Recovery of proteins and other biological compounds using fibrous materials: I. Adsorption by salt additionChen, Li Ang; Carbonell, Ruben G; Serad, George A
doi: 10.1002/(SICI)1097-4660(199908)74:8<733::AID-JCTB111>3.0.CO;2-4pmid: N/A
An adsorption and filtration process for the recovery of proteins and other biological compounds from aqueous streams has been developed, using cellulose‐based fibrous materials. Of the many cellulose derivatives studied, cellulose acetate fibrets (CAF) and cellulose triacetate fibrets (CTF) have been shown to be the most effective. In the presence of salts, they lead to protein adsorption by hydrophobic interactions. Model proteins, such as bovine serum albumin (BSA), have been recovered by incubating these solutions with CTF in the presence of ammonium sulfate, followed by filtration through a 20 µm pore size filter. The amount of salt necessary varies with the protein type, but decreases with increasing temperature and protein concentration. High protein recovery has been obtained from an actual wastewater system at low salt dosages. © 1999 Society of Chemical Industry
Recovery of proteins and other biological compounds using fibrous materials: II. Flocculation by polyelectrolyte additionChen, Li Ang; Carbonell, Ruben G; Serad, George A
doi: 10.1002/(SICI)1097-4660(199908)74:8<740::AID-JCTB112>3.0.CO;2-1pmid: N/A
Polyelectrolytes have been used in wastewater treatment processes to destabilize colloidal suspensions of proteins, cells and other biological compounds, resulting in flocculation. When a solution containing a single model protein, bovine serum albumin (BSA), is treated with a polyelectrolyte, carboxymethyl cellulose (CMC), large and strong flocs are formed, which are easily retained by a 20 µm pore size filter. However, when a mixture of proteins, cells, and fats from an actual wastewater sample is treated in the same manner, smaller and weaker flocs are observed. An adsorption and filtration process for the recovery of valuable biological compounds using cellulose‐based fibrous materials has been developed. When used simultaneously with CMC, cellulose acetate and triacetate fibrets (CAF and CTF) resulted in high recovery of biomolecules from solution at very low dosages of both polyelectrolyte and fibrets. CMC interacts with biomolecules by electrostatic interactions and polymer bridging, while CTF/CAF facilitate floc growth by adsorption and bridging of primary particles and by entrapment of small aggregates within their highly fibrillated microstructure. © 1999 Society of Chemical Industry
Lipase‐catalyzed enantioselective esterification of S (+)‐naproxen ester prodrugs in cyclohexaneTsai, Shau‐Wei; Lin, Shiang‐Fei; Chang, Chun‐Sheng
doi: 10.1002/(SICI)1097-4660(199908)74:8<751::AID-JCTB86>3.0.CO;2-Mpmid: N/A
A lipase‐catalyzed enantioselective esterification process in cyclohexane was developed for the synthesis of S(+)‐naproxen ester prodrugs containing the moiety of N,N‐dialkylamino, ethylene glycol or alkyl ether of ethylene glycol. A high enantiomeric ratio of 44 was obtained when di(ethylene glycol) was selected as the best acyl acceptor. A reversible ping‐pong Bi Bi mechanism has been employed to elucidate the enzymatic behavior of the initial conversion rate for S(+)‐naproxen and the time‐course conversions for both enantiomers. Improvement of the enzyme activity was demonstrated when alcohol in excess of its cyclohexane solubility limit was used. The application of excess racemic naproxen in the presence of solid substrate suspensions showed enhanced productivity and enantioselectivity for the desired S(+)‐ester. Studies of the recovery and racemization of the remaining R(−)‐naproxen are also reported. © 1999 Society of Chemical Industry
Surface properties of emulsan‐analogsZhang, Jinwen; Lee, Soo‐Hyoung; Gross, Richard A; Kaplan, David
doi: 10.1002/(SICI)1097-4660(199908)74:8<759::AID-JCTB88>3.0.CO;2-Tpmid: N/A
The colloidal properties of emulsans formed by incubations of Acinetobacter calcoaceticus RAG‐1 on different carbon sources were studied. The apparent critical micelle concentrations (CMC) of the emulsans tested ranged from 25 to 58 mg/dm−1. Surface and interfacial tensions of the solutions showed little dependence on pH between 2 and 10. In contrast, increasing the pH from 2 to 6.5 resulted in a substantial increase in their ability to effectively emulsify aliphatic hydrocarbons. Hexadecane‐in‐water emulsions were prepared having droplet sizes between 6 and 19 µm. Many of the emulsions thus formed were found to be stable with respect to coalescence for several months. Certain structural features such as the total content of fatty acids and hydroxy fatty acids were found to have a significant effect on emulsifying activity. The maximum emulsifying activity occurred for emulsans containing about 460 nmol of total fatty acid per mg of emulsan (nmol mg−1). Emulsifying activity also showed a maximum at about 170 nmol mg−1‐emulsan of 2‐ and 3‐ hydroxy dodecanoic acids. For substituents having chain lengths ≥15 carbonatoms, the emulsifying activity on hexadecane increased with their content up to 190 nmol mg−1. On the other hand, for substituents having chain lengths of <15 carbonatoms, the emulsifying activity on hexadecane showed no obvious effect with their content up to 220 nmol mg−1. A further increase in the shorter chain length fatty acids resulted in a decrease in emulsifying activity. Hence, a substrate‐specific interaction between emulsans and the dispersed phase was observed. © 1999 Society of Chemical Industry
Characteristics of gold biosorption from cyanide solutionNiu, Hui; Volesky, Bohumil
doi: 10.1002/(SICI)1097-4660(199908)74:8<778::AID-JCTB99>3.0.CO;2-Qpmid: N/A
Gold adsorption from cyanide solution by bacterial (Bacillus subtilis), fungal (Penicillium chrysogenum) and seaweed (Sargassum fluitans) biomass was examined. At pH 2.0, these biomass types were capable of sequestering up to 8.0 µmol g−1, 7.2 µmol g−1 and 3.2 µmol g−1, respectively. An adverse effect of increasing solution ionic strength (NaNO3) on gold biosorption was observed. Gold‐loaded biomass could be eluted with 0.1 mol dm−3 NaOH with efficiencies higher than 90% at pH 5.0 at the Solid‐to‐Liquid ratio, S/L, = 4 (g dm−3). Cyanide mass balances for the adsorption, desorption as well as for the AVR process indicated the stability of the gold‐cyanide which did not dissociate either upon acidification or upon binding by biomass functional groups. Gold biosorption mainly involved anionic AuCN2− species bound by ionizable biomass functional groups carrying a positive charge when protonated. FTIR analyses indicated that the main biomass functional groups involved in gold biosorption are most probably nitrogen‐containing weak base groups. The present results confirmed that waste microbial biomaterials have some potential for removing and concentrating gold from solutions where it occurs as a gold‐cyanide complex. © 1999 Society of Chemical Industry
Kinetics and mechanism of homogeneous catalytic hydroxylation of maleic acid by hydrogen peroxide: III. Kinetics of the hydrolysis of cis ‐epoxysuccinic acidOludipe, John O
doi: 10.1002/(SICI)1097-4660(199908)74:8<785::AID-JCTB102>3.0.CO;2-Mpmid: N/A
The objective of this work was to study the hydrolysis kinetics and also the character of the involvement of the epoxidation catalyst (Na2WO4 – sodium tungstate) on the hydrolysis of cis‐epoxysuccinic acid (the initial product in the hydroxylation reaction of maleic acid by hydrogen peroxide). The results obtained at 65 °C clearly revealed that the hydrolysis reaction exhibits a considerably low rate in the absence of a catalyst whilst the rate is significantly enhanced by the introduction of catalytic quantities of Na2WO4. The phenomenon of end‐product inhibition was observed in this study and the results obtained permitted the development of a kinetic model consistent with experimental observations. Analysis of the kinetic model shows that the reaction is first order with respect to the concentrations of the catalyst and the epoxide. However, tartaric acid has a strong inhibitive influence on the overall reaction rate. © 1999 Society of Chemical Industry
The effect of nitrite correction on the evaluation of the rate of nitrate utilization under anoxic conditionsSözen, Seval; Orhon, Derin
doi: 10.1002/(SICI)1097-4660(199908)74:8<790::AID-JCTB106>3.0.CO;2-Cpmid: N/A
The nitrogen utilization requirement (NUR) test is a useful respirometric procedure for the assessment of major kinetic constants in activated sludge systems designed for nitrogen removal. The electron transfer mechanism of nitrogenous compounds often involves significant nitrite accumulation which impairs the accuracy of the NUR test. Experimental results revealed no meaningful correlation between nitrite accumulation and the initial nitrate concentration or the food/microorganism (F/M) ratio. Significant impact of nitrite accumulation was observed both on the assessment of the readily biodegradable COD component, the correction factor for anoxic growth and the denitrification rates applicable to domestic sewage and a number of industrial wastewaters. © 1999 Society of Chemical Industry