Boron nitride adsorbents with sea urchin-like structures for enhanced adsorption performance

Water pollution, especially caused by organic pollutants, seriously affects people's health and even threatens life. Boron nitride (BN) adsorbents with unique sea urchin-like structures were fabricated after low-temperature treatment, freeze–drying, and high-temperature calcination. Results indicated that the sea urchin-like structure was a combination of fibers spreading outward from the center to its surroundings. As the temperature difference was gradually increased in the low-temperature treatment, the diameter of the sea urchin-like structure decreased and the Brunner-Emmett-Teller surface area increased. The adsorbents showed efficient adsorption rates and excellent reusability for dyes and antibiotics. Specifically, the maximum adsorption capacities for methylene blue and tetracycline were higher than those described in most of the literature, reaching 592.37 and 369.79 mg/g, respectively. This may have be attributed to the sea urchin-like structure of the porous fibers able to trap organic pollutants in the center, which showed strong intermolecular interactions with organic pollutants, that is, π–π bond binding force and acid-base complexation. The obtained BN adsorbents with sea urchin-like structures have great applicability in areas where organic pollutant adsorption is prevalent.     

The latest development on amine functionalized solid adsorbents for post-combustion CO2 capture:Analysis review

Global warming and associated global climate change have led to serious efforts towards reducing CO2 emissions through the CO2 capture from the major emission sources.CO2 capture using the amine func-tionalized adsorbents is regard as a direct and effective way to reducing CO2 emissions due to their large CO2 adsorption amount,excellent CO2 adsorption selectivity and lower energy requirements for adsor-bent regeneration.Moreover,large number of achievements on the amine functionalized solid adsorbent have been recorded for the enhanced CO2 capture in the past few years.In view of this,we review and analyze the recent advances in amine functionalized solid adsorbents prepared with different supporting materials including mesoporous silica,zeolite,porous carbon materials,metal organic frameworks(MOF)and other composite porous materials.In addition,amine functionalized solid adsorbents derived from waste resources are also reviewed because of the large number demand for cost-effective carbon dioxide adsorbents and the processing needs of waste resources.Considering the importance of the stability of the adsorbent in practical applications,advanced research in the capture cycle stability has also been summarized and analyzed.Finally,we summarize the review and offer the recommendations for the development of amine-based solid adsorbents for carbon dioxide capture.     

苯蒸汽回收活性炭吸附剂的筛选研究

以苯蒸汽回收的吸附剂筛选为出发点,研究了苯蒸汽在不同系列吸附剂上的吸附、脱附性能以及活性炭微孔结构对吸附性能的影响。结果表明:所用吸附剂的吸附容量和工作容量优于一般市售活性炭。可望应用于国内石化企业等行业的苯蒸汽吸附回收利用。     

Results of testing various natural gas desulfurization adsorbents

This article presents the results of testing many commercially available and some experimental sulfur adsorbents. The desired result of our testing was to find an effective method to reduce the quantity of sulfur in natural gas to less than 100 ppb volume (0.1 ppm volume). An amount of 100 ppb sulfur is the maximum limit permitted for Siemens Westinghouse solid oxide fuel cells (SOFCs). The tested adsorbents include some that rely only on physical adsorption such as activated carbon, some that rely on chemisorption such as heated zinc oxide, and some that may use both processes. The testing was performed on an engineering scale with beds larger than those used for typical laboratory tests. All tests were done at about 3.45 barg (50 psig). The natural gas used for testing was from the local pipeline in Pittsburgh and averaged 6 ppm volume total sulfur. The primary sulfur species were dimethyl sulfide (DMS), isopropyl mercaptan, tertiary butyl mercaptan, and tetrahydrothiophene. Some tests required several months to achieve a sulfur breakthrough of the bed. It was found that DMS always came through a desulfurizer bed first, independent of adsorption process. Since the breakthrough of DMS always exceeds the 100 ppb SOFC sulfur limit before other sulfurs were detected, an index was created to rate the adsorbents in units of ppm DMS × absorbent bed volume. This index is useful for calculating the expected adsorbent bed lifetime before sulfur breakthrough when the inlet natural gas DMS content is known. The adsorbents that are included in these reports were obtained from suppliers in the United States, the Netherlands, Japan, and England. Three activated carbons from different suppliers were found to have identical performance in removing DMS. One of these activated carbons was operated at four different space velocities and again showed the same performance. When using activated carbon as the basis of comparison for other adsorbents, three high-performance adsorbents were found that removed about 100 to 150 times as much DMS as activated carbon before breakthrough. This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was organized by P. Singh, Pacific Northwest National Laboratory, S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National Laboratory, and T. Dubois, U.S. Army CECOM.     

Utilization of peanut shells as adsorbents for selected metals

Peanut shells of mesh size 10–20 were modified by combinations of treatments following a 3² factorial design. Treatments consisted of either no wash, water wash or base wash followed by no modification or modification with 0.6 M citric acid or 0.6 M phosphoric acid. The nine samples were evaluated for their uptake of five metal ions (Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II)) from solution. The results were compared with metal ion adsorption by three commercial cation exchange resins, namely, Amberlite® 200, Amberlite® IRC 718 and Duolite® GT‐73. The percent of metal ions adsorbed per gram of adsorbent was significantly increased by each of the acid treatments, average values ranged from 19 to 34% compared with non‐acid treated samples at 5.7%. The percent of metal ions adsorbed for base‐washed samples were higher than water‐washed or unwashed shells. Interaction between wash and acid treatment was not significant for most of the experimental conditions used. Acid‐treated samples were as effective as Duolite® GT‐73 in the adsorption of Cd(II) and almost twice as effective in the adsorption of Zn(II) from solutions containing a single metal ion. In solutions containing multiple metal ions, citric acid samples were found to be most effective and selective for Cu(II) compared with Cd(II), Ni(II), and Zn(II). In general, phosphoric acid‐modified shells removed the most metals from solution for the experimental samples and were more effective in removing Cd(II) and Zn(II) than two of the three commercial resins. Acid‐modified peanut shells are promising as metal ion adsorbents. © 1999 Society of Chemical Industry     

氧化铝改性污泥生物炭粒制备及其对Pb(Ⅱ)的吸附特性

为拓展城市剩余污泥资源化利用途径,本文以剩余污泥球粒为原料在高温限氧条件下制备污泥生物炭粒（SBC）,同时以氢氧化铝溶胶为前体浸渍污泥球粒后在500℃下热解获得氧化铝改性污泥生物炭粒（SBC-Al）。使用BET、XRD、FTIR和SEM对生物炭粒进行了表征,并研究了生物炭粒改性前后对Pb(Ⅱ)的吸附特征及效果。结果表明：SBC-Al比表面积和总孔容分别达到83.266m²/g和0.158cm³/g,相比于SBC分别增大了142.42%和167.80%;XRD显示氢氧化铝溶胶浸渍使SBC-Al表面负载了γ-Al₂O₃粒子,FTIR红外谱图说明氧化铝改性可能会增加炭粒表面官能团数量,同时SEM显示出SBC-Al表面相较于SBC具有更多的层片状结构,从而增加生物炭粒的吸附性能。Pb(Ⅱ)的吸附动力学符合二级动力学方程和Elovich方程,同时用二阶段颗粒内扩散模型可以较好地拟合。吸附等温线以Freundlich模型为主,且SBC和SBC-Al对低浓度（＜50mg/L）Pb(Ⅱ)的去除率均较高,分别在95%和99%以上,实测最大吸附量可分别达626.73mg/g和663.97mg/g,但SBC-Al提高了对更高浓度（50～100mg/L）Pb(Ⅱ)的去除率。热力学计算数据表明吸附过程为吸热反应;脱附解吸试验说明,生物炭粒具有良好的循环再生利用性能。     

球磨时间对机械化学法NaBr改性飞灰脱汞性能的影响

采用全方位行星式球磨机对燃煤飞灰进行机械化学改性。在固定床反应装置上探究了球磨时间对改性飞灰脱汞性能的影响,并对飞灰改性前后的理化特性和脱汞机理进行了分析。结果表明,在单一机械球磨改性条件下,飞灰的脱汞效率随着球磨时间的增加出现先升高后降低的趋势。这是由于球磨过程中飞灰粒径变小,非晶相程度增加,Hg⁰与飞灰样品接触面积增加,有利于Hg⁰的脱除;但过长的球磨时间会造成飞灰孔隙结构的破坏并发生细微颗粒的团聚,使比表面积降低,不利于Hg⁰的脱除。机械球磨条件下添加改性剂NaBr后,飞灰的脱汞效率显著提升,并随着球磨时间的增加而单调增加,这是由于在机械球磨与NaBr的共同作用下,在飞灰表面产生了较多的羰基、羧基/酯基等活性官能团,同时生成C-Br共价基团,促进Hg⁰的吸附脱除。原始飞灰和单一机械化学改性飞灰对Hg⁰的脱除主要以吸附为主,氧化作用占比较少,约为吸附作用的1/3。机械化学NaBr改性飞灰对Hg⁰的吸附能力和氧化能力均显著提升,且吸附作用和氧化作用占比相当。     

纳米CaCO3孔径调控及其对碳酸化反应性能的影响

研究了纳米CaCO₃颗粒间孔径调控对CaO与CO₂碳酸化反应性能的影响。通过有机模板法制备得到一系列比表面积相近、孔径分布不同的纳米CaCO₃,并考察其再生和碳酸化反应性能差异。结果表明：增大平均孔径能促进纳米CaCO₃的热分解反应,并降低分解温度约15℃。将平均孔径由15 nm增大至113 nm可显著提高碳酸化反应速率和转化率。研究认为平均孔径和比表面积对碳酸化反应转化率的影响存在交互作用;比表面积小的纳米CaCO₃,表现出碳酸化反应转化率受扩散控制影响较大,而比表面积较大的表现为碳酸化反应转化率以表面反应影响控制为主的规律。     

Extended adsorption transport models for permeation of copper ions through nanocomposite chitosan/polyvinyl alcohol thin affinity membranes

Transport of copper ions through nanocomposite chitosan/polyvinyl alcohol thin adsorptive membranes has been mathematical y investigated in the current study. Unsteady-state diffusive transport model was coupled with the Freundlich isotherm to predict the concentration of the ions in dialysis permeation operation. Pristine model was not successful in predicting the experimental data based upon its low coefficients of determination (0.1﹤R2﹤0.65). Well-behaved polynomial and exponential functions were used to describe time-dependency of the inlet-concentration in the first extension of the model with a little improvement in the model adjustment (0.4﹤R2﹤0.69). Similar time-dependent functions were employed for tracking the ion diffusivity and then applied in combination with the optimized functions of inlet-concentration in the second extension of the model. A sensible enhancement was obtained in the adjustment of the second extended models as a result of this combination (0.73﹤R2﹤0.93). APRE, AAPRE, RSME, RMSE, STD and R-square statistical analyses were per-formed to verify the agreement of the models with the experimental results. Concentration distribution versus time and location (inside the membrane) was obtained as 3D plots with the help of the optimized models. Modeling results emphasized on the transiency of diffusivity and feed-side concentration in dialysis permeation through chitosan membranes.     

柔性MOFs材料Cu(BDC)的氨气吸附及可逆转化性能

氨气（NH₃）作为氮肥合成的主要原料和PM_2.5的重要间接来源,在工业生产倡导绿色循环的大势之下,减排与回收是绿色发展的必行之路。基于吸附法具有氨气无相变,富集得到的氨气可以直接与二氧化碳反应合成氮肥（如尿素）的优势,研究了具有可逆转化性质的柔性MOFs材料Cu（BDC）的氨气吸附性能。实验中通过水热法制备了三维致密结构的Cu（BDC）（DMF）,高温加热脱除DMF后晶体结构发生改变,得到了具有一维孔道结构的Cu（BDC）材料,比表面积为535 m²·g^-1,纯氨气的吸附量在一个大气压下高达18.4 mmol·g^-1,高于传统吸附剂以及其他新型的多孔MOFs和COFs等材料,并且通过减压和加热,材料可以逐步实现再生,具有优良的“载氨”特性。直接制备的Cu（BDC）（DMF）也可以在氨气的环境中（DMF被NH₃替代）转变为Cu（BDC）（NH₃）₂,省去了制备Cu（BDC）的过程。