Activated Carbons for Water Treatment Prepared by Phosphoric Acid Activation of Hydrothermally Treated Beer Waste

Abstract

Activated carbons were produced by chemical activation of hydrothermally carbonized (HTC) beer waste, with phosphoric acid as the activation agent. The activation was optimized within a full factorial design, using the outcome of 19 different experiments. Four different parameters (concentration of the acid, activation time, activation temperature, flow rate) were analyzed with respect to their influence on the median pore size. The concentration of H3PO4 had a strong positive effect on the median pore size. The specific surface areas of these activated carbons were ∼1000 m2/g, which compared well commercially available activated carbons. The activated carbons had mostly large pores with a size of ∼4 nm, and a significant amount of acid surface groups. Scanning electron microscopy (SEM) revealed that the morphology of the HTC beer waste changed significantly after the chemical activation. The capacity to adsorb methylene blue from aqueous solutions was 341 mg/g, for one of the activated carbons at pH 7. A Langmuir model described the uptake of the dye quite well, which suggested a homogeneous adsorption of Methylene Blue (MB).

Valorization of Food and Agricultural Waste: A Step towards Greener Future

“…Phosphoric acid has the ability to penetrate through the plant matrix and cause swelling of the cell followed by dissolution of biomass. It also chemically modifies the biomass to produce new polymeric structure which gives thermal resistance to the material …”

Sorption of hydrophobic organic compounds to a diverse suite of carbonaceous materials with emphasis on biochar

“…In addition, increasing production temperature leads to increasing sorbent surface area and pore volume (James et al, 2005). Exceedingly high temperatures (>800 C) in combination with oxidizing activation chemicals have been shown to result in collapse of the pore structure and much lower surface area, porosity and thus sorption (Hao et al, 2014).…”

Physically (CO2) activated hydrochars from hickory and peanut hull: preparation, characterization, and sorption of methylene blue, lead, copper, and cadmium

“…Hydrochars oen have high VOC contents that may not be removed through washing. [15][16][17][18] While several studies have examined the sorptive properties of hydrochar and activated hydrochars (AHCs) for various contaminants, 19,20 few have examined the effects of activation conditions on AHC physicochemical properties and its resulting sorption ability. In addition, the low ash content of hydrochar makes it a more attractive option for activation than char created through dry pyrolysis.…”