Pine Bark Research Articles

Combining behavioural TOPSIS and six multi-criteria weighting methods to rank biomass fuel pellets for energy use in Sweden

EU energy and climate policies continue to drive interest in biomass fuel pellets which can be produced from a wide variety of feedstock. The use of multi-criteria decision analysis (MCDA) to support feedstock selection has the potential for more transparent and better decision-making. This study applies the behavioural TOPSIS, a prominent MCDA technique, to rank pellets for energy use in Sweden produced from under-utilised forest and agricultural biomass. Seven criteria were used to assess and rank the biomass pellets. The alternatives include 88 types of pellets from 11 biomass materials. Possible attitudes of an expert towards the risk of losses (risk averse, risk neutral and risk-seeking) were combined with six sets of criteria weights obtained using six weighting methods – a total of 18 input settings (scenarios). Despite having different input settings, almost identical results were obtained in all scenarios, meaning that the rankings were stable and consistent. Across all 18 scenarios, pellets produced from a reference spruce/pine sawdust blend are ranked ahead of other pellet types. Pellets produced from Scots pine bark exhibited stable and consistent rankings across all scenarios; and thus this biomass is the second-best overall. The next best materials overall are poplar, reed canary grass and wheat straw, whereas torrefied pellets (torrefied beech, poplar and wheat straw) were ranked last in all scenarios. Combining behavioural TOPSIS and a variety of criteria-weighting methods is a meaningful way of improving decision-making with respect to producing a more valid and reliable ranking of biomass fuel pellets for energy use in Sweden.

Effect of proanthocyanidins from different sources on the digestibility, physicochemical properties and structure of gelatinized maize starch

The effect of proanthocyanidins (PAs) from Chinese bayberry leaves (BLPs), grape seeds (GSPs), peanut skins (PSPs) and pine barks (PBPs) on physicochemical properties, structure and in-vitro digestibility of gelatinized maize starch was investigated. The results showed that all PAs remarkably retarded starch digestibility, meanwhile, BLPs highlighted superiority in increasing resistant starch content from 31.29 ± 1.12 % to 68.61 ± 1.15 %. The iodine-binding affinity analysis confirmed the interaction between PAs and starch, especially the stronger binding of BLPs to amylose, which was driven by non-covalent bonds supported by XRD and FT-IR analysis. Further, we found that PAs altered the rheological properties, thermal properties and morphology structure of starch. In brief, PAs induced larger consistency, poorer flow ability, lower gelatinization temperatures and melting enthalpy change (ΔH) of starch paste. SEM and CLSM observation demonstrated that PAs facilitated starch aggregation. Our results indicated that PAs especially BLPs could be considered as potential additives to modify starch in food industry.

Pine Bark as a Potential Source of Condensed Tannin: Analysis through Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX)

This study aimed to evaluate the tannin content in the bark of five pine species from a forest harvesting area of the Ixtlán de Juárez community, Oaxaca, México. The species studied were Pinus patula, Pinus ayacahuite, Pinus rudis, Pinus douglasiana, Pinus pseudostrobus. The bark samples were subjected to a drying, grinding, and sieving process. These compounds were extracted using two methods: by constant reflux with ethanol for three hours or in a water bath with distilled water for two hours. The percentage of total extract, Stiasny number, and condensed tannins were quantified. The quantitative number of condensed tannins present in the bark for each of the five species studied ranged from 0.65% to 5.14% for the ethanolic extracts and 0.14% to 1.46% for the aqueous extracts. Analysis by Fourier transform infrared spectroscopy (FTIR) identified polyphenolic compounds and functional groups characteristic of tannins. Analysis by scanning electron microscopy (SEM) and X-ray dispersive spectroscopy (EDX) provided the elemental analysis and chemical composition of the tannin extracts, respectively, finding trace elements of silver, cadmium, phosphorus, iodine, and sulfur, which are minerals present in the soil, meaning that through processes of micronutrient absorption, these can interact with the tannins or polyphenols in the barks of the tree species being studied. The results indicate that the bark of P. patula and P. ayacahuite have a higher concentration of condensed tannins, 5.14% and 4.71%, respectively, in the ethanol extraction, and may be susceptible to exploitation due to the amount of bark generated in forestry activities.

Removal of Zinc Ions from Aqueous Solutions with the Use of Lignin and Biomass Part II

Abstract In response to the trend toward sustainable management of by-products from the pulp and paper industry as well as plant waste, practical and economical methods are being developed to use them in a way that does not pose a threat to the environment. The main aim of the research was to study the possibility of using lignin and plant biomass as biosorbents for the removal of zinc ions from aqueous solutions. The secondary aim was to build an optimal multilayer system made of biosorbents selected during the research in order to obtain the highest sorption efficiency and to determine the best conditions of the sorption process. The effectiveness of zinc ion sorption was assessed using an appropriate combination of sorbents such as lignin, oat bran, rice husk, chitosan, pectin, sodium alginate, pine bark, coconut fiber and activated carbon, selected on the basis of literature data and the preliminary results of tests carried out using FTIR and AAS. The main component of the sorption system was lignin separated from black liquor. Results indicate that the best Zn sorption system was based on coconut fiber, lignin, and pine bark, for which the maximum sorption efficiency was 95%. The research also showed that the increase in the process temperature, the mass of biosorbents used and the alkaline pH are the factors that increase the efficiency of the sorption. It can be concluded that lignin and plant biomass can be used as ecological sorbents of zinc ions from water solutions. They are safe for the environment, produced from renewable sources, and are by-products or waste materials, which is part of the sustainable development and circular economy currently promoted in the EU.

Evaluation of Substrate Stratification, Fertilizer Placement, and Mulching on Growth of Common Nursery Weed Species and Container-Grown Ornamental Species

The objective of this study was to determine how topdressing or incorporating fertilizer with stratified or mulched substrates could affect the growth of Hibiscus rosa-sinensis ‘Snow Queen’, a popular ornamental plant, and the growth of liverwort (Marchantia polymorpha) and bittercress (Cardamine flexuosa), two common nursery weed species. Five different substrate treatments were evaluated, which included three stratified substrates composed of pine bark screened to a small (0.63–1.27 cm), medium (≤1.90 cm), and large (0.96–1.90 cm) particle size and two industry-standard substrates that were either mulched with rice hulls or remained unmulched. All treatments were then fertilized via either topdressing or incorporating a controlled-release fertilizer (CRF). Bittercress control was highest in mulched containers, followed by those stratified using the medium pine bark, and its growth increased overall in topdressed vs. incorporated containers regardless of substrate or mulch treatment. All the stratification treatments resulted in a decrease in liverwort coverage compared to the industry standard treatment, but topdressing generally increased liverwort coverage compared with incorporating fertilizer. In conclusion, both topdressing and incorporation appear to be compatible with fertilizer placement methods with substrate stratification from a crop production standpoint; however, weed growth may increase if fertilizer is topdressed.

Features of Scots Pine Mortality Due to Incursion of Pine Bark Beetles in Symbiosis with Ophiostomatoid Fungi in the Forest-Steppe of Central Siberia

Forest decline is a significant issue affecting critical ecosystem processes worldwide. Here, we describe mortality in Pinus sylvestris L. monitored trees caused by the inhabitation of pine bark beetles (Tomicus minor Hart.) in symbiosis with ophiostomatoid fungi (Ophiostoma piceae (Munch) H. et P. Sydow) infection in the forest-steppe of central Siberia. Stem sap flow (Q) and stem diameter fluctuations (dRc) were monitored in eight pine trees during seven consecutive growing seasons (2015–2021). In addition, microcore sampling every ten days allowed the determination of stem wood formation in monitored trees in the 2021 growing season. During 2020 and 2021, two cases of Q termination were recorded among the monitored trees, with microcores revealing no cambium formation. Thus, the seasonal Q onset matches the beginning of the beetle dispersal period when they attack and inhabit tree stems. The decline of circumferential stem size began 10–12 days after Q onset, during the massive inhabitation of beetles into the stems. The disturbance of Q in trees occurred in 21–23 days, and total cessation of Q was observed 23–26 days after the Q onset at the beetle’s egg development phase. The timing of dRc disturbance and Q cessation observed directly coincides with the beetle life cycle. Thus, the phenology of pine trees and T. minor beetles is driven by seasonal weather conditions, particularly the cumulative air temperature (>0 °C).

Adsorbing Volatile Organic Compounds within Bitumen Improves Colloidal Stability and Air Quality

The mass loss of bitumen due to volatilization is one of the deterioration mechanisms through which the chemical composition of bitumen deviates from its original condition, leading to change in the physical and rheological properties of bitumen. The emissions from bitumen not only accelerate its aging but also negatively impact air quality and consequently human health. Here, we characterized the molecular compositions of the volatiles emitted from bitumen in an isothermal aging process (150 °C for 24 h). We also investigated the impact of losing these compounds on the association behavior of asphaltene stacks. Based on the GC-MS results, the main mass loss of SARA (saturates, aromatics, resins, asphaltenes) fractions is attributed to the emission of lightweight nonpolar aromatic and aliphatic compounds. The most dominant volatiles are single-ring aromatics carrying short side chains, followed by saturated and unsaturated aliphatic compounds including short-chain n-alkanes, iso-alkanes, cyclic alkenes, alkenes, and dienes. Using molecular modeling in the framework of density functional theory (DFT), we showed how the reduction in aromatics and saturates can impact the colloidal stability of asphaltenes in the matrix of bitumen. Based on the DFT results, the surface adsorption of aromatics and saturates on asphaltene planes provides the steric repulsion required to maintain the asphaltene planes at a distance sufficient to inhibit their agglomeration. In addition, aromatic molecules with the least hindrance repulsion can disturb the π–π interfacial interactions between asphaltene planes, facilitating their deagglomeration. Therefore, a direct consequence of the mass loss of bitumen due to volatilization is disturbing the asphaltene distribution within the bitumen and stimulating the aggregation of asphaltenes. We also studied the merits of incorporating biochar into the bitumen surface to reduce bitumen’s mass loss. Modification of bitumen separately with each of six biochars derived from biomass feedstocks (walnut shell, peanut shell, Douglas fir, pine bark, birch, and algae) showed the efficacy of each biochar to reduce the volatiles emitted from bitumen, thereby reducing the changes in the composition of maltene with consequent colloidal stability losses. The study outcomes highlight the importance of reducing emissions from bitumen to delay its aging and minimize negative impacts on air quality and human health.

Production of Pyrolysis Liquid from Pine Bark with Improved PID System and Analysis of Its Components by GC-MS

In this research, the bark of pine trees is procured, dried, and ground in the province of Elazığ (Türkiye). In an inert environment, the liquid of the pyrolysis vapor is condensed using a double condenser system in the improved PID-controlled pyrolysis reactor. In experimental studies, using response surface methodology (RSM) in the pyrolysis process, temperature, time, and amount of mass are optimized. Two phases are formed in the obtained pyrolysis liquid and these phases are separated with the help of a separating funnel. Low-density compounds are in the upper phase, and high-density liquid is in the lower phase. According to the results, maximum efficiency is obtained at 376 °C, 185 minutes, and 519 grams of pine bark powder. The efficiency of wood vinegar is found by the ratio of the amount of acetic acid to components other than water. The efficiency is calculated by gas chromatography-mass spectrometry (GC-MS) values. Experimental data and RSM model results have been evaluated by statistical analysis. Considering the amount, color, and components of the pyrolysis liquid, an evaluation can be made about the quality of this liquid. Also, as the particle size of the pinebark decreases, the surface area increases, so the pyrolysis time reduces.

Self-Assembled CNF/rGO/Tannin Composite: Study of the Physicochemical and Wound Healing Properties.

In this study, a conductive composite material, based on graphene oxide (GO), nanocellulose (CNF), and tannins (TA) from pine bark, reduced using polydopamine (PDA), was developed for wound dressing. The amount of CNF and TA was varied in the composite material, and a complete characterization including SEM, FTIR, XRD, XPS, and TGA was performed. Additionally, the conductivity, mechanical properties, cytotoxicity, and in vitro wound healing of the materials were evaluated. A successful physical interaction between CNF, TA, and GO was achieved. Increasing CNF amount in the composite reduced the thermal properties, surface charge, and conductivity, but its strength, cytotoxicity, and wound healing performance were improved. The TA incorporation slightly reduced the cell viability and migration, which may be associated with the doses used and the extract's chemical composition. However, the in-vitro-obtained results demonstrated that these composite materials can be suitable for wound healing.

Nest-Site Features and Breeding Ecology of Chestnut-Vented Nuthatch Sitta nagaensis in Southwestern China.

The breeding ecology of birds is the cornerstone of bird life-history theory, and breeding success directly affects the survival and development of populations. We studied the breeding ecology of a secondary cavity-nesting bird, the chestnut-vented nuthatch Sitta nagaensis, in southwestern China from March to June in 2020, 2021, and 2022. In total, 16 nests in nest boxes and 19 nests in natural cavities were studied. The nesting habitat was mainly Pinus yunnanensis forest (68.4%), and the nest trees were mainly P. yunnanensis and pear Pyrus spp. Cavities made by woodpeckers and knot holes were used as nest sites, and the nuthatches plastered the hole entrance with mud. The nesting material was mainly pine bark. The clutch size was 3.47 ± 0.56 (range 2-4, n = 30), with an incubation period of 16.06 ± 0.91 days (range 15-19 days, n = 18). The nestling period was 20.88 ± 1.90 days (range 18-23 days, n = 23), and both parents fed the nestlings.

Experimental and theoretical study of heat and mass transfer in a continuous, vertical and coaxial pyrolysis reactor for high porosity biochar production

The development of a high porosity biochar production facility to meet an industrial need requires a detailed knowledge of the thermochemical phenomena of pyrolysis. The main challenge of this work is the production of biochar with a high porosity in large quantities, and producing a residual gas that can be used for drying biomass. Two complementary tools have been here developed and operated: a patented prototype and a designing numerical model. The model was developed in parallel with tests on the prototype and a characterisation phase of the various materials involved in the pyrolysis process in order to increase the correspondence between numerical model and experimental results. The model is used to predict, depending on the geometry chosen, the temperature in the pyrolysis zone, the heating rate and residence time corresponding to the applied biomass flow rate, as well as the biochar and gas mass yields.This study demonstrated the ability of the experimental plant to produce a high porosity biochar with a specific surface of 200m2.g-1 in the best case and a constant carbon content around 90% on dry basis due to the separation of the partial oxidation and pyrolysis zones. Following a material characterisation phase and a customisation of the parameters of the Arrhenius formalism adapted to pine bark, the numerical model shows a strong correspondence in terms of temperatures, biochar yield and thermochemical kinetics with the experimental observations from the prototype.

Adsorption of antibiotics on bio-adsorbents derived from the forestry and agro-food industries

Antibiotic consumption at high levels in both human and veterinary populations pose a risk to their eventual entry into the food chain and/or water bodies, which will adversely affect the health of living organisms. In this work, three materials from forestry and agro-food industries (pine bark, oak ash and mussel shell) were investigated as regards their potential use as bio-adsorbents in the retention of the antibiotics amoxicillin (AMX), ciprofloxacin (CIP) and trimethoprim (TMP). Batch adsorption/desorption tests were conducted, adding increasing concentrations of the pharmaceuticals individually (from 25 to 600 μmol L−1), reaching maximum adsorption capacities of ≈ 12000 μmol kg−1 for the three antibiotics, with removal percentages of ≈ 100% for CIP, 98–99% adsorption for TMP onto pine bark, and 98–100% adsorption for AMX onto oak ash. The presence of high calcium contents and alkaline conditions in the ash favored the formation of cationic bridges with AMX, whereas the predominance of hydrogen bonds between pine bark and TMP and CIP functional groups explain the strong affinity and retention of these antibiotics. The Freundlich's model provided the best prediction for AMX adsorption onto oak ash and mussel shell (heterogeneous adsorption), whereas the Langmuir's model described well AMX adsorption onto pine bark, as well as CIP adsorption onto oak ash (homogeneous and monolayer adsorption), while all three models provided satisfactory results for TMP. In the present study, the results obtained were crucial in terms of valorization of these adsorbents and their subsequent use to improve the retention of antibiotics of emerging concern in soils, thereby preventing contamination of waters and preserving environment quality.

Changes in Production Practices Used for Disease Management in Blueberry Nurseries in Georgia, USA, Over a 15-year Period

Surveys of blueberry [rabbiteye blueberry (Vaccinium virgatum) and southern highbush blueberry (Vaccinium corymbosum interspecific hybrids)] nurseries in the State of Georgia, USA, were conducted in 2007 and 2022 to determine the prevalence of and associations among propagation practices, especially related to disease management. As indicated by the reduction in surveyed nurseries in 2022 (7) compared with 2007 (18), the Georgia blueberry nursery industry has consolidated. However, cultural disease management practices have generally improved in these remaining nurseries. In 2007, in nurseries where cuttings were grown in containers, 77.8% reused containers and 66.7% did not sterilize them before use. The growing medium [pine (Pinus sp.) bark] was reused for subsequent production cycles in 29.4% of nurseries, although such reuse of media tended to be associated with production in beds as opposed to containers (P = 0.08). Nurseries used well water in 88.2% and pond water in 11.8% of cases. Cuttings were grown on benches (vs. the ground) in slightly fewer than half of the nurseries. In contrast, all nurseries surveyed in 2022 grew their cuttings in containers, used well water, and had increased bench use, albeit only slightly. Although all nurseries reused containers, only 28.5% did not sterilize containers before use, and only 14.3% of nurseries reported reusing media. Most nurseries surveyed in 2007 (83.3%) were on a routine, calendar-based fungicide program using a.i. targeted primarily against aboveground diseases (blights and leaf spots) and secondarily against soil-borne water molds (Phytophthora and Pythium species of the Oomycetes class). In contrast, 42.8% of those surveyed in 2022 were on a 2- to 3-week spray schedule, 42.8% used fungicides on an as-needed basis, and 14.4% were on a monthly schedule, indicating that fungicide scheduling varied dramatically among the remaining nurseries.

The Use of Black Pine Bark for Improving the Properties of Wood Pellets

The requirement for alternative raw materials for fuel pellets that would enable the use of readily available low-cost renewable resources and waste materials, such as bark, has always attracted interest. The aim of the current work was to assess the effect of black pine (Pinus nigra L.) bark content (0%–100%) as well as densification temperature on the properties of black pine wood pellets produced in a single pellet die. The quality assessment of the pellets was carried out by the determination of radial compression strength, density, moisture content, ash content, and surface roughness. The results showed that adding black pine bark to the pellet feedstock resulted in the production of substantially smoother and moderately denser pellets, which also exhibited higher mechanical strength than that of the respective pellets of pure wood. Finally, it was shown that black pine bark can be a valuable raw material, which can induce improved bonding of biomass particles and may provide the opportunity to create pellets of favorable characteristics at a lower temperature compared to those made of pure wood.

Analysis of changes on substrates filling constructed wetland systems after landfill leachate treatment - FTIR study

A rapid and inexpensive method, Fourier transform infrared spectroscopy (FTIR), can be used to identify impurities and determine the functional groups responsible for the sorption of specific ions. The FTIR method has already been used in research. However, there is a lack of research on constructed wetland (CW) infill materials used to treat landfill leachate (LL). Therefore, the aim of this study was to verify the changes occurring in selected substrates (zeolite, expanded clay and bark) constituting vertical flow CW infill (VFCW) supplied with municipal LL. The principal component analysis carried out mainly showed differences in the results between the variants of the experiment with an infill of expanded clay and the others (for the values obtained at wave numbers in the range 1600-400 cm−1, in which most changes occurred). All peaks of the FTIR spectra of the pine bark filling the CW differ in location and intensity between the samples. In most cases, the stripes were elongated at exposure to 25% and 100% LL (compared to tap water). In all CW variants infill made of zeolite, peaks occurred at wave numbers within 1049-1012 cm−1, which were most likely caused by the presence of inorganic substances corresponding to clay minerals, and to silica. The FTIR spectra for zeolites, do not show large differences between the different infill samples used for LL treatment (100% LL and 25% LL). In all CW variants with expanded clay infill, peaks in the 1250-900 cm−1 wave number region, possibly indicating the presence of polysaccharides and phosphodiesters. FTIR spectroscopy has proven to be a very useful tool for rapid grade assessment determination of changes occurring on selected substrates and the identification of contaminants that remained after treatment in VFCWs fed with LL.

The enhancement of nutrients removal performance in a vertical up-flow constructed wetland system using iron-carbon substrates

The reclaimed water was usually further treated by the constructed wetland (CW) to remove nitrogen and phosphorus before it was discharged to water bodies. In this work, the iron-carbon (Fe-C) substrate and plant-based carbon source were added to the vertical up-flow CWs to enhance the denitrification of reclaimed water. It was found that the removal efficiency of nitrate (NO3--N), total nitrogen (TN) and total phosphorus (TP) in the Fe-C amended CWs were significantly increased by 20–35%, 10–25%, and 10–35%. Moreover, the plant-based carbon source also contributed to TN and TP removal. The additional substrates also reduced the emission of NO2 and CH4 from the CWs. Finally, the microbial community was analyzed to disclose the mechanism involved in the enhanced performance of CWs. The enriched hydrogenotrophic and heterotrophic denitrifiers by the Fe-C substrates and pine bark contributed to the enhanced nitrification.

Estimation of Scots pine bark biomass delivered to the wood industry in Northern Germany

Abstract Scots pine (Pinus sylvestris L.) is the most widely distributed pine species in the world. In Germany, as in many other European countries, it is a very important species both culturally and economically. Few studies have focused on bark volumes being delivered to the wood industry together with the roundwood, being potentially a valuable resource for material or energetic utilization. Therefore, logs from six different forest sites were collected and bark variables including double bark thickness (DBT) in three different categories, diameter, and bark damage (as a degree of miss-DBT) in three different categories, diameter, and bark damage (as a degree of missing bark) were measured and analyzed in order to model bark volume (Vbark) and bark mass (Mbark). The correlation analysis using Pearson’s method showed that the highest correlation coefficients were observed from the correlation between DBT and Vbark, as well as between DBT and Mbark. Also, results demonstrated that with DBT greater than 20 mm, the percentage of Vbark exceeded 20%. Finally, different linear regression models were recommended to predict Vbark and Mbark based on the other variables. The results of this study can be used in different wood industries in order to predict bark volume and bark mass of e.g. truckloads or roundwood stacks.

Ecotoxicity study of reduced-Cr(III) generated by Cr(VI) biosorption

Hexavalent chromium (Cr(VI)) is a known carcinogen in living organisms, and many studies have investigated Cr(VI) removal methods. Biosorption, one of the Cr(VI) removal methods, is dominated by chemical binding, ion exchange, physisorption, chelation and oxidation-reduction. Among these mechanisms, Cr(VI) can be removed by nonliving biomass through a redox reaction, which has been recognized as ‘adsorption-coupled reduction’. Cr(VI) is reduced to Cr(III) during biosorption, but there are no studies on the property and toxicity of the reduced-Cr(III). In this study, the harmfulness of reduced-Cr(III) was identified through assessment of mobility and toxicity in nature. Pine bark, a low-cost biomass, was used to remove Cr(VI) from aqueous solution. Reduced-Cr(III) was characterized by structural features using X-ray Absorption Near Edge Structure (XANES) spectra, mobility assessed using precipitation, adsorption and soil column test, and toxicity using radish sprouts and water flea. XANES analysis confirmed that reduced-Cr(III) has an unsymmetrical structure, and the reduced-Cr(III) showed low mobility and was virtually non-toxic, and helpful for plant growth. Our findings demonstrate that Cr(VI) biosorption technology using pine bark is a groundbreaking technology for Cr(VI) detoxification.

Particle size distribution of growing media constituents using dynamic image analysis: Parametrization and comparison to sieving

AbstractGrowing media constituents have heterogeneous particle size and shape, and their physical properties are partly related to them. Particle size distribution is usually analyzed through sieving process, segregating the particles by their width. However, sieving techniques are best describing more granular shapes and are not as reliable for materials exhibiting large varieties of shapes, like growing media constituents. A dynamic image analysis has been conducted for a multidimensional characterization of particle size distribution of several growing media constituents (white and black peats, pine bark, coir, wood fiber, and perlite), from particles that were segregated and dispersed in water. Diameters describing individual particle width and length were analyzed, then compared to particle size distribution obtained by dry and wet sieving methods. This work suggests the relevance of two parameters, FeretMAXand ChordMINdiameters for assessing particle length and width, respectively. They largely varied among the growing media constituents, confirming their non‐spherical (i.e., elongated) shapes, demonstrating the advantages of using dynamic image analysis tools over traditional sieving methods. Furthermore, large differences in particle size distribution were also observed between dynamic image analysis and sieving procedures, with a finer distribution for dynamic image analysis. The discrepancies observed between methodologies were discussed (particle segregation, distribution weighing, etc.), while describing in details methodological limitations of dynamic image analysis.

Combination of adsorption/desorption and photocatalytic reduction processes for PFOA removal from water by using an aminated biosorbent and a UV/sulfite system

Per- and polyfluoroalkyl substances (PFAS) are stable organic chemicals, which have been used globally since the 1940s and have caused PFAS contamination around the world. This study explores perfluorooctanoic acid (PFOA) enrichment and destruction by a combined method of sorption/desorption and photocatalytic reduction. A novel biosorbent (PG-PB) was developed from raw pine bark by grafting amine groups and quaternary ammonium groups onto the surface of bark particles. The results of PFOA adsorption at low concentration suggest that PG-PB has excellent removal efficiency (94.8%–99.1%, PG-PB dosage: 0.4 g/L) to PFOA in the concentration range of 10 μg/L to 2 mg/L. The PG-PB exhibited high adsorption efficiency regarding PFOA, being 456.0 mg/g at pH 3.3 and 258.0 mg/g at pH 7 with an initial concentration of 200 mg/L. The groundwater treatment reduced the total concentration of 28 PFAS from 18 000 ng/L to 9900 ng/L with 0.8 g/L of PG-PB. Desorption experiments examined 18 types of desorption solutions, and the results showed that 0.05% NaOH and a mixture of 0.05% NaOH + 20% methanol were efficient for PFOA desorption from the spent PG-PB. More than 70% (>70 mg/L in 50 mL) and 85% (>85 mg/L in 50 mL) of PFOA were recovered from the first and second desorption processes, respectively. Since high pH promotes PFOA degradation, the desorption eluents with NaOH were directly treated with a UV/sulfite system without further adjustment. The final PFOA degradation and defluorination efficiency in the desorption eluents with 0.05% NaOH + 20% methanol reached 100% and 83.1% after 24 h reaction. This study proved that the combination of adsorption/desorption and a UV/sulfite system for PFAS removal is a feasible solution for environmental remediation.