Removal of methylene blue from aqueous solutions by adsorption onto chemically activated halloysite nanotubes

This study examines the adsorption behavior of methylene blue (MB) from aqueous solutions onto chemically activated halloysite nanotubes. Adsorption of MB depends greatly on the adsorbent dose, pH, initial concentration, temperature and contact time. The Langmuir and Freundlich models were applied to describe the equilibrium isotherms and the Langmuir model agrees very well with experimental data. The maximum adsorption capacities for MB ranged from 91.32 to 103.63 mg·g⁻¹ between 298 and 318 K. A comparison of kinetic models applied to the adsorption data was evaluated for pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion equation. The results showed the adsorption process was well described by the pseudo-second-order and intra-particle diffusion mode. Thermodynamic parameters suggest that the adsorption is spontaneous and endothermic. The obtained results indicated that the product had the potential to be utilized as low-cost and effective alternative for dye removal in wastewater.     

枸杞杆制活性炭对亚甲基蓝的吸附研究

以宁夏农业废弃物枸杞杆为原料,用不同的活化剂分别制备磷酸-活性炭（P-AC）、氢氧化钾-活性炭（K-AC）、磷酸-氢氧化钾-活性炭（P-K-AC）,利用比表面积测试（BET）、X射线衍射（XRD）、红外光谱（FT-IR）、扫描电镜（SEM）解析活性炭的孔结构和表面特性,并探究活性炭对水溶液中亚甲基蓝（MB）的去除效果。研究结果表明：P-K-AC比P-AC、K-AC具有更大的比表面积（1 519.84 m²/g）和总孔体积（0.81 cm³/g）,P-AC、K-AC、P-K-AC的平均孔径分别为5.28、2.58、1.99 nm,P-K-AC以微孔为主,K-AC、P-AC均为介孔。3种活性炭表面均分布着丰富的含氧官能团和大量的无定型碳,为吸附MB提供了活性位点。在25 ℃条件下,将10 mg的P-AC、K-AC、P-K-AC分别加入50 mL质量浓度为100 mg/L的MB溶液中用于吸附MB实验。结果表明：P-K-AC的吸附效果最好,吸附率达到95%、吸附量为480.81 mg/g;其次是K-AC,吸附量为352.26 mg/g;P-AC吸附量最小,为225.01 mg/g。P-AC,K-AC、P-K-AC对MB的吸附过程都符合伪二级动力学模型、颗粒内扩散模型和Langmuir等温吸附模型。     

Mercury (II) adsorption by activated carbon made from sago waste

The preparation of activated carbon (AC) from sago industry waste is a promising way to produce a useful adsorbent for Hg (II) removal, as well as dispose of sago industry waste. The AC was prepared using sago industry waste with H₂SO₄ and (NH₄)₂S₂O₈ and physico-chemical properties of AC were investigated. Adsorptive removal of mercury (II) from aqueous solution onto AC prepared from sago industry waste has been studied under varying conditions of agitation time, metal ion concentration, adsorbent dose, particle size and pH to assess the kinetic and equilibrium parameters. Adsorption equilibrium was obtained in 105 min for 20 mg l⁻¹ and 120 min for 30, 40, and 50 mg l⁻¹ Hg (II) concentrations. The Langmuir and Freundlich equilibrium isotherm models were found to provide an excellent fitting of the adsorption data, with r² 0.9999 and 0.9839, respectively. The adsorption capacity of Hg (II) (Q_o) obtained from the Langmuir equilibrium isotherm model was found to be 55.6 mg g⁻¹ at pH 5.0 for the particle size range of 125-250 μm. The percent removal increased with an increase in pH from 2 to 10. This adsorbent was found to be effective and economically attractive.     

Mercury oxidation and adsorption characteristics of chemically promoted activated carbon sorbents

Previous entrained-flow tests conducted under elemental mercury (Hg⁰)-laden air found that significant amounts of oxidized mercury (Hg²⁺) are not adsorbed onto cupric chloride-impregnated carbon (CuCl₂-AC) and brominated activated carbon (DARCO Hg-LH), but entrained to the gas phase. In this study, these sorbents were tested in a fixed-bed system and a filter-added entrained-flow system to further investigate Hg⁰ oxidation and adsorption characteristics of CuCl₂-AC and DARCO Hg-LH. These test results suggested that CuCl₂-AC has different sites available for Hg⁰ oxidation and Hg adsorption, and the resultant oxidized mercury generated from the reaction between Hg⁰ and CuCl₂ is re-adsorbed at the site of CuCl₂-AC available for adsorption. The resultant oxidized mercury was also found to be easily re-adsorbed onto CuCl₂-AC and DARCO Hg-LH in the filter connected to the entrained-flow reactor.     

壳聚糖质活性炭对亚甲基蓝的吸附性能研究

用壳聚糖制成活性炭,研究其对亚甲基蓝的吸附能力,并分析了吸附动力学以及吸附等温线。结果显示,壳聚糖质活性炭对亚甲基蓝最佳的吸附条件为:投入量为0.3 g,吸附时间为60 min,亚甲基蓝体积为10 mL;吸附温度为50℃,吸附过程较为符合二级吸附动力学方程、Freundlich模型。     

基于BP神经网络的活性炭吸附甲基紫废水过程模拟

为了研究活性炭吸附甲基紫废水过程模型,采用BP人工神经网络算法,以实验所得的32组实验数据为训练样本,建立了以甲基紫废水浓度为输入变量,以不同甲基紫废水浓度下活性炭处理后甲基紫溶液的吸光度为输出变量的吸附模型,模型输出的预测结果与实验数据吻合较好,说明该模型对活性炭吸附处理甲基紫废水过程模拟的可行性和有效性.     

软锰矿-含油污泥基活性炭对亚甲基蓝的吸附特性

以含油污泥为原料,添加适量软锰矿制备活性炭,用于吸附水中的亚甲基蓝并探究其吸附性能与吸附机制。采用SEM、BET、XPS、FTIR表征活性炭的微观形貌和物相结构,利用二维红外相关光谱探究活性炭与亚甲基蓝的吸附点位及吸附机制。结果表明,活性炭是比表面积达464.409m²/g的介孔材料,且表面含有大量的含氧官能团,活性炭吸附亚甲基蓝的过程符合准二级动力学方程和Langmuir模型,主要受化学吸附控制的单分子层吸附。结合移动窗口二维红外相关光谱分析发现,在活性炭吸附亚甲基蓝的过程中吸附较低浓度的亚甲基蓝参与的官能团较多,以各种含氧官能团为主,当亚甲基蓝浓度升高,以π-π相互作用为主;吸附机制包括氢键作用、含氧官能团参与和π-π相互作用等。     

Methylene blue adsorption from aqueous solutions to flexible poly(vinyl chloride) silica composites

Methylene blue (MB) adsorption studies were performed with poly(vinyl chloride)‐(dioctyl phthalate)‐silica composites, which were obtained by using plastisol‐plastigel technology. The films were flexible, having elastic modulus of 1.0–1.5 GPa. Diminishing MB concentration in the aqueous phase was followed as the adsorption process advanced by using visible spectroscopy. Contributions of the individual components of the composites to adsorption were also investigated. Although the MB adsorption capacity was extensively high for silica, it was moderate for the composite, most likely owing to the occlusion of pores of silica by plasticizer to some extent. The improvement of MB adsorption capacity of the composites as the silica ratio increased was explicitly deduced from the optical microscopy photographs. The diffusion coefficients of MB through the composites were 5 × 10^?13, 6 × 10^?13, and 3 × 10^?13 m² s^?1 with regression coefficients of 0.73, 0.89, and 0.88 for 0, 2, and 16% silica‐containing composites, respectively. Because of the slow diffusion of MB in poly(vinyl chloride)‐silica composites, using them as dynamic column adsorbent was not practical. However, these versatile plastics can be used as plastic labels, colored clothing, leather substitutes, antimicrobial medical devices, and laser printable surfaces. J. VINYL ADDIT. TECHNOL., 21:42–50, 2015. © 2014 Society of Plastics Engineers     

改性榛壳对水中孔雀石绿和亚甲基蓝吸附性能的研究

用NaOH对榛壳粉进行化学改性,研制出新型吸附剂SCHFS。未经改性的榛子壳(CHFS)及改性后的榛子壳(SCHFS)用FTIR、SEM进行表征。结果表明,改性后吸附剂表面褶皱、孔隙增多,含氧官能团含量显著增加,这些都有利于吸附的进行。吸附实验结果表明,在实验浓度范围内,SCHFS对亚甲基蓝、孔雀石绿的吸附遵循Langmuir等温吸附模型,R>0.99。SCHFS吸附亚甲基蓝、孔雀石绿的速度非常快,达到平衡的时间分别为30,60 min。SCHFS是一种去除水中亚甲基蓝和孔雀石绿的高效的、新型的、环境友好型吸附剂。     

Microwave treated activated carbon from industrial waste lignin for endosulfan adsorption

BACKGROUND: Disposal of large amounts of recurring industrial waste lignin is a big problem for the paper industries and there is need for a rational alternative to utilize this waste lignin. Thus highly porous activated carbons (ACs) were prepared from lignin using H₃PO₄ as an activating chemical with and without microwave treatment in a self‐generated environment at 600 °C and the influence of different types of impregnation on the adsorption–desorption capacities of endosulfan from a liquid phase was studied. RESULT: The maximum adsorption capacities (X_m) for ACs prepared by a microwave treatment and using a simple impregnation method were 6.2422 mg g^?1 and 3.9557 mg g^?1, respectively. Equilibrium adsorption time determined from kinetic experiments was 5 h and the experimental kinetic data were described by a pseudo‐second‐order rate model. Surface characteristics and desorption patterns showed considerable difference between the two ACs with the microwave treated AC showing less hysteresis, greater X_m and established overall superiority over the other. CONCLUSION: Use of microwave treatment produced more oxygen surface functional groups. Results indicate that surface chemistry of the microwave treated sample is more important than the textural properties for the higher adsorption of endosulfan. The microwave treated sample also resulted in less hysteresis and fewer carbonyl surface groups. Desorption patterns cannot be predicted from adsorption alone. Copyright © 2011 Society of Chemical Industry     

向日葵制活性炭对亚甲基蓝的吸附研究

含有亚甲基蓝（MB）的废液直接排放会造成严重的水体污染。为研究生物质活性炭对MB的吸附性能,以农业废弃物向日葵为原料、磷酸（H₃PO₄）为活化剂,制备粉状活性炭（PAC）和块状活性炭（BAC）,并研究PAC对MB的吸附性能。利用比表面积测试（BET）、X射线光电子能谱（XPS）、X射线衍射（XRD）、红外光谱（FT-IR）和扫描电镜（SEM）等方法解析活性炭的孔结构和表面特性。结果表明：活性炭前驱体的形状对活性炭的微观结构有较大的影响。PAC比BAC具有更大的比表面积（分别为701.95 m²/g和566.49 m²/g）和总孔体积（分别为2.23 cm³/g和1.04 cm³/g）;PAC和BAC的平均孔径分别为7.31 nm和12.66 nm,均具有介孔材料的结构特性。两种活性炭表面均分布着丰富的含氧官能团和大量疏松的无定形碳,而存在的偏磷酸盐对孔隙起到支撑作用,这为MB的吸附提供了更多的活性位点和吸附通道。在25 ℃、pH为8、PAC用量为50 mg条件下,PAC对100 mL质量浓度为200 mg/L的MB溶液的吸附效果最好,吸附率达到72.2%。吸附过程符合伪二级动力学模型、颗粒内扩散模型和Langmuir等温吸附模型。     

改性榛壳对水中孔雀石绿和亚甲基蓝吸附性能的研究

用NaOH对榛壳粉进行化学改性,研制出新型吸附剂SCHFS。未经改性的榛子壳(CHFS)及改性后的榛子壳(SCHFS)用FTIR、SEM进行表征。结果表明,改性后吸附剂表面褶皱、孔隙增多,含氧官能团含量显著增加,这些都有利于吸附的进行。吸附实验结果表明,在实验浓度范围内,SCHFS对亚甲基蓝、孔雀石绿的吸附遵循Langmuir等温吸附模型,R0.99。SCHFS吸附亚甲基蓝、孔雀石绿的速度非常快,达到平衡的时间分别为30,60 min。SCHFS是一种去除水中亚甲基蓝和孔雀石绿的高效的、新型的、环境友好型吸附剂。     

An economically viable removal of methylene blue by adsorption on activated carbon prepared from rice husk

Application of an agricultural waste material, rice husk, has been investigated for preparation of activated carbon. The rice husk‐activated carbon (RHAC) was successfully utilised for the removal of a cationic dye, methylene blue (MB) from aqueous solutions. The activated carbon was prepared in presence of ZnCl₂ as an activating agent under inert nitrogen atmosphere. RHAC was characterised for surface area, pore structural parameters, and point zero charge (pH_ZPC). The activated carbon was further characterised by Fourier transformation infrared (FT‐IR) spectrometer, X‐ray diffractometer (XRD), and scanning electron microscope (SEM). The effect of different parameters such as contact time and initial concentration, adsorbent dose, and temperature on removal of the dye from aqueous solutions was investigated. The experimental data fitted well in both the Freundlich and Langmuir isotherm models. The maximum adsorption capacity for MB was found to be 9.73 mg g⁻¹ at 303 K. During the study of effect of adsorbent dose, almost a 100% removal was achieved at a higher dose of RHAC. Most of the experiments were carried out at an initial concentration of MB of 60 mg/L and at 303 K. Different thermodynamic parameters, viz., changes in free energy (G°), enthalpy (H°), and entropy (S°) have also been determined to explain feasibility of the process of removal. The sorption of MB on RHAC was found to be feasible, spontaneous, and endothermic in nature.     

Removal of Pb(II) from aqueous solution by adsorption using activated tea waste

A basic investigation on the removal of Pb(II) ions from aqueous solutions by using activated tea waste was conducted in batch conditions. An inexpensive and effective adsorbent was developed from waste tea leaves for the uptake of Pb(II) from aqueous solution. The influence of different experimental parameters—shaking time, particle size, adsorbent dose, initial pH, temperature, etc.—on lead uptake was evaluated. Lead is adsorbed by the developed adsorbent up to maximum of 99.7%. The initial Pb(II) concentrations were 5, 10, 15 and 20 mg/l in the experiment. The adsorption was found to be exothermic in nature. The Langmuir, Freundlich and Tempkin isotherm models were tried to represent the equilibrium data of Pb(II) adsorption. The adsorption data was fitted very well to the Langmuir isotherm model in the studied concentration range of Pb(II) adsorption. Isotherms have been used to determine thermodynamic parameters of the process: free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°). Column experiments were performed to study the practical applicability of the system. The kinetics and the factors controlling the adsorption process were also discussed. Activated tea waste is a better adsorbent compared to other adsorbents available in literature.     

三维粒子电极光电催化亚甲基蓝研究

以蛭石作为载体,采用溶胶—凝胶法制备 TiO2/蛭石,TiO2/蛭石与石墨组成粒子电极,以溶胶凝胶法制备的钛网光电极为主电极,石墨片为阴极,亚甲基蓝溶液为目标降解物,支持电解质为无水硫酸钠溶液,固定光源为20 W 紫外灯,在恒定外电压的作用下,研究三维光电催化体系对亚甲基蓝溶液光电催化降解的效率。实验结果表明：当二氧化钛光电极的煅烧温度为550℃,TiO2/蛭石粒子的煅烧温度500℃,石墨0.8 g, TiO2/蛭石0.2 g,外接电压2 V,电极距离3 cm,无水硫酸钠溶液浓度0.02 mol/L,亚甲基蓝溶液浓度5 mg/L 时,三维光电催化实验对亚甲基蓝的脱色率达到51.9%。     

Adsorption of phenol by chemically activated D coal

The adsorption of phenol by D coal carbonized at 800°C for 1 h, in the presence of potassium hydroxide (1: 1 KOH/coal ratio, by mass), is considered. The kinetics of phenol adsorption and the isotherms (20°C) in the region of initial phenol concentrations 0.1–3.0 mg/mL are investigated. The effectiveness of phenol adsorption, the order of the reaction, and the limiting stage are determined.     

一步法制备富氧木质素活性炭及其亚甲基蓝吸附性能

以硫酸盐造纸黑液木质素为原料,分别采用磷酸活化和磷酸、硫酸混合酸活化制备了两类不同结构的木质素活性炭,对其进行了扫描电镜（SEM）、红外光谱（FTIR）、氮气吸附脱附、元素分析和Boehm酸值滴定等表征分析,并将制备的活性炭应用于模拟亚甲基蓝（MB）染料废水的吸附。结果表明,混合酸活化制备的木质素活性炭比单独磷酸活化的木质素活性炭的比表面积、总孔体积、介孔体积、氧含量分别增加了27.9%、26.4%、29.3%和29.2%,并且孔径分布更趋集中。混合酸活化活性炭在pH为2~9的范围内对亚甲基蓝均有优异的吸附性能,最大饱和吸附量达到1118.90 mg·g^-1,比磷酸活化木质素活性炭的吸附量增加了20.3%,表现出良好的吸附性能。吸附速率快,吸附过程遵循Langmuir等温线和伪二级动力学方程,颗粒内扩散不是唯一的决速步骤。     

Enhanced mercury adsorption in activated carbons from biomass materials and waste tires

Agricultural residues and waste tires constitute an important source of precursors for activated carbon production. Activated carbons offer a potential tool for mercury emissions control. In this work, pine and oak wood, olive seed and tire wastes have been used for the preparation of activated carbons, in order to be examined for their mercury removal capacity. In the case of activated carbons produced from pine/oak woods and tire wastes, a two stage physical activation procedure was applied. Activated carbons derived from olive seeds were prepared by chemical activation using KOH. Pore structure of the samples was characterized by N₂ and CO₂ adsorption, while TPD-IR experiments were performed in order to determine surface oxygen groups. Hg° adsorption experiments were realized in a bench-scale adsorption unit consisting of a fixed-bed reactor. The influence of activation technique and conditions on the resulted activated carbon properties was examined. The effects of pore structure and surface chemistry of activated carbons were also investigated. Activated carbons produced from olive seeds with chemical activation possessed the highest BET surface area with well-developed micropore structure, and the highest Hg° adsorptive capacity. Oxygen surface functional groups (mainly lactones) seem to be involved in Hg° adsorption mechanism.     

Binary vapor adsorption by activated carbon

The adsorption of binary vapor mixtures has been investigated on BPL grade activated carbon. Vapor mixtures include $\text{CNCl}\text{H}{}_2\text{O}$, $\text{HCN}\text{H}{}_2\text{O}$ and $\text{HCN}\text{CNCl}$. Preadsorption of one vapor generally lowers the adsorption of the second vapor below its single vapor isotherm value. Adsorption of CNCl after pre-adsorbing HCN is greater than the adsorption of HCN after pre-adsorbing CNCl. correlating with the higher affinity coefficient observed for CNCl. The adsorption of H₂O vapor is reduced to very low levels by pre-adsorbing HCN or CNCl.