硅酸盐学报

为探索钢渣高附加值利用新途径，采用微波加热–磷酸活化法复合制备了钢渣–花生壳复合活性炭(SPAC)，考察其室温条件下低质量浓度甲醛(HCHO)脱除行为，并对最佳样品的表面化学性质和微观结构进行了描述和分析。结果表明：当微波功率为550 W、浸渍比为1.25:1.00、钢渣超微粉掺量(质量分数)为15%时，所制备的钢渣–花生壳复合活性炭对甲醛气体脱除率最高，即93.2%。钢渣–花生壳复合活性炭的脱除率与甲醛初始质量浓度呈负相关、而与脱除量呈正相关，其脱除动力学行为更加符合准二级动力学模型，化学因素是控制脱除反应速率的重要因素；脱除平衡特征更加符合Freundlich模型，属于优惠脱除，化学键力起到重要作用。钢渣–花生壳复合活性炭一方面具有优良的多孔结构及较大比表面积，对低质量浓度甲醛起到聚集作用；另一方面含有的铁元素(Fe²⁺、Fe³⁺价态)与锰元素(Mn²⁺价态)协同作用，实现对甲醛进一步吸附富集的同时，发生催化氧化脱除甲醛。该研究不仅为钢渣基功能材料的探索研究提供参考，而且为室温低浓度甲醛高效脱除提供理论支撑。

Introduction As a bulk solid waste in iron and steel industry,steel slag occupies a large amount of land,and causes environmental pollution,having a great burden to iron and steel industry and society.It is thus of great theoretical and practical significance to explore effective ways of steel slag recycling and utilization.Formaldehyde (HCHO) as a colorless,irritating smell of toxic gas is one of common volatile organic compounds (VOCs) in indoor air,which can cause chronic respiratory diseases,leukemia,and bronchial asthma and damage to the nervous system.Activated carbon (AC) is extensively used as an adsorbent for removal of HCHO.AC is an extraordinary adsorbent,but its adsorption efficiency for HCHO is low.The modification of AC using metal oxides (such as V_2O₅,Mn O₂,CuO,Fe_2O₃,etc.) can improve the service life of AC and its formaldehyde adsorption performance.However,the preparation cost will increase due to the high price of metal oxides.Steel slag is rich in oxides of calcium,silicon,magnesium,iron,manganese,phosphorus and other elements.Therefore,the composite preparation of ecological AC by steel slag and biomass waste materials solves the problems of high modification cost,short service life and poor absorptivity,and expands a way of high value-added utilization of steel slag.Methods Steel slag/peanut shell activated carbon (SPAC) was firstly prepared via microwave heating and phosphoric acid activation.According to the national standard of“Formaldehyde emission limit in wood-based panels and their Products of Interior Decoration Materials”(GB18580–2017),a formaldehyde absorptivity experiment by SPAC was systematically made.The porosity of samples was determined by a model ASAP 2020M surface area&porosity analyzer based on the N₂ adsorption-desorption isotherm.The microscopic morphology of SPAC was analyzed by a model NANO SEM430 scanning electron microscope with energy disperse spectroscope (SEM–EDS).The elements content of SPAC in ultra-high vacuum with Al K_α laser radiation (hυ=1486.6 eV) was characterized by a model ESCALAB250 X-ray photoelectron spectrometer (XPS).Results and discussion The result show that the sample has an excellent removal efficiency (i.e.,93.2%) under the preparation condition of 550 W microwave power,1.25 impregnation ratio and 15% steel slag content.The correlation coefficients of the experimental results and the fitted values for the pseudo-second-order kinetic model and the Freundlich model are 0.9980 and 0.9537,respectively.It is indicated that the removal process of formaldehyde on SPAC is more dominant due to chemisorption.The N₂ adsorption-desorption isotherm is a type IV adsorption isotherm with H3 and H4 hysteresis loops,indicating that the sample is a mesoporous material.Based on the results of SEM–EDS and XPS,steel slag is loaded into the SPAC sample and elements Fe and Mn have a crucial role for the absorptivity of formaldehyde.This study provided a reference for the exploration of steel slag based functional materials,and a theoretical support for the efficient formaldehyde removal at room temperature.Conclusions Steel slag powder could be loaded into the composite activated carbon.The prepared composite activated carbon still retained the porous structure characteristics suitable for removal of formaldehyde.The synergistic action of the elements Fe and Mn from steel slag powder was beneficial to improving the formaldehyde removal.