Particle Size Enlargement Research Articles

Tumor‐specific and photothermal‐augmented chemodynamic therapy by ferrocene‐carbon dot‐crosslinked nanoparticles

AbstractExtensive research have been devoted to the exploration of multifunctional theranostic agents for cancer, but the poor tumor specificity and unsatisfactory treatment efficacy are some of the critical obstacles for their clinical translations. Herein, ferrocene‐carbon dot‐crosslinked nanoparticles (Fc‐CD NPs) were designed and fabricated for achieving highly specific and photothermal‐augmented chemodynamic therapy (CDT). The Fc‐CD NPs were found not only to inherit the immanent fluorescence, photoacoustic, and photothermal properties of carbon dots (CDs), but also be endowed with CDT that could occur selectively in tumor microenvironment (TME) due to the presence of Fc for triggering Fenton reaction. Moreover, the enlarged particle size of Fc‐CD NPs facilitated their effective accumulation at tumor sites, thus realizing great improvement for antitumor treatment outcomes. Once docking at tumor and being exposed to 660 nm laser irradiation, significantly amplified CDT effect of Fc‐CD NPs was observed due to heat‐accelerating generation of reactive oxygen species (ROS). More interestingly, since the produced ROS could in turn alleviate the thermal‐resistance of photothermal therapy (PTT), the therapeutic efficiency of integrated PTT and CDT was synergized to the maximum extent. This study on the one hand provides a facile approach to fabricate CDs‐based multifunctional theranostic nanoplatform with enhanced tumor accumulation and specificity, on the other hand emphasizes the merits of synergizing mutually beneficial therapeutic modalities for more efficient cancer therapy.

Aerodynamic size-resolved composition and cloud condensation nuclei properties of aerosols in a Beijing suburban region

Abstract. The size-resolved physiochemical properties of aerosols determine their atmospheric lifetime, cloud interactions and the deposition rate on the human respiratory system; however most atmospheric composition studies tend to evaluate these properties in bulk. This study investigated size-resolved constituents of aerosols on mass and number basis, and their droplet activation properties, by coupling a suite of online measurements with an aerosol aerodynamic classifier (AAC) based on aerodynamic diameter (Da) in Pinggu, a suburb of Beijing. While organic matter accounted for a large fraction of mass, a higher contribution of particulate nitrate at larger sizes (Da>300 nm) was found under polluted cases. By considering the mixing state of refractory-black-carbon-containing particles (rBCc) and composition-dependent densities, aerosols including rBCc were confirmed to be nearly spherical at Da>300 nm. Importantly, the number fraction of rBCc was found to increase with Da at all pollution levels. The number fraction of refractory black carbon (rBC) is found to increase from ∼3 % at ∼90 nm to ∼15 % at ∼1000 nm, and this increasing rBC number fraction may be caused by the coagulation during atmospheric ageing. The droplet activation diameter at a water supersaturation of 0.2 % was 112±6 and 193±41 nm for all particles with Da smaller than 1 µm (PM1) and rBCc respectively. As high as 52±6 % of rBCc and 50±4 % of all PM1 particles in number could be activated under heavy pollution due to enlarged particle size, which could be predicted by applying the volume mixing of substance hygroscopicity within rBCc. As rBCc contribute to the quantity of aerosols at larger particle size, these thickly coated rBCc may contribute to the radiation absorption significantly or act as an important source of cloud condensation nuclei (CCN). This size regime may also exert important health effects due to their higher deposition rate.

Programmed Stimuli-Responsive Carbon Dot-Nanogel Hybrids for Imaging-Guided Enhanced Tumor Phototherapy.

For harmonizing the contradiction of nanotheranostic agents between enhanced tumor accumulation and penetration, efficient cell internalization and fast elimination are key tactics for promoting their clinical applications. Herein, programmed stimuli-responsive poly(N-isopropylacrylamide)-carbon dot (PNIPAM-CD) hybrid nanogels are designed to address the abovementioned conflicts. The enlarged particle size of PNIPAM-CDs enables one to effectively improve their accumulation at tumor sites. Once the hybrid nanogels are docked in tumors and exposed to deep-red-light (660 nm) irradiation, heat and reactive oxygen species (ROS) are generated from the CDs, consequently activating photothermal therapy (PTT) and photodynamic therapy (PDT) effects and meanwhile inducing partial degradation of PNIPAM-CDs for deep tissue penetration. Further, enhanced cellular internalization of the functional components can be achieved owing to the pH-responsive charge reversal and temperature-dependent hydrophilic/hydrophobic conversion characteristics of PNIPAM-CDs. Finally, the overexpressed glutathione (GSH) in tumor cells would trigger further cleavage of the partially degraded hybrid nanogels, which is beneficial for their rapid clearance from the body. This work not only proposed a novel strategy to fabricate nanotheranostic agents using just a single functional component (i.e., the versatile CDs) to simplify the preparation process but also achieved effective delivery of agents into tumor cells by overcoming the multiple biological barriers to enhance therapeutic efficacy and decrease side effects.

Mechanical properties and strengthening mechanism of silty sands stabilized with steel slag-based geopolymer binder

Geopolymer binder has the advantages of early strength, fast solidification, high volume stability, and low permeability. It is beneficial to improve the mechanical performance of silty sands, saving cement consumption and being environmentally friendly. However, the strength improvement of silty sand stabilized with steel slag-based geopolymer was significantly controlled by their material composition and technical parameters. This study conducted a series of unconfined compression tests to investigate the material composition of steel slag-based geopolymer binders and their reasonable mixing ratio for silty sand stabilization. The optimum mixing ratio of precursor (steel slag) to alkaline activator (the combination of Na₂SiO₃ and CaO) and the optimum dosage of steel slag-based geopolymer for silty sand stabilization were explored. The strengthening mechanism of geopolymer-stabilized silty sands was discussed based on microstructural images and elemental concentrations of primary components observed by SEM and EDS. The results show that when the mass ratio of Slag : Na₂SiO₃ : CaO was 80:35:21, and the steel slag-based geopolymer material was 15%, the silty sand could achieve the best mechanical performance improvement. The microstructural characteristics of geopolymer-stabilized silty sands at different curing ages illustrated that the compactness and integrity of silty sand structures were enhanced over the curing age. The improving cementitious contact among particles and enlarging particle size was responsible for the strength improvement of silty sand. This research can provide a reference for applying steel slag-based geopolymer in silty sand stabilization in engineering practices.

Enhanced nutrient removal from stormwater runoff by a compact on-site treatment system

Efficient and space-saving technologies for on-site treatment of stormwater runoff are required to control water pollution in the urban surface. The intermittent nature of stormwater runoff and extremely limited land available greatly hindered the application of current wastewater treatment technologies, and thus synchronous removal of multiple contaminants (especially for nutrient) efficiently was failed by current processes. In this study, a new compact CFFA treatment system, consisting of coagulation, flocculation, filtration and ammonium ion exchange units, was constructed for on-site treatment of stormwater runoff based on batch test optimization and pilot-scale test verification. The coagulation process effectively aggregated particles and precipitated phosphorus by dosing Al2(SO4)3, while flocculation using anionic polyacrylamide further enlarged particle size for efficient micromesh filtration. The dynamic micromesh filtration obtained turbidity and phosphorus removal efficiencies comparable to 30 min gravity settling with greatly smaller footprint. Ion exchange by zeolite showed higher exchange capacity owing to lower initial ammonium nitrogen concentration in the stormwater runoff. The pilot-scale experiments with treatment capacity of 1 L/s showed that the CFFA treatment system achieved synchronous removal of particles (97.2%), nitrogen (79.7%), phosphorus (95.0%) and organic matters (83.3%) efficiently within short hydraulic retention time of 0.35 h, yielding effluent with chemical oxygen demand, suspended solids, total phosphorus and total nitrogen of 38.7, 7.80, 0.22 and 2.80 mg/L, respectively. The CFFA treatment system had the highest pollutant removal loads compared to reported runoff treatment processes in literatures, and was well suited to on-site treatment of stormwater runoff with high space utilization efficiency.

Hazardous characteristics and transformation mechanism in hydrometallurgical disposing strategy of secondary aluminum dross

To further understand the transformation behavior of active phase during hydrometallurgical disposal, and then provide theoretical guidance for the recovery and utilization of secondary aluminum dross (SAD) valuable resource, factors affecting the harmlessness efficiency, transformation behavior of active phase and kinetics of the leaching process investigated. The results indicate that harmless residues can be achieved when treated at the conditions of liquid-solid ratio of 5, leaching temperature of 80 ℃, extracting time of 4 h and SAD particle size less than 2000 μm. The capacity of emissing gas, which is composed of small amount of ammonia, methane and dominant proportion of hydrogen, increases with the enlargement of particle size. The small particles with relative high proportion of aluminum carbide and aluminum nitride tend to release more methane and ammonia. During hydrometallurgical process, the active substances generate intermediate phase of aluminum hydroxide spontaneously, cover on the interface of SAD particles, and then react with acidic or alkaline medium. The hydrolysis of active phases and the dissolution of fluoride follow the Avrami-Erofeyev Model and internal diffusion model, respectively, while the rate both of them are all controlled by diffusion. This work is hopeful for providing a deep insight into disposal and comprehensive utilization of SAD.

Enhanced sludge dewaterability via ozonation catalyzed by sludge derived biochar loaded with MnFe2O4: Performance and mechanism investigation

In order to develop an efficient and environmental-friendly alternative for enhancing dewatering performance of waste activated sludge (WAS), the sludge derived biochar loaded with MnFe2O4 (MnFe2O4@SBC) was firstly prepared for catalyzing ozonation of sludge. The optimal condition was determined to be pH = 6, O3 dosage = 60 mg/g VS and MnFe2O4@SBC dosage = 600 mg/g VS, under which the capillary suction time (CST) and specific resistance to filtration (SRF) of WAS declined from 98.3 ± 1.0 s and 1.1 ± 0.03 × 1014 m/kg to 18.3 ± 0.8 s and 0.32 ± 0.03 × 1014 m/kg, respectively. The water content (Wc wt.%) of sludge cake declined from 87.1 ± 0.98% to 68.1 ± 0.87%. The mechanism for enhanced dewatering performance of WAS by MnFe2O4@SBC was systematically clarified. Firstly, the circulation of valence states for Fe and Mn on the surface of MnFe2O4@SBC was found promoting the conversion of O3 into highly active free radicals and the generation of hydroxyl radicals (·OH). Secondly, the density functional theory (DFT) calculation firstly manifested that O3 molecules were easier to be activated and dissociated into ·OH groups on the surface of MnFe2O4 phase. With the above promotion of ·OH generation, the inner part of sludge flocs especially the protein in extra-cellular polymers (ECPS) was destructed strongly, with significant release of bound water and the decrease in water bound energy. The organic biopolymers with negative charges were diminished followed by the increased zeta potential and enlarged particle size, resulting in the enhanced dewatering performance of WAS. This study illustrated the rationality and validity of the new strategy for enhanced sludge dewatering in both practice and theory, shedding light on the further development of sludge dewatering technology.

Effects of Scale-Up and Impeller Types on Spherical Agglomeration of Dimethyl Fumarate

Spherical agglomeration (SA) allows for intensifying a crystallization process through simultaneous particle size enlargement and process efficiency enhancement, without a compromise between bioavailability and processability of active pharmaceutical ingredients (APIs). Inefficient collision intensity may encounter during scale-up of an SA process, while mixing intensity and flow patterns do play critical roles especially in a batchwise stirred tank. In the present study, the scalability of an SA process by operating at all the same configurations of different scales, 0.5, 2, and 10 L, using a common one-layered impeller with four pitched blades was examined through the use of dimethyl fumarate as a model API. Insights into the guidelines for scaling up of the SA process are also given. Furthermore, the effects of impeller types, including the one-layered impeller, the two-layered impeller with four pitched blades, and the maxblend impeller, on the size, size distribution, and roundness of dimethyl fumarate agglomerates were investigated carefully.

On mode II fracture toughness of sintered silver based on end-notch flexure (ENF) test considering various sintering parameters

Shearing fracture toughness of sintered silver (Ag) is an important parameter to reflect its shearing resistance. In this paper, mode Ⅱ fracture toughness of sintered Ag is investigated based on end-notched flexure (ENF) test. Various sintering conditions are adopted to study the effect of sintering parameters on mode Ⅱ fracture toughness of sintered Ag. The results show that the fracture toughness of sintered Ag increases rapidly with the increase of sintering temperature and holding time. Three shearing crack types are confirmed, i.e., interface delamination, tunneling cracking and cohesive cracking, and the cracking type varies from “interface delamination” or “tunneling cracking” to “cohesive cracking” with the increase of sintering temperature and holding time. An empirical equation is proposed to predict the mode II fracture toughness of sintered Ag. Through statistics investigation on microstructure evolution, it is found that the shearing fracture toughness heightens with enlargement of the Ag particle size, increase of the particle shape form factor, and decrease of the porosity. This study provides an alternative method to rigorously evaluate the shearing fracture toughness of die-attach materials in electronics packaging.

Early‐age behavior and mechanical properties of cement‐based materials with various types and fineness of recycled powder

AbstractRecycled powder (RP) that includes recycled paste powder (RPP), recycled mortar powder (RMP), and recycled concrete powder (RCP) is an eco‐friendly alternative binder. This work investigated the influence of RP types and fineness on early‐age behavior and mechanical strength of cement‐based materials. The results show that substituting RP for cement causes the reduction of new hydration products in cement‐based materials. The blended RP decreases the fluidity of paste mixture, and the fluidity of paste including fine RPP is lower than that of paste including fine RMP and RCP; moreover, the fluidity increases following the growth of RP particle size. Incorporating fine RPP shortens the setting time of cement‐based materials, while the setting time is prolonged as RMP and RCP incorporate; in addition, the enlarged particle size of RP prolongs the setting time. The drying shrinkage increases following the increasing replacement ratio of RPP. Incorporating less proportion of fine RMP and RCP lessens the drying shrinkage of paste, while the drying shrinkage increases after coarse or high‐volume RMP and RCP substituting. The maximum shrinkage of paste including 30% fine and coarse RCP is 3.4% and 7.3% higher than that of plain paste. Substituting fine RP for less dosage of cement has less impact on the mechanical strength of its newmade mortar, while the mechanical strength markedly decreases after high‐volume or coarse RP substituting. The compression strength of mortar including 30% fine and coarse RCP is 22.2% and 35.1% lower than that of plain mortar.

Changes in Particle Size, Sedimentation, and Protein Microstructure of Ultra-High-Temperature Skim Milk Considering Plasmin Concentration and Storage Temperature.

Age gelation is a major quality defect in ultra-high-temperature (UHT) pasteurized milk during extended storage. Changes in plasmin (PL)-induced sedimentation were investigated during storage (23 °C and 37 °C, four weeks) of UHT skim milk treated with PL (2.5, 10, and 15 U/L). The increase in particle size and broadening of the particle size distribution of samples during storage were dependent on the PL concentration, storage period, and storage temperature. Sediment analysis indicated that elevated storage temperature accelerated protein sedimentation. The initial PL concentration was positively correlated with the amount of protein sediment in samples stored at 23 °C for four weeks (r = 0.615; p < 0.01), whereas this correlation was negative in samples stored at 37 °C for the same time (r = −0.358; p < 0.01) due to extensive proteolysis. SDS-PAGE revealed that whey proteins remained soluble over storage at 23 °C for four weeks, but they mostly disappeared from the soluble phase of PL-added samples after two weeks’ storage at 37 °C. Transmission electron micrographs of PL-containing UHT skim milk during storage at different temperatures supported the trend of sediment analysis well. Based on the Fourier transform infrared spectra of UHT skim milk stored at 23 °C for three weeks, PL-induced particle size enlargement was due to protein aggregation and the formation of intermolecular β-sheet structures, which contributed to casein destabilization, leading to sediment formation.

Improving settleability and dewaterability of Friedel's salt for chloride removal from saline wastewater

As an effective method for chloride removal from saline wastewater, Friedel's salt (FS) precipitation generates high concentration of precipitate requiring efficient solid-liquid separation. Effects of temperature, reaction time, polyacrylamides (PAM) type and dosage on settleability and dewaterability of FS precipitate were investigated to explore improving strategies for separation by using actual flue gas desulfurization wastewater. Raw FS precipitate was difficult to separate by gravity settling and mechanical dewatering owing to their small particle size and high solid concentration. Anionic PAM with higher hydrolysis degree and molecular weight greatly improved settleability and enlarged particle size of FS. The composition and crystal structure of FS varied with reaction temperature. Increasing temperature to 40 °C obtained the highest chloride removal, and improved settleability because layers spacing of FS decreased. FS precipitate was gradually broken down to Ca3Al2(OH)12 and NaCl at temperature above 60 °C. Prolonging reaction time enhanced chloride removal by adsorption effects, and improved settleability by facilitating crystals growth and aging. The 0.5 m3/h pilot-scale experiment confirmed that the FS precipitation process was operated stably with improved settleability and dewaterability of precipitate by dosing PAM and elevating temperature. Techno-economic analysis showed that 37 °C was optimal for chloride removal and solid-liquid separation.

Optimization of Microwave-Assisted Alkali Pretreatment for Enhancement of Delignification Process of Cocoa Pod Husk

In this study, the optimization of microwave-assisted alkaline (MAA) pretreatment is performed to attain the optimal operating parameters for the delignification of cocoa pod husk (CPH). The MAA performance was examined by heating the CPH solid with different particle sizes (60–120 mesh) and NaOH solution with a different sample to a solvent (SS) ratio (0.02–0.05 g/L), for short irradiation time (1–4 min). Box-Behnken Design (BBD) was utilized to optimize the percentage of lignocellulose composition changes. The results show that by enlarging particle size, the content of lignin and cellulose decreased while hemicellulose increased. By prolong irradiation time, the content of lignin and hemicellulose decreased while cellulose elevated. On the other hand, increasing the SS ratio was not significant for hemicellulose content changes. From FTIR and SEM characterization, the MAA drove the removal of lignin and hemicellulose of CPH and increased cellulose slightly. Supported by kinetic study which conducted in this work, it was exhibited that MAA pretreatment technology is an effective delignification method of CPH which can tackle the bottleneck of its commercial biofuel production. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Cellulose derivatives agglomerated in a fluidized bed: Physical, rheological, and structural properties

Understanding the agglomeration of cellulose derivatives is crucial for the production of instant gum-based food thickeners. In the present study, physical, rheological, and structural properties of agglomerated water-soluble cellulose gums (CGs), such as carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC), and methylcellulose (MC), were investigated at different concentrations of maltodextrin (MD) as a binder for fluidized-bed agglomeration. Among the CG agglomerates in the presence of MD, CMC exhibited better flowability and lower cohesiveness, showing lower Carr index and Hausner ratio values. The MC agglomerates with 20% MD exhibited higher porosity than the other CGs due to the size enlargement of MC particles, which was confirmed via scanning electron microscopy images and size distribution profiles. The dynamic moduli of the CG agglomerates were significantly decreased by the addition of MD and also decreased with increasing MD concentration. The tan δ values of the agglomerates increased with increasing MD concentration, indicating the enhancement of their viscous properties. These results suggest that the physical, rheological, and structural properties of cellulose derivatives with different types of CG can be greatly influenced by their agglomerate growths during fluidized-bed agglomeration of particles with the different concentrations of MD binder.

Population Balance and CFD Simulation of Particle Aggregation and Growth in a Continuous Confined Jet Mixer for Hydrothermal Synthesis of Nanocrystals

Population balance and computational fluid dynamics models are built and integrated to carry out a simulation study of the reactive crystallisation process in a confined jet mixer (CJM) for the continuous flow synthesis of TiO2 nanoparticles at a supercritical water condition. In the population balance model, the crystal growth in size is modelled as being due to combined nanocrystal aggregation as well as surface growth. A free molecular model is used to predict the particle aggregation. The performance of the combined aggregation and surface growth models is compared with models that only consider surface growth as the only mechanism for particle size enlargement. It was found that the combined model gives a more accurate prediction of particle size distribution.

Frictional performance of ostrich (Struthio camelus) foot sole on sand in all directions.

To study the ostrich (Struthio camelus) foot sole with an irregular surface and papillae, we designed a multi-angle device to measure its friction properties on sand. The observed macro- and micro-structures of the ostrich foot sole intensified friction by tightly gripping sand particles. The sliding friction of the ostrich foot on a single-layer sand board increased with the enlarging particle size. A loose sand all-direction test showed that the coefficient of friction (COF) of the ostrich foot sole was higher than that of the nonpapillary foot. The COF of the ostrich foot sole minimized to 0.30 at 0° and maximized to 0.61 at 180°, and that of the nonpapillary foot minimized to 0.23 at 300° and maximized to 0.54 at 180°, suggesting the ostrich papillae exerted a friction effect. Significant differences in COF were observed among the ranges 10°-40°, 90° and 120°-350°, indicating the papillae can steadily enhance the frictional performance. This study provides an important theoretical basis for the design of frictional robots for deep space exploration and other soft media.

Polymer-assisted modification of metal-organic framework MIL-96 (Al): influence of HPAM concentration on particle size, crystal morphology and removal of harmful environmental pollutant PFOA

A new synthesis method was developed to prepare an aluminum-based metal organic framework (MIL-96) with a larger particle size and different crystal habits. A low cost and water-soluble polymer, hydrolyzed polyacrylamide (HPAM), was added in varying quantities into the synthesis reaction to achieve >200% particle size enlargement with controlled crystal morphology. The modified adsorbent, MIL-96-RHPAM2, was systematically characterized by SEM, XRD, FTIR, BET and TGA-MS. Using activated carbon (AC) as a reference adsorbent, the effectiveness of MIL-96-RHPAM2 for perfluorooctanoic acid (PFOA) removal from water was examined. The study confirms stable morphology of hydrated MIL-96-RHPAM2 particles as well as a superior PFOA adsorption capacity (340 mg/g) despite its lower surface area, relative to standard MIL-96. MIL-96-RHPAM2 suffers from slow adsorption kinetics as the modification significantly blocks pore access. The strong adsorption of PFOA by MIL-96-RHPAM2 was associated with the formation of electrostatic bonds between the anionic carboxylate of PFOA and the amine functionality present in the HPAM backbone. Thus, the strongly held PFOA molecules in the pores of MIL-96-RHPAM2 were not easily desorbed even after eluted with a high ionic strength solvent (500 mM NaCl). Nevertheless, this simple HPAM addition strategy can still chart promising pathways to impart judicious control over adsorbent particle size and crystal shapes while the introduction of amine functionality onto the surface chemistry is simultaneously useful for enhanced PFOA removal from contaminated aqueous systems.

Glycine significantly enhances bacterial membrane vesicle production: a powerful approach for isolation of LPS-reduced membrane vesicles of probiotic Escherichia coli.

SummaryBacterial membrane vesicles (MVs) have attracted strong interest in recent years as novel nanoparticle delivery platforms. Glycine is known to induce morphological changes in the outer layer of bacteria. We report here that glycine dramatically facilitates MV production in a flagella‐deficient mutant of the non‐pathogenic probiotic Escherichia coli strain Nissle 1917. Supplementation of culture medium with 1.0% glycine induced cell deformation at the early exponential phase, eventually followed by quasi‐lysis during the late exponential to stationary phase. Glycine supplementation also significantly increased the number of MVs with enlarged particle size and altered the protein profile with an increase in the inner membrane and cytoplasmic protein contents as compared to non‐induced MVs. Of note, the endotoxin activity of glycine‐induced MVs was approximately eightfold or sixfold lower than that of non‐induced MVs when compared at equal protein or lipid concentrations respectively. Nevertheless, glycine‐induced MVs efficiently induced both immune responses in a mouse macrophage‐like cell line and adjuvanticity in an intranasal vaccine mouse model, comparable to those of non‐induced MVs. We propose that the present method of inducing MV production with glycine can be used for emerging biotechnological applications of MVs that have immunomodulatory activities, while dramatically reducing the presence of endotoxins.

Fusing of Silver Nanoparticles at Room Temperature Using Halide Solutions for Conductive Inks

Fusing of silver (Ag) nanoparticles synthesized in an aqueous system was observed at room temperature using halide solutions. The as-synthesized Ag nanoparticles have an average diameter of about 24 nm. After dispersing the Ag nanoparticles in a halide solution, a significant increase in particle size to about 188-197 nm was observed. The enlargement of particle size was accompanied by the increase in conductivity of the Ag nanoparticle ink. The resistance was reduced from 110 kiloohms to 35 and 9.3 ohms for the as-prepared and sintered Ag nanoparticles using NaBr and NaCl solution, respectively.

Experimental Bench-Scale Study of Residual Biomass Syngas Desulfurization Using ZnO-Based Adsorbents.

Dry-bed adsorptive desulfurization of biomass-based syngas with a low- to medium sulfur content using ZnO was studied as an alternative to conventional wet-scrubbing processes for a small- to medium-scale biomass-to-liquid process concept. Following laboratory-scale long-term H2S breakthrough experiments in a previous study, desulfurization tests were scaled-up to bench-scale with actual bio-syngas to verify the lab-scale results under more realistic process conditions. A desulfurization unit was constructed and connected to a steam-blown atmospheric pilot-scale fluidized bed gasifier. Two successful 70+ h test campaigns were conducted with H2S removal below the breakthrough limit using full-sized ZnO adsorbent particles. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy elemental analysis, and Brunauer–Emmett–Teller (BET) surface area characterization of the fresh and spent adsorbent pellets were performed. SEM micrographs displayed the outward enlarging particle size in the sulfided layer. Characterization showed significant core–shell sulfidation behavior with a few hundred micron-thick sulfided layer leaving the majority of ZnO unutilized. Adsorbents lost most of their porosity in use, which was evident from BET surface area results. Simultaneous COS removal was found possible by the hydrolysis reaction to H2S. Furthermore, evidence of minor chlorine adsorption was found, thus highlighting the need for a dedicated HCl removal step upstream of desulfurization.