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%.

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.

Optimized photocatalytic regeneration of adsorption-photocatalysis bifunctional composite saturated with Methyl Orange

Photo-responsive adsorption-photocatalysis nanocomposites are generally used in water and wastewater decontamination;however,the prolonged adsorption capacity of composites and the role of adsorption in concomitant photocatalysis are typically neglected.These composites can be regenerated under light irradiation as their adsorption capacity decreases.Herein,a novel adsorption-photocatalysis bifunctional nanocomposite,Bi-doped TiO2 supported on powdered activated carbon(Bi2O3/TiO2/PAC),was prepared using the solimpregnation-hydrothermal procedure.Bi2O3/TiO2/PAC with a secondary calcination temperature of 700℃under a nitrogen atmosphere was selected for maximum adsorption capacity on Methyl Orange(MO).The composite displayed an excellent adsorption capacity and was easily separated and recycled.The results demonstrate that 71.2%photocatalytic regeneration efficiency could be attained under visible light irradiation for 1 hr at an intensity of 750 W/m^2 and pH 7.Characterization of the as-prepared Bi2O3/TiO2/PAC nanocomposite(700℃)indicates that it possesses a highly specific surface area and great optical properties,showing bifunctional adsorption-photocatalysis characteristics.The p-n heterojunction of the composite played a dominant role in the photocatalytic regeneration process,and effective degradation of MO could be achieved along with composite regeneration.

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.

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。

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。

活性炭吸附再生技术在化工废水处理中的应用

化工废水由于生化性较差、盐分、硬度较高,其深度处理已经成为行业亟需处理的重要问题。化工废水的深度处理有生化法、高级氧化法、膜法和吸附法。吸附法具有操作简单,对各种污染物具有广谱适用性、处理效果好等优点。同时通过选择合适的再生工艺,解决活饱和性炭的再生问题,可极大的拓展该工艺的使用范围。本文着重讨论了活性炭对化工废水有机污染物的吸附、活性炭再生机理及各项设计参数,通过工程实际运用,进一步验证了该工艺的可行性。

粉末活性炭深度处理垃圾渗滤液及其过硫酸盐再生研究

采用粉末活性炭对垃圾渗滤液进行深度处理,并通过过硫酸盐(PDS)高级氧化法实现活性炭的再生。通过等温吸附试验确定了活性炭的最佳投加量,并在吸附效果最佳的条件下研究了不同因素对再生效率的影响。结果表明:活性炭的最佳投加量为0.34 g/L,同时吸附过程需持续48 h以上;当投加的PDS与吸附的化学需氧量(COD)质量之比为5、再生温度为70℃、pH值为10时,可获得最佳再生效果:采用分次投加PDS的方法,可进一步提高再生效率至85%;在多次再生循环中,通过稀盐酸浸泡处理,可使7次循环后的再生效率保持在65%左右:在最佳条件下实现活性炭的再生,可降低药剂费用至2.17元/m^(3),相比不再生的情况节约了25%的费用。

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.

电化学工作站在锌电积中的试验研究

对不同的电解液进行锌电积和返溶试验,用净化指数PI (即反溶时间和锌电积时间之比)反映电解液的质量,试验结果表明:氧化锌粉浸出带来的杂质会影响锌电积,用活性炭吸附可改善电解液质量,使锌电积效率≥85%。

Synthesis and Application of Granular Activated Carbon from Biomass Waste Materials for Water Treatment:A Review

There is an increased global demand for activated carbon(AC)in application of water treatment and purification.Water pollutants that have exhibited a greater removal efficiency by AC included but not limited to heavy metals,pharmaceuticals,pesticides,natural organic matter,disinfection by-products,and microplastics.Granular activated carbon(GAC)is mostly used in aqueous so-lutions and adsorption columns for water treatment.Commercial AC is not only costly,but also obtained from non-renewable sources.This has prompted the search for alternative renewable materials for AC production.Biomass wastes present a great potential of such materials because of their availability and carbonaceous nature.This in turn can reduce on the adverse environmental effects caused by poor disposal of these wastes.The challenges associated with biomass waste based GAC are their low strength and attrition resistance which make them easily disintegrate under aqueous phase.This paper provides a comprehensive review on recent advances in production of biomass waste based GAC for water treatment and highlights future research directions.Production parameters such as granulation conditions,use of binders,carbonization,activation methods,and their effect on textural properties are discussed.Factors influencing the adsorption capacities of the derived GACs,adsorption models,adsorption mechanisms,and their regeneration potentials are reviewed.The literature reveals that biomass waste materials can produce GAC for use in water treatment with possibilities of being regenerated.Nonetheless,there is a need to explore 1)the effect of preparation pathways on the adsorptive properties of biomass derived GAC,2)sustainable production of biomass derived GAC based on life cycle assessment and techno-economic analysis,and 3)adsorption mechanisms of GAC for removal of contaminants of emerging concerns such as microplastics and unregulated disinfection by-products.

活性炭的电化学再生机理

通过研究ｐＨ值对苯酚在活性炭上的吸附平衡的影响，活性炭在不同电极上的电化学再生效率和循环再生对活性炭再生效率的影响，结合以前的有关研究结果分析认为活性炭的电化学再生过程机理中包括电脱附，ＮａＯＨ 碱再生，ＮａＣｌＯ 化学氧化等过程．实验结果表明，电化学再生活性炭具有较高的再生效率．

不同化学方法再生活性炭的对比研究

本文研究了苯酚水溶液在活性炭上的吸附平衡关系,溶液pH值对活性炭吸附性能的影响。对比研究了各种操作方式下采用NaOH碱法再生活性炭和电化学方法再生活性炭的再生效率,实验结果表明,电化学方法再生活性炭比NaOH碱法再生活性炭从再生效率上考虑要明显优越。同时用两种再生方法对吸附苯酚后的活性炭进行循环多次再生,探讨了多次再生对活性炭再生效率的影响。