Agricultural solid waste for the removal of organics: adsorption of phenol from water and wastewater by palm seed coat activated carbon

Adsorption studies for phenol removal from aqueous solution on activated palm seed coat carbon (PSCC) were carried out under varying experimental conditions of contact time, phenol concentration, adsorbent dose and pH. Adsorption equilibrium was reached within 3 h for phenolic concentrations 10-60 mg l(-1). Kinetics of adsorption obeyed a first order rate equation. The percent removal remained constant over the pH range 4-9 for a phenolic concentration of 25 mg (l-1). The equilibrium data could be described well by the Freundlich isotherm equation. The adsorption of phenol on PSCC follows the film diffusion process. A comparative study with a commercial activated carbon showed that PSCC is two times more effective than commercial activated carbon. The studies showed that the palm seed coat carbon can be used as an efficient adsorbent material for the removal of phenolics from water and wastewater.     

Bioremediation of Chlorobenzene-Contaminated Groundwater on Granular Activated Carbon Barriers

During the past decade, various promising technologies have been developed for the decontamination of groundwater insitu which do not require long-term pumping or high energy consumption. One approach is to use funnel and gate technology. In the case described here, the combination of adsorption of contaminants on granular activated carbon (GAC) and its biodegradation is applied to considerably extend the operating time of the filling material in the barrier system. Monochlorobenzene (MCB), a recalcitrant groundwater contaminant under anaerobic conditions, undergoes high-capacity adsorption on GAC up to about 450 mg per gram. Aerobic enrichment cultures, obtained from a contaminated aquifer, were able to mineralize initially adsorbed MCB. In respirometer experiments the rate of carbon dioxide formation was dependent on the equilibrium concentration of MCB. The oxygen consumption of activated carbon by means of autoxidative reactions may delay aerobic biodegradation in GAC filters. The oxygen uptake of pristine activated carbon amounted to 5.6 mg per gram GAC in laboratory column experiments. When GAC was pre-loaded with MCB, autoxidation rates were considerably reduced. Hence, it is advisable not to stimulate the biodegradation of MCB by oxygen supply in GAC biobarriers until after an initial period of solely sorptive MCB removal from the groundwater flow.     

废水处理三维电极体系中填料的选择评价方法

以瞬时电流效率和电耗为衡量标准,对填充活性炭、涂膜活性炭和石英砂3种填料的废水处理三维电极体系进行了研究。实验结果表明：活性炭的瞬时电流效率最高、电耗最低;3种填料对苯酚的选择性氧化系数依次为0.63,0.57,0.46,表明3种填料对苯酚的降解能力依次降低;在初始苯酚质量浓度为600mg/L、Na₂SO₄质量分数为3%、电流为1A、进水流量为0.60L/h的条件下,以活性炭作为填料,苯酚废水的COD去除率可达80.52%。     

Bisolute Equilibrium Studies for the Sorption of Basic Dyes on a GAC from Almond Shells: A Nonlinear Approach

Aqueous phase adsorption of three textile dyes onto a granular activated carbon produced from acid activation of almond shells is presented. Primarily, the sorption of three basic dyes, methylene blue, rhodamine b, and malachite green oxalate were studied. Four models, the Freundlich, the Langmuir, the Redlich-Peterson, and the Toth isotherms were compared for their quality of fit to the single-solute sorption data. Next, sorption of the three likely binary systems was examined. Four bi-solute models, the extended Langmuir with and without an interaction term, the extended Redlich-Peterson with an interaction term, and the empirical extended Freundlich model were used to predict sorption in the binary systems. Nonlinearly determined constants of the corresponding single-solute isotherms were used in the binary models to compare with experimental binary sorption data. For the single-solute system, the three-parameter models of the Redlich-Peterson and the Toth isotherms outperformed the Langmuir and Freundlich models. The empirical extended Freundlich model produced the closest comparison to the binary data in each system. In general, the nonlinear method provided a simple and computationally effective technique of producing optimal fitting parameters for the bi-solute sorption models.     

生物炭对铅离子的吸附性能

以废弃松木屑为原料,采用控制热分解法制备了生物炭。运用BET和FTIR等技术对生物炭进行了表征,考察了生物炭对铅离子的吸附效果,并探讨了吸附机理。表征结果显示,700℃氨气处理的生物炭,其比表面积和总孔体积显著增大。实验结果表明:生物炭对铅离子的吸附效果优于普通活性炭,且以700℃氨气处理的生物炭为最佳;随溶液pH的升高生物炭对铅离子的去除率增大,当pH为4~6时去除效果较好;在溶液pH为6、初始铅离子质量浓度为50 mg/L、吸附剂加入量为1 g/L、吸附时间为6 h的条件下,700℃氨气处理的生物炭对铅离子的去除率达99%以上;700℃氨气处理的生物炭的Langmuir吸附常数和Freundlich吸附常数远大于普通活性炭和其他工艺的生物炭;铅离子在生物炭上的吸附过程符合拟二级动力学方程。     

Fe2+/活性炭非均相Fenton试剂氧化法降解苯酚

采用Fe2+/活性炭非均相Fenton试剂催化处理高浓度模拟苯酚废水.以体积分数为40％的硫酸对颗粒活性炭进行预处理后加入质量分数为10％的硫酸亚铁溶液,制备Fe2+/活性炭.在非均相Fenton试剂氧化体系中,Fe2+/活性炭初次使用时,苯酚去除率为92％;连续重复使用5次,苯酚去除率仍可达53％.     

活性炭催化臭氧氧化水中诺氟沙星

以椰壳基活性炭为催化剂,采用催化臭氧氧化工艺降解诺氟沙星(NF),优化了工艺条件,评价了催化活性,并对反应机理进行了探讨。实验结果表明:活性炭催化臭氧氧化工艺的优化条件为臭氧通量80 mg/h、初始NF质量浓度15.0 mg/L、反应温度25℃、初始NF溶液p H 5.0;在该优化条件下反应60 min时,TOC去除率达51.5%,较单独臭氧氧化的32.5%和单独活性炭吸附的11.5%有明显改善;在活性炭催化臭氧氧化工艺中臭氧氧化与活性炭吸附之间存在一定的协同作用,活性炭具有较好的催化活性;活性炭催化臭氧氧化工艺对NF的去除主要是基于臭氧的直接氧化作用。     

D401与N-117负载 Fe（Ⅱ）非均相Fenton法催化降解苯酚

分别采用D401和N-117负载Fe（Ⅱ）制备非均相Fenton催化剂,探讨两种催化剂在不同初始溶液pH、初始H₂O₂质量浓度和保存条件下,催化降解苯酚的效果和铁溶出情况。结果表明：两种催化剂均能拓展Fenton反应pH范围;D401负载Fe（Ⅱ）催化苯酚降解速率较快,苯酚降解率随初始溶液pH升高而下降,溶出铁催化的均相Fenton反应是苯酚降解的主要原因;N-117负载Fe（Ⅱ）催化剂苯酚降解速率随初始溶液pH升高而下降,非均相Fenton反应是主要反应过程;初始H₂O₂质量浓度升高能使D401负载Fe（Ⅱ）的溶出总铁质量浓度显著升高,但对N-117负载Fe（Ⅱ）影响很小;水中较高的DO能显著降低两种催化剂的苯酚降解效果。     

NaOH改性活性炭的表面特征及吸附甲醛的性能

研究了NaOH改性活性炭(AC)的表面官能团变化特征及其吸附甲醛的性能.实验结果表明:改性AC表面的羧基、酚羟基、内酯基等官能团均与NaOH发生化学反应;质量分数为30%的NaOH溶液对AC表面的清洗作用最大,能将AC表面的杂质基本清除,此时AC表面羧基、酚羟基、内酯基和羰基浓度均达到最大;NaOH溶液质量分数为30%时,改性AC吸附甲醛的效果最好;改性AC表面酚羟基浓度的大小与改性AC吸附甲醛气体穿透时间的长短呈正比.     

钛铁矿造孔核桃壳基活性炭的制备及其吸附性能

以核桃壳为原料,钛铁矿为造孔剂,制备钛铁矿造孔核桃壳基活性炭。实验结果表明：在氯化锌浓度为3mol/L、碳化时间为40min、碳化温度为400℃、钛铁矿加入量为5%的条件下,制得的钛铁矿造孔核桃壳基活性炭对苯酚、碱性品红、Pb²⁺的吸附量分别达到了156.80,181.35,35.84mg/g,比核桃壳活性炭分别提高了25.84%,18.59%,19.10%;钛铁矿作为造孔剂制备活性炭,可以降低碳化温度和缩短碳化时间,且对活性炭中孔的形成起促进作用,有利于对大分子物质和重金属的吸附去除。     

花生壳活性炭吸附溶液中的铀

以农林废弃物花生壳为原料、氢氧化钾为活化剂、微波为热源,制备了花生壳活性炭。以花生壳活性炭为吸附剂吸附溶液中的U(VI),考察了初始U(VI)质量浓度、活性炭加入量、溶液pH、吸附时间对U(VI)去除效果的影响。实验结果表明,在溶液中初始U(VI)质量浓度为30mg/L、活性炭加入量为0.5g/L、溶液pH为5.5、吸附时间为150min的较佳条件下,活性炭对U(VI)的吸附量为56.37mg/g,U(VI)去除率为93.94％。     

Uptake of chromium by Aspergillus foetidus

Aspergillus foetidus has the ability to take up chromium during the stationary phase of growth and under growth-nonsupportive conditions. We observed a 97% decrease in hexavalent chromium (initial concentration 5 µg/g) at the end of 92 h of growth, which may be due to its reduction to Cr (III) and/or complexation with organic compounds released due to the metabolic activity of the fungus. Replacement culture studies under growth-nonsupportive conditions revealed that the maximum uptake of Cr (VI) at pH 7.0 is 2 mg/g of dry biomass. At low or high pH values, Cr (VI) uptake is significantly reduced. In addition, the initial rate of total chromium uptake is also enhanced by higher biomass concentrations and the presence of glucose. The results obtained through this investigation indicate the possibility of treating waste effluents containing hexavalent chromium using Aspergillus foetidus.     

Experimental and Modeling Studies for the Removal of Crystal Violet Dye from Aqueous Solutions using Eco-friendly <Emphasis Type="Italic">Gracilaria corticata</Emphasis> Seaweed Activated Carbon/Zn/Alginate Polymeric Composite Beads

This research article describes, an eco-friendly activated carbon prepared from the Gracilaria corticata seaweeds which was employed for the preparation of biodegradable polymeric beads for the efficient removal of crystal violet dye in an aqueous solution. The presence of chemical functional groups in the adsorbent material was detected using FTIR spectroscopy. The morphology and physical phases of the adsorbent materials were analyzed using SEM and XRD studies respectively. Batch mode dye adsorption behavior of the activated carbon/Zn/alginate polymeric beads was investigated as a function of dosage, solution pH, contact time, initial dye concentration and temperature. Maximum dye removal was observed at a pH of 5.0, 1 g of adsorbent dosage with 60 mg/L dye concentration, 50 min of contact time and at 30 °C. The equilibrium modeling studies were analyzed with Freundlich and Langmuir adsorption isotherms and the adsorption dynamics was predicted with Lagergren’s pseudo-first order, pseudo-second order equations and intra particle diffusion models. The process of dye removal followed a pseudo second-order kinetics rather than pseudo first order. The thermodynamic parameters like standard Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) were determined and the results imply that the adsorption process was spontaneous, endothermic and increases the randomness between the adsorbent and adsorbate. The results from the experimental and correlation data reveal that the Gracilaria corticata activated carbon/Zn/alginate polymeric beads have proved to be an excellent adsorbent material for the removal of CV dye.     

Activated carbon from Ceiba pentandra hulls, an agricultural waste, as an adsorbent in the removal of lead and zinc from aqueous solutions

The ability of low-cost activated carbon prepared from Ceiba pentandra hulls, an agricultural waste material, for the removal of lead and zinc from aqueous solutions has been investigated. In the batch tests experimental parameters were studied, including solution pH, contact time, adsorbent dose and initial metal ions concentration. The adsorbent exhibited good sorption potential at pH 6.0. Maximum removal of lead (99.5%) and of zinc (99.1%) with 10 g/l of sorbent was observed at 50 mg/L sorbate concentration. Removals of about 60-70% occurred in 10 min, and equilibrium was attained at around 50 min for both metals. The functional groups (CO, SO,-OH) present on the carbon surface were responsible for the adsorption of metal ions. The adsorption parameters were analysed using both the Freundlich and Langmuir models. The data are better fitted by the Freundlich isotherm as compared to Langmuir model, and the adsorption capacities for lead and zinc were 25.5 and 24.1 mg/g, respectively. Kinetics of adsorption obeyed a second order rate equation and the rate constant was found to be 2.71 x 10(-2) and 2.08 x 10(-2) g/mg/min for lead and zinc, respectively. The desorption studies were carried out using dilute HCl, and the effect of HCl concentration on desorption was studied. Maximum desorptions of 85% for lead and 78% for zinc were attained with 0.15 M HCl.     

阳离子嫩黄染料与苯酚在活性炭上竞争吸附的研究

用阳离子嫩黄染料和苯酚作为分子量差异悬殊的两种机吸附质，研究它们在两种国产活性炭上的吸附性能。在双组分竞争吸附中，阳离子嫩黄染吸附占明显优势，而 酚的吸附量则比在单组分系统时要小。本文还用理想吸附溶液（ＩＡＳ）模型对双组分竞争吸附作了预测。     

Microbiological degradation of phenol using mixed liquors of Pseudomonas putida and activated sludge

This work investigated the biodegradation potential of phenol using mixed liquors of Pseudomonas putida (ATCC 31800) and activated sludge. Experiments were made as a function of solution pH (6-10), temperature (30-36 degrees C), nitrogen source (NH4)2SO4 (0.5-0.8 g/l), and carbon source glucose (0.5-0.8 g/l). Response surface methodology by the Box-Behnken model was used to examine the role of four process factors on phenol degradation. It was shown that a second-order polynomial regression model could properly interpret the experimental data with an R2-value of 0.9997 and an F-value of 3605.45, based on which the maximum degradation of phenol was estimated up to 80.1% within the range examined. Interactions between process parameters and each significance effect on phenol degradation were also discussed.     

硝酸改性活性炭的制备及其对Cr（Ⅵ）

利用硝酸对颗粒活性炭进行改性,处理含铬废水,并考察了吸附时间、溶液pH、吸附剂加入量对改性活性炭吸附Cr（Ⅵ）效果的影响。实验结果表明：经过硝酸氧化改性的活性炭比表面积有所增加,官能团总量增加明显;吸附剂对Cr（Ⅵ）的去除率随振荡时间的增加而增加;对于质量浓度为10mg/L的100mLCr（Ⅵ）溶液,当溶液pH为中性,30%（体积分数）硝酸改性的颗粒活性炭的加入量为0.4g,其对Cr（Ⅵ）的最大去除率为98%。     

Orange peel as an adsorbent in the removal of acid violet 17 (acid dye) from aqueous solutions

The effectiveness of orange peel in adsorbing Acid violet 17 from aqueous solutions has been studied as a function of agitation time, adsorbent dosage, initial dye concentration and pH. The adsorption follows both Langmuir and Freundlich isotherms. The adsorption capacity Q0 was 19.88 mg/g at initial pH 6.3. The equilibrium time was found to be 80 min for 10, 20, 30 and 40 mg/L, dye concentration respectively. A maximum removal of 87% was obtained at pH 2.0 for an adsorbent dose of 600 mg/50 ml of 10 mg/L dye concentration. Adsorption increases with increase in pH. Maximum desorption of 60% was achieved in water medium at pH 10.0.     

Textural and surface chemical characteristics of activated carbons prepared from cattle manure compost

Two activated carbons (ACs) prepared from cattle manure compost (CMC) by ZnCl(2) activation were selected and out-gassed in a helium flow at various temperatures for 2h. The pore structure and surface chemical properties of the two selected ACs and their out-gassing treated ACs were characterized using N(2) adsorption-desorption, elements analysis, SEM and Boehm titration. A basic dye, methylene blue (MB), was chosen as an adsorbate to investigate the adsorption capacity for organic contaminant onto the activated carbons. It was found that the out-gassing treatment at 400 degrees C had little effect on the textural characteristics of the carbons but significantly changed the surface chemical properties such as surface functional groups concentration, pH and pH(PZC). The CMC-based activated carbons exhibited excellent performance for MB adsorption due to their high surface area, large mesopore volume and high nitrogen content. The kinetics of MB adsorption onto the activated carbons followed a pseudo-second-order equation, and the equilibrium data agreed well with the Langmuir model under the experimental conditions. The highest adsorption rate constant of k(ad) and the largest adsorption capacity of q(m) were found be 1.44x10(-4)g/mgmin and 519mg/g, respectively. The results suggested that the CMC-based activated carbons were effective adsorbents for the removal of methylene blue from aqueous solution.     

Removal of Cr6 + and Ni2+ from aqueous solution using bagasse and fly ash

Raw bagasse and fly ash, the waste generated in sugar mills and boilers respectively have been used as low-cost potential adsorbents. Raw bagasse was pretreated with 0.1N NaOH followed by 0.1N CH3COOH before its application. These low-cost adsorbents were used for the removal of chromium and nickel from an aqueous solution. The kinetics of adsorption and extent of adsorption at equilibrium are dependent on the physical and chemical characteristics of the adsorbent, adsorbate and experimental system. The effect of hydrogen ion concentration, contact time, sorbent dose, initial concentrations of adsorbate and adsorbent and particle size on the uptake of chromium and nickel were studied in batch experiments. The Sorption data has been correlated with Langmuir, Freundlich and Bhattacharya and Venkobachar adsorption models. The efficiencies of adsorbent materials for the removal of Cr(VI) and Ni(II) were found to be between 56.2 and 96.2% and 83.6 and 100%, respectively. These results were obtained at the optimized conditions of pH, contact time, sorbent dose, sorbate concentration of 100 mg/l and with the variation of adsorbent particles size between 0.075 and 4.75 mm. The order of selectivity is powdered activated carbon > bagasse > fly ash for Cr(VI) removal and powdered activated carbon > fly ash > bagasse for Ni(II) removal.