Tham khảo tài liệu 'progress in biomass and bioenergy production part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Recovery of Ammonia and Ketones from Biomass Wastes 289 Fig. 7. Adsorption isotherms of ammonium ions at room temperature on the adsorbent obtained by treating MAP at 378 K and 573 K Fumoto et al. 2009 . MAP MgNH4PO 6H2O Mg .-PO O Adsorbent before adsorption co cz CD Adsorbent after adsorption of ammonium ions 10 20 30 40 50 60 29 deg Fig. 8. XRD patterns of MAP and adsorbent treated at 378 K before and after the adsorption of ammonium ions Fumoto et al. 2009 . 290 Progress in Biomass and Bioenergy Production The amount of ammonium ions adsorbed on the adsorbent treated at 573 K was significantly less than that of the adsorbent treated at 378 K as shown in Fig. 7. Furthermore the experimental value was less than the calculated capacity in the case of the adsorbent treated at 573 K. The fewer nanopores and smaller surface area of the adsorbent treated at 573 K caused the lower adsorption of ammonium ions. The surface chemical properties of the adsorbent may be different between the adsorbents treated at 378 K and 573 K. Consequently the adsorbent obtained by treating MAP at 378 K was more suitable for the adsorption of ammonium ions. Recovery of ammonium ions from animal wastes The feasibility of recovering ammonia from biomass wastes was demonstrated using cow urine. The urine was pretreated under a hydrothermal condition at 573 K for 1 h to convert nitrogen compounds in the urine into ammonium ions. The pH was adjusted to by adding sodium hydroxide and the adsorbent treated at 378 K was added to the pretreated urine at an adsorbent to urine weight ratio of 1 10. The nitrogen concentration was analyzed after 1 h of stirring. Recovery yield mol -N Impurities deposition mol mol C N S N Pretreated urine 0 Untreated urine Table 2. Nitrogen recovery yield and impurities deposited on the adsorbent from urine solution Fumoto et al. 2009 . Table 2 lists the nitrogen recovery yield and the impurities deposited on the adsorbent from the
