高比表面积活性炭(HSAAC)对水中Ni2+吸附性能的研究

以石油焦基为原料,采用KOH活化法制取高比表面积活性炭。考察了高比表面积活性炭吸附水中Ni(Ⅱ)时,PH值、Ni(Ⅱ)浓度、吸附时间和活性炭用量等因素对Ni(Ⅱ)吸附量和水中Ni(Ⅱ)残余浓度的影响。实验结果表明高比表面积活性炭在适宜条件下对Ni(Ⅱ)具有较大的吸附量和良好的再生效果。为HSAAC在废水中的实际应用提供了理论依据。     

活性炭材料对Cr(VI)的吸附研究

以HCl-AC、NAC和AC-Fe_3O_4为吸附剂,对其进行比表面积和孔结构测定,并对比研究3种活性炭对Cr(VI)的吸附动力学及等温吸附,同时对其吸附效率及影响因素进行探究。结果表明,准2级吸附动力学模型比较吻合3种活性炭对Cr(VI)的吸附动力学,Freundlich等温吸附模型能较好的描述HCl-AC和AC-Fe_3O_4对Cr(VI)的吸附过程,而NAC对Cr(VI)的吸附过程则以Langmuir吸附模型拟合结果更好。HCl-AC比表面积高达1 204 m~2/g,以其作为吸附剂对Cr(VI)具有良好的亲和性和吸附能力,投加量超过5 g/L时可以吸附40 mg/L以上的Cr(VI)。较低p H有利于Cr(VI)的吸附,较多的材料添加量和吸附时间显著提高了Cr(VI)的去除率。该结果对于含Cr(VI)废水的处理具有重要意义。     

柠檬酸改性活性炭对水中Cr(VI)的吸附性能研究

为使养猪废水中的氮磷等以植物营养液的形式得以资源化利用,并有效去除其中重金属污染物,对木质、煤质、杏壳和椰壳4种活性炭进行柠檬酸改性,并考察对养猪废水厌氧发酵液中Cr(VI)的吸附效果。结果表明,4种改性活性炭中椰壳活性炭对Cr(VI)的吸附率最高。在常温、p H为4、吸附6 h、0.6 g的改性椰壳活性炭处理质量浓度50mg/L的Cr(VI)溶液,吸附率为100%,是原椰壳活性炭对Cr(VI)吸附率的2.3倍。吸附过程遵循Langmuir等温吸附方程,最大吸附容量7.933 mg/g,是原活性炭5.9倍;且改性活性炭对Cr(VI)的吸附符合准2级动力学模型。优化吸附条件下,改性椰壳活性炭对实际养猪废水厌氧发酵液中吸附Cr(VI)去除率提高近50个百分点,达到了61.32%。     

榛子壳活性炭对Cr(VI)重金属废水的吸附研究

以榛子壳为原料，磷酸为活化剂，通过700℃高温炭化150 min制备活性炭，评价榛子壳活性炭对Cr(VI)重金属模拟废水的吸附性能，分别考察活性炭添加量、接触时间、溶液初始pH值、Cr(VI)初始浓度对Cr(VI)吸附能力的影响，通过傅里叶变换红外光谱对活性炭表面的官能团进行表征，利用扫描电镜对吸附前后活性炭的表面形貌进行观察。结果表明，Cr(VI)的最佳吸附条件为活性炭用量0.4 g(100 mL体系),接触时间240 min,溶液初始pH值=3.0,Cr(VI)初始质量浓度50 mg·L^-1,吸附率高达98.67%。红外光谱分析显示活性炭表面存在大量以—OH、—C=O、—C=C基团为主的官能团，对活性炭的吸附性能具有至关重要的作用。吸附前后活性炭微粒的扫描电镜显示，吸附后的活性炭颗粒由于表面附着有大量Cr(VI),较吸附前的活性炭颗粒明显变长，说明榛子壳活性炭的吸附能力较强。本研究表明，利用磷酸为活化剂，经高温活化制备的活性炭具有良好的Cr(VI)吸附性能，为进一步开发农林果壳废弃物的高附加值环保吸附剂材料提供了实验依据。     

废白土榴莲壳粘土生物炭的制备及对Cr(VI)的吸附

以废白土与榴莲壳为原料制备了粘土生物炭吸附剂(spent bleaching earth biochar,SBEC)、以废白土为原料制备了粘土炭基吸附剂(spent bleaching earth,SBE)吸附废水中的Cr（VI）。用比表面积分析、SEM、XRD、FTIR对吸附剂进行了表征。考察了溶液初始pH、Cr(VI)溶液浓度、吸附剂投加量、吸附时间和吸附温度分别对吸附Cr(VI)的影响。25℃下pH为3时、SBEC 投加量为0.5g/L、Cr(VI)初始浓度为100mg/L、吸附时间120min,SBEC对Cr(VI)去除效率最高为86.1%,SBE则在pH为2去除效率最高为52.5%。SBEC、SBE对Cr(VI)的吸附过程符合准二级动力学模型，SBEC吸附过程符合Freundlich模型，SBE则与Langmuir吸附等温线模型较符合；吸附行为是自发吸热过程。经过5次吸附-脱附后,SBEC对Cr(VI)的去除率达58.8%。     

废白土榴莲壳粘土生物炭的制备及对Cr(VI)的吸附

以废白土与榴莲壳为原料制备了粘土生物炭吸附剂(spent bleaching earth biochar,SBEC)、以废白土为原料制备了粘土炭基吸附剂(spent bleaching earth,SBE)吸附废水中的Cr（VI）。用比表面积分析、SEM、XRD、FTIR对吸附剂进行了表征。考察了溶液初始pH、Cr(VI)溶液浓度、吸附剂投加量、吸附时间和吸附温度分别对吸附Cr(VI)的影响。25℃下pH为3时、SBEC 投加量为0.5g/L、Cr(VI)初始浓度为100mg/L、吸附时间120min,SBEC对Cr(VI)去除效率最高为86.1%,SBE则在pH为2去除效率最高为52.5%。SBEC、SBE对Cr(VI)的吸附过程符合准二级动力学模型,SBEC吸附过程符合Freundlich模型,SBE则与Langmuir吸附等温线模型较符合;吸附行为是自发吸热过程。经过5次吸附-脱附后,SBEC对Cr(VI)的去除率达58.8%。     

石油焦基高比表面积活性炭处理废水中苯酚的研究

探讨了高比表面积活性炭(HSAAC)吸附水中苯酚时,活性炭用量、pH值和吸附时间等因素对苯酚吸附量和去除率的影响。实验结果表明,HSAAC用量越大,去除效果越好。当HSAAC用量为0.2g.L-1时,去除率达94%以上;在酸性条件下HSAAC对苯酚的去除效果较好,当pH值小于6时,HSAAC对苯酚的去率可达95%以上;HSAAC对废水中苯酚的吸附主要发生在前十几小时;活性炭对苯酚的吸附量和残余质量浓度均随废水中苯酚浓度的增加而增加。用碱再生HSAAC,一次再生率达93.3%,二次再生率达到了86.7%,说明高比表面积活性炭在适宜条件下对苯酚具有较好的吸附性能和良好的再生效果。     

改性镍铁渣吸附剂对Cr(VI)吸附性能的影响及机理分析

以镍铁渣为原料,加入硝酸和表面活性剂对其矿物相改性,制备改性镍铁渣吸附剂,考察表面活性剂种类、十六烷基三甲基溴化铵(CTAB)掺量、吸附剂掺量、溶液初始pH值、Cr(VI)浓度对Cr(VI)吸附效果的影响。结果表明:镍铁渣经改性后可制得结构疏松、比表面积高达180.6 m²/g的无定形SiO₂;改性镍铁渣对Cr(VI)的吸附率在10 min内可达到90%,吸附等温线符合Langmuir模型,最大理论吸附容量为42.55 mg/g,吸附动力学符合拟二级动力学模型。改性镍铁渣吸附剂对Cr(VI)的吸附机理主要是物理吸附和氧化还原,即吸附剂表面范德华力将HCrO ^-₄吸附至吸附剂表面,CTAB提供的电子对将Cr(VI)还原为Cr(III)。对镍铁渣改性获得的高比表面积无定形SiO₂不仅可以有效吸附净化Cr(VI),同时可以实现镍铁渣资源化利用,达到以废治污的目的,具有良好的环境效应和经济效益。     

改性活性炭吸附处理含铬电镀废水的研究

分别采用硫酸和双氧水对活性炭迚行改性,测定了改性后活性炭的表面面积和含氧官能团数量,以改性后的活性炭为吸附剂,用于处理含铬电镀废水。考察了pH值、吸附时间和吸附剂用量等对Cr(VI)去除率的影响,并研究了其吸附等温线。研究表明,相比未改性活性炭,改性后的活性炭含氧官能团数量明显增加,并且改性后活性炭有利于对废水中Cr(VI)的吸附,经双氧水改性后的活性炭的吸附效果最好。     

活性炭对Cr(VI)吸附机理的探讨

根据焦作电厂粉煤灰堆放场引起地下水中Cr(VI)污染的实际情况,在实验室里模拟配制水样,使其接近当地地下水中Cr(VI)浓度,进行活性炭对Cr(VI)的吸附试验。对所得的试验数据进行分析,探讨活性炭的吸附机理。这些工作为处理和修复被污染的地下水提供理论依据,此外,还对去除地下水中Cr(VI)提出合理建议。     

Mechanisms of Cr(VI) removal from water by various types of activated carbons

The removal mechanisms of Cr(VI) from water using different types of activated carbons, produced from coconut shell, wood and dust coal, were investigated in this project. Different types of activated carbons have different surface characteristics. The coconut shell and dust coal activated carbons have protonated hydroxyl groups on the surface (H‐type carbons), while the surface of the wood‐based activated carbon has ionised hydroxyl groups (L‐type carbons). The adsorption kinetics of chromium onto the activated carbons at pH values ranging from 2 to 6 were investigated. It was found that the optimum pH to remove total chromium was 2 for wood‐based activated carbon, while for coconut shell and dust coal activated carbons, the optimum pH was around 3–4. The difference in the optimum pH for different activated carbons to remove Cr(VI) from water can be explained by the different surface characteristics and capacity of the activated carbons to reduce Cr(VI) to Cr(III). © 1999 Society of Chemical Industry     

Adsorption of chromium by activated carbon from aqueous solution

Adsorption isotherms of Cr(III) and Cr(VI) ions on two samples of activated carbon fibres and two samples of granulated activated carbons from aqueous solutions in the concentration range 20–1000 mg/l have been studied. The adsorption isotherms have been determined after modifying the activated carbon surfaces by oxidation with nitric acid, ammonium persulphate, hydrogen peroxide and oxygen gas at 350°C and after degassing at different temperatures. The adsorption of Cr(III) ions increases on oxidation and decreases on degassing. On the other hand, the adsorption of Cr(VI) ions decreases on oxidation and increases on degassing. The increase of Cr(III) and the decrease of Cr(VI) on oxidation and the decrease of Cr(III) and the increase of Cr(VI) on degassing have been attributed to the fact that the oxidation of the carbon surface enhances the amount of acidic carbon–oxygen surface groups while degassing eliminates these surface groups. Thus while the presence of acidic surface groups enhances the adsorption of Cr(III) cations, it suppresses the adsorption of Cr(VI) anions.     

Retention of Cr(VI) and Hg(II) in Eucalyptus globulus‐ and peach stone‐activated carbons

Retention rate of Cr(VI) and Hg(II), from an aqueous medium by activated carbons obtained from peach stones and Eucalyptus globulus chips, is reported. To describe the retention rate of these ions, the effects of the activated carbon preparation variables: activating agent (steam and CO₂), and burn‐off, are analyzed. In addition, the effect of the following adsorption process variable: initial concentration of the metallic ion, system temperature, pH of the medium and particle size of the adsorbent is discussed. Cr(VI) was retained at a higher rate in E globulus‐ activated carbon than in peach stone‐activated carbon due to the higher volume of the transport pores in the former material. The retention rate appears to include a micropore diffusional control in the Hg(II) retention and a transport pore diffusion control in Cr(VI) retention. The retention rate of Hg(II) is also dependent on chemical functionality of the activated carbon surface and the retention is enhanced when carbon dioxide is used as activating agent, whereas Cr(VI) retention is higher when steam activation is used. © 1999 Society of Chemical Industry     

花生壳制活性炭及其脱六价铬研究

本文研究了用花生壳制备活性炭和用此活性炭去除水溶液中的Cr（Ⅵ）。采用化学活化法,即用H2SO4、H3PO4、ZnCl2、KOH活化花生壳中的炭。同时研究了这些活化剂的浓度和用量、热解时间和温度对活性炭性能的影响。采用亚甲基蓝吸附实验评价活性炭的性能。结果表明H3PO4和ZnCl2是良好的活化剂,KOH和H2SO4效果较差。溶液的pH值对活性炭吸附Cr（Ⅵ）的能力有很大影响。活性炭的吸附能力随着pH值的降低而升高,同时在不同的pH值下,炭的吸附速率也不同。pH值越低,Cr（Ⅵ）被吸附的越快。等温实验结果表明,在pH值等于2时,用H3PO4和ZnCl2活化的活性炭对Cr（Ⅵ）的吸附能力分别达到125．0和83．3mg·g^-1。花生壳活性炭吸附Cr（Ⅵ）的机理比较复杂,与溶液的pH值有关。在pH值等于2时,等温吸附可以用Langmuir模型模拟;在pH值等于2～7时,可以用Freundlich模型模拟。     

正磷酸活化木质素吸附Cr(Ⅵ)的固定床实验和模型(英文)

The advantage of using an available and abundant residual biomass,such as lignin,as a raw material for activated carbons is that it provides additional economical interest to the technical studies.In the current investigation,a more complete understanding of adsorption of Cr(VI) from aqueous systems onto H3PO4-acid activated lignin has been achieved via microcolumns,which were operated under various process conditions.The practice of using microcolumn is appropriate for defining the adsorption parameters and for screening a large number of potential adsorbents.The effects of solution pH(2-8),initial metal ion concentration(0.483-1.981 mmol·L-1),flow rate(1.0-3.1 cm3·min-1),ionic strength(0.01-0.30 mmol·L-1) and adsorbent mass(0.11-0.465 g) on Cr(VI) adsorption were studied by assessing the microcolumn breakthrough curve.The microcolumn data were fitted by the Thomas model,the modified Dose model and the BDST model.As expected,the adsorption capacity increased with initial Cr(VI) concentration.High linear flow rates,pH values and ionic strength led to early breakthrough of Cr(VI).The model constants obtained in this study can be used for the design of pilot scale adsorption process.     

Adsorption of hexavalent chromium from aqueous solutions by bio-chars obtained during biomass pyrolysis

In this study, bio-chars were evaluated as a potential adsorbent for the removal of Cr (VI) ions from aqueous solutions. The effects of some important parameters including initial pH (1.5–7), adsorbent dose (0.2–5 g/L), contact time (5–900 min) and initial Cr (VI) ion concentration (5–75 mg/L) were tested on the removal of Cr (VI) ions from aqueous solution in batch experiments. Maximum adsorption capacities of the tested bio-chars under the certain experimental conditions determined as optimal were 3.53 mg/g for NCBC, 3.97 mg/g for NZCBC and 6.08 mg/g for ACBC, respectively. Results of the kinetic and isotherm modeling studies revealed that the adsorption data fitted well with a pseudo-second order and Langmuir model. In among the tested bio-chars, the bio-char (ACBC) was largely equivalent to activated carbon: AC (9.97 mg/g) in terms of adsorption capacity. All results indicated that the bio-chars had higher adsorption capacity than some chars and activated carbons reported previously, and also that these bio-chars could be used successfully as low-cost adsorbents for the removal of chromium ions from aqueous solutions under the tested experimental conditions.     

A new strategy for germanium adsorption on activated carbon by complex formation

Considering that germanium species in solution are scarcely adsorbed on activated carbon, the objective of this research was to develop a method for its recovery from diluted aqueous solution by activated carbons. This process is based on the use of an organic compound as a ligand in order to form an adsorbable germanium complex; afterwards activated carbon is used as sorbent. Two different commercial activated carbons, showing similar textural properties but different surface chemistry, were used as sorbents. From the obtained results, it can be said that the use of activated carbon for the adsorption of the Ge complex is a simple, rapid and efficient method, allowing its concentration on the carbon surface and its subsequent desorption - and hence recovery of the Ge. The results also show that: (i) carbon surface functionalities have a notable effect on the adsorption of the Ge complex; (ii) initial pH and the ionic strength have a noticeable importance on the adsorption process. The recovery of germanium and the reuse of the spent activated carbon have been studied. Thus, after adsorption, activated carbons were submitted to a desorption process, based on the modification of the pH for the destruction of the Ge complex at acid pH. It has been demonstrated that after the desorption process the activated carbon can be reused in several adsorption-desorption cycles although with a slight decrease in its adsorption capacity after each cycle. Based on the suitability of the activated carbons to remove germanium and on its easy desorbing process, this is also a promising method to concentrate Ge from dilute solutions. Preliminary studies for aqueous metal ions mixtures have demonstrated that this method is selective for Ge recovery when other elements are present in the initial solution.     

Solvothermal polycondensation of novolacs phenolic-resin to nanopowders and their derived activated nanocarbons as efficient adsorbents for water cleaning

Novolacs phenolic-resin (PF) was easily polycondensed into polymeric powders with sizes and morphologies ranging from microspheres to nanoparticles by a simple solvothermal process without adding any crosslinking agent. Activating the highly divided PF powders by CO₂ resulted in nanosize activated carbons with high specific surface area (2092 m² g^?1) and large pore volume (1.33 cm³ g^?1) while preserving a high carbon yield of about 38 wt%. As for adsorption tests, the micropore-dominated activated nanocarbons exhibited fast and high adsorption capabilities towards both Cr(VI) ions and bulky rhodamine B molecules due to their much improved external surface area and the greatly shortened intra-particle diffusion distance. The equilibrium adsorption amounts of Cr(VI) and RB on the activated nanocarbons as estimated by the Langmuir model were 200 and 990 mg g^?1, achieved within an adsorption time of 30 and 360 min, respectively.