Decolorization of Distillery Effluent Using Poly(Vinyl Chloride) and Cellulose Acetate Phthalate as Adsorbents

Decolorization of distillery effluents, using low cost polymer adsorbents, is one of the challenging areas for environmental technologists. Untreated distillery effluents are harmful to the environment, causing foul smell, spoiling fresh water sources and killing aquatic life. The color of distillery effluents have been decolorized by using polymer based adsorbents, such as poly(vinyl chloride) (PVC) and cellulose acetate phthalate (CAP), which are water insoluble, easily available, and cheap. In the present article, special emphasis is given to studies such as the effect of contact time, dosage amount, dilution, and the variation in the amount of sample on the degree of decolorization of the effluent. The decolorization of a distillery effluent was monitored by using UV/Visible spectroscopy and Fourier transform infrared spectroscopy (FTIR). From these studies, it was noticed that moderate to fair results were obtained and it was also found that CAP was a better adsorbent, compared to PVC, for decolorization of distillery effluents.     

Characterization of natural and synthetic humic substances (melanoidins) by stable carbon and nitrogen isotope measurements and elemental compositions

Stable carbon isotope ratios of the starting sugars (SG) and amino acids (AA) are mostly preserved in laboratory synthetic melanoidins. Stable nitrogen isotope ratios may not be “imprinted” in melanoidins by SG and AA precursors in the same way, indicating that nitrogen fractionation could occur during the rate-determining step in the Maillard reaction. Carbon isotope ratios support the stoichiometric ratios for combination of sugars with amino acids, which are based on the elemental composition data of melanoidins. These findings may provide clues to asses the role of the Maillard reaction in the formation of natural humic substances.     

The role of peptides and proteins in melanoidin formation

High‐molecular‐weight (HMW) coloured compounds called melanoidins are widely distributed, particularly in foods. It has been proposed that they originate through the Maillard reaction, a non‐enzymatic browning reaction, due to the interaction between protein or peptide amino groups and carbohydrates. The melanoidin structure is not definitively known, and they have been generally defined as HMW nitrogen‐containing brown polymers. In order to gain information on the nature of melanoidins, a simple in vitro model was chosen to investigate the products of the reactions between sugars and peptide/proteins. This approach would elucidate whether melanoidin formation is due to the binding of different sugar units to a peptide/protein or vice versa. With this aim, the reactivity of two different peptides, EPK177 and physalaemin, and a low‐molecular‐weight (LMW) protein, lysozyme, was tested towards different saccharides (glucose, maltotriose (MT), maltopentaose and dextran 1000) in aqueous solutions at different temperatures. The incubation mixtures were analysed at different reaction times by MALDI/MS. Furthermore, in order to verify the possible role of sugar pyrolysis products in melanoidin formation, the products arising from the thermal treatment at 200 °C of MT were incubated with lysozyme, and the reaction products were analysed by the same MS approach. The obtained results allowed the establishment of some general views: melanoidins cannot simply originate by reactions of sugar moieties with proteins. In fact, the reaction easily occurs, but it does not lead to any coloured product, as melanoidins have been described to be; melanoidins cannot originate from the thermal degradation products of glycated proteins. In fact, the thermal treatment of glycated lysozyme leads to a severe degradation of the protein with the formation of LMW species, far from the view of melanoidins as HMW compounds; experimental evidence has been gained on the melanoidin formation through reaction of intact protein with the pyrolysis products of MT. This hypothesis has been supported either from MALDI measurements or from spectroscopic data that show an absorption band in the range 300–600 nm, typical of melanoidins. Copyright © 2009 John Wiley & Sons, Ltd.     

Salicylic-Acid-Mediated Enhanced Biological Treatment of Wastewater

Activated sludge represents a microbial community which is responsible for reduction in pollution load from wastewaters and whose performance depends upon the composition and the expression of degradative capacity. In the present study, the role of salicylic acid (SA) has been evaluated for acclimatization of activated sludge collected from a combined effluent treatment plant followed by analysis of the physiological performance and microbial community of the sludge. The biodegradative capacity of the acclimatized activated sludge was further evaluated for improvement in efficiency of chemical oxygen demand (COD) removal from wastewater samples collected from industries manufacturing bulk drugs and dyes and dye intermediates (wastewater 1) and from dye industry (wastewater 2). An increase in COD removal efficiency from 50% to 58% and from 78% to 82% was observed for wastewater 1 and wastewater 2, respectively. Microbial community analysis data showed selective enrichment and change in composition due to acclimatization by SA, with 50% of the clones showing sequence homology to unidentified and uncultured bacteria. This was demonstrated by analysis of partial 16S rDNA sequence data generated from dominating clones representing the metagenome which also showed the appearance of a unique population of clones after acclimatization, which was distinct from those obtained before acclimatization and clustered away from the dominating population.     

Pyrolysis of natural and synthetic humic substances

Thermogravimetric and Rock-Eval techniques were used for the characterization of natural (humic) and synthetic (melanoidins) substances and their hydrocarbon generation potential. A similarity between the thermal behaviour of humic substances and of melanoidins (prepared from an excess of sugar) and the unique thermal properties of melanoidins (prepared from basic amino acids) was observed. Rock-Eval analysis indicated that most synthetic melanoidins (also clay-complexed) generated more hydrocarbons and related compounds than terrestrial humic substances.     

Dye and its removal from aqueous solution by adsorption: A review

In this review article the authors presented up to-date development on the application of adsorption in the removal of dyes from aqueous solution. This review article provides extensive literature information about dyes, its classification and toxicity, various treatment methods, and dye adsorption characteristics by various adsorbents. One of the objectives of this review article is to organise the scattered available information on various aspects on a wide range of potentially effective adsorbents in the removal of dyes. Therefore, an extensive list of various adsorbents such as natural materials, waste materials from industry, agricultural by-products, and biomass based activated carbon in the removal of various dyes has been compiled here. Dye bearing waste treatment by adsorption using low cost alternative adsorbent is a demanding area as it has double benefits i.e. water treatment and waste management. Further, activated carbon from biomass has the advantage of offering an effected low cost replacement for non-renewable coal based granular activated carbon provided that they have similar or better adsorption on efficiency. The effectiveness of various adsorbents under different physico-chemical process parameters and their comparative adsorption capacity towards dye adsorption has also been presented. This review paper also includes the affective adsorption factors of dye such as solution pH, initial dye concentration, adsorbent dosage, and temperature. The applicability of various adsorption kinetic models and isotherm models for dye removal by wide range of adsorbents is also reported here. Conclusions have been drawn from the literature reviewed and few suggestions for future research are proposed.     

Pyrolysis/gas chromatography/mass spectrometry monitoring of fungal-biotreated distillery wastewater using Trametes sp. I-62 (CECT 20197)

Distillery wastewaters generated by ethanol production from fermentation of sugar-cane molasses, named vinasses, lead to important ecological impact due to their high content of soluble organic matter and their intense dark-brown color. Taking advantage of the well-known ability of white-rot fungi to degrade an extensive variety of organic pollutants, the capacity of Trametes sp. I-62 (CECT 20197) to detoxify this type of effluents was evaluated. In this work, pyrolysis/gas chromatography/mass spectrometry was applied to the chemical characterization of several fractions of Cuban distillery wastewater as well as to monitoring the changes which occurred after fungal treatment with this white-rot basidiomycete. Maximum effluent decolorization values and chemical oxygen demand reduction attained after seven days of fungal treatment were 73.3 and 61.7%, respectively, when 20% (v/v) of distillery vinasses was added to the culture medium. Under these conditions a 35-fold increase in laccase production by Trametes sp. I-62 was measured, but no manganese peroxidase activity could be detected. The pyrolysis/gas chromatography/mass spectrometry results showed a decrease in a number of pyrolysis products after seven days of fungal treatment, mainly furan derivatives. The decrease in the relative areas of these compounds could be related to the vinasse color-removal associated with melanoidin degradation. All these results indicated the potential use ofTrametes sp. I-62 in the detoxification of recalcitrant distillery vinasses.     

Removal of chromium(VI) from wastewater using Sorel's cement

Summary Synthetic Sorel's cement [3Mg(OH)₂ ^. MgCl₂ ^. 8H₂O], is used as a new adsorbent material for removal of chromium(VI) ion from wastewater effluents. Parameters including contact time, adsorbent dosage and pH are examined and optimized. The equilibrium data are fitted very well to the Langmuir and Freundlich isotherms rather than linear. The adsorption isotherm indicates that the monolayer coverage is 21.4 mg Cr(VI) ion per g of Sorel's cement. The adsorbent is considered as a better replacement technology for removal of Cr(VI) ion from aqueous solutions due to its low cost, good efficiency, fast kinetics, and simple preparation. It offers remarkable efficiency for Cr(VI) removal from wastewater compared with many other natural and synthetic adsorbents.     

Biosorption of Cr(VI) ions from aqueous solutions: kinetics, equilibrium, thermodynamics and desorption studies

Cr(VI) is a major water pollutant from industrial effluent whose concentration is to be reduced within the permissible limit. Present study reports a systematic evaluation of six different natural adsorbents for the removal of Cr(VI) from aqueous solutions in batch process. The adsorption kinetic data were best described by pseudo-second order model. The values of mass transfer coefficient for Cr(VI) adsorption indicated that the velocity of the adsorbate transport from the bulk to the solid phase was quite fast. The effective diffusivity of Cr(VI) removal for all the adsorbents were of the order of 10(-10) m(2)/s which suggested chemisorption of the process. The adsorption process was jointly controlled by film diffusion and intraparticle diffusion. Maximum monolayer adsorption capacities onto the natural adsorbents used were comparable to the other natural adsorbents used by other researchers. The thermodynamic studies and sorption energy calculation using Dubinin-Radushkevich isotherm model indicated that the adsorption processes were endothermic and chemical in nature. FT-IR studies were carried out to understand the type of functional groups responsible for Cr(VI) binding process. Desorption study was carried out with different concentration of NaOH solutions. Application study was carried out using electroplating industrial wastewater.     

Evaluation of PANI-Averraoha bilimbi leaves activated carbon nanocomposite for Cd2+ and Pb2+ removal from wastewater

In current investigation, we synthesized new Polyaniline-Averraoha Bilimbi Leaves Activated Carbon (PANI-ABLC) nanocomposites and utilized as cost effectual for the elimination of Cd²⁺ and Pb²⁺ ions from the wastewater. The synthesized nanocomposite was confirmed by Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray (EDX), Fourier Transform-Infrared (FT-IR) spectroscopy and X-Ray Diffraction (X-RD) techniques. A batch adsorption study carried in wastewater containing different concentrations of Cd²⁺ and Pb²⁺ ions in the temperature range of 303–343 K. The results show that, around 80% of Cd²⁺ and Pb²⁺ ions from the wastewater was successfully isolated by using PANI-ABLC nanocomposite. Attempts were made to fit adsorption to different isotherm models. The PANI-ABLC nanocomposite complied Langmuir adsorption model (R² = 0.999) and pseudo-second order kinetics. Further, maximum adsorption efficiency observed at 0.5 g of Polyaniline-Averraoha bilimbi leaves activated carbon nanocomposites. AC- Impedance Spectroscopy (IS) technique shows that, Polyaniline-Averraoha Bilimbi Leaves Activated Carbon (PANI-ABLC) nanocomposite is suitable for removal of Cd²⁺ and Pb²⁺ ions from the wastewater. AC impedance spectroscopy technique study shows that, the process of adsorption was controlled by charge transfer process.     

Trace analysis of lead by anodic stripping voltammetry with collection at interdigitated microelectrodes in small-volume samples

A simple and sensitive electroanalytical method was developed for microvolume trace elements determination. Commercially available interdigitated microelectrodes (IDA) from ALS Japan Inc. based on a thin carbon film technology were used. Anodic stripping voltammetry with collection at IDA was applied. Carbon IDA microbands were coated with a pre-deposited mercury film for better performance. The method with this sensor enables analysis of some heavy metals in total sample volumes as small as 0.05 cm³. The method was applied to Pb in blood samples determination by a standard addition method.     

超分子大环化合物用于染料吸附的研究进展

染料在许多工业领域中的长期广泛使用,带来了严重的环境水污染问题,威胁人类健康,因此有效地从水中去除染料是亟待解决的问题。吸附由于具有高效、简单和低成本的优点而成为降低水中染料含量最有吸引力的技术之一。吸附剂的选择对染料的高效吸附至关重要。具有大环空腔的超分子大环化合物作为主体分子对很多客体分子都具有较强的吸附作用,其作为染料吸附剂得到了极其广泛的关注。该文综述了基于大环化合物的吸附剂的制备及用于水体中染料去除的研究,对各种吸附剂的吸附性能进行了讨论,并对基于大环化合物的染料吸附剂的未来发展提出展望。     

Molten salts-modified MgO-based adsorbents for intermediate-temperature CO_2 capture: A review

Carbon dioxide(CO2) capture using magnesium oxide(MgO)-based adsorbents at intermediate temperatures has been regarded as a very prospective technology for their relatively high adsorption capacity,low cost, and wide availability. During the past few years, great effort has been devoted to the fabrication of molten salts-modified MgO-based adsorbents. The extraordinary progress achieved by coating with molten salts greatly promotes the CO_2 capture capacity of MgO-based adsorbents. Therefore, we feel it necessary to deliver a timely review on this type of CO_2 capturing materials, which will benefit the researchers working in both academic and industrial areas. In this work, we classified the molten saltsmodified MgO adsorbents into four categories:(1) homogenous molten salt-modified MgO adsorbents,(2) molten salt-modified double salts-based MgO adsorbents,(3) mixed molten salts-modified MgO adsorbents, and(4) molten salts-modified MgO-based mixed oxides adsorbents. This contribution critically reviews the recent developments in the synthetic method, adsorption capacity, reaction kinetics, promotion mechanism, operational conditions and regenerability of the molten salts-modified MgO CO_2 adsorbents. The challenges and prospects in this promising field of molten salts-modified MgO CO_2 adsorbents in real applications are also briefly mentioned.     

Quantification of deformed peaks in capillary gas chromatography (CGC): application to simultaneous analysis of free fatty acids and less polar compounds in aqueous distillery effluent

The purpose of this study was to find a simple and rapid method allowing the simultaneous quantification of some alcoholic fermentation inhibitors present in aqueous distillery effluent in order to evaluate its recycling properties. A capillary gas chromatography (CGC) method was tested for the quantification of both short chain fatty acids (acetic to hexanoic) and neutral compounds (butane 2,3-diol, 2-furaldehyde, phenyl-2-ethane1-ol). A polyvalent column coated with ^®trifluoro-propyl-polysiloxane, allowing water injection, was tested and experiments were performed directly on untreated samples. During the development of the method, a deformation of acid peaks was observed; that could be explained by a secondary equilibrium, added to the chromatographic equilibrium. Although the acid peaks were deformed, calibration curves were produced and rigorously validated, proving that quantification is possible even when the best chromatographic conditions have not been achieved. Eventually, the method enabled the concentration of eight major fermentation inhibitors in distillery effluent to be measured.     

Core Shell Nanostructure: Impregnated Activated Carbon as Adsorbent for Hydrogen Sulfide Adsorption

This study focuses on the synthesis, characterization, and evaluation of the performance of core shell nanostructure adsorbent for hydrogen sulfide (H₂S) capture. Commercial coconut shell activated carbon (CAC) and commercial mixed gas of 5000 ppm H₂S balanced N₂ were used. With different preparation techniques, the CAC was modified by core shell impregnation with zinc oxide (ZnO), titanium oxide (TiO₂), potassium hydroxide (KOH), and zinc acetate (ZnAC₂). The core structure was prepared with CAC impregnated by single chemical and double chemical labelled with ZnAC₂-CAC (single chemical), ZnAC₂/KOH-CAC, ZnAC₂/ZnO-CAC, and ZnAC₂/TiO₂-CAC. Then, the prepared core was layered either with KOH, TiO₂, NH₃, or TEOS for the shell. The synthesized adsorbents were characterized in physical and chemical characterization through scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) analyzers. Operation of the adsorber column takes place at ambient temperature, with absolute pressure at 1.5 bar. The H₂S gas was fed into the column at 5.5 L/min and the loaded adsorbents were 150 g. The performance of synthesized adsorbent was analyzed through the adsorbent’s capability in capturing H₂S gas. Based on the results, ZnAc₂/ZnO/CAC_WOS shows a better adsorption capacity with 1.17 mg H₂S/g and a 53% increment compared to raw CAC. However, the degradation of the adsorbents was higher compared to ZnAc₂/ZnO/CAC_OS and to ZnAc₂/ZnO/CAC_WS ZnAc₂/ZnO/CAC_OS. The presence of silica as a shell has potentially increased the adsorbent’s stability in several cycles of adsorption-desorption.     

Kinetic and Dynamic Aspects of Arsenic Adsorption by Fe(III)-Loaded Sponge

Nowadays there is a great concern about new adsorbent materials for either the removal or fixation of arsenic species because of their high toxicity and the health problems associated with such species. In this paper the kinetics of absorption of As(V) on Fe(III)-loaded sponge have been studied and the results are compared with those of other natural and synthetic adsorbents. Arsenate was adsorbed very rapidly by Fe(III)-loaded sponge with saturation being reached in less than ten minutes. Arsenate was also adsorbed by Fe(III)-loaded Lewatit-TP-207 and non-loaded Purolite A100S ion-exchange resins but the times required to reach total saturation of the adsorbent were more than 100 minutes. The experimental data followed first-order kinetics. The extraordinarily superior kinetics are postulated to be related to the open-celled internal structure of the sponge material. The effect of flow rate on the dynamic removal of As(V) was studied in a fixed-bed column reactor for Fe(III)-loaded sponge and Fe(III)-loaded resin. The adsorption of As(V) on fixed-bed columns of adsorbent also indicated better kinetic properties for the sponge. Column studies showed a good correlation between the experimental data and the calculated breakthrough curves obtained by the Wolborska and Clark models. Application of the Wolborska model to the data at low C/C ₀ ratios enabled the determination of the kinetic coefficient of mass transfer for the sponge and resin materials at the different flow rates used and gave a good prediction of the 5% breakthrough times. Furthermore, the breakthrough curves were well described by the Clark model at the ratios of concentration of effluent to influent up to 0.5 for the sponge and 0.3 for the Fe(III)-loaded resin. Above these levels, a large deviation occurred for the resin adsorption. Thus, the sponge was found to be kinetically effective and favored for As(V) adsorption from solution over the conventional adsorbents used and for most of the adsorbents reported in the bibliography.     

Adsorption of phenolic compounds on low-cost adsorbents: A review

Adsorption techniques are widely used to remove certain classes of pollutants from wastewater. Phenolic compounds represent one of the problematic groups. Although commercial activated carbon is a preferred adsorbent for phenol removal, its widespread use is restricted due to the high cost. As such, alternative non-conventional adsorbents have been investigated. The natural materials, waste materials from industry and agriculture and bioadsorbents can be employed as inexpensive adsorbents. The review (i) presents a critical analysis of these materials; (ii) describes their characteristics, advantages and limitations; and (iii) discusses the various mechanisms involved. There are several issues and drawbacks concerned on the adsorption of phenolic compounds that have been discussed in this review article. It is evident from the review that low-cost adsorbents have demonstrated high removal capabilities for certain phenolic compounds. In particular, industrial waste might be a promising adsorbent for environmental and purification purposes.     

Recent advances in application and progress of advanced materials as adsorbents in sample preparation for plant growth regulators

Plant growth regulators are a class of physiologically active substances that could modify or regulate basic physiological processes in the plant and defense against abiotic and biotic stresses, including natural plant growth regulators and synthetic ones. Different from natural plant growth regulators with low content and high cost of extraction in plants, synthetic ones can be produced in large-scale production and widely used in agriculture for increasing and securing yield and quality of the harvested produce. However, like pesticides, the abuse of plant growth regulators will have negative impacts on human beings. Therefore, it is important to monitor plant growth regulators residues. Due to the low concentration of plant growth regulators and complex matrices of food, it is necessary to isolate and extract plant growth regulators by appropriate adsorbents in sample preparation for obtaining satisfactory results. In the last decade, several advanced materials as adsorbents have shown superiority in sample preparation. This review briefly introduces the recent application and progress of advanced materials as adsorbents in sample preparation for extraction of plant growth regulators from the complex matrix. In the end, the challenge and outlook about the extraction of plant growth regulators of these advanced adsorbents in sample preparation are presented.     

Nanoporous Lanthanum Tungstate: A Viable Adsorbent for Heavy Metals and Organic Pollutants

Removal of heavy metal cations from synthetic and industrial electroplating effluents by means of mesoporous lanthanum tungstate sorbents was thoroughly investigated. Three types of such sorbents, namely I‐LT, II‐LT and III‐LT, uncalcined and calcined, were produced and characterized by means of X‐ray diffraction, nitrogen sorption isotherms and thermogravimetry analysis (TGA). Results of the experiments for chromium, copper, mercury, iron and lead removal from both synthetic and real industrial wastewater solutions, using these novel sorbents, exhibit promising. Details of this new approach towards wastewater treatment have been discussed and the potentials of technological advancement using mesoporous lanthanum tungstate for environmental purposes addressed. Comparison with the literature shows superiority of the produced adsorbents over reported products.