内电解-厌氧-好氧工艺处理染料化工废水的研究

研究了高浓度和高色度的有机染化废水在内电解 -厌氧 -好氧组合工艺下的处理效果及其影响因素。结果表明 ,内电解 -厌氧 -好氧组合工艺应用在高浓度、高色度 (COD为 6 0 0 0～ 70 0 0mg/L ,色度 >10 0 0 0倍 )染化废水处理中具有较高的COD和色度去除率。在全工艺流程下 ,COD、色度的去除率均达到 92 %以上     

On additivity of the yields of ethylene formed from methane and naphtha by an integrated process

A heat-effective ‘integrated’ process carried out in one reactor, composed of exothermic oxidative coupling of CH₄ over the catalyst fixed bed and endothermic pyrolysis of naphtha injected from the outside to the stream of gaseous coupling products in the hot oxygen-free postcatalytic zone, has been studied. An additivity of the yields of ethylene formed in both component processes was examined under varied operating conditions (type of naphtha fraction, flow rate of reagents and temperature of pyrolysis). A very high degree of additivity of the yields of ethylene and its main coproducts was observed, independently of the relative contribution of the component processes to the integrated process and of applied variations in the process conditions. Evidently, the mutual interactions between the component processes and products were negligible under experimental conditions. © 1998 Society of Chemical Industry     

直接降解稻草菌种筛选及降解稻草过程优化

以稻草降解率为指标,研究了从稻草等筛选到的菌株对稻草降解的活性。对最优菌株进行形态和18S rDNA基因序列分析表明,该菌株为烟曲霉(Aspergillus fumigatus)。进一步优化了菌株XC6稻草降解的过程参数,结果表明,最优参数条件下,该菌株可以实现对稻草的完全降解[降解率为(100±0.2)%];同时生物量也高达(22.9±1.1)g/L。为今后这方面进一步发酵放大研究打下了基础。     

蛋白土与硫酸铵煅烧反应产物及过程动力学

蛋白土具有良好的应用前景,但是其自然白度较低制约了其开发应用。蛋白土硫酸铵煅烧法可去除其中的显色金属氧化物,提高蛋白土的白度,同时提取其中Al₂O₃。本文采用热重-差示扫描量热（TG-DSC）、同步热分析与红外质谱（TG-FTIR-MS）联用系统,结合X射线衍射对煅烧过程的固相及气相产物进行了表征分析,明析了其化学过程。结果表明,蛋白土中的Al₂O₃和Fe₂O₃在200~350℃时反应生成（NH₄）₃（Al,Fe）（SO₄）₃,同时逸出NH₃和H₂O;350~450℃时,进一步反应转化为NH₄（Al,Fe）（SO₄）₂,同时逸出NH₃、H₂O、SO₂和O₂;450~550℃时,NH₄（Al,Fe）（SO₄）₂分解生成（Al,Fe）₂（SO₄）₃,同时逸出NH₃、H₂O、SO₂和O₂;550~750℃时（Al,Fe）₂（SO₄）₃分解生成Al₂O₃和Fe₂O₃,同时逸出SO₂和O₂。采用Kissinger微分法与Ozawa积分法分别计算出4个阶段表观活化能后取二者平均值,分别为101.74kJ/mol、104.52kJ/mol、201.40kJ/mol、232.51kJ/mol,并获得对应4个热化学反应阶段的频率因子、反应级数和动力学方程。     

Thermal plasma vitrification process as an effective technology for fly ash and chromium‐rich sewage sludge utilization

The main goal of the vitrification process for environmental research is the destruction of hazardous waste. This study proposes the use of a thermal plasma treatment process to transform fly ash and chromium‐rich sewage sludge into glassy products called vitrificates that can be stored on the land without harmful environmental effects. This is achieved by: (i) decreasing the temperature and energy used to adjust process cost minimization; and (ii) stabilization of vitrificates for different compositions of waste mixture. The chemical stabilization of final products was examined by heavy metals leachability tests. Hardness tests were done to verify the physical stabilization of vitrificates. The most stable vitrificates were obtained from a sample consisting of 90 wt% fly ash and 10 wt% chromium sludge. The thermal plasma treatment is an effective method which can be used to convert hazardous waste mixtures into less toxic or inert glassy products. The chemical composition of raw materials influenced the chemical and physical properties of the vitrificates and determined their internal structures. Mixtures of two different hazardous wastes reduces the process cost without negative environmental impact, which is an innovation in thermal plasma treatment technology. © 2013 Society of Chemical Industry     

Kinetics of toluene and sulfur compounds removal by means of an integrated process involving the coupling of absorption and biodegradation

BACKGROUND: Scrubbing using an organic solution instead of an aqueous solution could be a useful way to improve the removal of hydrophobic compounds. Absorption of toluene, dimethyldisulfide (DMDS) and dimethylsulfide (DMS) in an organic solution (di‐2‐ethylhexyladipate—DEHA), followed by biodegradation by activated sludge was considered, with particular attention to kinetic aspects. DEHA was selected for its relevance in terms of absorption capacity and absorption velocity of the selected volatile organic compounds (VOCs). After the biodegradation step and owing to its cost, recycling of the VOC‐free solvent should be considered. RESULTS: Enhancement of VOC mass transfer from the organic to the aqueous phase due to bacterial activity was highlighted and the main driving force was found to be biosurfactant production rather than biodegradation reaction. However, the mass transfer rate between the two phases was shown to be lower than VOC biodegradation rate; hence, significant biodegradation of DMDS and toluene was recorded in a few days during batch experiments, 0.10 and 0.09 mmol respectively. Toluene showed higher biodegradation rates (about 0.05 and 0.10 mg h^?1 for DMDS and toluene), leading to higher growth rates. Contrarily, owing to its high volatility, important DMS losses were observed. CONCLUSION: The relevance of the proposed integrated process was shown for hydrophobic VOC removal, at least for toluene and DMDS. Unfortunately, the absorbent phase was also degraded, proved by detection of by‐products during analyses of the aqueous phase headspace. The comparison of DEHA with other solvents or solid polymers available for multiphase bioreactor applications may be a reliable option to continue this work. Copyright © 2010 Society of Chemical Industry     

Equilibrium and kinetic studies of the extraction of chelated copper(II) anions with Aliquat 336

The equilibrium and kinetics of solvent extraction of Cu²⁺ from aqueous solutions containing equimolar EDTA with Aliquat 336 in n‐decanol and kerosene at 298 K were investigated. The concentrations of Cu²⁺ (8–50 mol m^?3), Cl^? (5–60 mol m^?3), and Aliquat 336 (20–100 mol m^?3) were varied. A semi‐empirical model with three parameters was proposed to describe the equilibrium behavior, in which the non‐idealities in both aqueous and organic phases were considered. Over the ranges studied, the model agreed reasonably well with the experimental data (standard deviation, 15%). The forward and backward reaction rate constants were determined as (5.31 ± 0.16)×10^?6 m^9/4 mol^?3/4 s^?1 and (2.62 ± 0.09)×10^?7 s^?1, respectively, at 298 K. An interfacial reaction mechanism was proposed, which revealed that the reaction between the chelated anions and trimeric amine molecules at the interface was rate limiting. The derived rate laws were consistent with the experimental results. © 2002 Society of Chemical Industry     

Investigating the efficiency of gas re‐injection process of an oil field using combined integrated field simulation and intelligent proxy model application

Integrated asset modelling is a novel method to overcome the limitations associated with using individual models. This method integrates all the individual models of a field into a single model that relates all the sub‐models using proper boundary conditions. Reservoir, wells, surface, and economic models of an oil reservoir, under gas re‐injection, are integrated. The main goal of this study is to propose a novel approach in integrated asset modelling. An integrated model of a field is used to study how gas must be distributed among injection wells. Another aim of this study is to understand the effects of 4 input parameters on the Net Present Value (NPV) of the field. The input variables are: oil production rate, gas injection rate, and the distribution of gas between injection wells. A comprehensive model of a field was built. Using the experimental design results, a neuro‐fuzzy logic network was developed. The proxy model predicted the simulation outputs with a reasonable accuracy. The effects of input variables were studied. Oil production has an optimum value of 6050 STBD per well. The optimum fractions of injected gas for injection wells 1 and 2 are 0.4 and 0.6 of total injected gas, respectively. This means that 40 % of the total injection gas must be injected to well 1 to have the maximum NPV. The greater the gas injection rate, the higher NPV is.

     

Application of tobacco hairy roots for the removal of malachite green from aqueous solutions: Experimental design,kinetic, equilibrium,and thermodynamic studies

Tobacco hairy roots (THR) were used to evaluate its potential for the biosorption and removal of malachite green (MG) from aqueous solutions. A 3² full factorial design was applied to study the effects of pH and THR concentration on the biosorption capacity. Under the optimal conditions (pH of 7.0 and THR concentration of 1?g?L^?1), dye removal efficiency was around 92%. Experimental data obtained from kinetic studies demonstrated good concordance with the pseudo-second-order model. Equilibrium studies were developed and the data were evaluated by Langmuir, Freundlich, and Sips models, being the Sips model the most adequate (maximum biosorption capacity of 277.2?mg?g^?1). Thermodynamically, the biosorption of MG on THR proved to be endothermic, spontaneous, and favorable. Desorption was feasible under acidic conditions and the biosorbent could be reused three times. THR was tested in simulated effluent and the removal percentage was 87%, demonstrating that this material is a promising biosorbent which can be used to treat colored wastewaters.     

New prototype for the treatment of falling film liquid effluents by gliding arc discharge part I: Application to the discoloration and degradation of anthraquinonic Acid Green 25

Gliding arc discharge (GAD) reactors are continuously in progress in order to improve the treatment efficiency of recalcitrant compounds. However, up to now, they remain difficult to transfer to industrial applications because of some technical constraints in their design. In this study, a new efficient prototype is proposed for the treatment of gravity falling film shaped of liquid effluents. The liquid flow rate is now continuous as the tank containing the solution to be treated is replaced by an inclined plate along which flows the liquid. The various working parameters are optimized and the new prototype efficiency is tested on discolouration and degradation of the anthraquinonique Acid Green 25. The optimized values obtained are: the liquid flow rate ω = 1 L h⁻¹, the plate tilt angle α = 45° and the channel width Δ = 3 mm. The rates of discolouration and degradation reach 95% and 90% respectively after 12 cycles (180 min) of plasma exposition. The GAD in the presence of humid air generates highly oxidizing radical species such as ^•OH with a standard potential E°[(^•OH/H₂O) = 2.85 V/SHE] and its reducer agent H₂O₂ [E°(H₂O₂/H₂O) = 1.68 V/SHE.     

Design and optimization of an integrated process for the purification of propylene oxide and the separation of propylene glycol by-product

It is difficult to separate the methanol and hydrocarbons in the propylene oxide (PO) purification process due to their forming azeotrope. As for this, a novel PO separation process, in that the deionized water is employed as extractant and 1,2-propylene glycol (MPG) that is formed from the PO hydrolysis reaction is recovered, is presented in this work. The salient feature of this process is that both the non-catalyzed reactions of PO hydrolysis to form MPG and dipropylene glycol (DPG) are simultaneously considered and MPG by-product with high purity is obtained in virtue of the deionized water as reflux liquid and side take-off in MPG column. In addition, the ionic liquid (IL) extractant is screened through the conductor-like screening model for segment activity coefficient (COSMO-SAC) and the comparisons of separation efficiency between the IL and normal octane (nC₈) extractant for the separation of PO and 2-methylpentane are made. With the non-random two-liquid (NRTL) thermodynamic model, the simulation and optimization design for the full flow sheet are performed and the effects of the key operation parameters such as solvent ratio, theoretical stages, feeding stage etc. on separation efficiency are detailedly discussed. The results show that the mass purity and the mass yield of PO can be up to 99.99% and 99.0%, and the condenser duty, reboiler duty and PO loss in the process with IL extractant can be decreased by 69.66%, 30.21% and 78.86% compared to ones with nC₈. The total annual cost (TAC) calculation also suggests that the TAC would be significantly reduced if using IL in replace of nC₈ for the investigated process. The presented results would provide a useful guide for improving the quality of PO product and the economic efficiency of industrial plant.     

Equilibrium and kinetic studies on the extraction of gadolinium(III) from nitrate medium by di‐2‐ethylhexylphosphoric acid in kerosene using a single drop technique

The liquid–liquid extraction of Gd(III) from aqueous nitrate medium was studied using di‐2‐ethylhexylphosphoric acid (HDEHP) in kerosene. On the basis of the slope analysis data, the composition of the extracted species was found to be [Gd A₃(HA)] with the extraction equilibrium constant (K_ex) = (1.48 ± 0.042) × 10^?12 mol dm^?3. The results of the effect of temperature on the value of the equilibrium extraction constant indicated the endothermic character of the extraction system. The kinetics of the forward extraction of Gd³⁺ from nitrate medium by HDEHP in kerosene was investigated using the single drop column technique. The rate of flux (mass transfer per unit area) was found to be proportional to [Gd(III)], [H₂A₂]_(o), [NO₃^?], and [H⁺]^?1 in the liquid drop organic phase. The forward extraction rate constant, k_f, was 2.24 × 10^?3 m s^?1 using the equation: Copyright © 2005 Society of Chemical Industry     

Cost analysis for the degradation of highly concentrated textile dye wastewater with chemical oxidation H2O2/UV and biological treatment

The efficiency and cost‐effectiveness of H₂O₂/UV for the complete decolorization and mineralization of wastewater containing high concentrations of the textile dye Reactive Black 5 was examined. Oxidation until decolorization removed 200–300 mg g^?1 of the dissolved organic carbon (DOC). The specific energy consumption was dependent on the initial dye concentration: the higher concentration required a lower specific energy input on a weight basis (160 W h g^?1 RB5 for 2.1 g L^?1 versus 354 W h g^?1 RB5 for 0.5 g L^?1). Biodegradable compounds were formed, so that DOC removal could be increased by 30% in a following biological stage. However, in order to attain 800 mg g^?1 overall mineralization, 500 mg g^?1 of the DOC had to be oxidized in the H₂O₂/UV stage. A cost analysis showed that although the capital costs are much less for a H₂O₂/UV stage compared to ozonation, the operating costs are almost double those of ozonation. Thus, while H₂O₂/UV can compete with ozonation when the treatment goal only requires decolorization, ozonation is more cost‐effective in this case when mineralization is desired. Copyright © 2006 Society of Chemical Industry     

Development and simulation studies of an unsteady state biofilter model for the treatment of cyclic air emissions of an α‐pinene gas stream

This paper describes the development and simulation of an unsteady state biofilter model used to predict dynamic behaviour of cyclically‐operated biofilters and compares it with experimental results obtained from three, parallel, bench‐scale biofilters treating both periodically fluctuating concentrations and constant concentrations of an α‐pinene‐laden gas stream. The dynamic model, using kinetic parameters estimated from the constant concentration biofilter, was able to predict the performance of cyclic biofilters operating at short cycle periods (ie, in the order of minutes and hours). Steady state kinetic data from a constant concentration biofilter can be used to predict unsteady state biofilter operation. At a 24 h cycle period, the dynamic model compared well with experimental results. For long cycle periods (ie, hours and days), removal efficiency decreased after periods of non‐loading: the longer the period of non‐loading, the poorer the biofilter's performance at the re‐commencement of pollutant loading. At longer time scales the model did not effectively predict transient behaviour, as adsorption and changes in kinetic parameters were not accounted for. Modelling results showed that similar biofiltration performance for the cyclic and constant concentration biofiltration of α‐pinene is expected for biofilters operating solely in the first order kinetics regime. Poorer performance for cyclic biofilters following Monod kinetics spanning the entire kinetics range is expected as the cycle amplitude increases. The most important parameters affecting the performance of a cyclically‐operated biofilter with short cycle periods are: amplitude of cyclic fluctuations, C_{g, max}/C_g, relative value of the half‐saturation constant in the Monod expression, K_s, and effective diffusivity of α‐pinene in the biofilm, D_e. Copyright © 2005 Society of Chemical Industry     

An optimization and modeling approach for H2O2/UV‐C oxidation of a commercial non‐ionic textile surfactant using central composite design

BACKGROUND: Industrial surfactants are biologically complex organics that are difficult to degrade and may cause ecotoxicological risks in the environment. Until now, many scientific reports have been devoted to the effective treatment of surfactants employing advanced oxidation processes, but there is no available experimental study dealing with the optimization and statistical design of surfactant oxidation with the well‐established H₂O₂/UV‐C process. RESULTS: Considering the major factors influencing H₂O₂/UV‐C performance as well as their interactions, the reaction conditions required for the complete oxidation of a commercial non‐ionic textile surfactant, an alkyl ethoxylate, were modeled and optimized using central composite design‐response surface methodology (CCD‐RSM). Experimental results revealed that for an aqueous non‐ionic surfactant solution at an initial chemical oxygen demand (COD) of 450 mg L^?1, the most appropriate H₂O₂/UV‐C treatment conditions to achieve full mineralization at an initial pH of 10.5 were 47 mmol L^?1 H₂O₂ and a reaction time of 86 min (corresponding to a UV dose of 30 kWh m^?3). CONCLUSION: CCD allowed the development of empirical polynomial equations (quadratic models) that successfully predicted COD and TOC removal efficiencies under all experimental conditions employed in the present work. The process variable treatment time, followed by the initial COD content of the aqueous surfactant solution were found to be the main parameters affecting treatment performance, whereas the initial H₂O₂ concentration had the least influence on advanced oxidation efficiencies. The H₂O₂ concentration and surfactant COD were found to be more important for TOC abatement compared with COD abatement. Copyright © 2009 Society of Chemical Industry     

A compact process for the treatment of olive mill wastewater by combining OF and UV/H2O2 techniques

Olive oil production results in important quantities of wastewater containing large amounts of total solids and organic carbon as well as low oil concentrations. This paper describes the treatment of olive mill wastewater (OMW) by combining an ultrafiltration (UF) technique and an advanced oxidation process (AOP) using UV/H₂O₂. It further demonstrates the technical feasibility of this compact and stable process to remove a large part of total solids and organic carbon. Indeed, OF reduces the pollutants contained in the OMW with an apparent rejection coefficient R_COD in the range of 94%. The UV/H₂O₂ oxidation process may be easily used, in combination with UF, to finish the treatment of the permeate. The results obtained in batch and continuous mode showed that this technique offered a treated solution which complies with legal requirements. A final concentration of 17 mg_TOC dm⁻³ was obtained, which corresponds to a final COD of 52 mg dm⁻³, while the legal requirement is 125. Furthermore, the final effluent is fully decolorized.