Synthesis of iron composites on nano-pore substrates: Identification and its application to removal of cyanide

Two types of nano-pore substrates, waste-reclaimed (WR) and soil mineral (SM) with the relatively low density, were modified by the reaction with irons (i.e. Fe(II):Fe(III) = 1:2) and the applicability of the modified substrates (i.e. Fe-WR and Fe-SM) on cyanide removal was investigated. Modification (i.e. Fe immobilization on substrate) decreased the BET surface area and PZC of the original substrates while it increased the pore diameter and the cation exchange capacity (CEC) of them. XRD analysis identified that maghemite (γ-Fe₂O₃) and iron silicate composite ((Mg, Fe)SiO₃) existed on Fe-WR, while clinoferrosilite (FeSiO₃) was identified on Fe-SM. Cyanide adsorption showed that WR adsorbed cyanide more favorably than SM. The adsorption ability of both original substrates was enhanced by the modification, which increased the negative charges of the surfaces. Without the pH adjustment, cyanide was removed as much as 97% by the only application of Fe-WR, but the undesirable transfer to hydrogen cyanide was possible because the pH was dropped to around 7.5. With a constant pH of 12, only 54% of cyanide was adsorbed on Fe-WR. On the other hand, the pH was kept as 12 without adjustment in Fe-WR/H₂O₂ system and cyanide was effectively removed by not only adsorption but also the catalytic oxidation. The observed first-order rate constant (k_obs) for cyanide removal were 0.49 (±0.081) h⁻¹. Moreover, the more cyanate production with the modified substrates indicated the iron composites, especially maghemite, on substrates had the catalytic property to increase the reactivity of H₂O₂.     

介孔纳米γ-Al2O3对稀土元素锎、铈的吸附性能

以介孔纳米γ-Al2O3为吸附材料,重点研究了吸附剂投加量、溶液pH、吸附时间及温度对介孔纳米γ-Al2O3吸附稀土元素镧、铈的影响。通过正交实验优选出介孔纳米γ-Al2O3对稀土元素镧铈吸附的最优参数,采用10mg／L的La^3＋、Ce^4＋标准溶液,选择投加量、pH、吸附时间为影响因素,进行3因素3水平的正交实验。通过正交实验与单因素实验综合分析表明最佳实验方案为：投加量为0．20g,pH为7,吸附时间为15min。在初始浓度为10～100mg／L时,介孑L纳米γ-Al2O3对La^3＋、Ce^4＋的吸附符合Langmuir等温吸附式。拟合得到的理论饱和吸附量分别为22．32mg／g和23．75mg／g。     

CuMnOx／γ-Al2O3及稀土助剂对VOCs催化燃烧性能的影响

利用浸渍法制备了Cu—Mn复合氧化物催化剂和加入不同稀土含量的Cu—Mn复合氧化物催化剂,通过实验优选出加入稀土催化剂中稀土含量的最优配比,以气相色谱为检测手段,考察了加入稀土和不加稀土催化剂的催化燃烧性能,结果表明,加入稀土的催化剂T99（催化处理效率达到99％时的温度）比不加稀土的催化剂降低30～40℃,具有更好的低温活性,且对多种VOCs均能降低反应温度。     

γ-Fe2O3抗As2O3中毒能力的分子模拟

采用密度泛函理论研究了γ-Fe₂O₃表面As₂O₃的吸附以及掺杂改性提高抗As₂O₃中毒性能的作用机理.计算了As₂O₃在完整以及O缺陷γ-Fe₂O₃（001）表面的吸附性能,包括吸附位点、吸附结构、吸附能、PDOS等.同时建立了Mo、Ti、Mg掺杂的γ-Fe₂O₃模型,探讨了助剂掺杂对抗砷中毒能力的作用机制,并考虑了掺杂量的影响.结果表明：As₂O₃倾向于以O端化学吸附在γ-Fe₂O₃（001）表面Fe_oct位,吸附过程发生强烈的相互作用和电荷转移.当表面存在O缺陷时,As₂O₃的吸附能得到提高.Mo、Ti、Mg倾向于掺杂在Fe_oct位,增强了对As₂O₃的吸附能力,并且增大Mo的掺杂量可以强化As₂O₃的吸附.As₂O₃倾向于与活性较强的Mo、Ti、Mg发生反应,从而保护活性Fe位不受砷中毒,Ti和Mg的掺杂还抑制了相邻Fe位对As₂O₃的吸附.Mo、Ti、Mg的掺杂还促进了催化剂表面对NH₃的吸附,增强了表面酸性强度,有利于SCR反应.Mo、Ti、Mg原子的掺杂有利于提高γ-Fe₂O₃催化剂的抗砷中毒性能.     

微波对γ-Al_2O_3膜/污泥活性炭组成与孔结构的影响

将制得的污泥活性炭浸于[AlO(OH)]透明溶胶中,再干燥,最后经微波处理得到γ-Al2O3膜/污泥活性炭。研究微波处理工艺对γ-Al2O3膜/污泥活性炭组成与孔结构的影响。分别用X射线衍射、扫描电镜、红外光谱及孔径分布分析了γ-Al2O3膜/污泥活性炭的组成和孔结构。结果表明:增大微波功率γ-Al2O3膜/污泥活性炭的晶相由γ-Al2O3膜相和污泥活性炭相组成,辐照时间过长不利于形成γ-Al2O3相和污泥活性炭相。随着微波功率的增大,形成了附着于污泥活性炭孔内的多孔膜;γ-Al2O3膜/污泥活性炭的孔径呈双峰分布,峰明显变窄,但是随着辐照时间的过长,孔径分布向大孔移动,整个双峰变宽。因而,微波可以辅助物理活化法制备γ-Al2O3膜/污泥活性炭。     

The deployment of γ-irradiation for reducing polycyclic aromatic hydrocarbons and microbial load in wheat kernels

Food contamination may contribute to serious human health problems. In this work, the effect of γ-irradiation 0, 5, 10, and 15 kGy doses on the removal of polycyclic aromatic hydrocarbons from wheat kernels was investigated. Additionally, variations in the contents of 16 congeners on bacterial load and other chemical parameters were studied. Polycyclic aromatic hydrocarbons concentrations were determined by high-performance liquid chromatography followed by fluorescence detection. The effects of γ-irradiation on the concentrations varied for each congener, with the highest irradiation dose being the most effective. Benzo[a]pyrene was reduced by ～50%, and the total concentration of all congeners decreased dramatically from 154 to 21 µg.kg^?1 upon 15 kGy irradiation at a dose rate of 8.49 kGy h^?1. The total bacterial load was reduced from 2.4 to < 1 log₁₀ cfu g^?1, while wheat chemical properties were not affected.     

CuxCe1-xO2/γ-Al2O3催化剂催化燃烧甲苯性能的研究

以γ-Al₂O₃ 为载体,以复合氧化物Cu_xCe_1-xO₂为活性组分,其中,x=0.1,0.2,0.4,0.6,0.8,通过浸渍法制备了一系列Cu_xCe_1-xO₂/γ-Al₂O₃催化剂.在固定床反应器中评价了催化剂对甲苯的催化活性,通过XRD、SEM对催化剂进行表征,并运用ICP-MS分析并计算Cu、Ce的摩尔比以及活性组分的负载量.结果表明,在Cu_xCe_1-xO₂/γ-Al₂O₃催化剂中Cu、Ce摩尔比的实际值与理论值相近,活性组分的负载量在19%以上,而且对甲苯都有较好的低温催化活性,其中当x=0.2时,即Cu_0.2Ce_0.8O₂/γ-Al₂O₃催化剂对甲苯的催化活性最高,其中T₁₀=160 ℃,T₉₀=265 ℃;当甲苯的进口浓度在700~3000 mg·m^-3时,进口浓度对Cu_0.2Ce_0.8O₂/γ-Al₂O₃催化剂的催化活性影响较小,且经过连续80 h的稳定性操作后转化率仍然保持在90%以上.     

Simultaneous adsorption and degradation of γ-HCH by nZVI/Cu bimetallic nanoparticles with activated carbon support

Cu amended zero valent iron bimetallic nanoparticles were synthesized by doping Cu on the surface of iron. They were incorporated with granular activated carbon (AC) to prepare supported particles (AC-Fe⁰-Cu), which were used to remove γ-HCH. Cu on the surface of iron enhanced the dechlorination activity of Fe⁰. The dechlorination rate constant (k_obs) increased with the Cu loading on the surface of iron and the maximum was achieved with 6.073% Cu. AC as a support was effective for increasing the dispersion of the nanoparticles and avoiding the agglomeration of the metallic nanoparticles. The simultaneous adsorption of γ-HCH on AC accelerated the degradation rate of γ-HCH by the bimetals. After reaction for 165 min, around 99% of γ-HCH was removed by the solids of AC-Fe⁰-Cu. In addition, AC could adsorb the degradation products. The degradation of γ-HCH was mainly through dehydrochlorination and dichloroelmination based on the intermediate products detected by GC/MS.     

负载型催化剂联合低温等离子体去除甲苯

为了解负载型催化剂联合低温等离子体对甲苯去除效率的影响,考察了5A分子筛、γ-Al2O3和混合载体负载Mn、Mn/Cu和Mn/Cu/Ce金属氧化物对甲苯去除率及碳平衡和CO2选择性的影响效果,并对催化剂进行了BET、SEM、XRD和FT-IR表征研究。结果表明,相同载体条件下,对甲苯的去除效率依次为MnOx/CuOx > MnOx/CuOx/CeOx > MnOx > 无负载,其中负载型催化剂MnOx/CuOx/γ-Al2O3稳定后对甲苯的去除效率高达80%。无负载条件下,3种载体对碳平衡和CO2选择性大小依次为γ-Al2O3 > 混合载体>分子筛。催化剂表征可知,MnOx/CuOx活性组分在催化剂表面高度分散,保证了催化剂的高活性;FT-IR红外光谱发现,无负载的γ-Al2O3载体反应后其表面活性基团—OH明显减少,而负载型催化剂反应前后其表面的—OH基团变化不大。