Nitrate removal from water by spherical sponge iron prepared by H2 reduction.
Junguo Li, Fan Wang, Feng YanPing, Li ShouZhang, Xiaolin Yan · Environmental Science & Technology · 2010
Porous spherical sponge iron with 1mm～5mm diameter was prepared by mini-pellet sintering integrated with H2 direct reduction. Static state experiment was done to investigate nitrate removal efficiency from polluted water by spherical sponge iron and to explore nitrate reduction reaction kinetics. Results indicated that initial pH in solution had significant influence on nitrate removal rate. Nitrate removal rate decreased with increasing of initial pH when pH value was below 3,while increased when pH value was above 3. Nitrate removal rate increased with increasing of initial nitrate concentration when it was below 10mg-N/L,with concentration of nitrate residues about 0.4mg-N/L. When initial nitrate concentration was higher than 20mg-N/L,nitrate removal rate decreased slightly with increasing of nitrate concentration. Nitrate reduction by spherical sponge iron appeared to be the first order reaction,with the reaction order 0.970～1.378 and apparent reaction rate constant 0.314h-1～0.536h-1. Major product of nitrate reduction was ammonium. Molecule-state ammonia could escape from water solution because pH value increased along with the reduction reaction carrying through.