Rapid removal of triazine pesticides by P doped biochar and the adsorption mechanism

Spray-freeze-drying (SFD) is an unconventional freeze drying
technique that produces uniquely powdered products whilst
still including the benefits of conventionally freeze dried products.
SFD has potential applications in high value products due
to its edge over other drying techniques in terms of product
structure, quality, and the retention of volatiles and bioactive
compounds. In cases where other drying techniques cannot
provide these product attributes, SFD stands out despite the
costs and complexities involved. This paper outlines the principles,
methods, significant process parameters, particle
morphology and quality aspects of SFD. Recent developments
in this technique are reviewed including ultrasonic sprayfreeze-
drying, the application of computational fluid dynamics
and mathematical modelling, and the incorporation of new
technologies to improve product quality. In addition, the advantages,
limitations and future scope for research in the field
of SFD are discussed.

Spray-freezedrying: A novel process for the dryingof foods and bioproducts

Recent developments in biomass-derived carbon as a potential sustainable material for super-capacitor-based energy storage and environmental applications

The use of design of experiments for the evaluation of the production of surface rich activated carbon from sewage sludge via microwave and conventional pyrolysis

Surface modification of phosphoric acid activated carbon by using non-thermal plasma for enhancement of Cu(II) adsorption from aqueous solutions

Two kinds of pinewood sawdust activated carbon adsorbents were prepared by fast activation with H3PO4 in a spouted bed, and the application in adsorption of copper ions was investigated. With only 3 min of activation time, the BET surface area of activated carbons reached 1537.5 m2/g for impregnation mass ratio of H3PO4 to sawdust at 1:1 and activation temperature of 500 °C (IR1-500), whereas it was 1750.7 m2/g for the impregnation ratio at 4:1 and activation temperature of 800 °C (IR4-800). The pseudo second-order reaction kinetics well describes the experimental adsorption of copper ion in this study, indicating chemisorption dominated in the process. By the C1s spectrum, activated carbons from IR1-500 contained more carboxyl groups (-COOH) and carbonyl groups (C=O), which played an important role in copper ions adsorption. In addition, it was found that the P-containing groups (metaphosphates) also involved in the adsorption of copper ion.

Adsorption kinetics and mechanisms of copper ions on activated carbons derived from pinewood sawdust by fast H3PO4 activation

Droplet collision with cold solid surfaces is a fundamental phenomenon observed in low-temperature processes. In this work, a single droplet impacting on a cold surface was investigated by analyzing changes in droplet shape and dimensions recorded with a high-speed camera. At low surface temperatures (−5°C and −10°C), the droplet spreads in a very short period upon impact and then retracts, but to a diameter larger than that at room temperature, dependent on surface material property and texture. Higher impact velocity expands the spreading diameter and promotes the retraction to an extent, but at lower surface temperature (i.e., −20°C) the droplet is quickly frozen with smaller change in diameter on the stainless-steel surface rather than on the Teflon plate. The change of droplet shape upon impacting on a 30° inclined surface was also studied. The surface texture of the stainless-steel plate produced by the polishing process has an obvious effect on the droplet dimension retraction. A proper selection o...

Characteristics of Single Droplet Impact on Cold Plate Surfaces

Activated carbons were produced from waste pine wood sawdust using fast activation with H3PO4 in a spouted bed. In this study, activation temperature was set as 800 °C, and activation time ranged from 1 to 15 min. Experimental results show that sawdust impregnated with higher mass ratio of H3PO4 would be agglomerated in spouted bed, and difficult to fluidize. Therefore, an amount of quartz sand was added to assist for good fluidization. Fluidization of particle can improve the BET surface area or micropore volume of activated carbons. High BET surface area activated carbons can be obtained with activation time of only 1–5 min by combining the fluidization and H3PO4 fast activation. The obtained activated carbons contained developed pore structure and abundant surface functional groups (carboxyl, carbonyl and P-containing groups) by SEM–EDS, FTIR and XPS techniques. The particles of impregnation ratio of 1:1 can achieve fluidization without adding the quartz sand, which was convenient for experimental operation and even industrial production, and the BET surface area can reach more than 1000 m2/g in activation time of only 5 min.

Preparation and characterization of high surface area activated carbon from pine wood sawdust by fast activation with H 3 PO 4 in a spouted bed

The disposal of waste plastics is a major environmental issue all over the world. As an alternative to disposal that also adds value to the waste product, polycarbonate particles were used as model waste plastic material, mixed with sodium hydroxide and then pyrolyzed at 773 K to produce activated carbon. Activated carbon has numerous industrial applications, including use as adsorbents in adsorption heat pumps and several environmental applications. Activated carbon obtained upon pyrolysis was characterized by determining its adsorption capacity for liquid nitrogen and water vapor. The effects of the key process variables, i.e., chemical ratio and activation time, on micropore development and water adsorptivity were evaluated by response surface methodology. The quadratic models were found to be satisfactory in describing their performance. Based on the contour plots, activated carbon with a maxima of surface area and micropore volumes can be produced at an optimal level of chemical ratio along with longer activation time. The water adsorptivity generally has less difference at low relative pressures, but inflexion of water adsorptivity occurs at a relative pressure of P/P
 0 ≈ 0.4. The optimized water adsorptivity in the operating pressure range of adsorption heat pumps (P/P
 0 = 0.11–0.38) can exceed 0.24 kg/kg.

Preparation of activated carbons from polycarbonate with chemical activation using response surface methodology

Soy sauce residue needs drying to avoid fermentation and oxidation during storage and transportation, and its reutilization as a useful resource is expected. Superheated steam drying was applied to investigate the effects of drying conditions on the drying characteristics and the content changes of salt and protein. The results showed that the inversion temperature was about 130°C, beyond which superheated steam drying was faster than hot air-drying. The drying time approaching equilibrium moisture content was reduced with elevated drying temperature as well as higher steam mass flow rate in the present experimental conditions. The effect of bed thickness on drying time was not obvious when drying temperature increased. Interestingly, the salt content of soy sauce residue could be decreased by 34.8% due to condensate water in the initial drying period (wetting), while protein content had no significant loss (p < 0.05) after superheated steam drying.

Qing Xu

Papers

Adsorption kinetics and mechanisms of copper ions on activated carbons derived from pinewood sawdust by fast H3PO4 activation

Characteristics of Single Droplet Impact on Cold Plate Surfaces

Preparation and characterization of high surface area activated carbon from pine wood sawdust by fast activation with H 3 PO 4 in a spouted bed

Preparation of activated carbons from polycarbonate with chemical activation using response surface methodology

Drying of soy sauce residue in superheated steam at atmospheric pressure