Fluorescence‐based fouling prediction and optimization of a membrane filtration process for drinking water treatment

A novel fluorescence‐based approach is proposed for modeling, predicting, and optimizing different fouling dynamics in an ultrafiltration (UF) process for drinking water treatment. Principal component analysis (PCA) was used to extract information in terms of principal components (PCs), related to major membrane foulant groups, from fluorescence excitation–emission matrix measurements captured during UF of natural river water. The evolution of PC scores during the filtration process was then related to membrane fouling using dynamic balances of latent variable values (PC scores). This approach was found suitable for forecasting fouling behaviors with good accuracy based solely on fluorescence data collected 15 min from the start of the filtration. The proposed approach was tested experimentally through model‐based optimization of backwashing times with the objective of minimizing the energy consumption per unit amount of water produced during the filtration process. This approach was also useful for identifying fouling groups contributing to reversible and irreversible fouling. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Yeast‐mediated enantioselective synthesis of chiral R‐(+)‐ and S‐(−)‐1‐phenyl‐1‐butanol from prochiral phenyl n‐propyl ketone in hexane–water biphasic culture

BACKGROUND: The hydrophobic phenyl n‐propyl ketone was used as a model compound to examine alcohol dehydrogenase activity in Saccharomyces cerevisiae mediated cell culture. Parameters such as pH, hexane‐to‐water volume percentage, and the amount of cofactor Zn²⁺ ion for either cell growth or reduction were studied to see their effect on the enantioselectivity toward the product R‐(+)‐ or S‐(?)‐1‐phenyl‐1‐butanol. RESULTS: The pH for cell growth in aqueous culture was 7.0, while the pH for reduction in the aqueous portion of the biphasic culture was 5.0. Without Zn²⁺ ion the biphasic cultures of middle to high hexane‐to‐water volume percentage exhibited an R‐(+)‐1‐phenyl‐1‐butanol enantiomeric excess of 53.7% to > 99%. Without Zn²⁺ ion the biphasic cultures at low hexane‐to‐water volume percentage possessed an S‐(?)‐1‐phenyl‐1‐butanol enantiomeric excess of 14.5–46.5%. Exclusively, the enantioselectivity for biphasic cultures containing Zn²⁺ ion was an S‐(?)‐1‐phenyl‐1‐butanol enantiomeric excess of 27.5% to > 99%. Reduction mediated in aqueous culture with varied amount of Zn²⁺ ion by the yeast Candida utilis also showed an S‐(?)‐1‐phenyl‐1‐butanol enantiomeric excess of 79.2–95.4%. CONCLUSION: The enantioselectivity of S. cerevisiae mediated biphasic culture reduction of phenyl n‐propyl ketone can be manipulated through the cofactor Zn²⁺ ion and the hexane volume percentage of the biphasic culture. Copyright © 2008 Society of Chemical Industry     

Chemical treatment of cork‐processing wastewaters for potential reuse

The chemical treatment of cork‐processing wastewater by ozonation, alone and in combination with hydrogen peroxide and UV radiation was investigated. A reduction of the chemical oxygen demand (COD) ranging from 42% to 76% was obtained during ozonation after 3 h of reaction, depending on the experimental conditions. The additional presence of hydrogen peroxide and UV radiation enhanced the efficiency of the ozonation treatment due to the contribution of the OH radicals formed in the decomposition of ozone. Thus, final reductions of the COD higher than 90% and a complete elimination of phenolic compounds and absorbance at 254 nm were achieved in both Advanced Oxidation Processes (AOPs), O₃/H₂O₂ and O₃/UV. Therefore the effluent resulting from the ozonation treatments can be reused in the cork‐processing industry. In a second step, the chemical treatment was conducted by means of UV radiation alone and by the action of hydroxyl radicals, which were generated by the following AOPs: UV/H₂O₂, Fenton's reagent, and photo‐Fenton system. The single photochemical process resulted in 9% of the organic matter present being removed, while the AOPs significantly enhanced this reduction with values in the range 20–75%. Kinetic studies for both groups of treatments were performed, and apparent kinetic rate constants were evaluated. In the ozone‐based experiments, the rate constants ranged from 1846 to 10922 dm³ mol^?1 O₃ h^?1, depending on the operating conditions. In the oxidation experiments using oxidants other than ozone, the rate constants varied between 0.06 and 1.19 h^?1. Copyright © 2004 Society of Chemical Industry     

Evaluation of the fouling potential of ceramic membrane configurations designed for the treatment of oilfield produced water

During the treatment of oilfield produced water (PW) with ceramic membranes, process efficiency is primarily characterized by the specific permeate flux and the oil separation performance. In addition to membrane properties, the increase in total filtration resistance (fouling) and the decline in permeate flux are strongly dependent on the constituents of the PW as well as process conditions such as trans-membrane pressure and cross-flow velocity. The extensive study presented herein describes the characterization, application and performance of various ceramic membrane filtration technologies designed and developed for the efficient treatment of PW generated from tank dewatering and several oily model systems.     

Energy in chemical manufacturing processes: gate‐to‐gate information for life cycle assessment

Gate‐to‐gate process energy for 86 chemical manufacturing processes is presented. The estimation of the process energy follows design‐based methodology. Results show that the gate‐to‐gate process energy for half of organic chemicals ranges from 0 to 4 MJ per kg, and for half of inorganic chemicals ranges from ?1 to 3 MJ per kg. The main energy source in both organic and inorganic processes is steam energy followed by potential recovered energy. In organic chemicals, the fractions of heating oil and electricity use are relatively low, but these fractions are higher in the inorganic chemicals than in the organic chemicals. Furthermore, about 50% of the energy consumed in chemical processes is used for purifying the product, byproduct or recycled stream, which indicates that there are large opportunities for improving the process energy in chemical processes. The information presented in this study is very important for those in the life cycle assessment community in order for them to identify inaccurate information or information not based on actual process design. However, the range for the entire range of chemicals is very substantial and thus reflects the need of the life cycle inventory to separately evaluate the chemistry and degree of purity for chemical products. Copyright © 2003 Society of Chemical Industry     

Electro‐membrane process for the separation of amino acids by iso‐electric focusing

BACKGROUND: Amino acids (AAs) are usually produced commercially using chemical, biochemical and microbiological fermentation methods. The product obtained from these methods undergoes various treatments involving extraction and electrodialysis (ED) for salt removal and AA recovery. This paper describes an electro‐membrane process (EMP) for the charge based separation of amino acids. RESULTS: Iso‐electric separation of AAs (GLU–LYS) from their mixture, using ion‐ exchange membranes (IEMs) has been achieved by an efficient and indigenous EMP. It was observed that electro‐transport rate (flux) of glutamic acid (GLU) at pH 8.0 (above its pI) was extremely high, while that for lysine (LYS) (pH 9.6) across the anion‐exchange membrane (AEM) was very low, under similar experimental conditions. Under optimum experimental conditions, separation of GLU from GLU–LYS mixture was achieved with moderate energy consumption (12.9 kWh kg^?1), high current efficiency (CE) (65%) and 85% recovery of GLU. CONCLUSIONS: On the basis of the electro‐transport rate of AA and membrane selectivity, it was concluded that the separation of GLU–LYS mixture was possible at pH 8.0, because of the oppositely charged nature of the two amino acids due to their different pI values. Moreover, any type of membrane fouling and deterioration in membrane conductivity was ruled out under experimental conditions. This work clearly demonstrates the great potential of EMP for industrial applications. Copyright © 2010 Society of Chemical Industry     

Potential of microbial growth control in water hydraulic systems by UV‐irradiation and filtration

Water hydraulic systems use water as a pressure medium and, thus, do not pose such adverse environmental impacts as oil hydraulics. Microbial deterioration of the pressure medium and biofouling of the surfaces restrict the applicability of the water‐based technology. The potential of microbial growth control by UV‐irradiation and filtration was studied in a pilot‐scale water hydraulic system. The UV‐irradiation (25 m Ws cm^?2) of the pressure medium reduced the total viable counts of bacteria by 1–2 log₁₀ cfu cm^?3, whereas the total microbial cell numbers and the numbers of surface‐attached microorganisms remained unaffected. Prefiltration (1.2 µm, absolute) of the pressure medium decreased the total microbial cell number in the water phase and retarded the attachment of bacteria. The filtration during the operation (2 µm, absolute) decreased the total numbers of microbial cells and the total viable counts in the pressure medium, and microbial attachment on the surfaces. Microbial attachment was not prevented by filtration. The microbial water quality obtained by pre‐ and on‐line filtration of the pressure medium was sufficient to ensure the long‐term operation of the water hydraulic system assuming that clean work practices are complied with in assembly and during the operation. © 2002 Society of Chemical Industry     

Abatement of heavy metals and softening of hard water by the CoAlPO4‐5/polysulfone membrane

To improve the membrane, if CoAlPO₄‐5 was appropriately added, it could increase the rejection rate of metal ions compared with the PSf membrane. Besides, penetration rate would also increase, and the pressure applied could be lowered when the improved membrane was used. The optimum amount of CoAlPO₄‐5 added for Co : Al : P = 0.1 : 0.92 : 1.0 is about 5 wt %, while for the Co : Al : P = 0.08 : 0.93 : 1.0, this optimum value would shift toward a higher wt % because the latter has less active sites per unit weight of CoAlPO₄‐5. The hydrated radius of metal ion had great influence on the rejection rate. The larger the radius, for example, that of the +3 valence cations, the higher the rejection rate would exhibit, and the rate for Cd²⁺ was much lower because its radius was the smallest one. Moreover, although incompatibility existed in the improved membrane and the variation of applied pressure was limited, durability of this membrane under the operating conditions was good. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2768–2773, 2001     

Membrane‐Occluded Gold‐Palladium Nanoclusters as Heterogeneous Catalysts for the Selective Oxidation of Alcohols to Carbonyl Compounds

Pre‐formed polyvinylpyrrolidone‐stabilized gold‐palladium clusters, consisting of 80 mol% gold and with a mean size of 1.9 nm, were immobilized quantitatively in a porous polyimide membrane via the process of phase inversion, without loss of metal nanodispersion. The obtained gold‐palladium/polyimide membrane emerged as a highly active heterogeneous metal catalyst for the amide‐phase and solvent‐free oxidation of aliphatic, allylic and benzylic alcohols with full selectivity to the corresponding aldehydes and ketones, and could be recycled with excellently preserved catalytic activity and product selectivity. Occlusion of the optimized bimetallic clusters in the polyimide structure proved beneficial in view of their superior catalytic performance compared to the analogous colloidal gold‐palladium clusters.     

State‐of‐the‐art and progress in the optimization‐based simultaneous design and control for chemical processes

Significant progress in the area of simultaneous design and control for chemical processes has been achieved and various methodologies have been put forward to address this issue over the last several decades. These methods can be classified in two categories (1) controllability indicator‐based frameworks that are capable of screening alternative designs, and (2) optimization‐based frameworks that integrate the process design and control system design. The major objective is to give an up‐to‐date review of the state‐of‐the‐art and progress in the challenging area of optimization‐based simultaneous design and control. First, motivations and significances of simultaneous design and control are illustrated. Second, a general classification of existing methodologies of optimization‐based simultaneous design and control is outlined. Subsequently, the mathematical formulations and relevant theoretical solution algorithms, their merits, strengths and shortcomings are highlighted. Last, based on the recent advances in this field, challenges and future research directions are discussed briefly. An attempt is made with the help of this review article to stimulate further research and disseminate the simultaneous design methods to challenging problem areas. In particular, the application of optimization‐based simultaneous design and control methods to large‐scale systems with highly inherent nonlinear dynamics often the case in industrial chemical processes remains a challenging task and yet to be solved. © 2012 American Institute of Chemical Engineers AIChE J, 58: 1640–1659, 2012     

Towards a new strategy of a chitosan‐based molecularly imprinted membrane for removal of 4‐nitrophenol in real water samples

The issue of water contaminants, which affects human and environmental health, is not trivial. It is thus paramount to find new cheap and user friendly ways to detect and remove them from the environment. Here, the synthesis of a green chitosan (CS ) based molecularly imprinted membrane for the detection and quantification of 4‐nitrophenol (4‐NO₂Ph ) in aqueous media is proposed. The concentration of 4‐NO₂Ph in a water solution was measured by HPLC analysis. CS as a functional polymer, 4‐NO₂Ph as template, 4‐[(4‐hydroxy)phenylazo]benzenesulfonic acid as ligand, and glutaraldehyde as crosslinker in the presence of polyethylene glycol as porogen were used. The membrane was characterized by SEM and Fourier transform IR analyses, which confirmed the CS and polyethylene glycol backbone of the membrane. Kinetic studies of the detection system were performed by using pseudo‐first‐order and pseudo‐second‐order models. Then, the binding efficiency between 195.33 µmol L^?1 and 9235.55 µmol L^?1 of 4‐NO₂Ph was evaluated, finding a maximum adsorption of 723.25 µmol 4‐NO₂Ph per gram of membrane consistent with the Q _max calculated from the Langmuir isotherm. The selectivity of the membrane versus three phenolic competitor molecules, sharing very similar molecular structure to 4‐NO₂Ph , was demonstrated. Finally, the applicability of the membrane to real‐world samples was evaluated, by using drinking water spiked with 7.19 µmol L^?1 of 4‐NO₂Ph , obtaining a removal efficiency of 70.6%. © 2017 Society of Chemical Industry     

Regression‐based analysis of multivariate non‐Gaussian datasets for diagnosing abnormal situations in chemical processes

This article presents a regression‐based monitoring approach for diagnosing abnormal conditions in complex chemical process systems. Such systems typically yield process variables that may be both Gaussian and non‐Gaussian distributed. The proposed approach utilizes the statistical local approach to monitor parametric changes of the latent variable model that is identified by a revised non‐Gaussian regression algorithm. Based on a numerical example and recorded data from a fluidized bed reactor, the article shows that the proposed approach is more sensitive when compared to existing work in this area. A detailed analysis of both application studies highlights that the introduced non‐Gaussian monitoring scheme extracts latent components that provide a better approximation of non‐Gaussian source signal and/or is more sensitive in detecting process abnormities. © 2013 American Institute of Chemical Engineers AIChE J, 60: 148–159, 2014     

Effect of adding other metal ions on the removal of Cd2+ by the CoAlPO4‐5/polysulfone membrane

Based on our previous work, performance of separation of Cd²⁺ by the CoAlPO₄‐5/polysulfone membrane was not as good as that of the other metal ions. This could be significantly improved by the addition of other metal ions into the Cd²⁺ solution. The metal ions added were those with larger hydrated radius than that of Cd²⁺. When Mg²⁺ and Ca²⁺ were added, the rejection rate of Cd²⁺ could be increased from about 50% ([Cd²⁺] = 50 ppm) to nearly 100% and the rate would increase with concentration of Mg²⁺ and Ca²⁺. However, when the added ions were Fe²⁺ and Mn²⁺, although the performance of Cd²⁺ removal was still high, the rejection rate would inversely decrease with increasing concentration of Fe²⁺ and Mn²⁺. These phenomena were mainly attributable to the effect of hydrated ion and the effect of lowered pH value induced by the hydrolysis of the solution. As to the addition of Al³⁺, although the rejection rate would decrease with increasing Al³⁺ concentration up to 100 ppm, an abrupt increase was observed at 150 ppm, which was thought to be attributable to the concentration polarization effect caused by the formation of the high valence [Al_n(OH)_m]^{(3[supi]n?[supi]m)+} complex. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2172–2177, 2002     

Physico‐chemical parameters for the characterization of pure beeswax and detection of adulterations

Pure beeswaxes produced in different climatic regions of Spain have been characterized by the determination of nine physico‐chemical parameters: density, acid, saponification, ester, ratio number, iodine, peroxide, melting point and ash content values. The official methods of analysis to determine density and saponification values in fats and oils were not suitable for beeswaxes; alternative methods are proposed in this work for both parameters. After verifying the precision of the methods and the value guidelines, the usefulness of the physico‐chemical parameters to detect adulterations with paraffin, stearic acid, carnauba wax and tallow was tested: adulteration percentages of 5%, or higher, were commonly detected. Marketed foundation beeswax sheets, rejected or badly accepted by the bees, were also analyzed to discuss their quality; 25 out of 27 beeswax sheets show anomalous values for at least one parameter.