Alkali metal cation doping of metal-organic framework for enhancing carbon dioxide adsorption capacity

Metal-organic frameworks （MOFs） have attracted much attention as adsorbents for the separation of CO2 from flue gas or natural gas. Here, a typical metal-organic framework HKUST-I（also named Cu-BTC or MOF-199） was chemically reduced by doping it with alkali metals （Li, Na and K） and they were further used to investigate their CO2 adsorption capacities. The structural information, surface chemistry and thermal behavior of the prepared adsorbent samples were characterized by X-ray powder diffraction （XRD）, thermo-gravimetric analysis （TGA） and nitrogen adsorption-desorption isotherm analysis. The results showed that the CO2 storage capacity of HKUST-1 doped with moderate quantities of Li＋, Na＋ and K＋, individually, was greater than that of unmodified HKUST-1. The highest CO2 adsorption uptake of 8.64 mmol/g was obtained with 1K-HKUST-1, and it was ca. 11% increase in adsorption capacity at 298 K and 18 bar as compared with HKUST- 1. Moreover, adsorption tests showed that HKUST-1 and 1K-HKUST-1 displayed much higher adsorption capacities of CO2 than those of N2. Finally, the adsorption/desorption cycle experiment revealed that the adsorption performance of 1K-HKUST-1 was fairly stable, without obvious deterioration in the adsorption capacity of CO2 after 10 cycles.

Elements, Structure and Electrochemical Property of Carbon Derived from La^(3+) Adulterating Polystyrene Cation Exchange Resin

The polystyrene cation exchange resin was exchanged by La 3+ and then were carbonized to make resin carbon material. The electrochemical properties of the resin carbon material as the electrode of the lithium ion cell were investigated. The test results show that comparing with the polystyrene cation exchange resin without adulterating, the contents of hydrogen, oxygen and sulfur are changed obviously for the resin carbon material derived from the La 3+ adulterating polystyrene cation exchange resin. The contents of hydrogen and oxygen are increased, and the one of sulfur is decreased. The test results also indicate that it is more easily to form the stratum graphite minicrystal structure with bigger diameter for the La 3+ adulterating resin. According to the electrochemical test results, the electrode derived from La 3+ adulterating polystyrene cation exchange resin has much better electrochemical property, and the capacity of charge and discharge of the electrode is increased about 30 mAh·g -1 in average.

阳离子化无定形碳酸钙加填纸的制备及其蛋白分离功能

本研究采用液相沉积法,以氯化钙和碳酸钠为原料,引入氯化镁作为晶型稳定剂,成功合成了无定形碳酸钙(amorphous calcium carbonate,ACC)。对ACC进行阳离子化改性,以增强其正电性和分散性。结果表明,阳离子化ACC具有良好的吸附性能;当阳离子试剂质量浓度为2.0 mg/mL,制备的阳离子化无定形碳酸钙加填量为40%时,对牛血清白蛋白的吸附量为92 mg/g。

内蒙古平原灌区土壤固碳与养分吸附特征及秸秆还田调控

为内蒙古平原灌区春玉米连续高产稳产过程中秸秆培肥高产田和改良盐碱田提供理论依据。设置了玉米秸秆还田1~4 a(HT1~HT4)定位试验,以秸秆不还田作为对照(CK),测定了春播前和收获期土壤有机碳含量、全氮含量、有效氮含量、有效磷含量、阳离子交换量、pH值和酸碱缓冲曲线。结果表明,HT1~HT4收获期与春播前相比土壤有机碳含量、全氮含量、有效氮含量、有效磷含量、阳离子交换量的相对变化率为1.34%~3.62%,0.20%~1.51%,-0.11%~0.78%,0.89%~6.36%,0.09%~0.41%,CK收获期与春播前相比土壤有机碳含量、全氮含量、有效氮含量、有效磷含量、阳离子交换量的相对变化率为1.57%,-0.02%,-0.45%,-0.15%,-0.05%;HT2、HT3、HT4比CK的土壤pH值显著降低;土壤对碱的缓冲能力依次为HT4>HT3>HT2>HT1>CK。综上所述,随秸秆还田年限的增加,土壤固碳能力、保肥能力和缓冲性能增大,有效抵御因施化肥等因素导致土壤pH值剧烈变化的能力增强,秸秆还田培肥改土措施显著提升了土壤质量。

季铵盐阳离子表面活性剂在涤纶碱减量中的应用

为了降低传统涤纶碱减量中碱剂的用量,采用十二烷基二甲基苄基氯化铵(1227)、十六烷基二甲基苄基氯化铵(1627)、十八烷基二甲基苄基氯化铵(1827)三只季铵盐阳离子表面活性剂作为涤纶织物碱减量促进剂,研究了氢氧化钠和促进剂用量、促进剂分子结构以及保温时间等因素对涤纶织物碱减量的影响,并测试了涤纶织物的减量率,分析比较了碱减量后织物的服用性能与染色性能。结果表明,促进剂疏水链越长,对碱减量促进作用越显著,即促进效果大小为:1827>1627>1227。碱减量过程中,促进剂的使用可以改善涤纶织物减量后的亲水性、白度、强度等,且处理后涤纶织物染色K/S值明显高于传统液碱处理的涤纶织物,说明在达到相同碱减量效果的条件下,促进剂1827的使用可以有效降低碱剂的用量。

“双碳”战略背景下生活垃圾分类治理研究

在“双碳”战略背景下,生活垃圾分类治理是保证整体目标实现的推动性策略,在人居环境改善及资源循环使用等方面发挥着重要作用。从当前形势来看,生活垃圾分类治理工作模式在逐步优化,但是随着垃圾产量的不断增加,垃圾分类治理问题也日益凸显。为了高质量地推进生活垃圾分类治理工作,稳步实现双碳战略目标,需明确生活垃圾分类治理的困境及难点,由此提出高效可行的治理策略,持续扩大生活垃圾分类覆盖率,深入推进生活垃圾分类工作提质增效。

葡萄糖碳源对低碳氮比生活污水反硝化脱氮性能的影响探究

改良型Carrousel氧化沟耦合工艺处理低碳氮比的生活污水,是采用间歇曝气模式,氧化沟出口的溶解氧为2.0~3.0 mg/L,污泥浓度为2 500~3 500 mg/L,污泥回流比为80%~95%。在TN和氨氮常年超标的情况下,投加葡萄糖碳源,可以使该污水处理厂改良型Carrousel氧化沟工艺去除低碳氮比的生活污水中的氨氮、总氮、总磷、COD_(Cr)、BOD_(5)及酸碱度的效果很好,出水完全符合《城镇污水污水处理厂污染物排放标准》(GB 19918-2002)[1]的要求。

Soil exchangeable base cations along a chronosequence of Caragana microphylla plantation in a semi-arid sandy land,China

As a pioneer leguminous shrub species for vegetation re-establishment, Caragana microphylla is widely distributed in the semi-fixed and fixed sandy lands of the Horqin region, North China. C. microphylla planta- tions modify organic carbon （SOC）, nitrogen （N） and phosphorus dynamics, bulk density and water-holding capacity and biological activities in soils, but little is known with regard to soil exchange properties. Variation in soil ex- changeable base cations was examined under C. microphylla plantations with an age sequence of 0, 5, 10, and 22 years in the Horqin Sandy Land, and at the depth of 0-10, 10-20, and 20-30 cm, respectively. C. microphylla has been planted on the non-vegetated sand dunes with similar physical-chemical soil properties. The results showed that exchangeable calcium （Ca）, magnesium （Mg）, and potassium （K）, and cation exchange capacity （CEC） were significantly increased, and Ca saturation tended to decrease, while Mg and K saturations were increased with the plantation years. No difference was observed for exchangeable sodium （Na） neither with plantation years nor at soil depths. Of all the base cations and soil layers, exchangeable K at the depth of 0-10 cm accumulated most quickly, and it increased by 1.76, 3.16, and 4.25 times, respectively after C. microphylla was planted for 5, 10, and 22 years. Exchangeable Ca, Mg, and K, and CEC were significantly （P〈0.001） and positively correlated with SOC, total N, pH and electrical conductivity （EC）. Soil pH and SOC are regarded as the main factors influencing the variation in ex- changeable cations, and the preferential absorption of cations by plants and different leaching rates of base cations that modify cation saturations under C. microphylla plantation. It is concluded that as a nitrogen-fixation species, C. microphylla plantation is beneficial to increasing exchangeable base cations and CEC in soils, and therefore can improve soil fertility and create favorable microenvironments for plants and creatures in the semi-arid sandy land ecosystems.

Base cation concentrations in forest litter and topsoil have different responses to climate and tree species along elevational gradients

The forest litter is an essential reservoir of nutrients in forests, supplying a large part of absorbable base cations(BC) to topsoil, and facilitating plant growth within litter-soil system. To characterize elevational patterns of base cation concentrations in the forest litter and topsoil, and explore the effects of climate and tree species, we measured microclimate and collected the forest litter and topsoil(0-10 cm) samples across an elevational range of more than 2000 m(1243 ～ 3316 m a.s.l.),and analyzed the concentrations of BC in laboratory. Results showed that: 1) litter Ca concentration displayed a hump-shaped pattern along the elevational gradients, but litter K and Mg showed saddle-shaped patterns. Soil Ca concentration increased with elevation, while soil K and Mg had no significant changes. 2) Ca concentration in the forest litter under aspen(Populus davidiana) was significantly higher than that in all other species, but in topsoil, Ca concentration was higher under coniferous larch and fir(Larix chinensis and Abies fargesii). Litter K and Mg concentrations was higher under coniferous larch and fir, whereas there were nosignificant differences among tree species in the concentrations of K and Mg in topsoil. 3) Climatic factors including mean annual temperature(MAT), growing season precipitation(GSP) and non-growing season precipitation(NGSP) determined BC concentrations in the forest litter and topsoil. Soil C/N and C/P also influenced BC cycling between litter and soil. Observation along elevations within different tree species implies that above-ground tree species can redistribute below-ground cations, and this process is profoundly impacted by climate. Litter and soil Ca, K and Mg with different responses to environmental variables depend on their soluble capacity and mobile ability.

Parity Alternation of Silicon-doped Ternary Cationic Clusters HC_nSi_2^+(n=1～9)

Systematic study on the electronic/geometrical structures and the parity alternation effect of silicon-doped ternary cationic clusters HCnSi2＋（n = 1 ~9） have been carried out at the coupled cluster level. The ground-state （G-S） isomers of the clusters have been defined. The C, chains of the G-S isomers display polyacetylene-like structures. The even-n cations are more stable than the odd-n ones. Such a trend of even/odd alternation has been elaborated based on concepts of the bond character, atomic charge, incremental binding energy, ionization potential, proton affinity and fragmentation energies of the systems. The findings accord with the relative intensities of HC,,Si2＋ species recorded in the related mass spectrometric experiments.

Facile preparation of bi-functional iron doped mesoporous materials and their application in the cycloaddition of CO2

Two kinds of bi-functional transition metal doped mesoporous materials(Fe-HMS and Fe-MCM-41) are prepared using one-step hydrothermal method and then treated with hydrochloric acid ethanol solution.The N2 adsorption and HRTEM results show that both of Fe-HMS and Fe-MCM-41 possess mesoporous structure. The UV–vis results suggest that the Fe species are mainly located within the framework. The basicity of as-prepared samples was studied by temperature programmed desorption using CO2 as probe molecule(CO2-TPD). The catalytic performance of Fe-HMS and Fe-MCM-41 in CO2 cycloaddition largely depends on the amount of the accessible basic sites. The acid–base active sites, framework Fe and PDDA species cooperatively catalyze the CO2 cycloaddition for the production of cyclic carbonates under the condition without any co-catalyst. The conversion of epichlorohydrin(ECH) is 97.4% and the selectivity of chloropropene carbonate is 92.9% under optimal conditions. The approximate rate constant of cycloaddition reaction of CO2 with ECH under optimum reaction temperature is calculated. It is worth noting that the Fe-HMS material shows superior reusability than Fe-MCM-41. In addition, this work provides a facile way on the synthesis of bi-functional acid–base heterogeneous catalyst with outstanding catalytic performance for the fixation of CO2.

The effect of cations on gelation of cross-linked polymers

The effects of different cation concentrations and types on rheological property and stability of Guar, Xanthan, and Partially Hydrolyzed Polyacrylamide(HPAM) cross-linked gels were analyzed through experiments. Also, a new approach was developed to reduce the negative effects of cation by application of multi-walled carbon nano-tubes(MWCNTs). The presence of cations in cross-linked gel system will reduce the viscosity of gel, the higher the cation concentration is, the lower the viscosity will be. The bivalent cation has a greater viscosity reduction effect on gel than monovalent cation. The stability of cross-linked gels is worse with cations, this situation becomes more serious under higher salinity. MWCNTs were added to HPAM gel, cross-linked by(3-Aminopropyl) triethoxysilane(APTES), they surrounded cations and removed them from polymers and reduced the reaction possibility. This method enhances the viscosity and breakdown pressure of cross-linked gels, improves the stability of HPAM cross-linked gel under different operating conditions, and can be applied to related drilling projects.

Modeling of Carbon Monoxide Removal by Corona Plasma

Modeling of carbon monoxide （CO） removal by a corona plasma was conducted in this study. The purification efficiency of CO was calculated theoretically and the factors affecting the removal of CO were analyzed. The results showed that the main removal mechanisms of CO were direct dissociation by generated high-energy electrons and indirect oxidation by generated hydroxyl radicals. The purification efficiency of CO was dependent on the plasma parameters, indoor air humidity and initial concentration of CO. Good consistency between the theoretical calculation and the experimental results was observed.

阳离子表面活性剂遮蔽作用导致的酸化缓速研究

为了减轻传统稠化酸在碳酸盐岩多孔介质中的吸附滞留伤害,降低其对于致密碳酸盐岩改造后渗透率的伤害。提出采用阳离子表面活性剂遮蔽在岩石表面进行改性进而缓速的方式,以鄂尔多斯盆地马家沟组碳酸盐岩为研究对象,根据基本性质测试确定不同碳链长度阳离子表面活性剂界面改性能力,并利用分子模拟技术结合原子力显微镜、润湿角观测提出阳离子表面活性剂缓速机理,再通过动静态缓速性能测试和伤害评价实验研究阳离子表面活性剂缓速性能及地层伤害程度。研究结果表明:(1)碳链长度会影响表面活性剂分子吸附形态,进而改变其界面吸附效果,十四烷基三甲基氯化铵可在岩石表面形成直立致密吸附层,润湿改性效果最佳;(2)阳离子表面活性剂以界面吸附作用对岩石表面进行掩蔽覆盖,增加其疏水性能,阻碍H+接触到岩石表面,控制表面反应速率,达到缓速目的;(3)相较于常规酸,阳离子表面活性剂具有良好的动静态缓速性能,各项动力学参数降低50%~60%,减低了对碳酸盐岩孔喉伤害。研究认为:季铵盐阳离子表面活性剂具备分子量低、界面吸附能力强的优势,在保持缓速能力的同时,有效降低稠化酸对地层伤害程度;该项研究有助于认识表面活性剂缓速性能、改进缓速酸体系、提高碳酸盐岩储层改造效果等都具有积极的意义。

建筑用碳纤维增强铝基复合材料的工艺优化与性能研究

采用真空热压法制备了建筑用碳纤维增强铝基复合材料,以抗拉强度和致密度为考核指标,通过三因素三水平正交试验法优化了复合材料的热压工艺参数,并对断口形貌进行了观察。结果表明,以抗拉强度为考核指标时,对抗拉强度影响最大的是因素B(热压时间),其次是因素A(热压温度),而影响最小的是因素C(热压压力);以致密度为考核指标时,对致密度影响最大的是因素A(热压温度),其次是因素C(热压压力),而影响最小的是因素B(热压时间)。采用综合平衡法优化建筑用碳纤维增强复合材料的热压工艺参数组合为A1B3C3,即热压温度为510℃、热压时间为180min、热压压力为15MPa时,碳纤维增强复合材料可以取得最大的致密度和抗拉强度,此时复合材料的抗拉强度为286.98MPa、致密度为99.92%。

尾叶桉与木荷林对土壤理化性质及易氧化有机碳的影响

为了解林分类型对土壤理化性质及易氧化有机碳(ROC)的影响,采集广州市长岗山30年生尾叶桉和木荷人工林表层土壤,测定土壤碳(C)、氮(N)、磷(P)含量及阳离子交换量(CEC)、ROC含量等指标并进行对比分析。结果表明:尾叶桉林表层土壤总有机碳(TOC)和全氮(TN)含量显著高于木荷林;C/N表现为木荷林显著大于尾叶桉林,而C/P和N/P则表现为尾叶桉林大于木荷林,两种林分表层土壤N含量丰富,而P元素较缺乏。两种林分土壤CEC差异不显著,尾叶桉林土壤的交换性盐基离子总量和盐基饱和度显著高于木荷林;两种林分土壤交换性盐基离子含量表现为Ca^(2+)>Mg^(2+)>K^(+)>Na^(+)。尾叶桉林土壤的ROC含量显著高于木荷林,ROC/TOC表现为木荷林小于尾叶桉林但没有显著差异。尾叶桉林土壤的ROC含量与AP呈显著正相关(P<0.05),且ROC/TOC与TP呈显著正相关(P<0.05);木荷林土壤的ROC含量与CEC呈显著正相关(P<0.05),与ROC/TOC呈极显著正相关(P<0.01)。两种林分表层土壤的ROC含量存在显著差异,说明林分类型是影响土壤ROC含量的重要因素。木荷林的ROC/TOC小于尾叶桉林,说明其土壤碳稳定性高于尾叶桉林,对土壤碳固存效果更好。

阳-非离子型表面活性剂醇醚季铵盐的合成及性能

以Guerbet醇醚(C_(24)PO_(10)EO_(10)OH)非离子型表面活性剂为原料经氯代和季铵化反应合成了一种含支链烷基的醇醚季铵盐(C_(24)PO_(10)EO_(10)-TAC)。实验结果表明,这种新型的阳-非离子型表面活性剂具有优良的耐温耐盐性,当含量为0.3%(w)时,对水溶液中NaCl,CaCl_(2),Na_(2)SO_(4)三种无机盐的容忍度分别可达186000,170000,155000 mg/L,且在80℃下密封保存30 d后,有效物浓度保持率高达98.5%。这种表面活性剂在碳酸盐岩/水界面的吸附量仅为3.08×10^(-7)mol/g(0.45 mg/g),显著低于传统的阳离子型表面活性剂,同时可有效提高碳酸盐岩表面的亲水性。将C_(24)PO_(10)EO_(10)-TAC与亲水性非离子表面活性剂烷基糖苷APG-1214以及另一种阳-非离子型表面活性剂C_(18)PO_(25)EO_(20)-TAC复配,得到的二元或三元表面活性剂混合物可在总含量为0.06%~1.00%(w)的范围内将相关原油/模拟盐水(矿化度75346 mg/L)的界面张力降至超低。

低C/N污水培养好氧颗粒污泥研究进展

【目的】为解决低C/N污水难以培养好氧颗粒污泥(Aerobic Granular Sludge,AGS)的问题,对AGS的形成机理、影响因素等方面进行研究分析。【方法】综述了AGS形成的4种学说和影响AGS形成以及处理效果的6种因素,分析了AGS国内外工程应用情况,总结了AGS培养过程中的相关问题。【结果】低C/N污水培养AGS的过程中会受到原水基质浓度低、氮磷负荷难以协调的问题,还会受到溶解氧、曝气模式、剪切力、污泥龄、温度和周期设置的影响,颗粒化困难。后续可通过更改培养参数和运行策略满足生产需求。【结论】低C/N污水水质成分复杂,往往包含部分工业尾水,须规范行业制度,为AGS技术提供良好环境。低C/N污水培养AGS要求各类学科紧密配合,系统性整合产业链。通过工艺协调进水负荷,满足生产需求。此外还能通过采用协同处理的模式,引入工业废液改善水质,降低培养难度。

沸石中碱金属阳离子对CO_(2)/N_(2)O吸附分离性能的影响

氧化亚氮(N_(2)O)是仅次于CO_(2)和CH_(4)的第三大温室气体,排放后加剧温室效应,而N_(2)O具有广泛的用途,因此对其进行回收具有重要意义。苯酚法和环己烷法生产己二酸时排放的尾气中CO_(2)与N_(2)O共存,二者具有相同的动力学直径和相似的物理性质,它们的分离具有很大的挑战。研究了A型沸石中一价碱金属阳离子(Li^(+)、Na^(+)、K^(+)、Cs^(+))对CO_(2)/N_(2)O吸附分离性能的影响,通过XRD、ICP-OES、SEM和TGA进行表征,并对吸附性能、IAST选择性以及分离性能进行了研究。研究结果表明,随着碱金属阳离子半径的增大,CO_(2)和N_(2)O的吸附容量逐渐降低,CsA几乎对CO_(2)和N_(2)O均不吸附;但CO_(2)/N_(2)O选择性却呈相反的趋势,其中KA的选择性达到最高(2.6),混合气体(VCO_(2)/VN_(2)O=50%/50%)穿透实验结果也表明KA具有一定的CO_(2)/N_(2)O吸附分离性能。

海藻酸钠/改性氧化石墨烯微孔气凝胶纤维制备与吸附性能

为提升海藻酸钠(SA)/氧化石墨烯(GO)复合纤维对阳离子染料的吸附性能及其力学性能,以轻质碳酸钙作为成孔剂,马来酸酐接枝氧化石墨烯(MAH-GO)微粒作为增强剂,SA作为基体,采用湿法纺丝与冷冻干燥法,经酸性置换制备SA/MAH-GO微孔气凝胶纤维,并对其化学结构、形貌和粒度进行分析,探讨了MAH-GO质量分数对微孔气凝胶纤维断裂强度的影响,采用吸附动力学及吸附等温线模型对吸附实验数据进行拟合分析。结果表明:MAH-GO质量分数为0.5%时,SA/MAH-GO微孔气凝胶纤维的拉伸断裂强度最优,为0.513 cN/dtex,与SA/GO气凝胶纤维断裂强度相比提高了11.51%,其吸附过程符合准二级吸附动力学模型,主要受到化学吸附机制控制,对亚甲基蓝最大吸附量可达2 400.66 mg/g。