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In this work, an eco-friendly solution for the remediation of wastewater generated in the lignin recovery process from eco-industrial paper mill has been proposed in their way towards a more circular economy strategy. Thus, the application of the electro-Fenton process for the degradation of the non-recovered lignin and other organic compounds form a scarcely studied acid black liquor waste (ABLW) was successfully performed. This treatment was able to operate in a range of COD loads (0.5–19.5 mg O2·L–1) showing high degradation values of the ABLW determined by the abatement of color, total phenolic content and COD. Then, the optimization of the working conditions for the design of a sustainable treatment system with optimum efficiency was carried out using a response surface methodology. The experiment carried out in the calculated optimal conditions for the electro-Fenton degradation process (current intensity 132.5 mA, catalyst dosage of 0.10 mM, and temperature 40 °C) showed a COD removal of 74.82% and current efficiency 77.79%, close to the theoretical value predicted by the model 73.12% and 77.06%, respectively. In addition, the identification of the final products permitted to confirm the mineralization efficiency.

Gold nanoparticles (AuNPs) were directly synthesized and anchored on lignocellulose fiber without an external immobilizing agent via a facile green approach using unbleached kraft (UBK) softwood pulp. The obtained AuNPs were confirmed by UV–vis diffuse reflectance spectroscopy, field-emission scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The antioxidant behavior of the as-prepared AuNP-UBK fiber nanocomposite was evaluated by free radical scavenging of 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH). The nanocomposite fiber exhibited greatly enhanced radical scavenging activity compared to that of the pure fiber. As a consequence, AuNP-UBK nanocomposite paper showed exceptional antioxidant performance with a radical scavenging rate of over 98%, which is attributed to the synergistic effects of adsorption by the fiber–fiber network and subsequent catalytic activity of the AuNPs. This research indicated that AuNP-UBK fiber nanocomposites could be a new candidate for antioxidant active packaging for use in food preservation.

We have explored AuNPs (13 nm) both as a catalyst and as a core for synthesizing water-dispersible and highly stable core-shell structural gold@Prussian blue (Au@PB) nanoparticles (NPs). Systematic characterization by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) disclosed AuNPs coated uniformly by a 5 nm thick PB layer. Au@PB NPs were attached to single-layer graphene oxide (GO) to form Au@PB decorated GO sheets. The resulting hybrid material was filtered layer-by-layer into flexible and free-standing GO paper, which was further converted into conductive reduced GO (RGO)/Au@PB paper via hydrazine vapour reduction. High-resolution TEM images suggested that RGO papers are multiply sandwich-like structures functionalized with core-shell NPs. Resulting sandwich functionalized graphene papers have high conductivity, sufficient flexibility, and robust mechanical strength, which can be cut into free-standing electrodes. Such electrodes, used as non-enzymatic electrochemical sensors, were tested systematically for electrocatalytic sensing of hydrogen peroxide. The high performance was indicated by some of the key parameters, for example the linear H2O2 concentration response range (1-30 μM), the detection limit (100 nM), and the high amperometric sensitivity (5 A cm(-2) M(-1)). With the advantages of low cost and scalable production capacity, such graphene supported functional papers are of particular interest in the use as flexible disposable sensors.

Abnormal expression of MicroRNA-21 (miRNA-21) is considered to be a reliable biomarker for the early diagnosis of cancer. In this work, a novel paper based biosensor was fabricated to detect sub-micro molar concentrations of miRNA-21 based on peroxidase mimetic activity of DNA-templated Ag/Pt nanoclusters (DNA-Ag/Pt NCs), which could catalyze the reaction of hydrogen peroxide and 3,3′,5,5′ tetramethylbenzidine (TMB), to produce a blue color. The Mechanism of reaction was based on the inhibition effect of miRNA-21 on peroxidase-like activity of nanosensor which resulted to quantitative determination of miRNA-21 concentration. It was found that miRNA-21 could be linearly detected in the range from 1-700 pM (A652 = 0.16x-0.96, R2 = 0.99; x = -log [miRNA-21]) with a detection limit of 0.6 pM. Moreover, a paper assay was carried out on a Y-shaped paper-based microfluidic device in order to use the distinctive features of micro-channels such as short response time, very low reagent volume, low fabrication cost, etc. After performing paper based assay, a good linear range was observed between 10-1000 pM (y = 0.06x+147.48, R2 = 0.99; x = [miRNA-21]) with detection limit of 4.1 pM. The practical application of proposed method for detection of miRNA-21 in real sample was assayed in the human urine sample and indicated the colorimetric method had acceptable accuracy.

In this work, an environmental friendly RC/N-TiO2 nanocomposite thin film was designed as a green portable photocatalyst by utilizing recycled newspaper as sustainable cellulose resource. Investigations on the influence of N-doped TiO2 nanorods incorporation on the structural and morphological properties of RC/N-TiO2 nanocomposite thin film are presented. The resulting nanocomposite thin film was characterized by FESEM, AFM, FTIR, UV-vis-NIR spectroscopy, and XPS analysis. The results suggested that there was a remarkable compatibility between cellulose and N-doped TiO2 nanorods anchored onto the surface of the RC/N-TiO2 nanocomposite thin film. Under UV and visible irradiation, the RC/N-TiO2 nanocomposite thin film showed remarkable photocatalytic activity for the degradation of methylene blue solution with degradation percentage of 96% and 78.8%, respectively. It is crucial to note that the resulting portable photocatalyst produced via an environmental and green technique in its fabrication process has good potential in the field of water and wastewater treatment application.

A laminated paper-based analytical device (LPAD) combined with gold nanoparticles (AuNPs) catalyzed luminol chemiluminescence (CL) system for the determination of l -cysteine ( l -cys) was presented here. It is based on the principle that l -cys can greatly inhibit CL signal of AuNPs–luminol–H 2 O 2 system. The paper-based device was fabricated by a low-cost cutting method, followed by lamination with two polyester films. This approach of cutting/lamination to fabricate LPAD is very similar to making a lamination picture. A good linear relationship was obtained between the CL intensity and the concentrations of l -cys in the range from 1.0×10 −8 M to 1.0×10 −6 M with a detection limit at 8.2×10 −10 M ( S / N =3). This study shows the successful integration of the LPAD and the CL method. It will be of interest for use in areas such as disease diagnosis in the future.

Fibre crosslinking with polycarboxylic acids can be used to improve certain properties of paper products, including wet tensile and compressive strength. In the present work it was proposed that citric acid (CA) crosslinks the cellulosic fibres of linerboard by self-catalysed esterification of cellulosic hydroxyl groups, which makes an additional catalyst unnecessary. An increase in CA dose or curing temperature increased linerboard compressive strength. In CA-treated corrugated board most of the applied CA was esterified with fibres while some CA thermolysis products were also present. A significant portion of the applied CA was unaccounted for. The deficit was attributed to thermolysis to give volatile anhydrides of unsaturated acids. Under cyclic humidity and static compressive loading, CA-treated corrugated boxes showed a greater than three-fold increase in resistance to compressive creep, showing that CA treatment can be used to extend the lifetime of corrugated boxes used for horticultural produce storage.

In this work, a double-layered three-dimensional (3D) microfluidic paper-based analytical device (μPAD) with high resolution temporally resolved chemiluminescence (CL) emissions were designed for multiplexed CL analysis. The temporally resolved CL emissions were obtained by virtue of the 3D branched microfluidic channel design, which create time delays for luminol transported from one detection zone to another. The peak intensity and peak shape of the temporally resolved CL emissions were quite stable and base-line separated with resolution as high as 21.2–24.4. Then, the fabricated μPAD was applied to multiplexed determination of glucose, lactate, cholesterol, and choline as model analytes. The sample was added to four detection zone modified with CL catalyst cobalt ion and different oxidase by virtue of chitosan. When luminol flowed to μPAD, four temporally resolved CL peaks were successively generated from the cobalt ion catalyzed CL reactions between luminol and generated H2O2 from the specific enzymatic reactions between the oxidase and the analytes. The generated four CL emission peaks in the CL kinetic curve increased in proportion to the concentrations of glucose, lactate, cholesterol, and choline, respectively. Finally, four linear calibration curves were obtained for the detection of glucose (0.01–1.0 mmol/L), lactate (0.02–5.0 mmol/L), cholesterol (0.01–0.4 mmol/L), and choline (0.001–1.0 mmol/L). The detection limits were as low as 8 μmol/L, 15 μmol/L, 6 μmol/L, and 0.07 μmol/L for glucose, lactate, choline, and cholesterol detection, respectively. The present work provides a new strategy for the fabrication of simple and sensitive 3D μPAD with high resolution temporally resolved CL emissions for multiplexed CL analysis, which holds great application potential for point-of-care diagnosis.

This study is focused on defunctionalizing monomeric phenolics from lignin into simple phenols for applications such as phenol/formaldehyde resins, epoxidized novolacs, adhesives and binders. Towards this goal, Titanium dioxide (TiO2) was used to selectively remove hydroxyl, methoxy, carbonyl and carboxyl functionalities from the monomeric phenolic compounds from lignin to produce mainly phenol, cresols and xylenols. The results showed that anatase TiO2 was more selective and active compared to rutile TiO2. Catechols were found to be the most reactive phenolics and 4-ethylguaiacol the least reactive with anatase TiO2. An overall conversion of about 87% of the phenolics was achieved at 550°C with a catalyst-to-feed ratio of 5 w/w. Over 97% conversion of phenolics is achievable at moderate temperatures (550°C or ≤ 600°C) and a moderate catalyst-to-feed ratio of 6.5:1. The reactivity of catechols on TiO2 suggests that titania is a promising catalyst in the removal of hydroxyl moiety.

Laboratory studies were conducted to find out the efficacy of uniquely prepared zero valent iron impregnated silica in transforming xenobiotic chlorophenols namely 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol. Continuous mode column experiments were performed to investigate the transformation of chlorophenols by varying pH, column height, flow rate and initial chlorophenol concentration. Reusability study of the zero valent iron impregnated silica was studied as well as the morphological changes and the chemical composition of the catalyst medium were also investigated. Dechlorination kinetic studies were conducted and the order of dechlorination of chlorophenols was found to be 2,4,6-trichlorophenol > 2,4-dichlorophenol > 4-chlorophenol. The optimum pH, column height and flow rate were found to be 7, 20 cm and 0.75 L/hr respectively for all chlorophenols in the reaction duration of 4 hr. Intermediates formed during dechlorination study were identified by gas chromatography-mass spectroscopy analysis. This method was applied to real pulp and paper wastewater and was found satisfactory.

This work seeks the integral use of all major components of Hesperaloe funifera , separating hemicelluose by hydrothermal treatments; cellulose by pulping processes; and exploitation of lignin of pulping liquor by pyrolysis and gasification processes. By using sulfuric acid in the hydrothermal treatment (150–190 °C, 0–20 min after reaching operating temperature, 6–10 liquid/solid ratio, 0.1–0.5% sulfuric acid), the glucose and xylose of liquid fraction increase from 1.5% to 5.9%, and 4.0% to 12.4%, respectively; the yields of solid fraction decrease from 91.6% to 79.5%, and the lignin content increase from 23% to 32%. Pulps and paper sheets obtained from solid fractions hydrothermal treatments and from raw material pulped with diethanolamine, are worse than those obtained with soda–anthraquinone (Yield 57.8%; kappa number 24.9; Viscosity 711 mL/g; Brightness 54.8%; Tensile index 73.6 Nm/g; Stretch 2.84%; Burst index 6.13 kN/g and Tear index 1.69 mNm 2 /g). By acidification (pH 6) of soda pulping liquor it separate lignin-rich solids, which by pyrolysis gave a gas containing 1.13% H 2 , 31.79% CO and 1.86% CH 4 by weight. Gasification of the same sample provided a gas containing 0.18% H 2 , 24.50% CO and 17.75% CH 4 .

The re-oxidation capacity of partially reduced heptamolybdo-pentavanado-phosphate polyanion (HPA� 5red or heteropoly blue) by ozone in water and aqueous acetone solution has been examined under conditions simulating pulp bleaching process. Two oxidation stages/phases were revealed indicating the presence of two reactive states (forms) of catalyst in ozonation solution. The bulk of HPA� 5red (ca. 90%) was completely recovered within a few first minutes of ozonation ([HPA]red = 0.5 mM; 0.39 mmol O3/min), whereas residual catalyst portion reacted very slowly (two orders lower rate) with ozone. Addition of organic solvent was shown to have a favorable effect on HPA� 5red re-oxidation by ozone (k of 0.29 min � 1 vs. 0.43 min � 1 for ozonation, respectively, in water and 10% v/v acetone solution; pH 2), being evidently the principal reason for high efficiency of solvent-assisted HPA/O3 pulp bleaching approach. The pH of reaction media (medium acidity) was found to have a notable effect on HPA� 5red ozonation. 2010 Elsevier Ltd. All rights reserved.

The present work demonstrated that secondary pulp/paper sludge powder, with a higher heating value of 18.3MJ/kg on a dry basis, could be effectively converted into liquid oil products by direct liquefaction in hot-compressed water with and without catalyst. Treatments of secondary pulp/paper sludge in water at 250-380 degrees C for 15-120min in the presence of N(2) atmosphere resulted in yields of water-soluble oils at 20-45wt% and yields of heavy oils at 15-25wt%, with higher heating values of 10-15 and35MJ/kg, respectively. The higher caloric values for the heavy oil products were accounted for by their compositions of long-chain carboxylic acids, heterocyclic nitrogen compounds and phenolic compounds and derivatives as evidenced by the gas chromatograph (GC)/MS measurements. The liquefaction product yields were significantly influenced by the liquefaction temperature, the residence time, the initial biomass concentration, catalysts and the liquefaction atmosphere (inert or reducing). Within the temperature range (250-380 degrees C) tested, the lowest temperature produced the highest yield of total oils (at 60wt%), while the greatest yield of heavy oil (at about 24wt%) was obtained at 350 degrees C. If the temperature was fixed at 280 degrees C, a greater yield of heavy oil (reaching as high as 25wt% for 120min) was obtained as the length of reaction time increased. Similarly, a higher initial biomass concentration produced a greater yield of heavy oil but a reduced yield of water-soluble oil. The presence of 0.1M K(2)CO(3) dramatically enhanced organic conversion, but suppressed the formation of both heavy oil and water-soluble oil. The use of the two alkaline earth metal catalysts, i.e., Ca(OH)(2) and Ba(OH)(2), did not alter organic conversion, but it catalyzed the formation of water-soluble oil and produced higher yields of total oil products. It was also demonstrated that the reducing atmosphere (i.e., H(2)) in the liquefaction process promoted the heavy oil formation while suppressing the water-soluble oil formation. With the presence of 0.1M Ca(OH)(2) and 2MPa H(2), liquefaction of the sludge powder in water at 280 degrees C for 60min produced a higher yield of heavy oil (26wt%), almost two times as high as that in N(2) (13.6wt%), resulting in a greater net energy efficiency. It was thus suggested that direct liquefaction of secondary pulp/paper sludge in hot-compressed water with Ca(OH)(2) catalyst and in the presence of H(2) could be an effective approach to recovering energy from the waste for production of liquid oil products.

Reactive black 5 (RB5), an azo dye, was degraded by using UV-irradiated TiO 2 coated on non woven paper with SiO 2 as a binder. The adsorption capacity of the photocatalyst was studied at natural pH, superior to pH pzc of the binder, for various ionic strengths. Different salts such as NaCl, KCl, CaCl 2 , LiCl, Ca(NO 3 ) 2 were used to increase the ionic strength. The presence of salt increased the adsorption capacity. The electrostatic interactions between dye and oxide surface charges (TiO 2 /SiO 2 ) is very important in the adsorption phenomena. The effect of the ionic strength of the solution on photocatalyst degradation was studied. The rate of degradation was increased by the presence of salts in the range of the experimental conditions. The increase of the initial decolorization rate was observed in the following order: Ca 2+ > K + > Na + > Li + . Experiments with different anions (Cl − , NO 3 − ) had shown that nitrate was an indifferent electrolyte for the adsorption and photodegradation of the dye on SiO 2 /TiO 2 .

Pulp and paper mill wastewater is characterized by very high chemical oxygen demand (COD) values that inhibit the activity of microorganisms during biological oxidations. The electrochemical degradation of pulp and paper mill wastewater catalyzed by molybdenum and phosphate (Mo–P) modified kaolin with graphite as anode and cathode was investigated. The catalyst was characterized by XRD, XPS and SEM spectra and the effects of pH, metal ion and introduction of NaCl on the efficiency of the electrochemical degradation process were also studied. It was found out that the modified kaolin loaded with Fe 3+ had higher electrochemical catalytic activity in the electrochemical degradation of paper mill wastewater at pH 4. A 96% COD removal efficiency was obtained in 40 min of electrochemical treatment of the wastewater at current density 30 mA cm −2 . A possible mechanism for degradation of the mill wastewater constituents was also proposed.

The electrochemical oxidation of pulp and paper making wastewater assisted by transition metal (Co, Cu) modified kaolin in a 200 ml electrolytic batch reactor with graphite plate as electrodes was investigated. H(2)O(2), which produced on the surface of porous graphite cathode, would react with the catalysts to form strong oxidant (hydroxyl radicals) that can in turn destroy the pollutants adsorbed on the surface of kaolin. The transition metal (Co, Cu) modified kaolin was also characterized by XRD and SEM before and after the modification and the results showed that the transition metals were completely supported on kaolin and formed a porous structure with big BET surface. The mechanism was proposed on the basis of XPS analysis of the catalyst after the degradation process. Series of experiments were also done to prove the synergetic effect of the combined oxidation system and to find out the optimal operating parameters such as initial pH, current density and amount of catalyst. From the results it can be founded that when the initial pH was at 3, current density was 30 mA cm(-2); catalyst dose was 30 g dm(-3), COD (chemical oxygen demand) removal could reach up to 96.8% in 73 min.

Photocatalytic paper encompasses a range of materials based on paper and nonwoven fabrics which performs a function based on the light-activated catalytic activity of colloidal TiO(2). The literature describing photocatalytic paper is surveyed, including mechanisms, applications, limitations and future opportunities. The technology is in its infancy with less than 10 patents and as many scientific publications appearing over the last decade. The main applications described are the destruction of organic molecules (mineralization) and photo-disinfection (sterilization). These disclosures build upon a much larger literature describing photochemical properties of TiO(2) both supported on non-cellulose substrates or simply as suspended particles in water or air. Current photocatalytic paper developments include methods to fix TiO(2) to cellulose substrates to minimize photochemical damage to the paper. Another theme is the use of multiple approaches, such as zeolites, for enhanced mineralization, and metals, such as silver and copper, for enhanced photocatalytic disinfection.

The electrochemical oxidation of phenol in synthetic wastewater and paper mill wastewater catalyzed by metal ion supported on cation exchange resin in suspended bed electrolytic reactor with graphite electrode has been investigated. The catalyst was characterized by SEM and XPS spectra and the effects of pH, the different metal ion and NaCl on the efficiency of the electrochemical oxidation phenol process were also studied. It was found that the catalyst containing Fe3+ had the highest electrochemical catalytic activity for the electrochemical oxidation of phenol. When the initial concentration of phenol was 200 ppm, up to 90% chemical oxygen demand (COD) removal was obtained in 10 min. When the catalyst containing Fe3+ was used to the paper mill wastewater, it still showed high efficiency. The COD removal could get to 75% in 60 min.

A novel paper-based material containing titanium dioxide (TiO(2)) photocatalyst was successfully prepared by a papermaking technique with the internal addition of inorganic fibers on which TiO(2) particles were supported. Photodegradation performance of acetaldehyde gas, an indoor pollutant, and the durability of the TiO(2)-containing papers were investigated under UV irradiation. Ceramic fiber suspension and polydiallyldimethylammonium chloride as a cationic flocculant were mixed, followed by the addition of TiO(2) suspension and anionic polyacrylamide. Subsequently, the inorganic mixture was poured into a pulp suspension, and TiO(2) handsheets then prepared by a papermaking method. The tensile strength of TiO(2)-containing paper without a ceramic carrier decreased by more than 30% after 240-h UV irradiation (2 mW/cm(2)), although the strength of the TiO(2) sheet with ceramic fibers remained reasonably stable. The efficiency of acetaldehyde decomposition by the TiO(2) paper containing an inorganic carrier was nearly equal to that of the carrier-free TiO(2) paper. Scanning electron microscopic observation suggested that most TiO(2) particles were predominantly supported on the inorganic fiber matrix, and were mostly out of contact with organic pulp fibers. The TiO(2) paper with an inorganic carrier demonstrated both excellent photocatalytic performance and durability, which before had been mutually incompatible for organic materials containing TiO(2) photocatalyst. The two-stage mixing procedure for TiO(2) sheet-making is promising for the simple manufacture of high performance paper with photocatalytic ability.

Cellulose esters of both alkyl and aryl carboxylic acids have been prepared and tested as noncovalent adsorbents for enzymes. Phenoxyacetyl cellulose strongly bound all 10 of the enzymes tested. The bound enzymes, which were not desorbed by 1 m (NH4)2SO4 or moderate (25–50%) concentrations of nonaqueous solvents but which were at least partially desorbed by solutions containing nonionic detergents, usually exhibited nearly complete retention of catalytic activity. Other materials, paper, string, cotton, and glass beads, have been analogously derivatized with similar results. This simple and effective technique warrants consideration for applications in enzyme immobilization.

FDP aldolase has been purified and crystallized from the muscle of codfish. The specific activity of the codfish enzyme was found to be two-thirds that of rabbit muscle aldolase. Other catalytic properties, the molecular weight, and the carboxyl-terminal structure were similar to those of rabbit muscle aldolase. A tryptic peptide containing the Schiff base-forming lysine (1) has been isolated and its primary structure determined as: Ala-Leu-Ser-Asp-His-His-Val-Tyr-Leu-Gln-Gly-Thr-Leu-Leu-βGlys-Pro-Asn-Met-Val-Thr-Ala-Gly-His-Ser-CMCys-Ser-His-Lys. Extensive homology observed in this region of the aldolase molecules isolated from biologically divergent sources indicates the importance of this structure for catalysis of the aldolase reaction.