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The effects of paper waste (PW) ratio on biogas production by two-stage thermophilic anaerobic co-digestion (coAD) of food waste (FW) and PW, two main components of organic fraction of municipal solid waste, were evaluated in lab-scale continuously stirred tank systems with semi-continuous feeding. Four PW ratios (0, 20, 40, and 50%) were studied in the test. The experimental results showed the two-stage thermophilic coAD could operate stably after an adjustment period at all PW ratios. Although the increase of PW ratio decreased methane content, production and yield, reaction rates of four AD steps, it could increase the methane production of substrate when the FW was fixed. The pH, total volatile fatty acids, total alkalinity, and total ammonium of the sludge in the second stage of AD, also decreased with the increase of PW ratio in the test. The change of the substrate's organic composition, increase of carbohydrate and decrease of protein and lipid, were the main reason for the decrease of methane content, production and yield and changes of the second stage sludge characteristics. An apposite PW ratio (PW-20%) could enhance the degradation of matters (TS, VS and TCOD).

Currently, recycling and re-use of materials is extremely important due to the diminishing of natural resources. The objective of the European Union’s circular economy strategy is to increase recycling and the use of industrial waste materials and side streams as secondary raw materials. In this study, a chemical precipitation method to simultaneously remove ammonium nitrogen and phosphate from the liquid phase of anaerobic digestate using calcined paper mill sludge was studied. Papermill sludge is a waste material that forms in the paper-making process. In addition, commercial calcium oxide (CaO) was used as a reference precipitant. The suitability of the formed precipitate’s composition for recycled fertilizer use was also considered. The study results indicated that calcined paper mill sludge was as effective precipitant as commercial CaO in the removal of ammonium nitrogen and phosphate from the synthetic wastewater. In addition, the results indicated that calcined paper mill sludge removed efficiently phosphate from the liquid phase of anaerobic digestate, which led to the formation of hydroxyapatite, Ca5(PO4)3(OH). In this research we have shown, that calcined paper mill sludge can be used to produce recycled, slow-release, solid fertilizer. Another possible reaction, such as adsorption was also considered. peerReviewed

A planar solid-state ammonium-selective electrode, employing a composite mediator layer of graphite particles embedded in a polyvinyl butyral matrix on top of an inkjet-printed silver electrode, is presented in this paper. The effect of graphite powder mass fraction on the magnitude of the potentiometric response of the sensor was systematically verified using a batch-mode and a flow injection measurement setup. Under steady-state conditions, the paper electrode provided a Nernstian response of 57.30 mV/pNH4 over the concentration range of 10−5 M to 10−1 M with a detection limit of 4.8 × 10−6 M, while the analytical performance of the array in flow mode showed a narrower linear range (10−4 M to 10−1 M; 60.91 mV/pNH4 slope) with a LOD value of 5.6 × 10−5 M. The experimental results indicate that the prepared electrode exhibited high stability and fast response to different molar concentrations of ammonium chloride solutions. The pH-response of the paper NH4-ISE was also investigated, and the sensor remained stable in the pH range of 2.5–8.5. The potentiometric sensor presented here is simple, lightweight and inexpensive, with a potential application for in-situ analysis of environmental water samples.

Background This work investigated adsorption behaviors of NH4+ onto H2O2 modified paper waste sludge-derived hydrochar (HPSH). Methods Effect of various operational parameters, including modification ratio, solution pH, adsorbent dosage, initial NH4+ concentration and contact time on NH4+ adsorption was studied. Besides, the NH4+ adsorption isotherms, kinetics and thermodynamics at different operational temperatures were systematically investigated. The textural, morphology, crystalline structure and surface chemistry characteristics of hydrochars were analyzed. Specially, NH4+ adsorption mechanisms controlled by enriched oxygen-containing surface functional groups by treatment of H2O2 onto hydrochars were deeply discussed. Significant findings The results showed that the optimal treatment ratio between H2O2 and PPSH was 40. Characterization data indicated H2O2 modification increased the oxygen-containing functional groups on the hydrochar surface. The maximum adsorption capacity of HPSH-40 was 7.941 mg/g which was higher that of PPSH about double. NH4+ adsorption onto hydrochars was well described by the pseudo-second-order model and Langmuir isotherm. The thermodynamic studies showed NH4+ adsorption onto hydrochars was endothermic in nature. The mechanisms of NH4+ adsorption onto hydrochars included π-cation interaction, cation exchange, surface complexation and electrostatic attraction which were attributed to the vital role of enriched oxygen-containing surface functional groups on hydrochar's surface.

The electrochemical oxidation of paper mill wastewater belonging from Halfa industries (Tunisia) was performed by galvanostatic electrolysis using boron-doped diamond (BDD) anodes and Ti-Ru-Sn ternary oxide (TiRuSnO2). The effect of several operating parameters, such as applied current density, flow rate, temperature, initial pH value and addition of NaCl was evaluated. Chemical oxygen demand (COD) and ammonium measurements were carried out to study the treatment of the actual wastewater. The energy consumption analysis has been also discussed. The experimental results exhibited that galvanostatic electrolyses with BDD always allowed efficient COD removal in any conditions thanks to the reaction with hydroxyl radicals electrogenerated on BDD surface during electrolysis. On the contrary, using the TiRuSnO2 anode, the complete COD removal was only obtained in the presence of chloride ions. Comparison of the results of the two electrodes showed that BDD provided a faster removal with higher efficiency and lower energy consumption, while TiRuSnO2 was more efficient for ammonium removal.

Currently, recycling and re-use of materials is extremely important due to the diminishing of natural resources. The objective of the European Union’s circular economy strategy is to increase recycling and the use of industrial waste materials and side streams as secondary raw materials. In this study, a chemical precipitation method to simultaneously remove ammonium nitrogen and phosphate from the liquid phase of anaerobic digestate using calcined paper mill sludge was studied. Papermill sludge is a waste material that forms in the paper-making process. In addition, commercial calcium oxide (CaO) was used as a reference precipitant. The suitability of the formed precipitate’s composition for recycled fertilizer use was also considered. The study results indicated that calcined paper mill sludge was as effective precipitant as commercial CaO in the removal of ammonium nitrogen and phosphate from the synthetic wastewater. In addition, the results indicated that calcined paper mill sludge removed efficiently phosphate from the liquid phase of anaerobic digestate, which led to the formation of hydroxyapatite, Ca₅(PO₄4)₃(OH). In this research we have shown, that calcined paper mill sludge can be used to produce recycled, slow-release, solid fertilizer. Another possible reaction, such as adsorption was also considered.

Most of the on-site approaches for inferring of the post-mortem interval are still based on observative data from the direct body inspection, whereas, objective and quantitative analyses, such as potassium in the vitreous humor, are require laboratory instrumentation and skilled personnel. The present paper presents a simple and low cost analytical method suitable for use at the crime scene for inferring the time since death. The method uses a microfluidic paper-based device (μPAD) for the determination of ammonium in the vitreous humor (VH) based on the selective interaction between the ammonium and the Nessler's reagent. The color change was measured in terms of “RGB distance” by using a simple and free smartphone application. The optimized device showed a limit of detection of 0.4 mmol L−1, with between days precision less than 9.3% expressed as relative standard deviation, and accuracy between days from 94.5% to 104.5%. The selectivity of the Nessler's reaction was tested towards the main vitreous humor compounds, and no significant interferences were found. This paper-based analytical device was successfully used for the determination of ammonium ion in VH samples from forensic autopsies. The results obtained with the proposed method, although for a limited number of cases (n = 25), showed a close correlation with the data obtained with an instrumental analysis based on capillary electrophoresis. Moreover, in order to make the evaluation of results as simple as possible, a direct correlation between the color intensity, expressed as RGB distance, and the post-mortem interval was studied and a significant correlation was found (R2 > 0.78). In conclusion, the present preliminary study showes that the proposed device could be an additional tool to the traditional methods for a more accurate, although still presumptive, estimation of the time of death directly at the crime scene.

In this work, a granular activated carbon (GAC) was produced using primary paper mill sludge (PS) as raw material and ammonium lignosulfonate (AL) as binder agent. PS is a residue from the pulp and paper industry and AL is a by-product of the cellulose pulp manufacture and the proposed production scheme contributes for their valorisation together with important savings in GAC precursors. The produced GAC (named PSA-PA) and a commercially available GAC (GACN), used as reference material, were physically and chemically characterized. Then, these materials were tested in batch experiments for the adsorption of carbamazepine (CBZ), sulfamethoxazole (SMX), and paroxetine (PAR) from ultra-pure water and wastewater. Even though GACN and PSA-PA possess very similar specific surface areas (S) (629 and 671 m g, respectively), PSA-PA displayed lower maximum adsorption capacities (q) than GACN for the pharmaceuticals here studied (6 ± 1–44 ± 5 mg g and 49 ± 6–106 ± 40 mg g, respectively). This may be related to the comparatively higher incidence of mesopores in GACN, which might have positively influenced its adsorptive performance. Moreover, the highest hydrophobic character and degree of aromaticity of GACN could also have contributed to its adsorption capacity. On the other hand, the performance of both GACs was significantly affected by the matrix in the case of CBZ and SMX, with lower q in wastewater than in ultra-pure water. However, the adsorption of PAR was not affected by the matrix. Electrostatic interactions and pH effects might also have influenced the adsorption of the pharmaceutical compounds in wastewater., This work was funded by FEDER through Compete 2020 and by national funds through FCT by the research project PTDC/AAG-TEC/1762/2014. Vânia Calisto and Marta Otero also thank FCT for a postdoctoral grant (SFRH/BPD/78645/2011) and support by the FCT Investigator Program (IF/00314/2015), respectively. Thanks are also due for the financial support to CESAM (UID/AMB/50017-POCI-01-0145-FEDER-007638), to FCT/MEC through national funds, and the co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020

Fluorescent whitening agents (FWAs) are added to food packaging during manufacture to improve the whiteness and brightness. It is of great significance to develop a fast and sensitive FWAs detection method because their potential hazards to human health. Herein, we found that the quaternary ammonium salt ion pair reagents could enhance the fluorescence of FWAs, and then developed a fluorescent determination method for FWA 85 in paper food packaging. Under the optimized conditions, the linear range for the determination of FWA 85 was 5–200 ng/mL (R2 = 0.9996). The limit of detection was 1.20 ng/mL (S/N = 3) and the limit of quantitation was 3.99 ng/mL. The analytical feasibility was investigated further via determination of FWA 85 in paper food packing, which shows the recoveries were varied from 83.84% to 115.29% with RSDs from 1.64% to 7.22%. The method provides a new quaternary ammonium salt ion pair reagent sensitization for the detection of FWAs in paper food packaging.

An easy-to-use, portable 3D microfluidic paper-based analytical device (μPAD) for the determination of total ammonia (i.e., ammonia + ammonium) in freshwaters is described. It consists of two layers of paper patterned with hydrophilic circular zones, one impregnated with sodium hydroxide (sample zone) and another (detection zone) with an acid-base indicator (nitrazine yellow (NY) or bromothymol blue (BTB)), separated by a μ-distillation chamber. Ammonium ions present in the water sample are converted into ammonia gas by reaction with sodium hydroxide in the sample zone. Ammonia then diffuses through a headspace and reacts with an acid-base indicator in the detection zone, the reflectance of which can be related to the total ammonia concentration. The analytical signal at 7.8 mg L-1 offered by the μ-distillation chamber-based μPAD is more than double of that obtained using a gas-permeable membrane. The proposed μPAD is characterised by a limit of detection of 0.32 or 0.47 mg N L-1 and working concentration ranges of 0.5-3.0 mg N L-1 or 2.0-10 mg N L-1 when using NY or BTB indicators, respectively. This is the first μPAD whose working range covers almost the entire trigger value range (0.32-2.3 mg N L-1) for ammonia nitrogen in freshwater systems which makes it suitable as a field screening tool for ammonia in freshwaters. An inter- and intra-device repeatability of 7.6% and 9.0%, respectively, has been achieved for the NY-based μPAD (3 mg N L-1) and 13 and 2.5% (8 mg N L-1) for the BTB-based μPAD. The NY-based μPAD is stable under vacuum for at least 12 days at room temperature, and 56 days if stored in a freezer (≤-20 °C).

Previously (Glushakova et al. 2017), a cellulose-based cationic (Q) paper derivatized with quaternary ammonium groups was shown to be a convenient platform to collect, preserve, and store nucleic acids (NAs) derived from mosquito vectors infected with pathogens for surveillance. NAs bind electrostatically to Q-paper, but the quantity of NA bound depends on the paper’s binding capacity. To optimize the original technology for mosquito surveillance, factors that affected NA absorbance on Q-paper were evaluated. Sixteen variations of Q-paper were prepared with modifications of the derivatizing reagents and derivatization temperature. The binding capacities of these variations were determined first with 1,3,5-benzenetricarboxylic (BTCA), then viral RNA (purified or in infected mosquito samples) was used for validation. For this, samples with Zika (ZIKV) and chikungunya (CHIKV) RNA or virus-infected Aedes aegypti mosquito bodies were applied to sixteen Q-paper variants. Washing the paper samples with water versus elution with aqueous salt (1 M) gave samples that were analyzed for viral RNA by a PCR-based direct Luminex hybridization assay. The comparison ranked the Q-paper binding capacities from the lowest to the highest. The Q-paper with the highest RNA binding capability was further validated with ZIKV- and CHIKV-infected mosquito saliva.

Lignosulfonates are important by-products of the paper industry and may be transformed into different commodities. We studied the molecular properties of ammonium (LS-AM) and calcium Lignosulfonates (LS-C) and evaluated their bioactivity towards the early development of maize plantlets. The FT-IR, 13C NMR and 1H-13C-HSQC-NMR spectra showed that the two lignosulfonates varied in hydroxyl, sulfonate and phenolic content, while DOSY-NMR spectroscopy suggested a similar diffusivity. High Performance Size Exclusion Chromatography (HPSEC) was used to simulate the effects of root-exuded acids and describe the conformational dynamics of both LS substrates in acidic aqueous solutions. This technique showed that LS-C was stabilized by the divalent Ca2+ counterion, thus showing a greater conformational stability than LS-AM, whose components could not be as efficiently aggregated by the monovalent NH4+ counter-ion. The plant bioassays revealed that LS-AM enhanced the elongation of the root system, whereas LS-C significantly increased both total and shoot plant weights. We concluded that the lignosulfonate bioactivity on plant growth depended on the applied concentrations, their molecular properties and conformational stability.

The aim of the study was to grow microalgae on mixed municipal and industrial wastewater to simultaneously treat the wastewater and produce biomass and lipids. All algal strains grew in all wastewater mixtures; however, Selenastrum minutum had the highest biomass and lipids yields, up to 37% of the dry matter. Nitrogen and phosphorus removal were high and followed a similar trend in all three strains. Ammonium was reduced from 96% to 99%; this reduction was due to algal growth and not to stripping to the atmosphere, as confirmed by the amount of nitrogen in the dry algal biomass. Phosphate was reduced from 91% to 99%. In all strains used the lipid content was negatively correlated to the nitrogen concentration in the algal biomass. Mixtures of pulp and paper wastewater with municipal and dairy wastewater have great potential to grow algae for biomass and lipid production together with effective wastewater treatment.

To date there have been no reports of methods to determine Tinopal CBS-X. We developed a rapid and simple method to determine the Tinopal CBS-X content in rice noodles and rice papers using HPLC equipped with fluorescence detection. Heating the rice noodles and rice papers to 80°C after adding 75% methanol solution induced the release of Tinopal CBS-X from processed rice products. Tinopal CBS-X was separated using an isocratic mobile phase comprising 50% acetonitrile/water containing 0.4% tetrabutyl ammonium hydrogen sulphate at pH 8.0. The samples suspected to be positive by HPLC analysis were then confirmed by LC-MS/MS analysis. This study also investigated the Tinopal CBS-X content of three rice noodle products and two rice papers. The limits of quantification for rice papers and rice noodles were 1.58 and 1.51 µg kg(-1), respectively, and their correlation curves showed good linearity with r(2) ≥ 0.9997 and ≥ 0.9998, respectively. Moreover, rice papers had recoveries of 70.3-83.3% with precision ranging from 5.0% to 7.9%, whereas rice noodles had slightly lower recoveries of 63.4-78.7% and precisions of 8.5-11.5%. Only one rice noodle product contained Tinopal CBS-X, at around 2.1 mg kg(-1), whereas it was not detected in four other samples. Consequently, Tinopal CBS-X from rice noodles and rice papers can be successfully detected using the developed pre-treatment and ion-pairing HPLC system coupled with fluorescence detection.

This study reports a convenient and low cost paper-based analytical device (PAD) for measuring ammonium in soil. This PAD has been developed using an inexpensive UV resin solution, as a new hydrophobic material, with a screen-printing method to create hydrophobic areas. The paper-based colorimetric device was developed using a modified Berthelot reaction in which salicylate and dichloroisocyanurate are used in order to produce a green compound of 2-2 dicarboxyindophenol in the presence of ammonium. The concentration of ammonium is proportional to the intensity of the resulting green color, as analysed by ImageJ software. A variety of tests was carried out to optimize and evaluate various aspects of the PAD's fabrication and utilization. A linear range was obtained in the range of 10–100 mg L−1 with a limit of detection and limit of quantitation of 0.5 mg L−1 and 1.7 mg L−1, respectively. The relative standard deviation of intra-day measurements was 3.0% and the inter-day precision was 3.2% with good reproducibility. When recovery of ammonium added to samples was evaluated it ranged from 95.5 to 107.5%. The PAD was applied to detect ammonium in a variety of actual soil samples, and the results were validated against spectrophotometric results using a paired t-test, showing good accuracy. A convenient color comparison chart was also created on paper to enable the user to interpret the color results without the need for a color scanner. This developed PAD is fast, easy, inexpensive, and provides an alternative to existing methods for the determination of ammonium in soil.

The purpose of this study is to find the optimum conditions, including the type and concentration of solvent, and the solid/liquid ratio, for the extraction of calcium from Paper Sludge Ash (PSA). Solvents with different properties are divided into the following three groups to conduct the calcium extraction experiments: acid (acetic acid and hydrochloric acid), ammonium salt (ammonium chloride and ammonium acetate), and other (sodium citrate and water). The maximum efficiency of calcium extraction using acid is 54% at a concentration of 0.7 M and solid/liquid ratio of 1:25, while ammonium salt and sodium citrate extract calcium up to 30% and 28%, respectively, at a concentration of 0.3 M and solid/liquid ratio of 1:50.

Methanol-oxidizing bacteria may play an important role in the development and use of biological treatment systems for the removal of methanol from industrial effluents. Optimization of methanol degradation potential in such systems is contingent on availability of nutrients, such as nitrogen, in the most favorable form and concentration. To that end, this study examined the variation in growth, methanol degradation, and bacterial diversity of two mixed methylotrophic cultures that were provided nitrogen either as ammonium or nitrate and in three different concentrations. Methanol-degrading cultures were enriched from biofilms sampled at a pulp and paper mill and grown in liquid batch culture with methanol as the only carbon source and either ammonium or nitrate as the only added nitrogen source. Results indicate that growth and methanol removal of the mixed cultures increase directly with increased nitrogen, added in either form. However, methanol removal and bacterial diversity, as observed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) methods, were higher when using nitrate as the nitrogen source for enrichment and growth, rather than ammonium. Based on results described here, nitrate may potentially be a better nitrogen source when enriching or working with mixed methylotrophic cultures, and possibly more effective when used as a nutrient addition to biofilters.

Iron oxide–coated filter paper (Pi) can estimate labile phosphorus (P) in soil by acting as a P sink. The mechanism of Pi extraction may be more analogous to P sorption by plants than extraction with chemical extractants. The objective of this work was to compare strips of paper prepared by the Chardon method with Olsen, ammonium bicarbonate–diethylenetriaminepentaacetic acid (AB‐DTPA), Bray 1, and Mehlich 1 methods in determining available P in alfalfa (Medicago Sativa) and surface samples of 15 soils of the Hamadan province, western Iran. A pot experiment was carried out in a randomized block design with two P levels (0 and 200 mg P kg−1) and three replications. Plants were harvested in three cuttings in a period of 25 weeks and were used to measure plant‐available soil P. The following soil tests for P had increasingly higher average amounts of P: paper strips, Bray 1, Olsen, AB‐DTPA, and Mehlich 1. The P extracted by paper strips was significantly correlated with P extracted by Olsen and AB‐DTPA. In t...

Amylose inclusion complexes were prepared from high amylose cornstarch and hexadecyl- and octadecylammonium chloride. The complexes were applied to paper at concentrations of 2–4%. After drying the papers, a sodium hydroxide solution was applied to convert the complexes to the insoluble amine form, rendering the paper hydrophobic. SEM showed that the complexes were uniformly deposited onto the paper with no visible particles. Increased resistance of papers to water penetration was indicated by an increase in the contact angles of water droplets from not measurable to as much as 113°, and by longer times for total absorption of the droplets. Treated papers also absorbed less water than untreated papers, with the C16 amylose-hexadecylammonium chloride complex providing the greatest water resistance (81.2% less water absorbed than untreated paper). Unlike other technologies widely used for rendering paper hydrophobic, the materials used for this novel method are water soluble, non-toxic, biobased, and biodegradable.

In the field of forensic science, the investigation of soil for the determination of decomposition by geophysical, biological and chemical methods, is a fast growing area. During decomposition different substances are formed as a result of breakdown and dissolution. The analysis of ninhydrin reactive nitrogen (NRN: ammonium and organic amines) is helpful in the investigation of the decomposition process, because such products may result from degradation of proteins and amino acids. During this research a new application form of the well known ninhydrin reagent was developed and applied to soil and gravesoil.

This work studied to use paper waste sludge for hydrochar production by hydrothermal carbonization with supporting NaOH solution at carbonization temperature of 200 °C for ammonium adsorption. The obtained original hydrochar was then modified with FeCl3 to enhance the ammonium adsorption capacity. The batch adsorption experiments were conducted to test the effects of solution pH, contact time and initial ammonium concentration. The properties of original paper waste sludge hydrochar (OPSH) and iron modified paper waste sludge hydrochar (FPSH) were investigated using scanning electron microscopy (SEM, EDS), Powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results show that iron ions were successfully loaded on the OPSH with the most optimum adsorption capacity of ammonium at iron impregnation ratio of 10%(w/w). The results illustrate that the suitable conditions for ammonium adsorption were pH of 9, 120 min of contact time and an initial ammonium concentration of 80 mg/L. The highest adsorption capacities were 8.62 mg/g and 11.55 mg/g for OPSH and FPSH-10, respectively. The experimental data was fitted well by Langmuir, Sips models and the pseudo-second-order model with the R2 of 0.9797 and 0.9946 (Langmuir model), 0.9926 and 0.9958 (Sips model) for OPSH and FPSH, respectively. In addition, the R2 of the pseudo-second-order model were 0.9943 and 0.9881 for OPSH and FPSH, respectively. The adsorption process was controlled by monolayer chemisorption mechanism through cation exchange, surface complexation and electrostatic attraction.

Al-containing CaO-SiO(2)-H(2)O phases were prepared by hydrothermal treatment of mixtures of paper sludge ash (PSA) with various silica and calcia sources and their properties were determined with particular reference to the simultaneous uptake of ammonium and phosphate ions, which are implicated in the eutrophication of lakes and ponds. After examination of various silica and calcia sources, Ca(OH)(2) and SiO(2) sol were selected as the most appropriate starting materials. Dry milling was found to be superior to wet milling in avoiding contamination from the milling media during mixing. Nine samples with three different Ca/Si ratios and Al(2)O(3) contents were prepared with various mass ratios of Ca(OH)(2), PSA and SiO(2). The chemical compositions of the hydrothermal products of these mixtures moved towards the tieline of CaSiO(3)-PSA, with respect to the starting compositions. The major phase formed in all samples was poorly crystalline C-S-H(I), with hydroxysodalite also formed in the Al-containing mixtures. All the products showed a capacity for the simultaneous uptake of ammonium and phosphate ions. The saturated sorption capacities calculated from the Langmuir equation ranged from 0.9 to 2.4mmol/g for the ammonium ion and from 3.3 to 5.2mmol/g for the phosphate ion. Since the sorption capacities for both ions increased with increasing Ca contents of the product, substitution of Ca(2+) for NH(4)(+) and the formation of calcium phosphate phases such as apatite and brushite by precipitation are thought to be the main sorption mechanisms.

A novel, highly selective and sensitive paper-based colorimetric sensor for trace determination of copper (Cu(2+)) ions was developed. The measurement is based on the catalytic etching of silver nanoplates (AgNPls) by thiosulfate (S2O3(2-)). Upon the addition of Cu(2+) to the ammonium buffer at pH 11, the absorption peak intensity of AuNPls/S2O3(2-) at 522 nm decreased and the pinkish violet AuNPls became clear in color as visible to the naked eye. This assay provides highly sensitive and selective detection of Cu(2+) over other metal ions (K(+), Cr(3+), Cd(2+), Zn(2+), As(3+), Mn(2+), Co(2+), Pb(2+), Al(3+), Ni(2+), Fe(3+), Mg(2+), Hg(2+) and Bi(3+)). A paper-based colorimetric sensor was then developed for the simple and rapid determination of Cu(2+) using the catalytic etching of AgNPls. Under optimized conditions, the modified AgNPls coated at the test zone of the devices immediately changes in color in the presence of Cu(2+). The limit of detection (LOD) was found to be 1.0 ng mL(-1) by visual detection. For semi-quantitative measurement with image processing, the method detected Cu(2+) in the range of 0.5-200 ng mL(-1)(R(2)=0.9974) with an LOD of 0.3 ng mL(-1). The proposed method was successfully applied to detect Cu(2+) in the wide range of real samples including water, food, and blood. The results were in good agreement according to a paired t-test with results from inductively coupled plasma-optical emission spectrometry (ICP-OES).

A series of 2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) was prepared by the reaction of chitosan with glycidyl trimethyl ammonium chloride. Structure of HACC was characterized by FT IR and 1H NMR spectroscopies, and it was proved that substitution reaction mainly occurs on the N element. Antimicrobial activities of HACC was examined against S. aureus, E. coli, and A. niger. Results indicatd that the inhibitory effects of HACC solutions were varied with HACC concentration, quaternization degrees, pH values, metal ions, and heat treatment. The antimicrobial properties of handsheets prepared from HACC were studied by the inhibition zone method, and the sheets had good antimicrobial properties against S. aureus and E. coli, and low inhibition rate against A. niger.

The effects of different nitrogen sources and levels of application on the physical and histological properties, and on resultant values relevant to pulp and paper production, Gmelina arborea seedlings on latosolic soil were investigated. The nitrogen sources were: nitrate-nitrogen (NO 3 N) supplied as potassium nitrate (KNO 3 ), ammonium-nitrogen (NH 4 N) given as ammonium sulphate (NH 4 ) 2 SO 4 , ammonium nitrate-nitrogen (NH 4 NO 3 N) applied as calcium ammonium nitrate (CaNH 4 (NO 3 ) 2 ) and urea-nitrogen (urea-N) fed as compound urea. The levels of application were 0.0, 2.5, 5.0 and 7.5 g N per plant. The control treatment received no form of nitrogen fertilizer. All the nitrogen sources improved the specific gravity of gmelina wood on latosolic soil. The longest fibre cells were produced with NO 3 N and the shortest with NH 4 N. Urea-N produced the narrowest fibre cells while NH 4 N produced the widest fibres with the thickest walls. The coefficient of suppleness was not affected by the nitrogen sources. In relation to the control trees, urea-N and NO 3 N sources produced a significantly higher slenderness ratio. Runkel ratios obtained with the various nitrogen sources were homogeneous. In nearly all the parameters measured, the optimal values were recorded with the first level of nitrogen application (2.5 g N per plant). The implications of the findings on pulp and paper production using G. arborea grown on latosolic soil are discussed.

Microbial xylanases that are thermostable, active at alkaline pH and cellulase-free are generally preferred for biobleaching of paper pulp. We screened obligate and facultative marine fungi for xylanase activity with these desirable traits. Several fungal isolates obtained from marine habitats showed alkaline xylanase activity. The crude enzyme from NIOCC isolate 3 (Aspergillus niger), with high xylanase activity, cellulase-free and unique properties containing 580 U l(-1) xylanase, could bring about bleaching of sugarcane bagasse pulp by a 60 min treatment at 55 degrees C, resulting in a decrease of ten kappa numbers and a 30% reduction in consumption of chlorine during bleaching. The culture filtrate showed peaks of xylanase activity at pH 3.5 and pH 8.5. When assayed at pH 3.5, optimum activity was detected at 50 degrees C, with a second peak of activity at 90 degrees C. When assayed at pH 8.5, optimum activity was seen at 80 degrees C. The crude enzyme was thermostable at 55 degrees C for at least 4 h and retained about 60% activity. Gel filtration of the 50-80% ammonium sulphate-precipitated fraction of the crude culture filtrate separated into two peaks of xylanase with specific activities of 393 and 2,457 U (mg protein)(-1). The two peaks showing xylanase activity had molecular masses of 13 and 18 kDa. Zymogram analysis of xylanase of crude culture filtrate as well as the 50-80% ammonium sulphate-precipitated fraction showed two distinct xylanase activity bands on native PAGE. The crude culture filtrate also showed moderate activities of beta-xylosidase and alpha- l-arabinofuranosidase, which could act synergistically with xylanase in attacking xylan. This is the first report showing the potential application of crude culture filtrate of a marine fungal isolate possessing thermostable, cellulase-free alkaline xylanase activity in biobleaching of paper pulp.

Oxidative processes lead to enhanced degradation of cellulose in alkaline environment, especially in the presence of transition metals, such as iron and copper. Considerable parts of collections of manuscripts, drawings, maps and archival materials throughout the world are seriously damaged as the result of the use of iron gall inks and copper based pigments. The research on cellulose degradation and stabilization in the presence of transition metals is therefore crucial for the development of paper stabilization methods. The aim of this study was to evaluate the possibility of slowing down oxidative degradation of papers containing transition metals by their contact with paper folders containing antioxidant. The paper discusses the degradation rate constants of paper samples with elevated amounts of copper and iron ions and their mixtures during accelerated thermal ageing in contact with papers containing none or various amounts of quaternary ammonium salt. Their efficiency in respect to concentration of the antioxidants is presented. The research demonstrates that effective stabilization of paper samples with higher amounts of iron and copper ions in mildly alkaline environment by interleaving with papers, impregnated with antioxidant tetrabutylammonium bromide can be achieved under given conditions. Simple conservation procedure was proposed and evaluated for iron gall ink containing paper samples.

Quaternary ammonium cationic surfactants have very important application in the papermaking industry, which is a series of important paper softening agents. In order to obtain an environment-friendly paper softening agent, a novel diester gemini quaternary ammonium salt cationic surfactant has been prepared. Dodecyldimethyl amine, epichlorohydrin and adipic acid were used as raw materials to synthesize the surfactant, and Fourier transform infrared spectroscopy was used to characterize the groups in reaction product. Moreover, the softening effect of the diester gemini quaternary ammonium salt cationic surfactant was studied in detail.

Handmade mulberry paper was coated with flame retardants reagent: ammonium sulphate, at the various concentrations. The properties of mulberry paper, i.e. rate of water absorption, rate of flammability, flash point and mechanical properties expressed as Young’s modulus were studied. Mulberry paper coated with sulphate-based compound was not flammable and the rate of water absorption was decreased, while the elasticity was increased.

In 2001–2007 aerosols were measured in the coastal zone (11 campaigns) and over the open waters of the Gdansk Basin (southern Baltic) (5 campaigns). The marine aerosols contained nitrogen and sulphur compounds, which increased their acidity. This situation intensified during the cool months of the year, when fossil fuel emissions were higher, proportionate to energy and heat requirements. Irrespective of the season, these acidic aerosols were neutralized in the reaction with sea salt. The likelihood of sodium nitrate being formed increased at air humidities > 80% and nitrate concentrations > 30 nmol m− 3. Sodium sulphate was present in aerosols mostly in autumn and winter, with northerly advection, and at the highest wind speeds. The excess of free ammonia resulted in the formation of ammonium sulphate and ammonium nitrate in aerosols over the southern Baltic.