生物炭制备及其在水污染控制中的应用

生物炭孔隙发达、比表面积大、表面官能团丰富、具有"碳中性"特点,对很多物质表现出极强的吸附作用。近年来,生物炭的制备及应用备受关注。概述了生物炭的制备方法、性质及其影响因素,讨论了生物炭及其炭基复合材料的制备及应用研究,简述了生物炭对水体中有机污染物和重金属离子的去除效果和机理。虽然生物炭及其复合材料具有诸多优点,但生物炭的工程放大研究及技术经济可行性的系统评价方面的研究较少,仍是今后研究的重点。     

磁性生物炭复合材料研究进展

生物炭以其优良的污染物吸附效果受到关注,但不易从溶液中分离的难题限制了其应用。通过与磁性介质结合,将生物炭磁化,使其能够在磁场作用下实现固液分离,是解决该问题的有效方法。综述了磁性生物炭复合材料的结构类型及制备方法,分析了影响产物属性的浸渍比率、热解温度、保留时间等因素,并重点介绍了在重金属离子和有机污染物治理中的应用。最后对磁性生物炭发展趋势及该研究领域存在的问题进行了探讨。     

生物质复合材料吸附水中重金属离子的研究进展

随着现代工业的发展,重金属水污染已成为最重要的环境问题之一,重金属离子毒性强、难降解,在很大程度上对人类、水生动物和植物有害,破坏生态系统。吸附法低成本、去除效率高、可循环利用等优点使其成为废水处理的重要方法之一。生物质材料资源丰富、成本低、绿色环保,以其为新型吸附剂原料被广泛研究。基于此,该文以金属有机骨架、沸石、生物炭类为例,首先综述了生物质复合材料的制备及改性方法,总结了吸附剂的性能对金属离子吸附的影响,其次阐述其与金属离子之间的吸附机理,最后对生物质复合材料在水污染治理发展方面提出展望。     

聚合物基杂化纳米材料制备及对水中重金属离子高效净化

近年来,聚合物基杂化纳米复合材料作为典型重金属及典型无机污染物吸附荆备受关注。文章综述了该类纳米复合材料的制备方法和其对水中有毒重金属离子吸附性能及作用机制。此外,就该类纳米材料载体表面化学性质对纳米颗粒尺寸影响及纳米颗粒对复合材料机械强度的作用等方面特殊性能进行了评述。     

氧化石墨烯/壳聚糖复合材料的制备及吸附研究进展

综述了近年来氧化石墨烯/壳聚糖新型复合材料的研究进展,侧重介绍了该材料的常用制备方法及其对重金属离子和有机染料的吸附情况,讨论了该复合材料的脱附再生性能,指出了目前研究中尚存在的问题,并对未来的研究工作提出了一些建议。     

氧化石墨烯／壳聚糖复合材料的制备及吸附研究进展

综述了近年来氧化石墨烯／壳聚糖新型复合材料的研究进展,侧重介绍了该材料的常用制备方法及其对重金属离子和有机染料的吸附情况,讨论了该复合材料的脱附再生性能,指出了目前研究中尚存在的问题,并对未来的研究工作提出了一些建议。     

生物炭-膨润土共改性及其铅离子吸附与稳定化研究

重金属污染具有高毒性、持久存留和生物积累等特性, 严重危害人体健康和生态安全。本研究通过氯化钙对玉米芯残渣和膨润土混合物进行碱改性, 在无氧条件下高温煅烧制备了一种碱改性生物炭-膨润土复合物(CaO-Bent-CB)。该复合物的比表面积高, 达到441.1 m²/g, 明显高于直接煅烧制备的生物碳(132.7 m²/g)和碱改性生物炭(177.2 m²/g)。进一步评价了该复合物对水中铅离子吸附性能, 结果表明在水中铅离子浓度为120 mg/L, 膨润土与玉米芯残渣质量比为1:5, 用量为1 g/L条件下, 吸附6 h后铅离子去除率达98%, 吸附量为109.6 mg/g, 均高于生物炭(13.4 mg/g)、膨润土(72.9 mg/g)和碱改性生物炭(86.9 mg/g)。此外, 采用CaO-Bent-CB对铅离子污染土壤进行稳定化处理, 当土壤中铅离子浓度为2200 mg/kg, CaO-Bent-CB用量为土壤干重的8%时, 在pH=3.2的硫酸-硝酸浸提液中浸出12 h, 酸浸出铅离子浓度低至4.5 mg/L, 低于危险废物鉴别标准值(5 mg/L)。上述研究结果表明这种生物炭-膨润土共改性复合物在重金属污染水体和土壤修复中具有很好的应用前景。     

花生壳生物炭-黏土吸附水中的Cr(VI)

重金属铬的污染会严重威胁到土壤和水体的环境安全, 而水中的六价铬化合物则具有很强的迁移性、富集性和氧化性等特性, 更具有危害性且难以处理。吸附法是一种能简单、高效地处理含重金属污水的处理技术。在磁力搅拌条件下采用花生壳生物炭分别与高岭土和膨润土混合制备而成两种生物炭-黏土材料, 并分别对这两种生物炭-黏土的表面特性进行表征。结果发现所选用的两种黏土均能不规则地负载在生物炭的表面。吸附实验结果显示, 生物炭-高岭土(Biochar@Kaolin)吸附铬(VI)的能力显著高于生物炭-膨润土(Biochar@Bentonite)。从吸附动力学方程的分析可以看出, 合成的两种生物炭负载黏土吸附水中的铬(VI)均符合伪二级动力学方程。从吸附等温线分析中可以得到, Biochar@Bentonite吸附铬(VI)的过程符合Langmuir模型, 而Biochar@Kaolin吸附铬(VI)的过程符合Freundlich模型。研究结果显示, 采用生物炭-黏土的复合材料修复环境中的重金属污染具有广阔的应用前景。     

稻草生物炭对铕的吸附行为及机理研究

以农业残留物为原料制备的生物炭被广泛应用于去除重金属, 这对于环境保护具有双重意义。本研究以稻草为原料制备了生物炭, 通过系列静态实验和光谱技术研究其对重金属铕(Eu)的吸附行为及机理。研究发现溶液pH显著影响生物炭对Eu(III)的吸附量, 但不改变吸附反应时间; 腐殖酸/富里酸(HA/FA)在pH<7.0的溶液中能促进生物炭对Eu(III)的吸附, 而在pH>7.0的溶液中则抑制Eu(III)的吸附; 吸附过程主要涉及共沉淀或内表面络合机制; 该吸附属于化学吸附, 且吸附速率受内颗粒扩散过程的限制。此外, Freundlich模型对该吸附拟合最好, Langmuir模型显示稻草生物炭对Eu(III)的最大吸附量为40.717 mg/kg, 这可能与生物炭的层状结构和丰富的官能团有关; 热力学分析表明该吸附是自发的吸热过程。这些发现有利于评估稻草生物炭在去除水中重金属方面潜在的应用价值。     

花生壳生物炭–黏土吸附水中的Cr(Ⅵ)（英文）

重金属铬的污染会严重威胁到土壤和水体的环境安全,而水中的六价铬化合物则具有很强的迁移性、富集性和氧化性等特性,更具有危害性且难以处理。吸附法是一种能简单、高效地处理含重金属污水的处理技术。在磁力搅拌条件下采用花生壳生物炭分别与高岭土和膨润土混合制备而成两种生物炭–黏土材料,并分别对这两种生物炭–黏土的表面特性进行表征。结果发现所选用的两种黏土均能不规则地负载在生物炭的表面。吸附实验结果显示,生物炭–高岭土(Biochar@Kaolin)吸附铬(Ⅵ)的能力显著高于生物炭–膨润土(Biochar@Bentonite)。从吸附动力学方程的分析可以看出,合成的两种生物炭负载黏土吸附水中的铬(Ⅵ)均符合伪二级动力学方程。从吸附等温线分析中可以得到,Biochar@Bentonite吸附铬(Ⅵ)的过程符合Langmuir模型,而Biochar@Kaolin吸附铬(Ⅵ)的过程符合Freundlich模型。研究结果显示,采用生物炭–黏土的复合材料修复环境中的重金属污染具有广阔的应用前景。     

金属负载型生物炭材料在废水治理中的应用进展

有机物污染和重金属污染给生态环境和人类健康带来极大危害,成为人们最关注的环境问题之一,吸附是去除水体中污染物的有效方式。生物炭材料是一种含碳有机物在无氧环境下高温炭化制备的功能材料,具有比表面积大、孔隙率高、性能稳定、绿色环保等优点。近年来,金属负载型生物炭材料对有机物催化降解和重金属离子吸附,均表现出较好的应用潜力,可用于有机物和重金属离子污染废水的治理。综述了金属负载型生物炭材料在有机污染物和重金属离子废水治理中的应用新进展,并探讨了金属负载型生物炭材料的发展趋势。     

Glory and misery of biochar

Biochar refers to carbon-based dusty residues obtained from biomass pyrolysis. This recently rediscovered traditional soil improver is currently being glorified for its wide portfolio of favorable environmental aspects. With its lifetime of several centuries, it is being widely accepted as a promising method of carbon sequestration. Moreover, it has been demonstrated that biochar can reduce bioavailability of some heavy metals and that it has a high adsorption capacity to persistent organic pollutants. These effects are explained by a complex of physical, chemical and biological mechanisms. Besides agriculture, it has been currently used in food and chemical industries, as well as in the building industry. Many other promising applications are under investigation. However, contrary to many enthusiastic proclamations, no revolution in agriculture or environmental management is taking place. Despite significant achievements in reduction of biochar production costs, high demand from the industry and energy sector keeps the biochar price still high, which prevents a return of the ancient farming practice on a commercial scale.     

Ag-ZnO/生物质炭纳米复合材料的制备及协同可见光催化性能

以醋酸锌(Zn(CH₃COO)₂·2H₂O)为锌源、硝酸银(AgNO₃)为掺杂源、纤维素纳米晶体(Cellulose nanocrystal, CNC)为生物模板，通过溶胶-凝胶法结合碳化处理，制备了Ag-ZnO/生物质炭(Biochar)复合材料。采用TEM、XRD、BET、UV-Vis DRS对所制得的Ag-ZnO/Biochar复合材料进行表征。以亚甲基蓝(MB)为模型污染物，评价Ag-ZnO/Biochar复合材料在可见光源照射下的光催化性能，进一步阐明其光催化机制。结果表明:碳化后纳米ZnO仍保持良好的分散性，球形Ag纳米粒子均匀分散在ZnO表面，形成Ag-ZnO/Biochar三元复合材料。与Ag-ZnO和ZnO/Biochar复合材料相比，Ag-ZnO/Biochar复合材料在可见光下的光催化降解率显著提高。这是由于生物质炭赋予复合体系良好的吸附性能，使MB的光催化降解反应持续发生；而Ag纳米粒子的表面等离子体共振(Surface plasmon resonance, SRP)效应则增强了复合体系在可见光区的吸收。其中，当AgNO₃、CNC、Zn(CH₃COO)₂·2H₂O的质量比为0.01:0.25:1时，制得的Ag-ZnO/Biochar复合材料在可见光下具有最佳的光吸收性能和MB降解效率:室温条件下，黑暗中吸附30 min，再用可见光照射120 min，即可达到99%的MB降解率，显著高于Ag-ZnO(约23%)和ZnO/Biochar复合材料(约64%)。      

Use of biochar-coated polypropylene fibers for carbon sequestration and physical improvement of mortar

Biochar is widely recognized as an effective material for sequestration of carbon dioxide. The possibility of using it as a coating material on polypropylene fibers to improve mechanical properties and permeability mortar is explored in this study. Effectiveness of two types of biochar – fresh biochar and biochar saturated with carbon dioxide prior to application as coating – on compressive and flexural strength, post-cracking behavior and permeability of mortar is studied. The biochar used was derived from mixed wood saw dust by pyrolysis at 300 °C. Experimental results show that application of fresh biochar coating offer significant improvement in compressive strength and flexural strength of mortar. Residual strength and post-cracking ductility of mortar with biochar coated fibers is found to be higher than control samples, although fresh biochar coating offers the best performance. Mortar with polypropylene fibers coated with fresh biochar shows higher impermeability, compared to reference samples and mortar with saturated biochar coated fibers. The findings suggest that biochar coating could be a potential solution to improve properties of fiber reinforced cementitious composites that also promotes waste recycling and carbon sequestration.     

Investigation of Strontium (II) Sorption Kinetic and Thermodynamic onto Straw-derived Biochar

Biochars have attracted much research attention recently because of their potential applications in many environmental areas. In this study, rice straw-derived biochars produced at different pyrolysis temperatures (550–750°C) were used as adsorbents for the removal of strontium (II) under different experimental conditions of time, pH, and temperature. Sr(II) sorption equilibrium occurs after 30 min and its sorption maximum achieved at pH 6. The kinetic data obtained were analyzed to predict the constant rate of sorption using three common kinetic models: pseudo-first-order, pseudo-second-order equation, and intraparticle diffusion equation. The pseudo-second-order model was suitable for describing the sorption kinetics for the removal of Sr(II) from aqueous solution onto straw-derived biochar. Sorption of Sr(II) onto biochar was endothermic. Biochar has the highest Sr(II) sorption capacity in comparison to other adsorbents.     

Mid-infrared spectroscopy of biochars and spectral similarities to coal and kerogens: what are the implications?

Biochar is the solid residue produced by the pyrolysis of any bio-organic material under low, or no, oxygen conditions and has generated considerable interest as a means to sequester carbon in, and improve the quality of, soils. However, the exact properties of biochar depend on its composition, which in turn depends on the composition of the starting material and the temperature and conditions under which the biochar is produced. Mid-infrared spectroscopy offers an excellent and rapid method for characterizing both the starting materials and the resulting biochar. Results using diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) have shown that spectral changes can be easily correlated with the production temperature and that DRIFTS offers a rapid method for biochar characterization. It was demonstrated that as the temperature increases biochars become increasingly more aromatic and carbonaceous in nature. We also showed that biochars are spectrally very similar to kerogens and coals; therefore, the methods and knowledge developed from decades of studies on these materials should greatly improve our understanding of biochar composition and effects in soil. This work indicates that rapid characterization using DRIFTS can be used to predict the nature of biochar and to determine the production conditions needed to produce a so-called "Designer Biochar" which will have properties of benefit to soil quality as well as sequestering carbon.     

Enhanced biomethane production via thermophilic anaerobic digestion of cattail amended with potassium phosphate- and magnesium-modified biochar

Clean Technologies and Environmental Policy - Biochar can effectively strengthen anaerobic digestion (AD) and improve the treatment efficiency of organic wastes. However, the types of biochar...     

Biochar systems: Developing a socio-technical system framework for biochar production in Norway

Biochar is charcoal produced from feedstock under pyrolysis. It has gained interests among researchers in recent years because of its agronomic and environmental benefits. It is considered to increase soil fertility and crop productivity, and biochar might play an important role as a climate mitigation tool that is able to capture carbon in the soil.However, although research has focused on the chemical, biological, and technical aspects of biochar, we seem to be far away from the implementation of a functioning biochar system. One key aspect needed for the actual use of biochar technologies is increased awareness and emphasis on the social and organizational aspects of its implementation. As there are no functional markets for the services and products needed to ‘produce’ a biochar system, political and market devices are needed. This paper contributes to this debate by introducing a socio-technical framework that investigates the implementation of different biochar technologies in Norway. Based on this socio-technical system framework, we discuss necessary components of a sustainable biochar socio-technical system, and we outline variations of this system based on different levels of biochar production scaling.