Characterization of Metal Oxide-modified Walnut-shell Activated Carbon and Its Application for Phosphine Adsorption: Equilibrium, Regeneration, and Mechanism Studies

We prepared a kind of metal oxide-modified walnut-shell activated carbon(MWAC) by KOH chemical activation method and used for PH_3 adsorption removal. Meanwhile, the PH_3 adsorption equilibrium was investigated experimentally and fitted by the Toth equation, and the isosteric heat of PH_3 adsorption was calculated by the Clausius-Clapeyron Equation. The exhausted MWAC was regenerated by water washing and air drying. Moreover, the properties of five different samples were characterized by N_2 adsorption isotherm, SEM/EDS, XPS, and FTIR. The results showed that the maximum PH_3 equilibrium adsorption capacity was 595.56 mg/g. The MWAC had an energetically heterogeneous surface due to values of isosteric heat of adsorption ranging from 43 to 90 kJ/mol. The regeneration method provided an effective way for both adsorption species recycling and exhausted carbon regeneration. The high removal efficiency and big equilibrium adsorption capacity for PH_3 adsorption on the MWAC were related to its large surface area and high oxidation activity in PH_3 adsorption-oxidation to H_3 PO_4 and P_2 O_5. Furthermore, a possible PH_3 adsorption mechanism was proposed.

Adsorption and Regeneration of Volatile Organic Compounds(VOCs)on Coal-Based Activated Carbon by Ferric Nitrate Modification

In this study,the Heishan coal was used to prepare a series of activated carbon(AC)samples via a vapor deposition method.The effects of the Fe(NO_(3))3/coal weight ratio on the physicochemical properties of the activated carbon were systematically investigated,and the AC samples were analyzed by the N2 adsorption-desorption technique,the scanning electron microscopy,the X-ray diffraction,the Raman spectroscopy,and the Fourier transform infrared spectroscopy.Furthermore,the adsorption properties of ethyl acetate were investigated.The results indicated that as the Fe(NO_(3))3/coal mass ratio increased from 1:8 to 1:2,the specific surface area,the total pore volume and the micropore volume initially increased and then decreased.The specific surface area increased from 560.86 m^(2)/g to 685.90 m^(2)/g,and then decreased to 299.56 m^(2)/g.The total pore volume and micropore volume increased from 0.29 cm^(3)/g and 0.17 cm^(3)/g to 0.30 cm^(3)/g and 0.22 cm^(3)/g,and then decreased to 0.16 cm^(3)/g and 0.10 cm^(3)/g,respectively.The optimized ratio was 1:8.During the activation process,iron ions infiltrated the activated carbon to promote the development of the pore structure,the pore size of which was between 2.5 nm and 3 nm in daimeter.This approach could enhance the capacity for adsorption of ethyl acetate.It is worth noting that the ACs displaying the largest specific surface area and total pore volume(685.90 m^(2)/g and 0.30 cm^(3)/g)were formed under the optimized activation conditions(950℃,20%(volume)of CO_(2),ratio 1:5),and the maximum AC capacity for adsorption of ethyl acetate was 962.62 mg/g.After seven repeated thermal regeneration experiments,the saturated AC adsorption capacity was still above 90%.

Adsorption onto Activated Carbon Fiber Cloth and Electrothermal Desorption of Volatile Organic Compound(VOCs):A Specific Review

A general research program, focusing on activated carbon fiber cloths （ACFC） and felt for environmental protection was performed. The objectives were multiple： （i） a better understanding of the adsorption mecha- nisms of these kinds of materials; （ii） the specification and optimization of new processes using these adsorbents; （iii） the modeling of the adsorption of organic pollutants using both the usual and original approaches; （iv） applications of ACFC in industrial processes. The general question was： how can activated carbon fiber cloths and felts be used in air treatment processes for the protection of environment. In order to provide an answer, different approaches were adopted. The materials （ACFC） were characterized in terms of macro structure and internal porosity. Specific studies were performed to get the air flow pattern through the fabrics. Head loss data were generated and modeled as a fi.mction of air velocity. The performances of ACF to remove volatile organic compounds （VOCs） were approached with the adsorption isotherms and breakthrough curves in various operating conditions. Regenera- tion by Joule effect shows a homogenous heating of adsorber modules with rolled or pleated layers. Examples of industrial developments were presented showing an interesting technology for the removal of VOCs, such as dichloromethane, benzene, isopropyl alcohol and toluene, alone or in a complex mixture.

Preparation of Solid Waste-Based Activated Carbon and Its Adsorption Mechanism for Toluene

Regenerated activated carbon(RAC)samples were prepared by carbon activation using waste activated carbon from solid waste resources as the carbon source precursor coupled with adding alkaline additives,and then were further modified by potassium ferrate to finally prepare high-performance carbon for VOCs adsorption.At the same time,the samples before and after modification were systematically studied through characterization techniques such as SEM,Raman spectrometry,FT-IR,XPS,and dynamic/static adsorption.The results showed that the specific surface area and pore volume of the RAC after modification by the strong oxidant potassium ferrate increased by 1.4 times;the degree of defects was enhanced and the content of oxygen-containing functional groups on the surface increased significantly.Among them,the sample modified with potassium ferrate for 24 h had the best dynamic toluene adsorption performance(375.5 mg/g),and the dynamic adsorption capacity was twice that of the original sample(192.8 mg/g).The static adsorption test found that the maximum adsorption capacity of RAC-6%K_(2)FeO_(4)+H_(2)SO_(4)-24h was 796 mg/g,which indicated that the potassium ferrate modification treatment could significantly increase the VOCs adsorption performance of RAC.In addition,through consecutive toluene adsorption-desorption cycle tests,it was found that the RAC-6%K_(2)FeO_(4)+H_(2)SO_(4)-24h sample still retained 91%of adsorption activity after the fifth regeneration cycle.This indicates that RAC-6%K_(2)FeO_(4)+H_(2)SO_(4)-24h has good cycle stability and great application value for the efficient purification of industrial waste VOCs gas.

Batch Studies for the Removal of a Hazardous Azo Dye Methyl Orange from Water through Adsorption on Regenerated Activated Carbons

The study of the performances of regenerated activated carbons for the adsorption of MO(methyl orange)in an aqueous medium was carried out with the aim to evaluate the adsorption capacities of these activated carbons.Three regenerated activated carbons issued from the unit of oil treatment of the thermal power station of Dibamba(Cameroon)-DPDC(Dibamba Power Development Company)were obtained thermally and chemically.These three samples(namely CAR 400℃(chemical regenerated activated carbon at 400℃),CAR 700℃(physical regenerated activated carbon at 700℃)and CAR 900℃(physical regenerated activated carbon at 900℃))and the non-used one CA were characterized by iodine number,XRD(X-ray Diffraction)and FTIR(Fourier-transform infrared spectroscopy).MO adsorption tests were performed in batch mode;this technique allowed the study of the influence of the parameters such as:the contact time,the initial’s MO concentration and the pH.Moreover,different kinetic models(first-order,pseudo-second-order and Webber and Morris intra-particle diffusion)and adsorption isotherms(Langmuir and Freundlich)are used for the evaluation of adsorption capacities.The physicochemical characterization of these adsorbents showed that they were micro-porous(iodine value:600 mg/g)and strongly crystallized according to their regeneration pathways.The influence of the parameters revealed that the adsorption of MO is the most favorable for concentrations from 5 to 25 mg/L(for materials CA and CAR 400℃)and 10 to 25 g/L(for materials CAR 700℃ and 900℃);and that it was maximum in acid medium(at pH=3 on the materials CA,CAR 400℃,CAR 900℃ and at pH=5 on the material CAR 900℃).The modeling of the adsorption kinetics of MO has revealed the conformity of the kinetic model of pseudosecond-order and intra-particle diffusion for some of these materials.The study of isotherms has shown that the Langmuir isotherm best describes the adsorption of MO on most of these adsorbents.

Assessment of Surfactant Modified Activated Carbon for Improving Water Quality

Effluents containing inorganic contaminants are releasing into the environment untreated despite being hazardous to man and environment. It is costly and unsustainable to use conventional methods to remove them from dilute aqueous solution. Adsorption involving granular activated carbon is an alternative method for treating such effluents. Granular activated carbon is structurally strong, highly resistance to attrition and wearing, large and can easily separate from the effluents. However, its surface is highly hydrophobic and has little surface charge thereby reducing its adsorption capacity for anion or cation. This article reviews surfactant modification of activated carbon to enhance its adsorption capacity for inorganic contaminants and key factors affecting the adsorption efficiency. They include initial concentration of contaminants, contact time, solution pH, solution temperature, adsorbent concentration, ionic strength, competing ions, type of surfactant, and surfactant concentration. The modified activated carbon usually shows maximum contaminant uptake around its critical micelles concentration. Surfactant modification reduces specific surface area and/or micro pore volume but hot NaOH or HNO3 treatment before surfactant modification minimises this drawbacks and increases the net surface charge. Overall, surfactant modification is a simple but efficient method of enhancing adsorption capacity of activated carbon for removing anion or cation from aqueous solution. However, a handful publication is available on the regeneration of the spent (saturated) surfactant modified activated carbons. Hence, more research efforts should be directed towards proper regenerating reagents and the optimise conditions such as contact time, concentration, and temperature for regenerating spent modified activated carbons.

Application of Green Technology Using Biological Means for the Adsorption of Micro-Pollutants in Water

It is true that the world we have today is not the world we use to know. The Covid-19 pandemic has paralyzed all sector, hence the need for safety and enabling environment for mankind is of high importance. Adsorption technology is far the best and cheapest treatment technology for water and has extensively proven its worth for the uptake of micro-pollutant from surface, ground and water which are the major channels of home water. Over the years activated carbon is considered as the most common and universally used adsorbent for the eradication of different types of micro-pollutants from water. The contamination of surface water by micro-pollutant is a potential threat for the production of high quality and safe drinking water. Adsorption operation onto granulated activated carbon (GAC) in fixed-bed filters is often applied as a remedying step in the synthesis of safe and drinkable water. Activated carbon actively tends to act as a carrier material for a thin usually resistant layer of microorganisms (mostly bacteria) that forms on the coat of various surfaces (biofilm), hence biological simplification can be an alternative removal approach that can be adopted in granulated activated carbon filters. To evaluate the capacity of biofilm to biologically simplify micro-pollutants, it is very imperative to distinguish adsorption from biological simplification (biodegradation) as a removal mechanism. Experiment was carried out under the operating condition of a temperature range of 6?C to 20?C with biologically activated and autoclaved GAC to assess the biological simplification by the biofilm adsorbed on the GAC surface. Five micro-pollutants were selected as model compounds, of which some of them were biologically simplified by the GAC biofilm. Additionally, we observed that temperature can increase or decrease adsorption. Conclusively, comparison was made on the adsorption capacity of granulated activated carbon used for more than 50,000 beds.

颗粒活性炭对亚甲基蓝的吸附与再生研究

为推进颗粒活性炭在染料废水治理中的应用,采用自制的木质素基颗粒活性炭吸附亚甲基蓝(MB),考察了MB初始质量浓度、吸附温度和溶液pH值对吸附过程的影响,并利用吸附等温线和动力学对吸附过程进行了探讨,最后探索了活性炭的再生性能。研究结果表明:颗粒活性炭更适合高浓度MB吸附,吸附速率随溶液初始质量浓度的降低而降低;平衡吸附量受吸附初始质量浓度、吸附温度的影响较大,最佳吸附温度25℃,受溶液pH值影响较小。颗粒活性炭对MB的吸附等温线遵循Langmiur模型,吸附过程符合准二级动力学模型,颗粒内扩散模型分析表明内扩散及外扩散都是吸附的限速因素。吸附后活性炭在300℃热再生30 min,颗粒活性炭的MB吸附值可达240 mg/g,恢复达初始样品的94.12%,反复吸附再生4次后,颗粒活性炭的MB吸附值仍保持在85%以上。

煤基压块活性炭的制备及吸附水溶液中Cr(Ⅵ)的能力研究

为了降低压块活性炭的制备成本,以大同不黏煤为主料,桃山焦煤和重相沥青为黏结成分,以高温煤焦油和水为成型助剂制备压块活性炭。依靠调节配煤比例和改变活化条件来调控活性炭孔结构。利用碘吸附值、亚甲蓝吸附值、耐磨强度等表征活性炭常规性能;研究了样品吸附水溶液中Cr(Ⅵ)的能力,并考察了活性炭再生效率和质量损耗情况。结果表明:在大同不黏煤、桃山焦煤、重相沥青、高温煤焦油和水的配比为51∶24∶9∶7∶9的基础上,活化温度和时间分别为875℃和2.5 h的条件下制备出的压块活性炭性能最优,其耐磨强度为90%,碘吸附值为902 mg/g,亚甲基蓝吸附值为270 mg/g,比表面积为992.6 m^(2)/g;对水溶液中Cr(Ⅵ)最大吸附容量可达27.3 mg/g;质量分数为5%的硝酸溶液对饱和活性炭在50℃条件下再生8 h效果最佳,再生5次以后,其质量损耗率为21%,性能恢复率为70.06%。

活性炭吸附苯系物性能的研究进展

人类活动排放的挥发性有机物(VOCs),尤其是苯系物(BTEX),不仅影响空气质量,还会对人体健康产生不同程度的危害。室内苯系物具有浓度低、释放周期长及来源复杂等特点。由于活性炭(AC)优异的孔道结构和易调控的表面化学性质,采用活性炭吸附苯系物是封闭/半封闭空间空气污染控制的最有效策略之一。本文综述了封闭/半封闭空间苯系物的理化特征、活性炭的物理化学性质及其吸附苯系物的影响因素。这些因素主要包括活性炭物理结构、表面化学性质、苯系物分子结构和吸附条件。此外,还进一步探讨了活性炭再生技术,并展望了针对封闭/半封闭空间苯系物污染的活性炭吸附技术的改进策略。

碳基材料吸附二氧化碳的性能研究

为了验证煤基炭材料作为CO_(2)吸附剂的可行性,研究了不同表面结构的煤基炭材料的吸附性能。以褐煤为原料采用水蒸气活化的方法制备CO_(2)吸附剂,采用N 2吸附-脱附全自动比表面积和孔隙度分析仪(BET)、扫描电镜(SEM)对材料的孔道和表面结构进行了分析和表征;分别考察了活化时间、吸附剂用量以及吸附压力对混合气中CO_(2)吸附效果的影响;并对吸附饱和的吸附剂进行再生,研究其吸附的稳定性。结果表明:随着活化时间的增加,比表面积和孔径都显著增加;当半焦活化时间为30 min、吸附剂用量为5 g、床层压力为0.5 MPa时,吸附性能最好,饱和吸附量最高,可达30.11 mL/g;将该条件下吸附饱和的吸附剂循环再生使用4次后,其饱和吸附量仍能达到29.05 mL/g。煤基炭材料可用于CO_(2)吸附,研究结果可为煤基炭材料的改性提供数据支撑,也为煤炭资源的高值利用提供了新的思路。

煤质与木质活性炭吸附处理焦化RO浓水及再生试验研究

以某钢铁厂焦化RO浓水为研究对象,采用煤质颗粒活性炭与木质颗粒活性炭进行吸附处理,考察了活性炭投加量、pH值、吸附时间对吸附效果的影响,同时进行2种活性炭的Freundlich吸附等温线研究,研究了再生温度、再生时间、再生次数对活性炭再生后吸附性能及再生损失的影响。结果表明,在最佳吸附条件下,煤质和木质活性炭对废水中COD的去除率分别为61.1%、56.3%。最佳再生温度为500℃,煤质和木质活性炭最佳再生时间分别为1.5 h和1.0 h。多次再生试验证明,煤质活性炭可进行大于6次的再生,使用寿命优于木质活性炭。

“活性炭分散吸附+集中再生+资源化应用”模式在VOCs治理中的应用

本文主要介绍了“活性炭分散吸附+集中再生”的“绿岛”模式及其在挥发性有机物(VOCs)污染治理中的作用,并阐述了工业碳基固废资源化应用于该模式的意义。

焦化废水生物出水物化协同技术及污染物去除机制研究

焦化废水溶液性质复杂,经生化处理后,仍残留多环芳烃、苯、胺等难降解有机物,不仅对生态环境造成污染,也会对水回用构成技术障碍。随着环保要求的日益提高,亟需强化焦化废水的深度处理工艺,实现焦化废水的“零排放”。本文根据焦化废水生物出水的性质特征,选择混凝沉淀、活性炭吸附和臭氧氧化这三种物化技术来分质去除生物出水中的有机物,考察物化技术协同机制及其工艺有效性,为焦化废水深度处理的工艺路径提供优选方案。

活性炭吸附再生废润滑油技术的可行性及经济效益分析

基于活性炭的资源特征与环境,阐述了在工业废润滑油处理中应用活性炭吸附再生技术的可行性,结合当前的再生市场发展态势及环境,就活性炭吸附再生技术经济效益进行探讨,在探索废活性炭资源实现再利用、减少环境污染、提高经济效能的同时,能为符合资源节约、满足环保需求的废弃活性炭的资源化利用与良好处理提供理论依据。

大型油田含油污泥无害化处理技术及其应用研究

为了减少或消除污泥对环境和人体健康的危害,并实现对其资源化、能源化或再利用,提出大型油田含油污泥无害化处理技术。首先,在预处理阶段,将含油污泥进行破碎和混合均匀。破碎的目的是使污泥中的原油和水分尽可能均匀地分散在每个颗粒中,混合则是为了使污泥中的各种成分充分混合在一起。然后,借助化学氧化处理、活性炭吸附处理、生物处理方式,分别降低含油污泥中固体杂质、含油量,以及有机物质含量。最后,采用深度处理方法,如高温焚烧方法,对生物处理后的含油污泥进行减量化和资源化处理。在测试结果中,含油污泥的含油量下降幅度为5.01%,水分含量的下降幅度为6.61%,固体杂质含量的下降幅度为6.00%。

煤矿乏风瓦斯提浓研究

针对煤矿乏风瓦斯排放量大、所含甲烷对环境影响严重,且甲烷含量极低、无法直接利用的问题,开展了乏风瓦斯提浓研究。简述了煤矿乏风瓦斯排放特点及不同提浓方法的优缺点,确定了乏风瓦斯提浓采用变温吸附技术;以黏胶基活性炭纤维作为吸附剂开展了吸附等压线实验,实验得出:常压下、温度为20℃时吸附剂的甲烷吸附量为0.570 mol/kg,并确定了吸附剂的脱附温度为120℃;在此基础上设计了2500 m^(3)/h乏风瓦斯变温吸附提浓装置,运行结果表明,乏风瓦斯中甲烷体积分数可由0.29%提升至0.68%。

木焦油基活性炭的制备及其对亚甲基蓝的吸附性能

以甲醛化处理后的木焦油为前体,通过炭化-活化法制得了木焦油基活性炭(WAC)。利用FTIR、比表面积和孔结构分析仪、XPS、SEM以及XRD对WAC的结构进行了表征。以制备的WAC为吸附剂,考察了其对模拟废水中亚甲基蓝(MB)的吸附性能。结果表明,制备的多孔活性炭WAC比表面积可达1373 m^(2)/g,表面含有丰富的含氧官能团。WAC对MB具有良好的吸附性能,准二级动力学模型能更准确地描述WAC吸附MB的过程。吸附等温线更符合Langmuir等温吸附模型。WAC对MB的最大吸附容量可达559mg/g。热力学分析表明,MB在WAC上的吸附是放热和自发的。

城市污水处理系统中重金属污染物的检测及治理技术研究

为了明确城市污水处理系统中重金属元素的变化情况,提出更加高效的重金属污染物治理措施,以某城市污水处理厂A/O处理工艺中不同处理单元的水样为研究对象,采用电感耦合等离子体发射光谱仪和原子荧光光度计对水样中不同类型的重金属元素(Cu、Pb、Cr、Cd、Ni和Hg)质量浓度进行了检测,并针对性地开展了活性炭吸附试验。结果表明:目标城市污水处理厂进水水样中重金属Cu、Pb、Cr、Cd和Hg的质量浓度均超标,而经过A/O工艺处理后,不同处理单元出口的水样中重金属元素的质量浓度均有所降低,但最终出口水样中Pb和Cr的质量浓度仍超标,而Cu元素的质量浓度也高达0.283 mg·L^(-1)。活性炭吸附试验的最佳工艺参数为:吸附剂类型为改性活性炭E,吸附剂投加量为200mg·L^(-1),吸附时间为10min。在此最佳工艺条件下,水样中重金属Cu、Pb和Cr的质量浓度可分别降低至0.005 2、0.001 9、0.001 3 mg·L^(-1),均能达到国家标准GB/T 18918—2002中的排放要求。

碘氧化铋/活性炭复合材料吸附/光催化协同去除甲苯的研究

挥发性有机物(VOCs)对生态环境和人类健康有着重大影响,是影响环境空气质量的重要污染物.采用简单浸渍法制备了碘氧化铋/活性炭(BiOI/AC)复合材料,利用SEM、XRD、BET、XPS和UV-vis-DRS等技术研究复合材料的结构,并通过吸附/光催化化协同技术去除典型挥发性有机物甲苯.结果表明,当BiOI含量为4%,气体流量为100 mL·min^(−1),甲苯质量浓度为1600 mg·m^(−3)时,所制材料在160 min对甲苯的动态吸附去除率只有20.7%,而对其吸附/光催化协同的去除率达到92.95%.在相同的实验条件下,2%BiOI/AC复合材料吸附/光催化协同去除甲苯的最低去除率可达95.46%.更为重要的是,通过光催化技术可实现了吸附位点再生,提高了复合材料的重复利用性,降低成本.