Cyclodextrin-based polymeric materials for the specific recovery of polyphenolic compounds through supramolecular host–guest interactions

While the specific recovery of valuable chemicals from waste streams represents an environmentally-friendly and potentially economically-relevant alternative to synthetic chemical productions, it remains a largely unmet challenge. This is partially explained by the complexity of designing sorption materials able to target one specific compound and able to function in complex matrices. In this work, a series of cyclodextrin-based polymers (CDPs) were designed to selectively extract phenolic compounds from a complex organic matrix that is olive oil mill wastewater (OMW). In order to endow these polymers with selective adsorption properties, several monomers and cross-linkers were screened and selected. The adsorption properties of the CDPs produced were first tested with selected phenolic compounds commonly found in OMW, namely syringic acid, p-coumaric acid, tyrosol and caffeic acid. The selected CDPs were subsequently tested for their ability to adsorb phenolic compounds directly from OMW, which is known to possess a high and complex organic content. It was demonstrated through high-performance liquid chromatography-mass spectroscopy analyses that efficient removal of phenolic compounds from OMW could be achieved but also that two compounds, namely tyrosol and hydroxytyrosol, could be selectively extracted from OMW.     

Toxicity and biodegradability of olive mill wastewaters in batch anaerobic digestion

The anaerobic biodegradability and toxicity of olive mill waste-waters (OMW) were studied in batch anaerobic digestion experiments. Anaerobic digestion of OMW or the supernatant of its centrifugation, the methane production was achieved at up to 5–15% (V/V) dilution corresponding to only 5–20 g/L COD. The washed suspended solids of OMW were toxic at up to 80 g/L COD; however, the kinetic of biodegradability of OMW or the supernatant was faster than for suspended solids, which are constituted meanly of cellulose and lignin. The darkly colored polyphenols induce the problem of biodegradation of OMW, whereas the long chain fatty acids (LCFA), tannins and simple phenolic compounds are responsible its toxicity for methanogenic bacteria.     

Effects of gamma-ray treatment on wastewater toxicity from a rubber products factory

In order to reduce the toxicity of both raw wastewater and effluent from a rubber products factory, γ-ray treatment was applied at different dose levels. The γ-ray treatment did not completely removed the toxicity, suggesting that there were major toxicants other than destroyable organic compounds. Toxicity identification evaluation (TIE phase 1) was conducted to characterize major toxicants using Daphnia magna. The suspected toxicants in both raw wastewater and effluent were mostly filterable materials and EDTA chelatable metals and, to some degree, non-polar organic compounds. Anion-exchange removable compounds, most likely organics, were found only in raw wastewater. Metal analyses showed that zinc and copper concentrations were above levels causing toxicity to D. magna. After 20 kGy γ-ray treatment of raw wastewater, filtrations both at pH 3 and at the initial pH (pH 3.6) showed dramatic change (9 to 77% and 29 to 85%, respectively) in toxicity reduction, suggesting the formation of toxic filterable materials which are stable even at acidic conditions. Unlike raw wastewater, there was no significant change in TIE results after γ-ray treatment at 20 kGy for rubber effluent.     

Bleacing of olive mill wastewater by clay in the presence of hydrogen peroxide

Treatment of olive mill wastewater (OMW) with clayey soils in the presence of hydrogen peroxide (H₂O₂) allows the elimination of phenolic compounds responsible for the black-brownish color of this industrial effluent. The aim of this research was to define optimal physicochemical parameters for the bleaching of OMW with clay in the presence of hydrogen peroxide. Two clayey soil powders were tested (A and B) and the results obtained indicate that high bleaching could be reached after 24 hours exposure of OMW to 7 % (W/V) clay material A in the presence of 0.5 % (V/V) hydrogen peroxide. Under these conditions, the bleaching led to about 87 % decrease of polyphenols (PF) and a 66 % decrease of the Chemical Oxygen Demand (COD). The structure of clay and its concentration in iron salts have an effective adsorbent and catalytic effect on the removal of the majority of polyphenols.     

Microbial Application to Improve Olive Mill Wastewater Phenolic Extracts

Olive mill wastewater (OMW) contains valuable and interesting bioactive compounds, among which is hydroxytyrosol, which is characterized by a remarkable antioxidant activity. Due to the health claims related to olive polyphenols, the aim of this study was to obtain an extract from OMW with an increased level of hydroxytyrosol by means of microbial enzymatic activity. For this purpose, four commercial adsorbent resins were selected and tested. The beta-glucosidase and esterase activity of strains of Wickerhamomyces anomalus, Lactiplantibacillus plantarum, and Saccharomyces cerevisiae were also investigated and compared to those of a commercial enzyme and an Aspergillus niger strain. The W. anomalus strain showed the best enzymatic performances. The SP207 resin showed the best efficiency in selective recovery of hydroxytyrosol, tyrosol, oleuropein, and total phenols. The bioconversion test of the OMW extract was assessed by using both culture broths and pellets of the tested strains. The results demonstrated that the pellets of W. anomalus and L. plantarum were the most effective in hydroxytyrosol increasing in phenolic extract. The interesting results suggest the possibility to study new formulations of OMW phenolic extracts with multifunctional microorganisms.     

Use of C-18 reverse-phase cartridges for estimation of metal complexation by a residue from olive oil industry

 Formation of complexes between Cu and organic polymers present in olive mill wastewater (OMW) is shown to be a cause of metal solubilization by the residue, using C-18 reverse-phase cartridges (RPC) for separating the complexed metal. Nearly 100% of the metal released from a polluted river sediment by OMW solutions is retained by the cartridges. The proportion of Cu retained by the cartridges is somewhat lower (50–80%), if the OMW solution initially contains Cu. About 70–80% of Cu released by OMW from a soil column previously loaded with high doses of metal is also retained by the cartridges. Incomplete Cu retentions are not thought to be due to a lack of efficiency of RPC in immobilizing Cu complexes, but to the formation of an equilibrium between free and complexed forms of the metal. Received: 3 June 1996/Revised: 29 September 1996/Accepted: 10 October 1996     

Use of C-18 reverse-phase cartridges for estimation of metal complexation by a residue from olive oil industry

 Formation of complexes between Cu and organic polymers present in olive mill wastewater (OMW) is shown to be a cause of metal solubilization by the residue, using C-18 reverse-phase cartridges (RPC) for separating the complexed metal. Nearly 100% of the metal released from a polluted river sediment by OMW solutions is retained by the cartridges. The proportion of Cu retained by the cartridges is somewhat lower (50–80%), if the OMW solution initially contains Cu. About 70–80% of Cu released by OMW from a soil column previously loaded with high doses of metal is also retained by the cartridges. Incomplete Cu retentions are not thought to be due to a lack of efficiency of RPC in immobilizing Cu complexes, but to the formation of an equilibrium between free and complexed forms of the metal. Received: 3 June 1996/Revised: 29 September 1996/Accepted: 10 October 1996     

THERMODYNAMIC STUDY OF ADSORPTION OF PHENOLIC COMPOUNDS FROM AQUEOUS SOLUTION BY A WATER-COMPATIBLE HYPERCROSSLINKED POLYMERIC ADSORBENT

Equilibrium data for the adsorption of phenolic compounds, i.e., phenol, p-cresol, p-chlorophenol and p-nitrophenol from aqueous solutions by a water-compatible hypercrosslinked polymeric adsorbent (NJ-8) within temperature range of 283-323 K were obtained and correlated with a Freundlich-type of isotherm equation, so that equilibrium constants KF and n were obtained. The capacities of equilibrium adsorption for all the four phenolic compounds on the NJ-8 from aqueous solutions are around 2 times as high as those of Amberlite XAD-4, which may be attributed to the unusual micropore structure and the partial polarity on the network. The values of the enthalpy (always negative) are indicative of an exothermic process, which manifests the adsorption of all the four phenolic compounds on the two polymeric adsorbents to be a process of physical adsorption. The negative values of free energy change show that the solute is more concentrated on the adsorbent than in the bulk solution. The absolute free energy values of adsorption for NJ-8 are always higher than those for Amberlite XAD-4, which indicates that phenolic compounds are preferentially adsorbed on NJ-8. The negative values of the adsorption entropy are consistent with the restricted mobilities of adsorbed molecules of phenolic compounds as compared with the molecules in solution. The adsorption entropy values of phenolic compounds for NJ-8 are lower than those for Amberlite XAD-4, which means the micropores of NJ-8 require more orderly arranged adsorbate.     

The Valorisation of Olive Mill Wastewater from Slovenian Istria by Fe3O4 Particles to Recover Polyphenolic Compounds for the Chemical Specialties Sector

Olive oil production using three-phase decanter systems creates olive oil and two by-products: olive mill wastewater (OMWW) and pomace. These by-products contain the highest share of polyphenolic compounds that are known to be associated with beneficial effects on human health. Therefore, they are an attractive source of phenolic compounds for further industrial use in the cosmetic, pharmaceutical and food industries. The use of these phenolics is limited due to difficulties in recovery, high reactivity, complexity of the OMWW matrix and different physiochemical properties of phenolic compounds. This research, focused on OMWW, was performed in two phases. First, different polyphenol extraction methods were compared to obtain the method that yields the highest polyphenol concentration. Twenty-five phenolic compounds and their isomers were determined. Acidifying OMWW, followed by five minutes of ultrasonication, resulted in the highest measured polyphenol content of 27 mg/L. Second, the collection of polyphenolic compounds from OMWW via adsorption on unmodified iron (II, III) oxide particles was investigated. Although low yields were obtained for removed polyphenolic compounds in one removal cycle, the process has a high capability to be repeated.     

电化学催化氧化降解含酚废水的研究进展

酚类化合物具有高毒性,难降解性,国内外研究者越来越重视含酚废水的治理.电化学催化氧化技术在降解酚类化合物方面的研究较多.作者深入探讨了电化学催化氧化技术降解酚类化合物的机理和历程,概述了一些常用阳极材料的优缺点,最后指出了该技术存在的一些问题与发展前景.     

Radiolytic decomposition of pesticide carbendazim in waters and wastes for environmental protection

The radiolytic degradation of widely used fungicide, carbendazim, in synthetic aqueous solutions and industrial wastewater was investigated employing γ-irradiation. The effect of the absorbed dose, initial concentration and pH of irradiated solution on the effectiveness of carbendazim decomposition were investigated. Decomposition of carbendazim in 100 μM concentration in synthetic aqueous solutions required irradiation with 600 Gy dose. The aqueous solutions of carbendazim have been irradiated in different conditions, where particular active radical species from water radiolysis predominate. The obtained data have been compared with the kinetic modeling. The reversed-phase high-performance liquid chromatography was used for the determination of carbendazim and its radiolytic decomposition products in irradiated solutions. The changes of toxicity of irradiated solutions were examined with different test organisms and human leukemia cells.     

Bioelectrochemical evaluation of the total phenols content in olive oil mill wastewaters using a tyrosinase–colloidal gold–graphite–Teflon biosensor

The use of a robust tyrosinase biosensor, fabricated from graphite–Teflon rigid electrode matrices modified with gold nanoparticles, for the estimation of the total phenols content in olive oil mill wastewaters (OMW), is proposed. The performance of this bioelectrode using both continuous stirring and flow-injection amperometry was studied. A potential value of ?0.10?V was selected for the sensitive and stable detection of various phenolic compounds present in OMW samples: catechol, 3,4-dihydroxycinnamic acid (caffeic acid), 3,4-dihydroxyphenylacetic acid (DOPAC), 4-hydroxyphenylacetic acid, 4-hydroxyphenylethanol (tyrosol), and 4-hydroxyphenylpropionic acid. Using catechol as the target phenol, linear calibration graphs were obtained in the 1.0?×?10^?8???8.0?×?10^?6?mol?L^?1 (batch) and 1.0?×?10^?7???1.0?×?10^?5?mol?L^?1 (FI) concentration ranges, with slope values of 750?mA?L?mol^?1 and 103?mA?L?mol^?1, respectively. Batch amperometry was chosen for the analysis of real samples because of its higher sensitivity. For example, the limit of detection for caffeic acid was 80?nM. The ‘pool’ of phenolic compounds was estimated in OMW obtained from different extraction systems and containing phenols at diverse levels of concentration. A comparison of these results with those obtained by applying the Folin–Ciocalteau spectrophotometric reference method was carried out.     

Simple and Feasible Simultaneous Determination of Three Phenolic Pollutants on Boron‐Doped Diamond Film Electrode

A simple, rapid and feasible method is developed for direct and simultaneous determination of phenol (Ph), hydroquinone (HQ) and 4‐nitrophenol (4‐NP) on unmodified boron‐doped diamond (BDD) electrode. Results showed that the oxidative peaks of these three phenolic compounds can be completely separated on BDD electrode in acidic conditions by using electrochemical cyclic voltammetry technique. The peak potential separations are all higher than 0.35 V. Moreover, BDD electrode is extremely easy to be refreshed to obtain current values with good reproducibility, even if it is passivated by phenolic compounds with different adsorption characteristics. All the above features are on account of the outstanding electrochemical characteristics of BDD electrode, and lead to the advantage and feasibility for simultaneous determination of three phenolic compounds without any other separation operation. For each tested phenolic compound, the concentration range with linearity is in two or three orders of magnitude in the presence of other coexisting phenolic compounds with the concentrations more than 1000 times higher than that of the tested component. The present method is also shown to be promising for the determination of phenolic contaminants in the real wastewater samples.     

Radiolytic degradation mechanism of gallic acid and its end-products

Gallic acid is one of the most representative biorecalcitrant phenolic compounds present in cork processing wastewater. In this communication, chemical oxidation of gallic acid was studied by gamma irradiation as an advanced oxidation process. This technology turns out to be an advantageous tool for the degradation of gallic acid. The results obtained by UV-Vis and electrospray ionization mass spectrometry (ESI-MS) techniques are in agreement concerning the suitability of this technique to degrade gallic acid. ESI-MS and ESI-MS(2) monitoring of the non-irradiated and irradiated gallic acid solutions leads to the identification of the main intermediate products. Based on the overall results obtained a consistent mechanism of radiolytic degradation of gallic acid is proposed. The application of radiation as a tool to increase the biodegradability of wastewaters is an important issue from the perspective of Green Chemistry.     

One-Step Extraction of Olive Phenols from Aqueous Solution Using β-Cyclodextrin in the Solid State,a Simple Eco-Friendly Method Providing Photochemical Stability to the Extracts

The extraction of phenolic compounds from olive mill wastes is important, not only to avoid environmental damages, but also because of the intrinsic value of those biophenols, well-known for their high antioxidant potential and health benefits. This study focuses on tyrosol (Tyr) and hydroxytyrosol (HT), two of the main phenolic compounds found in olive mill wastes. A new, simple, and eco-friendly extraction process for the removal of phenolic compounds from aqueous solutions using native β-cyclodextrin (β-CD) in the solid state has been developed. Several β-CD/biophenol molar ratios and biophenol concentrations were investigated, in order to maintain β-CD mostly in the solid state while optimizing the extraction yield and the loading capacity of the sorbent. The extraction efficiencies of Tyr and HT were up to 61%, with a total solid recovery higher than 90% using an initial concentration of 100 mM biophenol and 10 molar equivalents of β-CD. The photochemical stability of the complexes thus obtained was estimated from ∆E*ab curve vs. illumination time. The results obtained showed that the phenols encapsulated into solid β-CD are protected against photodegradation. The powder obtained could be directly developed as a safe-grade food supplement. This simple eco-friendly process could be used for extracting valuable biophenols from olive mill wastewater.     

K2CO3活化煤矸石制备活性炭吸附剂

用Ｋ２ＣＯ３化学活化煤矸石制备适用于废水处理的活性炭吸附剂．考察了活化条件对产物的比表面、孔体积及灰分的影响．增加了前处理和后处理步骤以改善产物的性能．最佳条件下获得的活性炭吸附剂ＢＥＴ比表面达１２３６ｍ２／ｇ，孔体积０．６７９ｃｍ３／ｇ．所制得的吸附剂表面是疏水性的，对水溶液中的酚类污染物有良好的吸附性能．     

Olive mill wastewater treatment by a pilot-scale subsurface horizontal flow (SSF-h) constructed wetland

Performances of a pilot-scale reed bed for the olive mill wastewater (OMW) treatment were investigated, by monitoring influent and effluent pH, total suspended solids (TSS), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), total phosphorus and polyphenols. In order to reduce the suspended matter concentration and to avoid clogging, OMW was pre-treated by adding lime putty, calcium hydroxide and hydraulic lime. The best results were obtained with 2 g/L of hydraulic lime. Pre-treated OMW was dosed in the reed bed at dilution ratios of 1/3 and 1/10 (v/v), pointing up that the latter only did not give rise to reed suffering and allowed to obtain good and durable removal efficiencies, above all for COD (74.1+/-17.6%) and polyphenols (83.4+/-17.8%). Recycling of the effluent was quite effective for the improvement of the wastewater quality, allowing a further removal of 26-70%, depending on the parameter taken into account. A post-dosage study, carried out by feeding the reed bed with the effluent of an activated sludge plant, pointed up a rapid decreasing of the outlet concentrations of the investigated parameters to values compatible with Italian regulations concerning wastewater discharge in surface water. Polyphenols were the exception, being their outlet concentration at the end of post-dosage study around 2 mg/L.     

Removal of gadolinium ions from solutions using granulated zeolites

The possiblity of the use of granulated zeolites for the removal of gadolinium ions from solutions has been investigated. Measurements of gadolinium ion concentrations in solutions and of the distribution of gadolinium ions in column filligns (granulated zeolites), after passing the solution through columns filled with various granulated zeolites (zeolite 4A, zeolite 13X and synthetic mordenite), have shown that gadolinium ions can be effectively removed from nearly neutral or acidic solutions using granulated mordenite. The influency of pH, column filling and the flow rate of the solution through the column on the efficiency of gadolinium ion removal and on the distribution of gadolinium ions in the columns has been investigated. On the basis of the results obtained, the conditions for the most efficient removal of gadolinium ions from solutions have been obtained.     

Monitoring of environmental phenolic endocrine disrupting compounds in treatment effluents and river waters, Korea

The last two decades have witnessed growing scientific and public concerns over endocrine disrupting compounds (EDCs) that have the potential to alter the normal structure or functions of the endocrine system in wildlife and humans. In this study, the phenolic EDCs such as alkylphenol, chlorinated phenol and bisphenol A were considered. They are commonly found in wastewater discharges and in sewage treatment plant. In order to monitor the levels and seasonal variations of phenolic EDCs in various aquatic environments, a total of 15 water samples from the discharged effluent from sewage and wastewater treatment plants and river water were collected for 3 years. Ten environmental phenolic EDCs were determined by GC-MS and laser-induced fluorescence (LIF). GC-MS analysis revealed that most abundant phenolic EDCs were 4-n-heptylphenol, followed by nonlyphenol and bisphenol A during 2002-2003, while 4-t-butylphenol and 4-t-octylphenol were newly detected in aquatic environments in 2004.The category of phenolic EDCs showed similar fluorescence spectra and nearly equal fluorescence decay time. This makes it hard to distinguish each phenolic EDC from the EDCs mixture by LIF. Therefore, the results obtained from LIF analysis were expressed in terms of the fluorescence intensity of the total phenolic EDCs rather than that of the individual EDC. However, LIF monitoring and GC-MS analysis showed consistent result in that the river water samples had lower phenolic EDCs concentration compared to the effluent sample. This revealed a lower fluorescence intensity and the phenolic EDCs concentration in summer was lower than that in winter. For the validation of LIF monitoring for the phenolic EDCs, the correlation between EDCs concentration acquired from GC-MS and fluorescence intensity from LIF was obtained (R = 0.7379). This study supports the feasibility of the application of LIF into EDCs monitoring in aquatic systems.     

Whole cell immobilised biosensors for toxicity assessment of a wastewater treatment plant treating phenolics-containing waste

Wastewater treatment plants dealing with industrial wastes are often susceptible to overload of toxic influent that can partially or completely destroy treatment for extended periods. An obvious candidate for monitoring toxicity in such wastewater systems is bioluminescent bacteria. However, the natural bioluminescent bacteria can be particularly sensitive to some industrial wastes and therefore their response to normal operational conditions does not reflect the status of the microbial community responsible for treatment. Moreover, the salt dependence of the marine bioluminescent bacteria, and the temperature sensitivity of some strains, further complicate their use. Here we describe the construction of whole cell genetically modified bioluminescent biosensors and their immobilisation for use in monitoring the toxicity of a complex industrial wastewater containing phenolic materials. A hand-held luminometer was designed for laboratory or field use, and the immobilisation system designed with several things in mind: the geometry of the instrument; the need for containment of GM bacteria; the maximisation of the bioavailability of the wastewater to the biosensor. The performance of a candidate GM sensor was compared with Vibrio fischeri in liquid culture and after immobilisation in thin films of poly(vinyl alcohol) (PVA) cryogels. The biosensors were tested against pure phenol and 3-chlorophenol as a reference toxic chemical known to be much more toxic to bacteria than phenol. The biosensors were then tested with the phenolics-containing industrial wastewater. The immobilisation system proved to operate predictably with pure toxicants, and was able to discriminate toxicity of various zones within the wastewater treatment plant.