The relation between activated carbon adsorption and water quality indexes

In order to estimate the adsorbability by activated carbon of organic compounds dissolved in aqueous solutions, the contribution of individual atoms to the adsorption process is calculated. The contribution of carbon, bromine and chlorine atoms is positive, that of oxygen atoms is negative, that of hydrogen atoms is very small and that of nitrogen atoms is influenced by the kind of functional group in which they are contained. The dominant factors governing adsorption are the numbers of carbon and oxygen atoms in a molecule. The activated carbon's effectiveness for adsorption of organic compounds dissolved in solutions can be predicted from such water quality indexes as total organic carbon, total organic nitrogen, total organic halogen an total oxygen demand.     

Pentachlorophenol adsorption and desorption characteristics of granular activated carbon-I. Isotherms

The adsorption/desorption of pentachlorophenol (PCP) with Calgon F300 granular activated carbon (GAC) was studied and modelled. A modified Radke-Prausnitz (1972) isotherm model, incorporating a temperature- and pH-dependent proportionality constant, was found to best describe the observed PCP adsorption and desorption. The modified isotherm is valid in the ranges 4 ≤ pH ≤ 11 and 10 ≤ T ≤ 60°C. The activation energy of PCP adsorption was calculated to be 5.2 kJ/mol. At 30°C, PCP adsorbed strongly, and the rate of subsequent desorption was very low. However, the amount of PCP desorbed could be increased significantly by increasing the temperature to 60°C.     

Experimental study on adsorption capacity of an activated carbon-based adsorption water chiller

The objective of this study was to evaluate the adsorption capacity of a working pair for an adsorption water chiller. Activated carbon fibre–methanol, activated carbon fibre–ethanol and activated carbon pallet–ethanol were used as an adsorbent–adsorbate pair in this study. The experiment was conducted using a stainless steel adsorber, 110?mm diameter by 150?mm height, filled with adsorbent and transparent plastic evaporator, 100?ml capacity, filled with adsorbate. The experiment was performed by isobaric adsorption in the temperature range of 10–100°C at the evaporator temperature of 20°C (water chiller). An experimental investigation showed that the activated carbon fibre–methanol pair has the highest adsorption capacity (0.44?kg/kg) compared to the activated carbon fibre–ethanol and activated carbon pallet–ethanol pairs. The finding revealed that uniform structure and large surface area of adsorbent as well as low boiling point and large latent heat of adsorbate had highly significant effects on adsorption capacity. The effect of time and adsorber temperature on adsorption capacity is also discussed in this study.     

活性炭改性及其吸附甲苯和丁酮的初步研究

通过微波改性,电炉直接加热改性,氢氧化钠改性,硝酸改性等几种方法对活性炭进行改性,并对改性后活性炭的吸附能力进行研究,得出微波改性和电炉直接加热改性增强了活性炭吸附能力,氢氧化钠改性和硝酸改性则明显削弱其吸附能力。     

Pentachlorophenol adsorption and desorption characteristics of granular activated carbon-II. Kinetics

The kinetics of pentachlorophenol (PCP) adsorption/desorption with Calgon F300 granular activated carbon (GAC) was studied. A previously-developed model of GAC adsorption/desorption kinetics was applied to the case of PCP for both batch and continuous plug-flow liquid conditions. The model predictions were found to be in good agreement with the experimental observations.     

活性炭吸附去除重金属研究进展

介绍了国内外学者应用活性炭吸附去除包括:Cr(Ⅵ),Cu2 ,Zn2 ,Cd2 ,Pb2 ,Mn2 ,Hg2 以及混合重金属离子在内的各种废水的处理效果与影响因素,并对相应的吸附机理进行了讨论,以促进活性炭吸附去除重金属离子的进展。     

活性炭纤维吸附饮用水中硼的试验研究

通过静态试验,对经过简单预处理的活性炭纤维的除硼效果以及吸附时间、pH、温度和搅拌机转速等因素对吸附效果的影响进行了考察.结果表明.该吸附过程符合Freundlich吸附等温线模式,以物理吸附为主;最佳吸附时间为1 h;pH和温度对吸附效果影响均较大,pH值最佳范围为5～6.5,温度为15℃;搅拌机高速转动更利于吸附进行;采用了不同再生剂对吸附饱和的活性炭纤维进行再生试验,3%NaOH溶液再生效果最好,再生后吸附效率可达90.1%.     

氯苯和腐殖酸的活性炭竞争吸附模型曲面拟合

研究了氯苯和腐殖酸在活性炭上的竞争吸附。采用1stOpt和MATLAB数据拟合软件解决了氯苯和腐殖酸在活性炭上竞争吸附的多元非线性模型拟合问题，拟合得到的参数方程可以模拟氯苯和腐殖酸在活性炭上的竞争吸附行为。按照拟合方程绘制的三维图形表明，腐殖酸浓度越高，氯苯浓度越低，氯苯被活性炭吸附时受腐殖酸的影响越大，其影响程度可由方程计算得出，可为活性炭滤柱的设计提供基础参数。     

活性炭在微污染水源水处理中的应用综述

介绍了活性炭在微污染水源水处理中的应用情况,包括活性炭吸附、生物活性炭、臭氧活性炭技术等的对水源中有机物的去除效果和工艺特点,指出活性炭对去除水中微量有机物污染方面是其他水处理单元难以取代的,在微污染水源水处理中有较广泛的应用.     

Preparation of layered double hydroxides using boron mud and red mud industrial wastes and adsorption mechanism to phosphate

Phosphate removal was important for wastewater treatment, and adsorption was an efficient treatment process. In this study, the layered double hydroxide adsorbent (BR‐LDH), which was prepared under alkali conditions using industrial residues boron mud and red mud, was used to adsorb the phosphate. The prepared BR‐LDH was characterised by X‐ray diffraction, Scanning electron microscopy, Energy‐dispersive X‐ray spectroscopy, and Thermo‐gravimetric‐differential thermal analysis. Adsorption experiments were carried out as a function of dosage, contact time, temperature and initial pH of phosphate solution. The removal ratio of phosphate onto OBR‐LDH reached 93%. The adsorption data showed a good compliance with the pseudo‐second‐order kinetic model. In addition, the mineral composition, the functional groups, the valence of elements and zeta potentials of OBR‐LDH before and after adsorption were used to analyse the adsorption mechanism. The result of real wastewater suggested that OBR‐LDH was excellent adsorbent for phosphorus removal from actual wastewater.     

Prediction of multicomponent adsorption equilibria in background mixtures of unknown composition

In the past, most predictive mathematical modeling work has focused on mixtures of known composition. Unfortunately, drinking water and wastewater contain many competing organic solutes and most of them may never be identified. Accordingly, a technique has been developed to predict the adsorption equilibria of known organic solutes onto granular activated carbon (GAC) in mixtures of unknown composition.

Ideal adsorbed solution theory (IAST) was used to describe the competitive interactions between adsorbates. Theoretical components (TCs) were used in IAST calculations to account for the competitive effects of the unknown mixture. The TC isotherm parameters and concentrations were determined by conducting a multicomponent isotherm of a tracer component which is added to the unknown mixture or singled out of the unknown mixture. Once the TC parameters were determined, the identical parameters were used to predict the competitive interactions between any known component and the unknown mixture. This procedure was verified experimentally for two activated carbons, three synthetic mixtures and a contaminated groundwater. The organic solutes were halogenated one and two carbon aliphatics which are common groundwater contaminants.     

Single and competitive adsorption of Cd and Zn onto a granular activated carbon

Single and competitive adsorption of cadmium and zinc onto granular activated carbon DARCO 12–20 mesh has been investigated. This activated carbon has been shown as an effective adsorbent for both metals. Cadmium and zinc removals increased with pH and decreased with molar metal/carbon ratio. Surface precipitation phenomena have been detected for the higher pHs and molar ratios. The adsorption process has been modelled on the surface complexation Triple Layer Model (TLM). For this purpose, the amphoteric nature of the activated carbon has been studied. Single metal adsorption data have been used to calibrate TLM parameters. A dependence of the adsorption constants on pH and molar metal/carbon ratio has been observed, and a correlation for log K_ads has been determined. In the competitive system, the removal efficiency of the activated carbon decreased for both metals. The TLM model, using surface complexation constants determined from single adsorption experiments, successfully predicted cadmium and zinc removal from the two metal solutions.     

商丘市梁园污水处理厂污水处理工艺

阐述了商丘市梁园污水处理厂进水水质情况,通过对不同性质污水量的统计分析,并结合工程实际情况介绍了改良型氧化沟工艺、传统A/A/O工艺及Bardenpho工艺3种污水处理方案的优缺点。经比选最终选择Bardenpho工艺,采用混凝沉淀、砂滤及活性碳吸附的深度处理工艺,使出水水质达到一级A排放标准。     

Determination of the percentage adsorption of unknown organic compounds from water with a multi-column technique

A technique is presented for the determination on a laboratory scale of the percentage removal from water, by an adsorption column system, of one or more organic compounds which give a linear response in the column eluate. This response may be due to a physical, chemical or biological effect. The technique is useful for situations where the concentrations of organic substances in water cannot be determined, either directly on water or in an extract of the water.Formulae for this technique were derived and evaluated with organic compounds which could be determined in water.The use of the technique is illustrated by screening a number of adsorbents for their capacity to remove mutagens from water. The technique is especially useful in situations whether the percentage adsorption of unknown organic compounds, which can only be detected in the eluate, has to be determined.     

Impact of pH on the adsorption and desorption kinetics of 2-nitrophenol on activated carbons

The adsorption and desorption kinetics of 2-nitrophenol (2NP) from aqueous solutions using F-400 and WV-B granular activated carbons (GAC) have been studied at pHs 1, 4.6 and 13, using batch tests. Adsorption and desorption kinetics of 2NP on to both carbons were adequately described by the homogeneous solid surface diffusion model (HSSD). The adsorption and desorption kinetics can be predicted at different pHs by using adsorption kinetics parameters of the pH 4.6 and the isotherm parameters for the corresponding pH. Thus, the differences in the rates of adsorption are primarily attributable to the differences in the equilibrium loadings at the various pHs.     

Modeling the behaviors of adsorption and biodegradation in biological activated carbon filters

This investigation developed a non-steady-state numerical model to differentiate the adsorption and biodegradation quantities of a biological activated carbon (BAC) column. The mechanisms considered in this model are adsorption, biodegradation, convection and diffusion. Simulations were performed to evaluate the effects of the major parameters, the packing media size and the superficial velocity, on the adsorption and biodegradation performances for the removal of dissolved organic carbon based on dimensionless analysis. The model predictions are in agreement with the experimental data by adjusting the liquid-film mass transfer coefficient (k(bf)), which has high correlation with the Stanton number. The Freundlich isotherm constant (N(F)), together with the maximum specific substrate utilization rate (k(f)) and the diffusion coefficient (D(f)), is the most sensitive variable affecting the performance of the BAC. Decreasing the particle size results in more substrate diffusing across the biofilm, and increases the ratio of adsorption rather than biodegradation.     

Elucidating competitive adsorption mechanisms of atrazine and NOM using model compounds

Based on the relative adsorbability of natural organic matter (NOM) fractions with different molecular weights (MWs), two model compounds, poly(styrene sulfonate) (PSS) (nominal MW=1800 Dalton) and p-dichlorobenzene (DCB), were chosen to study the competitive effect of large and small NOM molecules on atrazine adsorption by two powdered activated carbons (PACs) with different pore size distributions. Both isotherm and kinetic tests of atrazine adsorption were conducted using fresh PAC and PAC preloaded with the model compounds. The model compounds were found to affect atrazine adsorption through two different mechanisms due to their size difference: direct competition for sites by p-DCB and pore constriction/blockage by PSS-1.8k. p-DCB was found to significantly reduce atrazine adsorption capacity but to have no effect on atrazine adsorption kinetics. In contrast, the effect of PSS-1.8k on atrazine adsorption capacity was very small. Furthermore, during simultaneous adsorption, PSS-1.8k had no effect on atrazine surface diffusion. However, preloading PAC with PSS-1.8k lowered the atrazine surface diffusion coefficient, D(s), by more than three orders of magnitude; D(s) decreased with increasing solid phase PSS-1.8k concentration. The pore size distribution of the PAC was found to play an important role in competitive adsorption. A high mesopore surface area could alleviate pore blockage significantly.     

First approach of desorption energies of water and organic molecules onto activated carbon by differential scanning calorimetry studies

The authors have determined the adsorption energies of water and organic materials on saturated and unsaturated activated carbons. The original technique used is the differential scanning calorimetry method (DSC). Water is always found to be present in the inner structure of the activated carbons. This water has a low energy of interaction. The desorption enthalpies have been determined for carbon loaded with organic compounds. An energy distribution is shown for some molecules and then approaches of the adsorption mechanisms are confirmed. The energy values are compared with the literature data determined by other analytical methods. The energies of solid solute interactions have been related to physical and chemical parameters of the solute. A good correlation is found for families of molecules.     

活性氧化铝吸附水中砷的动态试验研究

近年来,饮用水砷污染事件层出不穷,选择高效合适的除砷方法,已成为全球关注的问题.试验采用逆流式单床吸附柱的吸附方式,对活性氧化铝吸附砷做了动态试验研究.研究结果显示,当初始砷浓度为10mg/L时,砷的去除率均在90%以上;当初始砷浓度为50mg/L时,以5mg/L为穿透点,穿透体积为110L,动态吸附量为3.43mg/g.结果表明,在水中砷的去除方面,活性氧化铝可作为一种有效吸附剂.该研究对实际应用中的活性氧化铝改性及饮用水处理具有重要意义.     

生物活性炭在饮用水处理中的应用

介绍了活性炭的物理特性、使用寿命、在水处理中的作用以及生物活性炭工艺主要的影响因素.研究表明,压块破碎活性炭具有均匀、粗糙的表面,适合细菌的附着和生长,其丰富的孔结构能够保护细菌不受生物杀灭剂、杀虫剂和其他毒素的干扰.同时,与其他方法制得的活性炭相比,压块破碎活性炭具有更强的调节食物供给能力.