Ion Chromatographic Method with Post-Column Fuchsin Reaction for Measurement of Bromate in Chlorinated Water

An ion chromatographic method that employs a post-column reaction with fuchsin and spectrophotometric detection was optimized for measuring bromate (BrO3-) in water.  BrO3- is converted to Br2 by sodium metabisulfite and then reacted with acidic fuchsin to form a red-colored product that strongly absorbs at 530 nm.  The reaction of BrO3- and fuchsin reagent is optimum at pH 3.5 and 65 oC.  The method has a limit of quantitation of 4.5 µg L-1 and is linear up to 150 µg L-1 BrO3-.  Recoveries from spiked samples were high ranging from 95 to 102 % using external standard calibration and 87 to 103 % using standard addition method.  Intra-batch and inter-batch reproducibility studies of the method resulted to RSD values ranging from 0.62 to 2.01 % and percent relative error of 0.12 to 2.94 % for BrO3- concentrations of 10 µg L-1 and 50 µg L-1.  This method is free of interferences from common inorganic anions at levels typically found in chlorinated tap drinking water without preconcentration.  The optimized method can be applied to trace analysis of bromate in chlorinated tap drinking water samples

Pyrolysis of Real Packaging Plastic Waste Streams in a Fluidized-Bed Pilot Plant

Pyrolysis of different packaging plastics waste streams (DKR350) and films/foils (DKR310) was conducted at the pilot scale in a fluidized-bed reactor at 500 °C and 5 kg h-1 with the aim to investigate the impact of sorting, the variability of the feedstock, and process parameters on the yield and quality of feedstocks and product oils. Sorting involved enriching the feedstock in polyolefins content, by mostly removing PET and clogged materials. The results indicated that sorting improved the quality of oil to a limited extent, compared to unsorted streams, as further processing will still be required before due to the presence of heteroatoms (e.g., O, Cl). With the reactor and conditions used, the effect of the variable composition of this type of feedstock (e.g., depending on the location or season) is very limited, as the yield and quality of the condensable product remain similar. Both the effect of temperature and residence time is relevant and comparable, as an increase in either of these parameters favor cracking and aromatization reactions in the gas phase, leading to less condensable product and lower aliphatics/aromatics ratios in their composition.</p

Pyrolysis of mixed plastic waste (DKR-350):Effect of washing pre-treatment and fate of chlorine

Pyrolysis of a post-consumer plastic waste stream (DKR-350) has been performed at a laboratory scale in a fixed-bed reactor at 500 °C. DKR-350 is a complex mixture of post-consumer plastics comprising polyethylene, polypropylene, polystyrene, polyethylene terephthalate, clogged materials, multilayer flexibles, together with considerable amounts of biogenic and inorganic residues and halogens. The influence of different washing procedures on feedstock composition and pyrolysis product yields was investigated. Washing effectively lowers the biogenic, inorganic and halogen contents in DKR-350, though does not affect the yield of the desired oil/wax (66 to 69 wt%). 27% of the oil/wax lies in the boiling point range of naphtha and gasoline (150 ppm), showing the presence of recalcitrant organochlorides in the feed. Thus, post-treatment is still required to upgrade it to feedstock for the production of fuels and/or chemicals

An improved catalytic pyrolysis concept for renewable aromatics from biomass involving a recycling strategy for co-produced polycyclic aromatic hydrocarbons

Catalytic pyrolysis of crude glycerol over a shaped H-ZSM-5 zeolite catalyst with (partial) recycling of the product oil was studied with the incentive to improve benzene, toluene, and xylene (BTX) yields. Recycling of the polycyclic aromatic hydrocarbon (PAH) fraction, after separation from BTX by distillation and co-feeding with the crude glycerol feed, was shown to have a positive effect on the BTX yield. Further improvements were achieved by hydrogenation of the PAH fraction using a Ru/C catalyst and hydrogen gas prior to co-pyrolysis, and BTX yields up to 16 wt% on feed were obtained. The concept was also shown to be beneficial to other biomass feeds such as e.g., Kraft lignin, cellulose, and Jatropha oil

Effective feeding of lignin to pyrolysis units using molten salts in combination with a twin-screw extruder

Thermochemical conversions of waste lignocellulosic biomasses such as kraft lignin are highly relevant for the production of biobased chemicals and fuels. Of the many available thermochemical technologies, pyrolysis and (pressured) hydropyrolysis are promising pathways to produce liquids from biomass. However, pressurization and continuous feeding of solids into pyrolysis reactors operated at elevated temperatures and pressures is a practical challenge. In this study, we report the use of a molten salt (ZnCl2:NaCl:KCl with a molar composition of 60:20:20) in combination with a twin-screw extruder to pressurize and transport a molten salt-lignin mixture. The effect of different operating parameters such as the residence time (determined by residence time distribution (RTD) analysis) in the extruder and the mass ratio of lignin to salt was studied in detail at a fixed operating temperature of 230 °C. The mass of recovered lignin was up to 92 % at optimized conditions (35 s residence time, lignin to salt ratio of 1 to 10), the remainder being char. It was found that lower residence times and lower amounts of lignin in the feed have a positive effect on the amount of recoverable lignin. The extrusion process also affects the molecular structure of the lignin. 2D-NMR HSQC analysis of the modified lignin before and after processing showed a strong reduction in the intensity of peaks in the oxygenated aliphatic region, indicating demethoxylation during the extrusion process, supported by elemental analyses. The findings may be used to feed lignin effectively to pyrolysis or hydropyrolysis units.</p

Quantification of moisture in household plastic packaging waste using near-infrared hyperspectral imaging (NIR-HSI)

Quantifying moisture in plastic waste is crucial for optimizing recycling processes and improving the quality of recycled materials. Conventional methods, such as gravimetric analysis, are laborious and energy-intensive, limiting their efficiency in high-throughput industrial environments. This study presents and validates the use of near-infrared hyperspectral imaging (NIR-HSI) as a rapid, non-destructive method for moisture analysis in household plastic packaging waste (i.e., PE and PP films and rigids, PET, mixed plastics). By utilizing an NIR-HSI camera on a data collection conveyor belt, samples with varying moisture levels were analyzed. The method employs univariate calibration, correlating NIR absorbance from water with moisture concentration determined by the standard gravimetric method. To ensure accuracy, NIR absorbance from water was isolated by identifying and eliminating polymer-related absorbance through peak annotation. Principal component analysis (PCA) was subsequently applied to distinguish between rigids and films. Further refinement was achieved by normalizing the spectra and subtracting a dry reference spectrum, effectively eliminating the polymer signal. This approach enabled accurate quantification of moisture content and provided spatially resolved information on moisture distribution, including subsurface moisture. The method was successfully implemented in a pilot-scale sorting facility, where 95% of measurements achieved an accuracy within 2.6 percentage points. This integration underscores the significant potential of NIR-HSI for inline analysis and real-time feedback in recycling operations, offering significant advancements for future research and industrial applications in plastic waste recycling

Biorefining of pigeon pea:Residue conversion by pyrolysis

Pyrolysis is an important technology to convert lignocellulosic biomass to a renewable liquid energy carrier known as pyrolysis oil or bio-oil. Herein we report the pyrolysis of pigeon pea wood, a widely available biomass in the Philippines, in a semi-continuous reactor at gram scale. The effects of process conditions such as temperature (400-600 ◦C), nitrogen flow rate (7-15 mL min−1) and particle size of the biomass feed (0.5-1.3 mm) on the product yields were determined. A Box-Behnken three-level, three-factor fractional factorial design was carried out to establish process-product yield relations. Of particular interest is the liquid product (bio-oil), of which the yield was shown to depend on all independent variables in a complex manner. The optimal conditions for highest bio-oil yield (54 wt.% on dry feed intake) were a temperature of 466 ◦C, a nitrogen flow rate of 14 mL min−1 and a particle size of 1.3 mm. Validation of the optimized conditions proved that the average (n = 3) experimental bio-oil yield (52 wt.%) is in good agreement with the predicted value from the model. The properties of product oils were determined using various analytical techniques including gas chromatography-mass spectrometry (GC-MS), gel-permeation chromatography (GPC), nuclear magnetic resonance spectroscopy (13C- and HSQC-NMR) and elemental and proximate analyses. The bio-oils were shown to have low ash content (0.2%), high heating value (29 MJ kg−1) and contain high value-added phenolics compounds (41%, GC peak area) as well as low molecular weight aldehydes and carboxylic acids. GPC analysis indicated the presence of a considerable amount of higher molecular weight compounds. NMR measurements showed that a large proportion of bio-oil contains aliphatic carbons (~60%), likely formed from the decomposition of (hemi)cellulose components, which are abundantly present in the starting pigeon pea wood. Subsequent preliminary scale-up pyrolysis experiments in a fluidized bed reactor (~100 gfeed h−1, 475 ◦C and N2 flow rate of 1.5 L min−1) gave a non-optimized bio-oil yield of 44 wt.%. Further fractionation and/or processing are required to upgrade these bio-oils to biofuels and biobased chemicals

Novel Route to Produce Hydrocarbons from Woody Biomass Using Molten Salts

[Image: see text] The thermochemical decomposition of woody biomass has been widely identified as a promising route to produce renewable biofuels. More recently, the use of molten salts in combination with pyrolysis has gathered increased interest. The molten salts may act as a solvent, a heat transfer medium, and possibly also a catalyst. In this study, we report experimental studies on a process to convert woody biomass to a liquid hydrocarbon product with a very low oxygen content using molten salt pyrolysis (350–450 °C and atmospheric pressure) followed by subsequent catalytic conversions of the liquids obtained by pyrolysis. Pyrolysis of woody biomass in molten salt (ZnCl(2)/NaCl/KCl with a molar composition of 60:20:20) resulted in a liquid yield of 46 wt % at a temperature of 450 °C and a molten salt/biomass ratio of 10:1 (mass). The liquids are highly enriched in furfural (13 wt %) and acetic acid (14 wt %). To reduce complexity and experimental issues related to the production of sufficient amounts of pyrolysis oils for further catalytic upgrading, model studies were performed to convert both compounds to hydrocarbons using a three-step catalytic approach, viz., (i) ketonization of acetic acid to acetone, (ii) cross-aldol condensation between acetone and furfural to C(8)–C(13) products, followed by (iii) a two-stage catalytic hydrotreatment of the latter to liquid hydrocarbons. Ketonization of acetic acid to acetone was studied in a continuous setup over a ceria–zirconia-based catalyst at 250 °C. The catalyst showed no signs of deactivation over a period of 230 h while also achieving high selectivity toward acetone. Furfural was shown to have a negative effect on the catalyst performance, and as such, a separation step is required after pyrolysis to obtain an acetic-acid-enriched fraction. The cross-aldol condensation reaction between acetone and furfural was studied in a batch using a commercial Mg/Al hydrotalcite as the catalyst. Furfural was quantitatively converted with over 90% molar selectivity toward condensed products with a carbon number between C(8) and C(13). The two-stage hydrotreatment of the condensed product consisted of a stabilization step using a Ni-based Picula catalyst and a further deep hydrotreatment over a NiMo catalyst, in both batch setups. The final product with a residual 1.5 wt % O is rich in (cyclo)alkanes and aromatic hydrocarbons. The overall carbon yield for the four-step approach, from pinewood biomass to middle distillates, is 21%, assuming that separation of furfural and acetic acid after the pyrolysis step can be performed without losses

Full Utilization of Hard-to-Recycle Mixed Plastic Waste by Conversion toward Pyrolysis Oil and BTX Aromatics on a Pilot Scale

This study investigates the technological feasibility of recycling mixed plastic waste streams into chemical building blocks on a pilot scale. Postconsumer-separated DKR-350 mixed plastic waste was first separated into two fractions by using a two-step negative near-infrared (NIR) optical sorting process. The resulting two fractions (polyolefin-rich and polyolefin-poor) were subjected to thermal and ex situ catalytic pyrolysis, respectively. Both types of pyrolysis were performed in a fluidized bed pilot plant, continuously operated at feed rates of 5 kg h-1 and temperatures ranging from 460 to 550 °C. The polyolefin (PO)-rich fraction (∼81 wt % PE + PP) resulted in a maximum aliphatic-rich oil yield of 48 wt % and 26 wt % gas yield based on dry material intake. The PO-poor fraction, characterized by a lower PE/PP content (∼13 wt %) and high in PET and PS (43.5 and 14.4 wt %, respectively) normally unsuitable for efficient thermal pyrolysis, was processed through integrated cascading catalytic pyrolysis (ICCP) using a proprietary zeolite-based catalyst. This allowed for the successful transformation to 37 wt % aromatic-rich oil, with a total benzene, toluene, and xylenes (BTX) yield of 17 wt %, and 42 wt % gas. The high PET and PS content in the PO-poor fraction contributed to a significant increase in aromatic yields compared to the expected yield of a mixed plastic waste stream. This study thus demonstrates the potential to produce a full range of petrochemical building blocks, i.e., olefins and aromatics, from low-quality, hard-to-recycle plastic waste streams. Importantly, this work highlights that catalytic pyrolysis of the PO-poor residue stream, postsorting to yield PO-enriched streams, can effectively valorize this fraction, underscoring the technological viability of improved plastic recycling through targeted sorting and pyrolysis.</p

Iron Tetrasulfonatophthalocyanine-Catalyzed Starch Oxidation Using H2O2:Interplay between Catalyst Activity, Selectivity, and Stability

Oxidized starch can be efficiently prepared using H2O2 as an oxidant and iron(III) tetrasulfophthalocyanine (FePcS) as a catalyst, with properties in the same range as those for commercial oxidized starches prepared using NaOCl. Herein, we performed an in-depth study on the oxidation of potato starch focusing on the mode of operation of this green catalytic system and its fate as the reaction progresses. At optimum batch reaction conditions (H2O2/FePcS molar ratio of 6000, 50 °C, and pH 10), a high product yield (91 wt %) was obtained with substantial degrees of substitution (DSCOOH of 1.4 and DSCO of 4.1 per 100 AGU) and significantly reduced viscosity (197 mPa·s) by dosing H2O2. Model compound studies showed limited activity of the catalyst for C6 oxidation, indicating that carboxylic acid incorporation likely results from C-C bond cleavage events. The influence of the process conditions on the stability of the FePcS catalyst was studied using UV-vis and Raman spectroscopic techniques, revealing that both increased H2O2 concentration and temperature promote the irreversible degradation of the FePcS catalyst at high pH. The rate and extent of FePcS degradation were found to strongly depend on the initial H2O2 concentration where also the rapid decomposition of H2O2 by FePcS occurs. These results explain why the slow addition of H2O2 in combination with low FePcS catalyst concentration is beneficial for the efficient application in starch oxidation