Evaluation of slow pyrolyzed wood and rice husks biochar for adsorption of ammonium nitrogen from piggery manure anaerobic digestate slurry

The Review on Adsorption and Removing Ammonia Nitrogen with Biochar on its Mechanism

“…The source of biochar with the adsorption effect to ammonia nitrogen is rich [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] . Furthermore, the different adsorption properties are demonstrated, as the biochars are made of different biomass materials [14,15] .…”

“…Ma and other scholars have found that the Freundlich equation (R 2 =0.9762) is suitable for describing the behavior of the ammonia nitrogen adsorption of biochar, and the main form is the heterogeneous adsorption of the multi molecular layer [16,24,31,32,33] .…”

“…Based on the R 2 of the Langmuir model, the fitting data have perfectly showed that the adsorption to ammonia nitrogen often occurs in monolayer. On the other hand, the R 2 of the Langmuir model is usually more than 0.95, which indicated that there is a certain degree of physical adsorption, but the chemical adsorption is more favorable because n -1 >1 [27,31,33,35] .…”

“…We can observe from it that for the adsorption data of CSBC400 to ammonia nitrogen, Freundlich adsorption isothermal equation is the best fitted one [27,28,33,36,38] .…”

“…Additionally, this trend is also related to the surface area of the adsorbent and the diffusion rate of the absorbed material. In general, assuming that the adsorption rate depends only on the surface area, the surface area of smaller particle will increase, and then dispersion path is shorten in the small adsorbent particle, because it provide a better opportunity to make the absorbed ions penetrate all internal pore structure [33,49,50] . The effect of particle size on the adsorption capacity of ammonia nitrogen has been also confirmed by the use of zeolite previously [51,52] .…”