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.     

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%.     

冰蓄冷系统中主机制冷量的确定

通过对三种不同配置的冰蓄冷系统的逐时负荷和各节点载冷剂温度变化的详细分析,指出根据目前常用的公式计算出的主机制冷量在很多场合不能满足实际负荷要求。通过对这几种系统控制性能的初步比较得出主机上游且融冰优先的串联系统最有效,同时指出配有基载主机的蓄冰系统的负荷分配设计中需要注意的问题。     

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。     

间接蒸发冷水机组设计开发及性能分析

基于间接蒸发冷却技术设计了高温冷水机组,其驱动源为室外干空气而非电能,冷水机组的理论出水温度可无限接近进口空气的露点温度。建立了数学模型,并提出了系统的串联冷水流程,以更充分地利用室外干空气的能量。合作开发了第一台间接蒸发冷水机组,通过测试得到了实际机组的性能。最后分析了冷水机组作为湿度独立控制空调系统的高温冷源在中国西部及其他地区的应用。     

关于风冷和水冷冷水机组的耗电量问题

认为比较两者的耗电量应明确机组装机容量与耗电量的区别及负荷分布机组效率和耗电量的影响。经比较得出，风冷机组耗电并不比水冷机组高多少，且其总运行费用可能还略低于后者。     

风冷冷水机组和水冷冷水机组的选择

本文从六个方面对风冷和水冷冷水机组的选用进行了比较，列举了风冷机组布置实例，并提出了冷水机组选择建议。     

新型活性炭吸附技术对降低某声学实验室甲醛浓度的实验研究

针对某声学实验室内甲醛污染物浓度严重超标的问题进行了实验分析,发现污染气体主要源头为制作声学实验室内壁的消声材料.针对实验室已建成并投入使用的实际情况,提出在实验室内设置具有浸渍铜锰氧化物的活性炭净化装置,以实现对甲醛的高效吸附.实验验证表明,浸渍铜锰氧化物的活性炭材料相比普通活性炭材料对甲醛的吸附效率明显提高,由普通...     

直燃型冷热水机组的应用分析

分析了直燃型冷热水机组的技术特点，并就一个具体工程与电力式冷水机组加热源系统进行了经济比较，提出了直燃型冷热水机组的应用条件与设计中应注意的问题。     

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.     

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.     

风冷型热泵冷水机组水系统设计及运转调试

设计时应注意保持水流量的恒定，保证冷冻水温差设计值，推荐采用一机一泵和设备水力平衡阀的方法。     

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。     

Calcium accumulation on activated carbon deteriorates synthetic organic chemicals adsorption

The accumulation of calcium on biological activated carbon (BAC) and their effects on adsorption of synthetic organic chemicals (SOCs) were studied using BAC, which have been operated for 5 (BAC5.0) and 3.5 (BAC3.5) years in a pilot-scale water purification plant, and granular activated carbon (GAC) preloaded with fulvic acid and/or calcium. The major inorganic material accumulated on BAC was calcium. The amounts of calcium on BAC5.0 and BAC3.5 were 36.6 and 29.7 mg g(-1), respectively. Seventy-one percent of calcium existed as calcium carbonate in both BACs. BAC5.0 had higher amount of accumulated calcium than BAC3.5 even though both BACs have already exhausted for NOM in the influent in 1-year operation, suggesting that calcium carbonate gradually accumulated on BAC even after the 3.5 years of operation. The isotherms of GAC preloaded with fulvic acid and/or calcium clearly indicated that the calcium accumulation on GAC reduced adsorption capacity for simazine. The conclusion also confirmed by significant recovery of adsorption capacity of both BACs by acid-washing to remove accumulated calcium from BACs. The difference of adsorption capacity between BAC3.5 and BAC5.0 was caused not only by the difference of adsorbed NOM but also the difference in the amount of accumulated calcium.     

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.     

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.     

Adsorption of non-ionic surfactants on activated carbon and mineral clay

A series of non-ionic surfactants of nonyl-phenol ethoxylates, with n = 4?23;0 ethylene oxide groups and dinonyl-phenol ethoxylate were studied in dilute aqueous solution. Their removal efficiencies and mechanisms by adsorption on powdered and granular activated carbon and on Na-montmorillonite clay were investigated. The powdered activated carbon proved to be the most efficient with 94–100% non-ionic surfactants removal by addition of 40–80 mg activated carbon.Various models of adsorption isotherms such as Langmuir, BET and S-type were used to determine Q⁴, the limiting adsorption capacity. The relationships between Q^o and parameters affecting the adsorption of non-ionic surfactants such as n, HLB and CMC were determined. The cross-sectional area σ₀ occupied by surfactant molecules on the adsorbent was calculated. Adsorption has been proven to be a potential advanced physicochemical treatment method for the effective removal of non-ionic surfactants present in effluents intended for reuse.     

Simplification of the IAST for activated carbon adsorption of trace organic compounds from natural water

Recent studies have shown that the ideal adsorbed solution theory (IAST) coupled with the concept of equivalent background compound (EBC) can be simplified for describing trace organic compound adsorption from natural water, provided that the adsorbent surface loading is dominated by competing natural organic matter. The resulting simplified IAST has been used to reduce the complexity of kinetic models for various dynamic adsorption processes. In order to be correctly applied, however, the simplified IAST requires some additional clarification and a quantitative evaluation of the deviation caused by the simplifying assumption. In this study, we derive a simple equation that relates the relative deviation of the simplified IAST directly to the molar ratio of EBC and trace organic compound surface loadings and their Freundlich isotherm exponents. We then verify the simplified IAST using the original IAST and experimental isotherm data from the literature for trace organic compounds at various initial concentrations in natural water. By further assuming that the adsorbed amount of the EBC is substantially greater than what remains in solution, a new pseudo single-solute isotherm equation is derived and a simple relation is subsequently established between the carbon dose and the remaining trace compound concentration. The results show that the adsorption capacity and relative removal of a trace organic compound at any carbon dose can be estimated directly with the simple equations developed here and data from a single isotherm experiment for the target compound conducted in the natural water of interest.     

Application of powdered activated carbon for the adsorption of cylindrospermopsin and microcystin toxins from drinking water supplies

Cylindrospermopsin (CYN) and microcystin are two potent toxins that can be produced by cyanobacteria in drinking water supplies. This study investigated the application of powdered activated carbon (PAC) for the removal of these toxins under conditions that could be experienced in a water treatment plant. Two different PACs were evaluated for their ability to remove CYN and four microcystin variants from various drinking water supplies. The removal of natural organic material by the PACs was also determined by measuring the levels of dissolved organic carbon and UV absorbance (at 254 nm). The PACs effectively removed CYN and the microcystins from each of the waters studied, with one of the PACs shown to be more effective, possibly due to its smaller particle diameter. No difference in removal of the toxins was observed using PAC contact times of 30, 45 and 60 min. Furthermore, the effect of water quality on the removal of the toxins was minimal. The microcystin variants were adsorbed in the order: MCRR > MCYR > MCLR > MCLA. CYN was found to be adsorbed similarly to MCRR.