巴旦木壳基生物炭的制备及其吸附性能表征

为控制环境污染领域提供新材料,分别在300、400和500℃条件下制备了巴旦木壳(BC)和干炒巴旦木壳(BCF)生物炭,并用不同浓度的HCl和NaOH对生物炭进行了改性。用国标法表征了生物炭的真密度、灰分、钙镁含量、pH值、焦糖脱色率、亚甲基蓝吸附量、碘吸附值及比表面积等基本性质,并对溶液中Pb²⁺和Zn²⁺的吸附特性进行了研究。实验结果显示,随着炭化温度的升高,两种生物炭的产率降低,灰分、钙镁含量、真密度、比表面积、孔体积、碘吸附值和pH值增加;BC500和BCF500的比表面积分别达到了199.97和295.44m²/g。BCF的灰分明显高于BC;酸碱及其浓度对不同参数产生的影响不一致。400℃碳化的两种生物炭的亚甲基蓝吸附值较高,酸碱改性后吸附值均增高;高温热解有利于制备碘吸附值高的生物炭,碱改性能提高碘吸附值,BC500和BCF500及其碱改性产物的碘吸附值达到330mg/g以上;两种生物炭及其改性产物的焦糖脱色率变化没有明显规律;高浓度酸碱改性显著降低了高温制备的BC和BCF的Pb吸附量;酸改性降低了、碱改性提高了两种生物炭的Zn吸附量。总之,两种巴旦木壳生物炭对不同物质的吸附特性不同,建议根据污染物的种类选择不同的生物炭制备工艺和改性剂。

Preparation and Characterization of Adsorptive Property of Almond Shell Based Biochar

In order to develop new materials for environmental pollution control,almond shell(BC)and torrefied almond shell(BCF)biochars were prepared at 300,400 and 500 ℃ and then modified with HCl and NaOH.The properties including true density,ash,magnesium calcium contents,pH,decolorization rate,methylene blue(MB)adsorption,iodine number and surface area were analyzed for the BC and BCF according to standard methods,furthermore,thus the adsorption capacity of BC and BCF for Pb and Zn were determined.Experimental results showed that higher carbonization temperatures lowered productivity but led to ash contents,true density,magnesium calcium content,surface area,pore volume,iodine number and pH all higher;The specific surface areas of BC500 and BCF500 were 199.97 and 295.44 m²/g,respectively.The effects of acid and base,and their concentration on the parameters of biochar were inconsistent;The ash content of BCF was higher than that of BC;BC/BCF400 exhibited higher MB adsorption,which was further improved by acid and base modification.The higher Iodine number was obtained by the biochar prepared at high temperature,and further increased by the base modification.The iodine number of BC500,BCF500 and their base modified products reached up to 330 mg/g.No significant differences in decolorization rates were observed for BC,BCF and their acid/base modified products.The high concentration acid/base modification decreased the Pb adsorption for BC or BCF prepared at high temperature;Base modification increased and acid modification decreased the Zn adsorption capacity of the biochar.In conclusion,the two biochars performed differently for different adsorbates,therefore,the preparating and modifying methods of bichar should be determined based on the particular contaminant present in a system.