Chemical fractionation method for characterization of biomass-based bottom and fly ash fractions from large-sized power plant of an integrated pulp and paper mill complex

The aim of this study was to extract the biomass-based bottom and fly ash fractions by a three-stage fractionation method for water-soluble （H2O）, ammonium-acetate （CH3COONH4） and hydrochloric acid （HCl） fractions in order to access the leaching behaviour of these residues. Except for Mo, S, Na and elements whose concentrations were lower than the detection limits, the extractable element concentrations in both ash fractions followed the order H2O＆lt;CH3COONH4＆lt;HCl. The elements concentrations in this study were also lower than those in our previous studies, in which certain extraction stages followed the BCR extraction procedure.

Biosorption of Ni(Ⅱ) ions from aqueous solution using modified Aloe barbadensis Miller leaf powder

This study aimed to investigate the biosorption potential of Na2CO3-modified Aloe barbadensis Miller (Aloe vera) leaf (MABL) powder for removal of Ni(II) ions from a synthetic aqueous solution. Effects of various process parameters (pH, equilibrium time, and temperature) were investigated in order to optimize the biosorptive removal. The maximum biosorption capacity of MABL was observed to be 28.986 mg/g at a temperature of 303 K, a biosorbent dose of 0.6 g, a contact time of 90 min, and a pH value of 7. Different kinetic models (the pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models) were evaluated. The pseudo-second-order kinetic model was found to be the best fitted model in this study, with a coefficient of determination of R^2 =0.974. Five different isotherm models (the Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, and Brunauer-Emmett-Teller (BET) models) were investigated to identify the best-suited isotherm model for the present system. Based on the minimum chi-square value (X^2 =0.027) and the maximum coefficient of determination (R^2 =0.996), the Langmuir isotherm model was found to represent the system well, indicating the possibility of monolayer biosorption. The sticking probability (S*) was found to be 0.41, suggesting a physisorption mechanism for biosorption of Ni(II) on MABL. The biosorbent was characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), zeta potential, and BET surface area, in order to understand its morphological and functional characteristics.

Acclimatization of microalgae Arthrospira platensis for treatment of heavy metals in Yamuna River

Bioaccumulation and biosorption in microalgae are effective approaches for the removal of heavy metals(HMs)from river water.The objective of this study was to investigate the potential for use of acclimatized microalgae in the removal of HMs from the Yamuna River water as an acclimatizing medium.An active culture of Arthrospira platensis(A.platensis)was acclimatized to HMs up to a concentration of 100 mg/L.It was gradually exposed to increasing concentrations of HMs in five subsequent batches with a step increase of 20 mg/L to acclimatize live cells in the simulated Yamuna River water.The presence of high levels of HMs in the Yamuna River water caused growth inhibition.An empirical growth inhibition model was developed,and it predicted high threshold concentrations of HMs(210.7e424.5 mg/L),producing a positive specific growth rate of A.platensis.A.platensis also showed high average removal efficiencies of HMs,including 74.0%for Cu,77.0%for Cd,50.5%for Ni,76.0%for Cr,76.5%for Pb,and 63.5%for Co,from HMs-enriched Yamuna River water.The findings demonstrated that the maximum specific removal amounts of Cu,Cd,Ni,Cr,Pb,and Co were 54.0,58.0,39.0,62.8,58.9,and 45.3 mg/g,respectively.The maximum yields of the value-added products chlorophyll and phycocyanin were 2.5 mg/g(in a batch of 40 mg/L for Cd)and 1054 mg/g(in a batch of 20 mg/L for Cu),respectively.Therefore,acclimatized A.platensis was proven to be a potential microalga not only for sequestration of HMs but also for production of valuable pigments.

Cellulose structure and lignin distribution in normal and compression wood of the Maidenhair tree(Ginkgo biloba L.)

We studied in detail the mean micro fibril angle and the width of cellulose crystals from the pith to the bark of a 15-year-old Maidenhair tree（Ginkgo biloba L.）. The orientation of cellulose micro fibrils with respect to the cell axis and the width and length of cellulose crystallites were determined using Xray diffraction. Raman microscopy was used to compare the lignin distribution in the cell wall of normal/opposite and compression wood, which was found near the pith. Ginkgo biloba showed a relatively large mean micro fibril angle,varying between 19° and 39° in the S2 layer, and the average width of cellulose crystallites was 3.1–3.2 nm. Mild compression wood without any intercellular spaces or helical cavities was observed near the pith. Slit-like bordered pit openings and a heavily lignified S2 L layer con firmed the presence of compression wood. Ginkgo biloba showed typical features present in the juvenile wood of conifers. The micro fibril angle remained large over the 14 annual rings. The entire stem disc,with a diameter of 18 cm, was considered to consist of juvenile wood. The properties of juvenile and compression wood as well as the cellulose orientation and crystalline width indicate that the wood formation of G. biloba is similar to that of modern conifers.

A novel trajectory-based online controller design approach to fault accommodation in NREL’s 5MW wind turbine systems

This paper presents a real-time mechanism to tolerate faults occurring in a wind turbine （WT） system. This system is composed of a FAST coded simulator designed by the U.S. National Renewable Energy Laboratory. The demonstrated mechanism lies under the taxonomy of active fault-tolerant control （FTC） systems, namely online redesign based approach. In the proposed approach, we do not use any a priori information about the model of the turbine in real-time. In fact, we use online measurements generated by the WT. Based on the given control specifications, and the observed measurement an occurred fault is accommodated by reconfiguring the online controller such that the WT generates rated power even under faulty conditions. Second, no explicit fault diagnosis （FD） module is used in this approach. As a result, issues of model uncertainty, false alarms, etc. associated with an integrated FD and controller reconfiguration approach to FTC systems are not experienced here.

Single-walled carbon nanotube networks for ethanol vapor sensing applications

Networks of pristine high quality single walled carbon nanotubes （SWNTs）, the SWNTs after Ar-plasma treatment （from 2 to 12 rain） and carbon nanobuds （CNBs） have been tested for ethanol vapor sensing. It was found that the pristine high quality SWNTs do not exhibit any ethanol sensitivity, while the introduction of defects in the tubes results in the appearance of the ethanol sensitivity. The CNB network showed ethanol sensitivity without plasma treatment. Both CNB and low defect （after 3 min treatment） SWNT networks exhibit significant drift in the resistance baseline, while heavily plasma-treated （9 min） SWNTs exhibited high ethanol vapor sensitivity without the baseline change. The mechanisms of the ethanol sensitivity and stability after the plasma irradiation are attributed to the formation of sensitive dangling bonds in the SWNTs and formation of defect channels facilitating access of the ethanol vapor to all parts of the bundled nanotubes.