Search

Soil aggregate is important to soil quality. Straw return is beneficial for soil amendment, but the effects of straw and straw-derived biochar on aggregate formation and stability in paddy soil are unclear. This study carried out a field experiment for 2 years in Northeast China with four treatments: conventional fertilization (CF), straw (ST, 7.5 t ha−1 year−1), biochar (BC, 2.5 t ha−1 year−1), and biochar-based fertilizer (BCF, 0.75 t ha−1 year−1). Compared with the CF and BCF, BC and ST improved the macroaggregates and significantly increased soil total carbon and aggregate organic carbon, indicating a sustained positive role in promoting the formation and stability of aggregates. BC significantly improved aggregate stability. Correlation analysis showed that macroaggregates (2–0.25 mm) can be increased by increasing the heavy fraction organic carbon (HFOC), BC and ST significantly increased the HFOC, and BC had a greater effect. Scanning electron microscopy (SEM) showed that the combination of biochar and soil particles can be captured with strong water scouring. BCF showed an increasing trend in the formation and stability of soil aggregates. In comparison, biochar had a greater effect on promoting the formation of macroaggregates and the stability of soil aggregates with a significant sustainable effect. [ABSTRACT FROM AUTHOR]

Continuous cropping obstacles limit soybean production. Biochar is beneficial for soybean growth, but it is unclear whether biochar performs a sustainable role in continuous cropping. To further explore the effects of biochar on soil properties and soybean growth, a ceramic Wagner pot-simulated field experiment was conducted with biochar at different doses (12, 24, and 48 t·ha−1) over a period of 3 years, no fertilizer, no biochar (CK) and fertilizer (F)treatments were used for comparison. The results showed that biochar significantly reduced soil bulk and improved the rhizosphere soil pH, available nutrients (N, K), and total nutrients (C, N, P, and K) compared with CK and F. Moreover, the soybean root length, surface area, volume, and exudates increased with biochar amendment. In particular, biochar significantly increased the nodule number, dry weight, and nitrogenase activity of soybean. Furthermore, biochar promoted soybean growth and increased soybean yield. In general, we found that the soybean yield increased with biochar and that biochar had a positive, sustainable effect on soil properties and soybean root growth, providing a new cultivation measure for soil health and soybean production in continuous cropping, which is very important for increasing soybean productivity to break the limitations of soybean traditional continuous cultivation. [ABSTRACT FROM AUTHOR]

Adsorption of levofloxacin (LEV) onto four types of magnesium (Mg)-impregnated biochars, fabricated via thermal pyrolysis of wood chips pretreated with MgSO4 was investigated. The Mg-impregnated biochars were characterized with various tools and techniques. Batch sorption experiments were conducted to determine the sorption kinetics and isotherms of LEV onto the Mg-impregnated biochars. The pseudo-second order kinetic model described the adsorption kinetic data better than the pseudo-first order kinetic model and the Elovich equation. Due to multi-mechanisms, the Freundlich model described the experimental isotherms better than the Langmuir model. The Langmuir maximum adsorption capacities of the Mg-impregnated biochars to LEV ranged from 7.38 to 25.2 mg g−1. In the fixed-bed column experiment, higher bed height and lower flow rate led to greater LEV removal. Findings from this work indicate that Mg-impregnated biochars can be used as an alternative adsorbent to effectively remove LEV from aqueous solutions. [ABSTRACT FROM AUTHOR]

Reducing the bioavailability of both cadmium (Cd) and arsenic (As) in paddy fields is a worldwide challenge. The authors investigated whether ridge cultivation combined with biochar or calcium-magnesium-phosphorus (CMP) fertilizer effectively reduces the accumulation of Cd and As in rice grains. Field trial showed that applying biochar or CMP on the ridges was similar to the continuous flooding, which maintained grain Cd at a low level, but grain As was reduced by 55.6%, 46.8% (IIyou28) and 61.9%, 59.3% (Ruiyou 399). Compared with ridging alone, the application of biochar or CMP decreased grain Cd by 38.7%, 37.8% (IIyou28) and 67.58%, 60.98% (Ruiyou399), and reduced grain As by 38.9%, 26.9% (IIyou28) and 39.7%, 35.5% (Ruiyou 399). Microcosm experiment showed that applying biochar and CMP on the ridges decreased As in soil solution by 75.6% and 82.5%, respectively, and kept Cd at a comparably low level at 0.13–0.15 μg L−1. Aggregated boosted tree (ABT) analysis revealed that ridge cultivation combined with soil amendments altered soil pH, redox state (Eh) and enhanced the interaction of Ca, Fe, Mn with As and Cd, which promoted the concerted reduction of As and Cd bioavailability. Application of biochar on the ridges enhanced the effects of Ca and Mn to maintain a low level of Cd, and enhanced the effects of pH to reduce As in soil solution. Similar to ridging alone, applying CMP on the ridges enhanced the effects of Mn to reduce As in soil solution, and enhanced the effects of pH and Mn to maintain Cd at a low level. Ridging also promoted the association of As with poorly/well-crystalline Fe/Al and the association of Cd on Mn-oxides. This study provides an effective and environmentally friendly method to decrease Cd and As bioavailability in paddy fields and mitigate Cd and As accumulation in rice grain. [Display omitted] • New soil habitat formed by ridging combined with biochar or CMP application. • Ridging combined with biochar or calcium-magnesium-phosphorus fertilizer reduce grain As and Cd. • Enhanced interaction with Ca, Fe and Mn promotes reduction of As and Cd bioavailability. • Fe/Mn-(hydro)oxides absorb As and secondary Mn mineral absorb Cd in soil solid phase. [ABSTRACT FROM AUTHOR]

Lanthanun oxide (La2O3) is a lanthanum chemical compound incorporates a sensible anionic complexing ability; however, it lacks stability at a low pH scale. Biochar fibers will give the benefit of their massive space and plethoric uses on the surface to support a metal chemical compound. Herein, wet spinning technology was used to load La3+ onto sodium alginate fiber, and to convert La3+ into La2O3 through carbonization. The La2O3-modified biochar (La-BC) fiber was characterized by SEM, XRD and XPS, etc. An adsorption experiment proved that La-BC showed an excellent adsorption capacity for chromates, and its saturation adsorption capacity was about 104.9 mg/g. The information suggested that the adsorption was in step with both the Langmuir and Freundlich models, following pseudo-second-order surface assimilation mechanics, which showed that the Cr (VI) adsorption was characterized by single-phase and polyphase adsorption, mainly chemical adsorption. The thermodynamic parameters proved that the adsorption process was spontaneous and endothermic. The mechanistic investigation revealed that the mechanism of the adsorption of Cr (VI) by La-BC may include electrostatic interaction, ligand exchange, or complexation. Moreover, the co-existing anions and regeneration experiments proved that the La-BC is recyclable and has good prospects in the field of chrome-containing wastewater removal. [ABSTRACT FROM AUTHOR]

Abstract Biochar is a promising material for soil amendment. However, the sustained effects of biochar vs. straw returning on cultivation in Albic soil are poorly understood. Two-year pot experiments were conducted to explore these effects and to compare the effect of different amounts of biochar on Albic soil. By the end of the 2-year experiment, biochar (10 g·kg−1 each year) and straw (30 g·kg−1 each year) returning had reduced the soil bulk density by 6.62% and 10.30%, respectively, and the higher-level biochar (30 g·kg−1 one-time addition) treatment had significantly reduced the density by 9.93%. The structure of Albic soil also changed: the ratio of the solid soil phase decreased annually, while the gas phase increased. The stability of soil aggregates significantly increased, with straw returning mainly affecting large grains and the biochar affecting grains of all sizes but particularly decreasing the amount of small grains. Biochar treatments altered the maximum field capacity and pH, which increased by 11.85% and 6.70%, respectively, on average. Straw, straw-biochar returning and both biochar amendment levels increased the total and available nitrogen, phosphorus, and potassium contents in Albic soil. Compared to those under straw returning, the contents of total nitrogen and phosphorus under biochar returning were increased by 9.83% and 25.56%, respectively, and the soil organic matter content of the biochar treatment increased significantly. Straw and straw-biochar returning had positive effects on soybean agronomic traits and nutrient (nitrogen, phosphorus, and potassium) absorption. The soybean yield of the biochar treatment was significantly increased by 10% compared to that of the straw returning, and this yield-improvement was maintained for 2 years. Compared to straw returning, biochar returning showed considerable advantages in overcoming the main limitations of cultivating Albic soil, such as increasing the soil pH and fertility, reducing the soil bulk density, and promoting crop nutrient absorption and yield. Overall, the treatment of 30 g·kg−1 biochar was the optimal treatment for Albic soil. Highlights • Both straw and straw-derived biochar returning improved Albic soil physical and chemical properties. • Straw-derived biochar promoted sustainable soybean growth and nutrient uptake. • Straw-derived biochar helped to generate an ideal "new layer" and prevent the physical recovery of Albic soil. • Straw-derived biochar overcame the key limitations to sustainable cultivation of Albic soil. [ABSTRACT FROM AUTHOR]

The potential for rice husk (RH) and wood chip (WC) biochars to remove levofloxacin (LEV) from aqueous solution was evaluated. The physical and chemical properties of the biochars were characterized using various tools and techniques. Furthermore, batch sorption experiments were conducted to determine the sorption ability of the biochars to LEV. The pseudo-second order kinetic model described the sorption kinetic data better than the pseudo-first order kinetic model and the Elovich equation because the process involved both surface adsorption and pore diffusion. For the isotherms, the Langmuir equation fitted the data better than the Freundlich equation. The maximum Langmuir sorption capacities of the biochars to LEV ranged from 1.49 to 7.72 mg g −1 . Thermodynamic parameters obtained from the experiments showed that the adsorption of LEV onto the WC biochar was spontaneous and exothermic, while its adsorption onto the RH biochar was spontaneous and endothermic under tested conditions. A mixture of 0.025 M phosphate buffer (80%, pH 3.0) and acetonitrile (20%) effectively desorbed the LEV from the biochars with a recovery rate up to 80%. Findings from this work indicate that biochars can be used as an alternative adsorbent to effectively remove emerging contaminants including LEV from aqueous solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel biochar (CHKBC) co-modified with KOH and chitosan was synthesized. • KOH activation significantly increased the loading of chitosan on biochar surface. • CHKBC showed strong adsorption for methylene blue in various environments. • Adsorption mechanisms were revealed by various characterization methods. The treatment of dye pollutants remains a challenge in the current management of the water environment. In this study, an innovative biochar material co-modified with KOH and chitosan was synthesized. The morphology and physicochemical properties of the modified biochar material were assessed by SEM, FTIR, XPS, XRD, and thermogravimetric analyses. The results revealed a significant enhancement in chitosan loading due to the pretreatment of biochar with KOH. The co-modified biochar with KOH and chitosan (CHKBC) exhibited an enriched composition of functional groups such as − COOH, −NH 2 , and − OH, leading to a substantial increase in the maximum adsorption of MB by the biochar from 8.83 mg g−1 to 62.04 mg g−1, a 7.03-fold increase. The excellent adsorption performance of CHKBC for MB was maintained at different solution temperature (288–––318 K) and pH (5–––11) conditions. The main adsorption mechanisms of MB removal by CHKBC involved ion exchange, pore filling, electrostatic attraction, π - π interactions, and hydrogen bonding. Overall, CHKBC has higher chitosan loading, more uniform chitosan distribution, and better adsorption efficiency of MB. It is a promising adsorption material with low cost and a simple production process. [ABSTRACT FROM AUTHOR]

In this work, human hair and Enteromorpha prolifera were firstly used to synthesize heteroatom-doped biochars. The effects of pyrolysis temperature and holding time on the yield and pore structure of the obtained biochars were investigated. The different pyrolysis characteristics of hair and E. prolifera were compared through thermogravimetric analyser under nitrogen atmosphere. The pore properties, surface morphology and surface chemical composition were studied by N 2 adsorption, scanning electron microscopy and X-ray photoelectron spectroscopy. The biochar from hair was typical dual O, N-doped material, which possessed 21.14 at.% of O-doped and 9.61 at.% of N-doped on the surface, while the biochar from E. prolifera was typical dual O, S-doped material, which possessed 30.68 at.% of O-doped and 5.18 at.% of S-doped on the surface. The present study provides a good prospect for development of heteroatom-enriched biochar materials from renewable biomass wastes. [ABSTRACT FROM AUTHOR]