The screening of various biochars for Cd2+ removal at relevant soil pH

Fourteen biochars from seven biomass sources were investigated on their long-term Cd2+ removal. The experiments consisted of a ten-day batch Cd2+ adsorption in a pH-buffered solution (pH = 6) to minimise pH effects. Insect frass, spent peat and chicken manure-derived biochars are promising Cd2+ adsorbents. Pyrolysis temperature was crucial for optimising Cd2+ removal by insect frass and spent peat-derived biochars. For these biochars, a pyrolysis temperature of 450 °C was optimal. In contrast, the Cd2+ removal by chicken manure biochars was independent of pyrolysis temperature. The Cd2+ removal by insect-frass and spent peat-derived biochars was associated with chemisorption on surface functionalities, while using chicken manure biochars was more associated with Cd2+ precipitation. The kinetics of Cd2+ removal over the course of ten days showed that insect frass biochar (450 °C) showed a gradual increase from 36 to 75 % Cd2+ removal, while chicken manure and spent peat-derived biochar (450 °C) already showed a higher Cd2+ removal (72 - 89 %) after day 1. This evidences that a long-term Cd2+ removal effect can be expected for some biochars. This should certainly be taken into consideration in future soil-based experiments.

X-ray Absorption (XRA): A New Technique for the Characterization of Granular Activated Carbons

The X-ray absorption (XRA) method using digital image processing techniques is a reliable technique to determine the exhaustion degree of granular activated carbons (GACs). Using an innovative digital image processing technique, the identification of individual adsorbed molecules or ions in a GAC was possible. Adsorption isotherm models (Langmuir and Freundlich) were used to simulate the adsorption equilibrium data of Methylene Blue (MB), nickel, cobalt and iodine. Freundlich equation was found to have the highest value of R² compared with Langmuir. The identification of distinctive patterns applying XRA for different adsorbed ions and molecules onto GAC was explored. It is demonstrated that unique XRA configurations for each adsorbed ion or molecule are found, as well as a proportional relationship between its incident energy (needed to achieve maximum photon attenuation) and the (effective) atomic number, the adsorbate mass and the molar or atomic mass of adsorbed molecule or ion. XRA method in combination with image histogram modifications was used to obtain a digital signature of adsorbed ions/molecules, giving distinct GSI values for each one in the used energy range. Probabilistic models prove that XRA results are within relationships between effective atomic number and photonic interaction probability, reinforcing the potentialities of XRA for monitoring (multi-)ion and/or molecule combinations on GAC using advanced digital image processing techniques. It was proved that the proposed approach could assess different adsorbed ions/molecules onto GACs in water purification systems.

Deciphering the Morphology of Motor Evoked Potentials

Motor Evoked Potentials (MEPs) are used to monitor disability progression in multiple sclerosis (MS). Their morphology plays an important role in this process. Currently, however, there is no clear definition of what constitutes a normal or abnormal morphology. To address this, five experts independently labeled the morphology (normal or abnormal) of the same set of 1,000 MEPs. The intra- and inter-rater agreement between the experts indicates they agree on the concept of morphology, but differ in their choice of threshold between normal and abnormal morphology. We subsequently performed an automated extraction of 5,943 time series features from the MEPs to identify a valid proxy for morphology, based on the provided labels. To do this, we compared the cross-validation performances of one-dimensional logistic regression models fitted to each of the features individually. We find that the approximate entropy (ApEn) feature can accurately reproduce the majority-vote labels. The performance of this feature is evaluated on an independent test set by comparing to the majority vote of the neurologists, obtaining an AUC score of 0.92. The model slightly outperforms the average neurologist at reproducing the neurologists consensus-vote labels. We can conclude that MEP morphology can be consistently defined by pooling the interpretations from multiple neurologists and that ApEn is a valid continuous score for this. Having an objective and reproducible MEP morphological abnormality score will allow researchers to include this feature in their models, without manual annotation becoming a bottleneck. This is crucial for large-scale, multi-center datasets. An exploratory analysis on a large single-center dataset shows that ApEn is potentially clinically useful. Introducing an automated, objective, and reproducible definition of morphology could help overcome some of the barriers that are currently obstructing broad adoption of evoked potentials in daily care and patient follow-up, such as standardization of measurements between different centers, and formulating guidelines for clinical use.

Automation of Potentiometric Measurements: Determination of Water-Extractable Sodium in Bread Using a Sodium Ion Selective Electrode with Minimum Sample Preparation

Different automated potentiometric procedures for the determination of NaCI in bread have been investigated and evaluated. The results are compared with data from atomic absorption spectrophotometry (AAS). A continuous potentiometric Na+ determination using a sodium ion selective electrode (ISE) is superior to all other methods. The sodium content can be measured by a reliable, rapid, and inexpensive potentiometric measurement of a finely ground and dried bread sample, extracted in the measurement beaker, as an alternative to the conventional and time-consuming AAS procedure.

Adsorption and photocatalytic removal of Ibuprofen by activated carbon impregnated with TiO2 by UV-Vis monitoring

The removal of Ibuprofen was investigated by activated carbon impregnated with TiO₂. Emphasis was given on the effect of different parameters, such as composite type, initial Ibuprofen concentration (5-25 mg/L), temperature (22-28 °C) and pH (acidic and alkaline solution). The experiment was carried out in a self-made tubular flow reactor, with one 15 W monochromatic UV lamp (254 nm). The composite AC90T10 gives the highest removal degree of 92% of Ibuprofen solution under UV light within 4 h, due to synergy of adsorption and photodegradation. It was found that weight ratio of composite/Ibuprofen has limited effect on the removal degree within the concentration range (5-25 mg/L), but reaction time under UV light (4 h) and pH (acidic solution) are very important. The kinetic experimental data obtained at pH 4.3 at 25 °C on different composites were fitted to pseudo-first, pseudo-second and Elovich models, obtaining a high accuracy based on R² values. From the results, composites of granular activated carbon and TiO₂ can enhance removal of Ibuprofen effectively, making recycle process much easier and less costly, which can be a promising method in future water treatment.

Enhanced cesium removal from real matrices by nickel-hexacyanoferrate modified activated carbons

After nuclear disasters, radioactive cesium partitions to soils and surface water, where it decays slowly. Hexacyanoferrates (HCFs) have excellent cesium removal properties but their structure is typically powdery. Many carrier materials, such as biomass or magnetic particles, have been used to provide a suitable substrate for HCFs that can be used in filters. This research uses the sorption properties of activated carbon (AC) to incorporate Ni-HCF, resulting in good structural properties of the hybrid material. These HCF-modified ACs show drastically improved sorption properties towards Cs after one, two and three HCF impregnation cycles. The activated carbon from brewer's spent grain with one modification cycle removes more than 80% of 1 mg L^-1 Cs in a sea water solution and more than 98% of 1 mg L^-1 Cs from surface water at a low AC dosage (0.5 g L^-1). Iron and nickel leaching is studied and found to be dependent on the type of modified AC used and the leaching solution. Iron leaching can be problematic in surface and seawater, whereas nickel leaching is especially pronounced in seawater.

A novel acoustic approach for the characterization of granular activated carbons used in the rum production

Acoustic analysis and sound patterns recognition techniques have been widely used in many branches of science, however; almost none focused on the characterization of granular activated carbon. A new methodology has been developed in order to characterize activated carbon based on the dynamic analysis in audible spectra of the sound's relative amplitude power produced by water flooded on granular activated carbon. A home-build recording set-up and management of acoustic measurements have been presented and correlated with the results of porous structure of carbons characterized by N2 adsorption. Five samples of granular activated carbons used in the rum production of different exhausted level have been evaluated by both methods. Parameters as the BET surface area and total pore volume showed a satisfactory correlation with acoustic measurement data when the signal is processed at 1000Hz. Three frequencies components of the produced sound were analyzed and related with the porous characteristics. The found relationship gives the possibility to predict and calculate textural parameters of granular activated carbons applying the acoustic technique. This methodology approach opens possibilities in using acoustic experiments for the characterization of high-porosity materials and to determine their exhausted level.

Rapeseed and Raspberry Seed Cakes as Inexpensive Raw Materials in the Production of Activated Carbon by Physical Activation: Effect of Activation Conditions on Textural and Phenol Adsorption Characteristics

The production of activated carbons (ACs) from rapeseed cake and raspberry seed cake using slow pyrolysis followed by physical activation of the obtained solid residues is the topic of this study. The effect of activation temperature (850, 900 and 950 °C), activation time (30, 60, 90 and 120 min) and agent (steam and CO₂) on the textural characteristics of the ACs is investigated by N₂ adsorption. In general, higher activation temperatures and longer activation times increase the BET specific surface area and the porosity of the ACs, regardless of the activation agent or raw material. Steam is more reactive than CO₂ in terms of pore development, especially in the case of raspberry seed cake. The performance of the ACs in liquid adsorption is evaluated by batch phenol adsorption tests. Experimental data are best fitted by the Freundlich isotherm model. Based on total yield, textural characteristics and phenol adsorption, steam activation at 900 °C for 90 min and CO₂ activation at 900 °C for 120 min are found as the best activation conditions. Raspberry seed cake turns out to be a better raw material than rapeseed cake. Moreover, AC from raspberry seed cake produced by steam activation at 900 °C for 90 min performs as well as commercial AC (Norit GAC 1240) in phenol adsorption. The adsorption kinetics of the selected ACs are best fitted by the pseudo-second-order model.

A hybridization approach to efficient TiO2 photodegradation of aqueous benzalkonium chloride

TiO2 get positively charged upon UV-irradiation and repel the cationic pollutants away from the surface. Hybridization of AC onto TiO2 (ACT) tends catalyst surface negatively charged besides providing highly favorable adsorptions sites for cationic pollutants. The photodegradation of benzalkonium chloride (BKC), a quaternary ammonium surfactant and a pharmaceutical, is investigated with ACT. The surface charge of the catalyst in surfactant and non-surfactant aqueous dispersion under UV-irradiation is investigated and explained. The anomalous increase in COD values at the beginning of BKC-photodegradation is explained. The intermediate products formed are identified in both solution and solid phase. Trace amount of dodecane remained adsorbed on the catalyst surface after 1h UV-irradiation, but complete mineralization of BKC is achieved with 2h UV-irradiation. We propose that BKC photodegradation starts by central fission of benzyl CN bond followed by dealkylation, and demethylation steps.

Activated carbon from pyrolysis of brewer's spent grain: Production and adsorption properties

Brewer's spent grain is a low cost residue generated by the brewing industry. Its chemical composition (high nitrogen content 4.35 wt.%, fibres, etc.) makes it very useful for the production of added value in situ nitrogenised activated carbon. The composition of brewer's spent grain revealed high amounts of cellulose (20.8 wt.%), hemicellulose (48.78 wt.%) and lignin (11.3 wt.%). The fat, ethanol extractives and ash accounted for 8.17 wt.%, 4.7 wt.% and 3.2 wt.%, respectively. Different activated carbons were produced in a lab-scale pyrolysis/activation reactor by applying several heat and steam activation profiles on brewer's spent grain. Activated carbon yields from 16.1 to 23.6 wt.% with high N-contents (> 2 wt.%) were obtained. The efficiency of the prepared activated carbons for phenol adsorption was studied as a function of different parameters: pH, contact time and carbon dosage relative to two commercial activated carbons. The equilibrium isotherms were described by the non-linear Langmuir and Freundlich models, and the kinetic results were fitted using the pseudo-first-order model and the pseudo-second-order model. The feasibility of an activated carbon production facility (onsite and offsite) that processes brewer's spent grain for different input feeds is evaluated based on a techno-economic model for estimating the net present value. Even though the model assumptions start from a rather pessimistic scenario, encouraging results for a profitable production of activated carbon using brewer's spent grain are obtained.

Study of the pyrolysis of sludge and sludge/disposal filter cake mix for the production of value added products

Slow and fast pyrolysis of sludge and sludge/disposal filter cake (FC) mix are performed to investigate the liquid and solid products for their use as value added products. The obtained slow pyrolysis liquid products separate in an oil, a water rich fraction and a valuable crystalline solid 5,5-dimethyl hydantoin. During fast pyrolysis, mainly an oil fraction is formed. Aliphatic acids and amides present in the water rich fractions can be considered as value added products and could be purified. The oil fractions have properties which make them promising as fuel (25-35 MJ/kg, 14-20 wt% water content, 0.2-0.6 O/C value), but upgrading is necessary. Sludge/FC oils have a lower calorific value, due to evaporation of alcohols present in FC. ICP-AES analyses reveal that almost none of the metals present in sludge or sludge/FC are transferred towards the liquid fractions. The metals are enriched in the solid fractions.

Characterisation of adsorbents prepared by pyrolysis of sludge and sludge/disposal filter cake mix

Copper and zinc removal from water (pH = 5.0) using adsorbents produced from slow and fast pyrolysis of industrial sludge and industrial sludge mixed with a disposal filter cake (FC), post treated with HCl, is investigated in comparison with a commercial adsorbent F400. The results show that a pseudo-second order kinetics model is followed. The Langmuir-Freundlich isotherm model is found to fit the data best. The capacity for heavy metal removal of studied adsorbents is generally better than that of commercial F400. The dominant heavy metal removal mechanism is cation exchange. Higher heavy metal removal capacity is associated with fast pyrolysis adsorbents and sludge/FC derived adsorbents, due to enhanced cation exchange. Improvement of Zn(2+) removal via 1 N HCl post-treatment is only effective when exchangeable cations of the adsorbent are substituted with H(+) ions, which boost the cation exchange capacity. Increase of temperature also enhances metal removal capacity. Fast pyrolysis sludge-based adsorbents can be reused after several adsorption-desorption cycles.

Economic assessment of flash co-pyrolysis of short rotation coppice and biopolymer waste streams

The disposal problem associated with phytoextraction of farmland polluted with heavy metals by means of willow requires a biomass conversion technique which meets both ecological and economical needs. Combustion and gasification of willow require special and costly flue gas treatment to avoid re-emission of the metals in the atmosphere, whereas flash pyrolysis mainly results in the production of (almost) metal free bio-oil with a relatively high water content. Flash co-pyrolysis of biomass and waste of biopolymers synergistically improves the characteristics of the pyrolysis process: e.g. reduction of the water content of the bio-oil, more bio-oil and less char production and an increase of the HHV of the oil. This research paper investigates the economic consequences of the synergistic effects of flash co-pyrolysis of 1:1 w/w ratio blends of willow and different biopolymer waste streams via cost-benefit analysis and Monte Carlo simulations taking into account uncertainties. In all cases economic opportunities of flash co-pyrolysis of biomass with biopolymer waste are improved compared to flash pyrolysis of pure willow. Of all the biopolymers under investigation, polyhydroxybutyrate (PHB) is the most promising, followed by Eastar, Biopearls, potato starch, polylactic acid (PLA), corn starch and Solanyl in order of decreasing profits. Taking into account uncertainties, flash co-pyrolysis is expected to be cheaper than composting biopolymer waste streams, except for corn starch. If uncertainty increases, composting also becomes more interesting than flash co-pyrolysis for waste of Solanyl. If the investment expenditure is 15% higher in practice than estimated, the preference for flash co-pyrolysis compared to composting biopolymer waste becomes less clear. Only when the system of green current certificates is dismissed, composting clearly is a much cheaper processing technique for disposing of biopolymer waste.

Hydrodechlorination of dichlorobiphenyls over Ni-Mo/Al2O3 catalysts prepared by spray-drying method

The hydrodechlorination (HDCl) process of 2,3-, 2,4- and 2,5-dichlorobiphenyls was studied over a sulphided Ni-Mo/Al(2)O(3) catalyst in a stirred autoclave at a hydrogen pressure of 3 MPa. The catalysts were prepared by spray-drying. They were characterized by N(2) adsorption, thermogravimetry and scanning electron microscopy with X-ray microanalysis. The reaction temperature of the catalytic HDCl process was varied in the range of 230-290 degrees C. Polychlorinated biphenyls (PCBs) free transformer oil was used as reaction medium. The HDCl degree of dichlorobiphenyl isomers was in the range of 82-93%. The efficiency in the chlorine removal was found to be related to the position of the substituted chlorine atom and decreased as follows 2,4-dichlorobiphenyl approximately 2,5-dichlorobiphenyl>2,3-dichlorobiphenyl. For comparison, the HDCl process of 2,3-dichlorobiphenyl (2,3-PCB) without catalyst was also studied. The chlorine removal was 85% for the catalytic HDCl of 2,3-PCB whereas non-catalytic process led only to 16% of dechlorination in the same operating conditions, i.e. at 290 degrees C after 120 min. Monodichlorobiphenyls were not detected in the reaction products. The data for both catalytic and non-catalytic conversion of 2,3-PCB fit to a first-order model. Kinetic constants and the activation energy of the overall HDCl reaction of 2,3-PCB to biphenyl were evaluated. Compared to non-catalytic process, a nearly threefold decrease in the activation energy was observed in the presence of Ni-Mo/Al(2)O(3) catalyst prepared by spray-drying (48 kJ mol(-1) vs. 124 kJ mol(-1)).

Molecular and functional characterization of ovine cardiac valve-derived interstitial cells in primary isolates and cultures

At present the involvement of cardiac valve interstitial cells (VICs) in growth, repair, and tissue engineering is understudied. Therefore, this study aims at characterizing ovine VICs in order to provide a solid base for tissue engineering of heart valves. Ovine ICs of the four heart valves were isolated by the explant outgrowth method and expanded in vitro up to passage 5. Vimentin and collagen I gene expression from freshly isolated or cultured ICs was measured by reverse transcriptase-polymerase chain reaction. Immunocytochemical stainings of vimentin, alpha-smooth muscle actin (ASMA), smooth muscle myosin, and procollagen I were performed on aortic VICs. In addition, migration and extracellular matrix deposition were studied in vitro in aortic VICs. ICs show stable vimentin and collagen I expression in culture. Expression is approximately doubled in cultured ICs compared with fresh isolates. More than 95% of ICs in each passage stain for vimentin and procollagen I. Freshly isolated ICs are ASMA and myosin negative, but ICs in culture partially stain for these contractile markers. ICs have stable matrix production for up to five passages, associated with stable migration of the cells. We conclude that ovine valve interstitial cells undergo phenotypic modulation to activated myofibroblasts under culture conditions but retain stable matrix production.

Lack of calcification of tissue engineered heart valves in juvenile sheep

The presence of viable endothelial cells may support longer durability and the absence of calcification in valve prostheses. This study shows the development of a tissue engineered heart valve, constructed from viable autologous endothelial cells on an acellular matrix and its evaluation in juvenile sheep. In 3-month-old sheep (n = 8) a piece of vein was harvested to culture autologous endothelial cells. A porcine acellular matrix was reendothelialized and implanted in juvenile sheep as pulmonary interposition. The valves were explanted after 1 week, 3 and 6 months. Examination was performed by X-ray, light microscopy, and atomic absorption spectrometry. Reendothelialization mean rate was 10.3 x 10(5) cells/cm(2) with a mean endothelial cell viability of 95.5% (0.98 x 10(5) cells/cm(2)). X-ray examination showed no cusp calcification at 1 week, 3 and 6 months, which was confirmed by light microscopy. Immunostaining for factor VIII demonstrated colonization of viable mature autologous endothelial cells on the heart valve after the seeding process. The atomic absorption spectrometry showed no significant increase of the calcium content after 3 (P value >.1) and 6 months (P value >.1) compared with nonimplanted tissue engineered heart valves. The tissue engineered valve showed no cusp calcification in the juvenile sheep after 3 and 6 months.

Antimineralization treatments in stentless porcine bioprostheses: an experimental study

BACKGROUND AND AIM OF THE STUDY

Photo-oxidation treatment of porcine stentless bioprostheses (Photofix) was compared with glutaraldehyde fixation, with either AOA (Freestyle valve) or Tween-80 (Edwards Prima Plus valve).

METHODS

Six valves of each type were implanted in juvenile sheep, in the pulmonary position. Valves were explanted after three or six months and examined macroscopically, by X-radiography, and by light and transmission electron microscopy. Calcium content was determined by atomic absorption spectrometry.

RESULTS

The cusps of all valves were free of calcification, and had normal histology and function. Calcium contents (median +/- IQR) were 0.63+/-0.45, 0.73+/-1.46 and 0.46+/-1.42 microg/mg for the Photofix, Freestyle and Prima Plus valves, respectively (p = NS). Calcium contents of the aortic wall portions were 0.71+/-1.27 (Photofix), 10.78+/-77.22 (Freestyle) and 28.70+/-66.53 (Prima Plus) (p <0.05 for Photofix versus Freestyle or Prima Plus).

CONCLUSION

Photo-oxidation of a porcine stentless valve prevents calcification not only in the cusps, but also in the aortic wall portion.

Calcification characteristics of porcine stented valves in a juvenile sheep model

BACKGROUND

Different antimineralization treatments of stented porcine bioprostheses were evaluated: ethanol (Epic), alpha-amino-oleic acid (AOA) (Mosaic), and sodium dodecyl sulfate (SDS) (Hancock II). A nontreated, glutaraldehyde-fixed valve (Labcor) served as control.

METHODS

For each treatment, six valves were implanted in juvenile sheep in the pulmonary position. Valves were explanted after 3 and 6 months and examined macroscopically, by roentgenogram and light and transmission electron microscopy. Calcium content (microg/mg) was determined by atomic absorption spectrometry.

RESULTS

The Labcor valves revealed small calcium deposits in the cusps, although calcium content remained low (median value 0.4+/-0.8 microg/mg). SDS did not prevent cusp calcification as assessed by histology and calcium content measurement, which was higher than in all other valves: 1.9+/-4.6 microg/mg (p < 0.05). Cusp retraction and rupture were occasionally found in the Hancock. The Mosaic and Epic valves showed no cusp calcification and had low calcium contents (0.3+/-2.4 microg/mg and 0.7+/-0.6 microg/mg, respectively). Epic showed less pannus formation, but had hematoma or iron staining in the cusps.

CONCLUSIONS

SDS is inefficient as an antimineralization treatment, in contrast to ethanol or AOA. Cusp hematoma after ethanol treatment needs further investigation.