential mechanisms along elevations in the subalpine area remain unclear. Here, we investigated the C stabilization pathway from litter to particulate and mineral-associated organic matter (POM and MAOM) and associated drivers along elevational gradients in the Hengduan Mountains, China, based on δ13C signatures. Our results showed C stabilization pathways from litter to POM to MAOM, irrespective of elevation. Unexpectedly, the δ13C values of SOM and its fractions (POM and MAOM) were not significantly related to litter δ13C across elevations although litter was the main source of SOM, suggesting that other potential drivers could weaken the coordination of δ13C among litter and SOM fractions. We observed that the△13CLitter→POM (△13C between litter and POM) was more dependent on the direct effect of soil texture (i.e., sand, silt and clay). However, the △13CPOM→MAOM (△13C between POM and MAOM) was more related to microbial attributes (i.e., microbial community and enzyme activities).These results emphasizing the different stabilization procedures between POM and MAOM. Particularly, soil temperature dominantly determined △13CLitter→POM, but soil pH was the primary factor regulating the △13CPOM→MAOM. Overall, our results suggested that POM and MAOM formation occurred with different regulation processes, the POM formation was primarily via more physical pathways and MAOM formation mainly via more microbial pathways, thus providing novel insights into the better understanding of SOM formation and stabilization mechanisms in mountain ecosystems.
103. 题目: Fertilization Weakens the Ecological Succession of Dissolved Organic Matter in Paddy Rice Rhizosphere Soil at the Molecular Level
104. 题目: Two-step pyrolytic preparation of biochar for the adsorption study of tetracycline in water
In this study, cow dung biomass was converted into biochar (BC). BC900 was obtained through one-step pyrolysis at 900 °C, while BC700–900 and BC900–700 were obtained via two-step pyrolysis at temperature ranges of 700–900 °C and 900-700 °C, respectively. The primary objective was to investigate the adsorption performance and application value of BCs for tetracycline (TC) in water. The samples underwent characterization using scanning electron microscopy and mapping analysis, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. Subsequently, the effects of reaction time, adsorbent dosage, temperature, pH, and ionic strength were analyzed. Based on the fitting results of adsorption kinetics, the pyrolytic BCs exhibited a better fit with the pseudo-secondary kinetic model. The adsorption isotherm indicated monolayer adsorption on the surface of the adsorbents, with maximum adsorption capacities of 158.93 mg/g for BC900–700, 150.15 mg/g for BC700–900, and 142.56 mg/g for BC900, respectively. Furthermore, results from simulated wastewater and regeneration experiments demonstrated that BC900–700 exhibited not only excellent adsorption performance in wastewater but also remarkable regeneration capabilities. The two-step pyrolysis BCs in this study displayed a higher adsorption capacity compared to the one-step pyrolysis BCs in practical applications. These findings provide insights for further exploring the adsorption mechanism and optimizing the process.
105. 题目: Hydraulic and pore functions of differently textured soils modified by biochar from different parts of the mango plant
Studies that elucidate the likely differential impact of biochar produced from different parts of the same plant on soil functions and structure are scanty. Therefore, in this study, biochar made from 2 feedstocks: Mango Twig (B1) and Mango Branch (B2) were pyrolyzed at 550 ○C, and mixed with 2 differently textured substrates (silt loam – S and sandy loam –SD) at application rates of 0%, 3%, 4.5% and 6%, and uniformly prepared to a bulk density (BD) of 1.4 g cm−3. The substrates were subsequently subjected to standard procedures to characterize the affected water retention properties, air permeability, and saturated hydraulic conductivity (Ks). The results indicate marked differences in the impact of biochar types on the available water and water retention capacity, depending on soil texture. The significant main effect of the biochar type on Ks in silty loam and the plant available water capacity in sandy loam highlights the relevance of the selected part of the feedstock pyrolyzed. The optimum amount of biochar required to achieve a significant increase in soil water content was about 3% in both substrates, while air permeability and pore continuity were significantly altered at about 6% biochar amendment rate. Moreover, significant (P < 0.05) improvements in the saturated hydraulic conductivity were observed in the biochar-amended soil compared to the control. Air permeability decreased as the added biochar increased, while the air-filled pores increased at defined matric potential in all treatments. The improvement in soil functions was mostly due to the modification of soil structure parameters (pore size distribution (PSD) and pore continuity), due to increased meso pores concomitant with biochar additions; and greater changes were obtained with B1. The varied impact of the biochar types especially on the soil water retention, available water capacity, pore continuity, and hydraulic properties for the different soil textures showed that even the selected plant part affects the options to improve soil functions.
106. 题目: Siltation of check dams alters microbial communities and thus limits organic carbon mineralization
Check dam interception in the Loess Plateau leads to a buildup of silt-based deep soil reserves. These deep soils tend to be high in organic carbon (C), and could dramatically impact our estimates of terrestrial C storage. Despite a growing interest in the terrestrial C cycle, little work has focused on deep soil organic carbon (SOC) pools. In this study, we observed how soil depth and consequential oxygen concentration may influence the way in which microorganisms act on the SOC mineralization process. We found that the change from aerobic to anaerobic environment led to a decrease in cumulative mineralization from 1.37 mg to 1.06 mg and a significant decrease in mineralization rate, which had a limiting effect on SOC mineralization. The reduction of oxygen concentration (approximating depth) also led to changes in the dominant population of bacteria/fungi. Microorganisms with higher C metabolism capacity in aerobic conditions had higher utilization of C sources than that in anaerobic conditions, and vice versa. The limiting factors affecting the amount of SOC mineralization in aerobic soil were carbohydrate, Rokubacteria and Mortierellomycota, and that in anaerobic soil were Amino acid, Mortierellomycota and Ascomycota. Microorganisms with high C metabolism in anaerobic conditions have a weaker metabolism in aerobic conditions, and vice versa. We further quantified the direct and interactive contribution of each factor to SOC mineralization and found that when the soil was aerobic, the contribution of single factor to SOC mineralization was significantly lower (0.32) than the interactions (0.65). Conversely, when the soil was anaerobic, the contribution of single factor to SOC mineralization was much higher (0.76) than the interactions (0.20). When the soil is in anaerobic condition for a long time, the contribution of single factor will gradually increase and the interactions among factors will gradually weaken, further limiting SOC mineralization. In this study, the mechanism of SOC mineralization based on microbial activity in anaerobic and aerobic environment of check dam was reported for the first time, providing theoretical support for understanding the contribution of check dam construction to SOC pool on the Loess Plateau.
107. 题目: Catalytic torrefaction effect on waste wood boards for sustainable biochar production and environmental remediation
Wood boards used in construction are generally treated with toxic chemicals, making them unsuitable for further use and causing environmental pollution. This study evaluates the possibility of using catalytic torrefaction as a pretreatment to improve wood pyrolysis and combustion for greener biochar production. Waste beech boards were impregnated with different K2CO3 solutions (0–0.012 M), then torrefied between 5 and 60 min at 275 °C. The ICP-AES showed that the board's surface held more potassium than the core. Torrefaction coupled with potassium decreased the C–O and –OH stretches. Thermogravimetric analysis of torrefied wood showed that the board's internal heating degraded the core more than the surface. The exothermic reactions made potassium's catalytic action more efficient in the core. Interactions between the potassium content and torrefaction duration decreased the pyrolysis' maximum devolatilization temperature. During combustion, potassium decreased the ignition temperature by up to 9% and 3% at the surface and core, respectively, while the torrefaction increased it. The catalytic torrefaction significantly decreased the devolatilization peak during combustion, thus making the wood's combustion similar to that of coal, having only the char oxidation step. These findings highlight the advantages and challenges of waste wood's catalytic-torrefaction for biochar production to reduce environmental pollution.
108. 题目: Enhanced adsorption performance of oxytetracycline in aqueous solutions by Mg-Fe modified suaeda-based magnetic biochar
Oxytetracycline (OTC) in the waste water can be removed by biochar adsorption. How to separate the biochar adsorbed antibiotics from the wastewater was also a problem. The nontoxic magnetic biochar was prepared from Suaeda biochar (800SBC) by mafic bimetal modification, and used for the removal of OTC. The results of XRD and VSM indicated that the main composition of biochar was ferrite. Then through batch adsorption experiments, the adsorption kinetics, isothermal adsorption, thermodynamics, and coexisting ion and adsorbent regeneration experiments were studied. Through the fitting of the adsorption model, it was found that Mg-Fe@800SBC(1:1) and 800SBC belonged to chemisorption. 800SBC was consistent with the Langmuir model, mainly monolayer adsorption, and Mg-Fe@800SBC(1:1) was consistent with the Freundlich model, mainly multilayer adsorption. The adsorption processes of the two materials were spontaneous, endothermic and entropic decreasing processes. The maximum adsorption capacity of the Mg-Fe@800SBC(1:1) for OTC from the Sips L-F model was 82.83 mg/g. Through various characterizations of magnetic biochar, it was found that the adsorption mechanism of the modified biochar included the hydrogen bonds between the oxygen-containing functional group of biochar and the –NH2 group of OTC, π-π EDA interaction, electrostatic attraction and complexation. Coexistence anions (CO32− and PO43−) have a negative effect on the adsorption process.
109. 题目: Aquatic Carbon Export and Dynamics in Mountain Headwater Streams of the Western U.S.
110. 题目: Effects of long-term green manure application on organic carbon fractions and clay minerals and their interactions in paddy soil aggregates
Background and aims
Green manure is commonly used to improve soil organic carbon (SOC) stock, which is mainly combined with soil minerals and stored in aggregates. The effects of three green manure varieties on mineral associated organic carbon (mSOC) and clay minerals in macroaggregates and microaggregates and SOC sequestration mechanism were explored in paddy soils in southern China.
A 36-year (1982–2018) field experiment was conducted on a rice-rice-green manure crop rotation system, including rice-rice-winter fallow (WF), rice-rice-Chinese milk vetch (MV), rice-rice-rape (RP), and rice-rice-ryegrass (RG). Fourier-transform infrared, X-ray diffraction, field emission scanning electron microscopy and high resolution transmission electron microscopy were used to analyze mSOC, revealing composition characteristics and interactions between SOC and minerals.
Green manure application increased SOC contents in the bulk soil by 8.4% (MV, p < 0.05), 1.2% (RP) and 4.8% (RG) compared to WF, and mainly altered SOC composition in mSOC of macroaggregates. Dominant functional groups in mSOC were polysaccharide C and alkene C. Phyllosilicate minerals of mSOC were mainly illite (51.0-61.9%) and kaolinite (29.2–37.3%). MV application caused significant changes in illite, with fractured lattice stripes within mSOC in macroaggregates and bent lattice stripes within mSOC in microaggregates. Futhermore, lattice fringe spacing under MV contracted from 1.0 to 0.7 nm within mSOC in microaggregates, suggesting that MV favored the transformation of illite into kaolinite. The SOC content of mSOC was positively correlated with the amount of illite but negatively with kaolinite.
Green manure returning (especially MV and RG) altered the SOC content of mSOC by converting 2:1 minerals into 1:1 minerals, and emerged as an effective strategy for SOC accumulation in paddy soils, which was further governed by aggregate size.
111. 题目: Global predictions of topsoil organic carbon stocks under changing climate in the 21st century
The organic carbon (OC) stored in global topsoil (0–30 cm) will be the most active participant in the carbon cycle under future climate change. Due to differences in focus regions or research methods, the spatio-temporal changes of future global topsoil OC stocks and how they will be affected by climate change are not systematically understood, which needs to be further explored. In this study, we developed data-driven models to predict the spatio-temporal dynamics of global topsoil OC stocks by combining 32,579 soil profiles with environmental variables and comprehensively explored the impact of future climate change on topsoil OC. It was found that the topsoil OC stocks were 1249.29 Pg in the baseline period (1971–1990). By 2100, under the normal and high representative concentration paths, it is predicted that the global topsoil OC stocks will decrease by 113.67 ± 25.93 Pg and 193.71 ± 39.76 Pg, respectively. In the future, the largest global topsoil carbon loss will occur in boreal forest areas, which are expected to lose 17.03–27.90 % (66.01–108.13Pg) of their carbon stocks. The influence of climate on topsoil OC stocks is mainly manifested in temperature, which has a negative influence on the global topsoil OC stock, and the contribution rate of temperature to the effect on the global topsoil OC stock is about 26.96 %. Overall, our results provide a high spatio-temporal resolution assessment of global topsoil OC stocks and their relationship to environmental factors, and highlight the spatial heterogeneity, which has been generally ignored in many experimental frameworks and prediction models. These results will help governments to make appropriate management decisions to mitigate climate change.
112. 题目: Effect of chemical aging on phosphate adsorption and ecotoxicological properties of magnesium-modified biochar
Using magnesium-biochar composites (Mg-BC) in adsorption allows for the efficient and economically relevant removal of phosphate (PO43−) from water and wastewater. Applying Mg-BC for pollutant removal requires evaluating the adsorption capacity of composites and their ecotoxicological properties. Investigating the composite aging during the application of these composites into the soil is also essential. In the present study, nonaged and aged (at 60 or 90 °C) Mg-BC composites were investigated in the context of pyrolysis temperature (500 or 700 °C). All analyzed biochars were examined by Fourier transform infrared spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and surface area. The content of polycyclic aromatic hydrocarbons (PAHs) (bioavailable Cfree and organic solvent-extractable Ctot), heavy metals (HMs), and environmentally persistent free radicals (EPFRs) were determined. Ecotoxicity was evaluated using tests with Folsomia candida and Allivibrio fischeri. The dependence of adsorption on pyrolysis temperature and composite aging time was observed. Changes in physicochemical properties occurring as a result of aging reduced the adsorption of PO43− on Mg-BC composites. It was found that nonaged Mg-BC700 was more effective (9.55 mg g −1) in the adsorption of PO43− than Mg-BC500 (5.75 mg g−1). The adsorption capacities of aged composites were from 21 to 61% lower than those of the nonaged composites. Due to aging, the content of Cfree PAHs increased by 3–5 times depending on the pyrolysis temperature. However, aging reduced the Ctot PAHs in all composites from 24 to 35% depending on the pyrolysis temperature. Ecotoxicological evaluation of Mg-BC composites showed increased toxicity after aging to both organisms. The use of aged BC potentially increases the contaminant content and toxicity of Mg-BC composites.
113. 题目: Source, composition and molecular diversity of dissolved and particulate organic matter varied with riparian land use in tropical coastal headstreams
Source, composition and molecular diversity determine the reactivity and stabilization of organic matter (OM, dissolved [DOM]/particulate [POM]), affecting its behavior and fate. Here, multiple spectral and mass spectrometry techniques were applied to examine how riparian land-use shaped the source, composition and molecular diversity of POM and DOM (HDOM) in adjacent headstreams. Compared to HDOM with abundant lignins, microbially-transformed heteroatoms and carboxyl-rich alicyclic acids (CRAMs), POM exhibited higher allochthonous characteristics and more bioactive components, but lower molecular weight and diversity in different land-use-dominated streams. Compared to wetland-dominated headstreams, both POM and HDOM exhibited more terrestrial origin and condensed aromatics/tannins molecules for agriculture-impacted headstreams and bio-labile lipids, proteins and carbohydrates for forest-impacted headstreams. Structural equation mode (SEM) showed that soil-derived DOM (SDOM) showed the most prominent influence on the source, composition and molecular diversity of POM and the source of HDOM. The molecular composition and diversity of HDOM were mainly influenced by soil properties/SDOM and aquatic microorganisms, respectively. Redundancy analysis (RDA) revealed that autochthonous, bio-labile compositions of POM in forest and wetland streams were positively related to aquatic Bacteroidetes/Cyanobacteria, and carbohydrates/biogenic index of SDOM, while that of HDOM were positively linked with aquatic Bacteroidetes/Cyanobacteria, and SDOM molecular diversity. Terrestrial and aromatic POM in agricultural headstreams were associated with aquatic total nitrogen/Actinobacteria, and humification degree, aromatic/phenolic substances of SDOM, while that of HDOM were mainly regulated by aquatic nitrate/total nitrogen/Actinobacteria, and aromatic/carboxylic-containing moieties of SDOM. Noteworthily, the molecular diversity of agricultural OM increased along the soil-stream continuum due to the input of soil condensed aromatics and tannins. The opposite trend was observed in forest and wetland streams due to the input of bioactive carbohydrates and the microbial-degradation in-stream. These results are helpful to predict the behavior and fate of OM and determine effective management strategies in tropical coastal regions undergoing intense anthropogenic alterations.
114. 题目: Simultaneous determination of carbendazim and carbaryl pesticides in water bodies samples using a new voltammetric sensor based on Moringa oleifera biochar
For the first time, a modified electrochemical sensor based on carbon paste was developed using biochar derived from the husks of Moringa oleifera pods to detect successfully and simultaneously carbendazim (CBZ) and carbaryl (CBR) pesticides. Biochar was obtained via pyrolysis at 400 °C, which required no additional activation or modification processes. The incorporation of the biochar modifier enabled the preconcentration of both pesticides under open potential circuit conditions, resulting in a significant enhancement in sensitivity compared to bare electrode. Under the optimized experimental conditions, the developed sensor exhibited excellent sensitivity to the target analytes, showing a linear relationship within the concentration range of 0.29–6.00 μM for CBZ and 29.9–502 μM for CBR. The limits of detection were calculated to be 0.12 μM for CBZ and 10.4 μM for CBR. The proposed method demonstrated remarkable selectivity for analytes even in the presence of diverse organic and inorganic species. Furthermore, the method was successfully applied to the determination of CBZ and CBR pesticides in various water matrices, including river, sea, drinking, and groundwater samples, without the need for any sample pretreatment, such as extraction or filtration. The observed recoveries ranged from 87% to 111%, indicating the efficiency and reliability of this method.
115. 题目: Removal of iron, manganese and ammonium from contaminated mine water by biochar immobilized Acinetobacter sp. AL-6 under acid condition, and the role of extracellular polymeric substances
In acidic mine wastewater, Mn and Fe are among the prime heavy metals and pose a great threat to the ecological environment and human health. Combining biological and physical methods to treat heavy metal contaminated water bodies is a promising remediation technique. In this study, grapefruit peel biochar immobilized Acinetobacter sp. AL-6 (co-system) was applied to treat the contaminated water with co-existing Mn2+, Fe2+ and NH4+-N. The results showed that almost 100% of Mn2+, Fe2+, Zn2+ and Cu2+ were removed in bioreactor, and was transferred to Mn2+, Fe3+, Zn2+ and Cu2+ precipitates on the surface of co-system without N2O accumulation. Especially, Mn2+ and Fe2+ were adsorbed in extracellular polymers (EPS) of strain AL-6. The present study mainly confirmed that the combined system of biochar and bacteria had great potential in the complex water removal of multiple heavy metals and NH4+-N, and also revealed the regulation of heavy metals by the EPS of strain.
116. 题目: Seasonal variation and dissolved organic matter influence on the distribution, transformation, and environmental risk of pharmaceuticals and personal care products in coastal zone: a case study of Tianjin, China
Pharmaceuticals and personal care products (PPCPs) are emerging contaminants that have raised urgent environmental issues. The dissolved organic matter (DOM) plays a pivotal role on PPCPs’ migration and transformation. To obtain a comprehensive understanding of the occurrence and distribution of PPCPs, a seasonal sampling focused on the riverine system in coastal zone, Tianjin, Bohai Rim was conducted. The distribution and transformation of thirty-three PPCPs and their interaction with DOM were investigated, and their sources and ecological risks were further evaluated. The total concentration of PPCPs ranges from 0.01 to 197.20 μg/L, and such value is affected by regional temperature, DOM and land use types. PPCPs migration at the soil-water interface is controlled by temperature, sunlight, water flow and DOM. PPCPs have a high affinity to the protein-like DOM, while the humus-like DOM plays a negative influence and facilitates the PPCPs’ degradation. It is also found that protein-like DOM can represent point source pollution, while humus-like substances indicate non-point source (NPS) emission. Specific PPCPs can be used as markers to trace the source of domestic discharge. Additionally, daily use PPCPs such as ketoprofen, caffeine and iopromide are estimated to be the main risk substances, and the PPCPs ecological risk varies on space, season and river hydraulic condition.
117. 题目: Synthesis and application of lanthanum-doped magnetic biochar composite adsorbent for removal of fluoride from water
Fluoride levels greater than 1.5 mg/L in drinking water are a global environmental issue that can seriously harm the health of humans. One of the most effective techniques for defluoridating water is adsorption. The main drawbacks of many adsorbent materials include their poor adsorption capabilities, prolonged contact times, excessively low or high pH levels, and high dosages. The biochar-based magnetic nanocomposite adsorbent was synthesized in the current study and used as an adsorbent for water defluoridation. Through slow pyrolysis, coffee husk waste was converted to biochar. The composite was created by chemically co-precipitating iron and lanthanum oxide nanoparticles onto the surface of biochar. By using X-ray diffraction analysis (XRD), Fourier transform infrared spectrometry (FTIR), Brunauer–Emmett–Teller (BET), and pHPZC values, researchers were able to describe the magnetic biochar nanocomposite material. The Central Composite Design (CCD), which uses four input variables including dosage (2–5 g/L), solution pH (4–8), contact time (30–70 min), and initial concentration (10–20 mg/L), was used to design the experiments. The quadratic model indicated that the ideal conditions for removing 98.994% of the fluoride from water (adsorbent dosage of 5 g L-1, pH 5.74, contact period of 60 min, and initial concentration of 12.245 mg/L) would be attained. The average triplicate value in ideal circumstances produced a removal effectiveness of 98.51%, demonstrating the proposed response surface's capacity for prediction. The findings of this investigation showed that the magnetic biochar nanocomposite that was created is an effective fluoride adsorbent.
118. 题目: Evaluation of a pH- and time-dependent model for the sorption of heavy metal cations by poultry litter-derived biochar
Common isotherm and kinetic models cannot describe the pH-dependent sorption of heavy metal cations by biochar. In this paper, we evaluated a pH-dependent, equilibrium/kinetic model for describing the sorption of cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) by poultry litter-derived biochar (PLB). We performed sorption experiments across a range of solution pH, initial metal concentration, and reaction time. The sorption of all five metals increased with increasing pH. For Cd, Cu, and Pb, kinetics experiments demonstrated that sorption rates were greater at pH 6.5 than at pH 4.5. For each metal, all sorption data were described using single set of four adjustable parameters. Sorption edge and isotherm data were well described with R2 > 0.93 in all cases. Time-dependent sorption was well described (R2 ≥ 0.90) for all metals except Pb (R2 = 0.77). We then used the best-fit model parameters to calculate linear distribution coefficients (KD) and equilibration times as a function of pH and initial solution concentration. These calculations provide a more robust way of characterizing biochar affinity for metal cations than Freundlich distribution coefficients or Langmuir sorption capacity. Because this model can characterize metal cation sorption by biochar across a wider range of reaction conditions than traditional isotherm or kinetic models, it is better suited for estimating metal cation/biochar interactions in engineered or natural systems.
119. 题目: Remediation potential of biochar/copper oxide nanoparticles composite for lead- and cadmium-contaminated wastewater
This study evaluates the batch scale performance of Sesbania bispinosa biochar (SBBC) and its nanocomposite with copper oxide nanoparticles (SBBC/CuO) to remove lead (Pb) and cadmium (Cd) from synthetic wastewater and groundwater. Point of zero charge (PZC), Scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Energy Dispersive X-ray (EDX) analysis were conducted to gain insight into the removal process. The batch scale experiment assessed the effects of initial concentrations of Pb and Cd (25–200 mg/L), solution pH (3–9), adsorbent dose (0.5–2.0 g/L) and interaction time (15–180 min) to remove Pb and Cd from synthetic wastewater. The highest removal of Pb (98.7%) and Cd (95.5%) was observed at 25 mg/L, optimum pH (5), time (60 min), and material dose (1.0 g/L). However, increasing the initial level of Cd and Pb decreased their removal from contaminated water. The SBBC/CuO showed excellent reusability for Cd and Pb with 4.3% and 5.1% decline, respectively, after four adsorption/desorption cycles. The adsorption of Pb and Cd onto SBBC/CuO composite was found to be 191.5 mg/g and 186.9 mg/g, respectively; signifying improved performance compared to SBBC adsorbent alone. The presence of other cations in groundwater competes with Cd and Pb and hence there is a decline in Cd and Pb removal depending on the concentrations of these competing cations. The fitting behavior of equilibrium experimental adsorption varied depending on the adsorbent material and Cd/Pb, while kinetic adsorption showed best fit with pseudo-second-order kinetic for both Cd and Pb adsorption. The results suggested that SBBC combined with nanoparticles is a promising adsorbent for metal removal from contaminated water.
120. 题目: C/N Ratio of Resuspended Sediment Regulates Phytoplankton Growth in Shallow Eutrophic Lakes