Effect of Biochar as Reductant on Magnetizing-roasting Behavior of Pyrite Cinder

The effect of biochar substituted for anthracite as reductant on magnetizing-roasting pyrite cinder was investigated.The key of magnetizing-roasting is the gasification reaction between reductants and CO2.Since biochar could react with CO2 more rapidly at lower temperature,the reactivity of biochar is better than that of anthracite.The gasification of biochar could produce reducing condition ofφCO/(φCO+φCO2)about 10%-20% between 700-800 ℃,which is in accord with the atmosphere and temperature of Fe2O3 reduction.So it is beneficial to the reduction of iron mineral of pyrite cinder.Compared with anthracite,biochar could decrease the roasting temperature from825 to 750 ℃ and roasting time from 20 to 15min,which shows that a better effect of magnetization could be obtained in the condition of lower temperature and shorter time.Using biochar as reductant,iron concentrate extracted from pyrite cinder as about 64%iron grade could be produced,and the recovery is over 90% under the condition of above 90% grinding particle less than 0.045 mm and magnetic intensity of 0.124-0.194 T.     

沼渣生物炭在水处理中的应用进展

以沼渣为原料制备生物炭是实现沼渣安全处置和资源化利用的有效途径之一.沼渣经过厌氧消化处理,在一定程度上优化了沼渣生物炭的组分结构和物化特性,因而沼渣生物炭具有低成本、来源广、吸附及催化性能好等特点被应用于去除水中污染物.该文对当前沼渣生物炭的原料来源、制备及改性方法进行了总结,归纳了沼渣生物炭作为吸附剂和碳基催化剂在水处理应用中的现状,同时阐述了沼渣生物炭的作用机理.最后总结了沼渣生物炭在水处理应用中存在的一些问题和挑战,并指出其发展方向.     

生物质炭对气态挥发性有机污染物的吸附性能及机理

为探究生物质炭对气态有机污染物的吸附能力及作用机理,以核桃壳和椰子壳为原料制备生物质炭.采用元素分析仪、傅里叶红外光谱仪、Boehm滴定和比表面积及孔隙率分析仪分析生物质炭理化特征,并利用吸附柱实验考察生物质炭对气态挥发性有机污染物(苯和甲苯)的吸附行为.结果表明:相同制备条件下,椰壳生物质炭吸附性能高于核桃壳生物质炭.在实验温度范围内(400~700℃),随着制备温度的升高,生物质炭吸附性能增大.低温下制备的生物质炭(400℃)吸附行为符合准二级动力学模型,高温下制备的生物质炭(700℃)的吸附过程符合准一级动力学模型.在吸附温度30℃时,生物质炭对苯和甲苯的等温吸附过程符合Toth模型,计算得到生物质炭最大的理论饱和吸附量为18.98 mg/g苯和61.73 mg/g甲苯.生物质炭的表面酸性官能团和孔道结构在吸附过程中起关键作用,影响吸附质在生物质炭的表面吸附和粒内扩散吸附过程.     

改良剂对旱地红壤pH和有效P含量的影响

针对我国南方红壤旱地酸性强,有效P含量低的问题,研究改良剂(生物质炭与过氧化钙)对旱地红壤pH和有效P含量的影响.结果表明施用生物质炭与过氧化钙后,土壤pH得到不同程度的提高,有效磷含量增大,生物质炭与过氧化钙配施效果优于单施,其中C1Ca1(生物质炭758 kg/hm2和过氧化钙61 kg/hm2)处理效果最好,各处理在0⁴0 cm土层土壤有效P与pH呈显著相关性.     

Analytic expressions for the isosteric heat of adsorption from adsorption isotherm models and two-dimensional SAFT-VR equation of state

The isosteric heat of adsorption is an important thermodynamic property used to characterize and optimize adsorption processes. In this work, analytic expressions for isosteric heats of adsorption are derived for a collection of commonly used isotherm models and a two-dimensional molecular equation of state based on the SAFT-VR approach. The use of these expressions is presented with an example of adsorption of nitrous oxide, N₂O, on biochar, which is a waste biomass charcoal that exhibits high adsorption potential. The results show that accurate fitting of the adsorption isotherms leads to consistent results obtained with different approaches; however, the predicted isosteric heat of adsorption exhibits strong variations in the regions where experimental data is insufficient such in the region of low pressure/low coverage. Convergence on the prediction of the isosteric heat of adsorption by the different models is only observed in the region where no extrapolation of experimental data is needed.     

一步法制备Mg改性玉米芯生物炭吸附磷酸盐研究

研究通过MgCl₂溶液浸泡玉米芯后在450℃下慢速热解1 h一步法制备获得Mg改性生物炭(Mg-BC),探究其对磷酸盐的吸附和影响因素。结果表明,Mg-BC吸附磷符合准1级、准2级动力学模型,说明吸附过程主要受物理、化学作用控制。Mg-BC对磷的等温吸附符合Langmuir方程,吸附类型为单分子层吸附,最大吸附量为56.54 mg/g。溶液中共存无机阴离子会显著抑制Mg-BC吸附PO₄^3-,其顺序为HCO₃^-> SO₄^2-> NO₃^->Cl^-;NaOH溶液解吸可使Mg-BC有效的再生利用,且循环4次后,其去除率仍高于60%。Mg-BC可有效去除P有高吸附量,为P去除提供了一种新型环保材料。     

TiO2-SnO2 coated bamboo biochar for electrochemical treatment of coking wastewater

A new type of bamboo biochar (BC) loaded TiO₂-SnO₂ particle electrode was prepared and characterized by SEM, FT-IR, BET and XRD for efficient treatment of the coking wastewater in a three-dimensional electrochemical reaction system(3DERs). The results showed that bamboo biochar had a dense microporous space structure, and a significant amount of Ti-Sn oxides existed on the surface and in the interior of the BC. The removal rates of COD and DOC in coking wastewater reached to 73.96% and 66.72% respectively, and UV₂₅₄ reduced from 6.65 cm^-1 to 3.00 cm^-1 by the electrolysis treatment of 150 min at the current density of 30 mA/cm². The three-dimensional fluorescence spectra indicated that the most of the soluble organic compounds and soluble microbial by-products were degraded and transformed. The addition of Ti and Sn enhanced the efficacy of the electrooxidation, electro-adsorption and electrocatalytic behavior of the BC particle electrodes, which improved the treatment effect on coking wastewater in the 3DERs. In addition, this study provides the possibility of basic research for the engineering practice of electrochemical oxidation treatment of coking wastewater.     

污泥炭田间老化对土壤重金属及养分的影响

污泥基生物炭内源重金属和养分含量因污泥来源的不同而差异较大。为探索污泥基生物炭“还田”后，其内源重金属变化和养分的去向问题，采用干湿交替对污泥基生物炭模拟老化处理，分析老化前后污泥基生物炭的Cu、Zn金属形态及TCLP浸出毒性的变化；研究污泥基生物炭BC1和BC2（分别以磷酸二氢钾、磷酸二氢钙与污泥混合后热解制备的生物炭）以5%和10%的质量分数与鲜土混合老化后对污泥基生物炭内源重金属稳定性及土壤有机碳和有效磷含量变化的影响。结果表明：两种污泥基生物炭与土壤混合老化后会使土壤中SiO2含量增加，但不会改变土壤的吸附类型；污泥基生物炭的添加会增加土壤的比表面积，其中BC2增幅较大，为36.17 m2/g；施加两种污泥基生物炭土壤中Cu、Zn生物有效性均有不同程度的降低。TCLP浸出毒性量相比老化前降低（BC1约降低37.5%）。此外，BC1对土壤有效磷的提升效果优于BC2（BC1 70 mg/kg，BC2 30 mg/kg）；BC2对土壤有机碳的提升效果优于BC1（BC2 2.2%，BC1 1.15%）。BC2还田更有利于Cu、Zn的固定以及土壤有机碳和有效磷的提升。