Studies of thermal decomposition of (NH4)2Fe(SO4)2·6H2O

Sustainable synthesis of rose flower-like magnetic biochar from tea waste for environmental applications

“…The highest amount of NH 4 + was adsorbed onto SS (49.43 mg g −1 ), and the highest amount of PO 4 3− was noted onto MW (112.61 mg g −1 ). These values were significantly higher than to those obtained in the studies of Wang et al [13] (4.13 mg g −1 NH 4 + and 19.75 mg g −1 PO 4 3− ), Cai et al [42] (2 mg g −1 P), Lu et al (19.26454 mg g −1 min −1 ) [60] or Wan et al (5.21 mg g −1 for PO 4 3− [62] ) but slightly lower than Xie et al (64.90 mg g −1 NH 4 + -N [41] ) or similar to Li et al (121.25 mg g −1 P [64] ).…”

“…However, at very high pH values (>10) increased electrostatic repulsions between the negative surface of TBC and the increasingly multivalent P oxyanions (pKa 2 = 7.21, pKa 3 = 12.67) can be observed. TBC can be applied for the removal of nutrients from water, especially that natural eutrophic waters are characterized by pH from 7 to 9 and P < 1 mg L −1 [42] . Similar effect was noted in the studies of Wan et al [62] or Cai et al [42] .…”

“…TBC can be applied for the removal of nutrients from water, especially that natural eutrophic waters are characterized by pH from 7 to 9 and P < 1 mg L −1 [42] . Similar effect was noted in the studies of Wan et al [62] or Cai et al [42] .…”

“…Generally, the sorption studies indicated that over SS and TF TBC surface there were less adsorption sites for anions on the surface and PO 4 3− have to compete with NH 4 + for the free adsorption sites. It was noted in literature that biochar with relatively high alkalinity (pH 7–12) was characterized by a low anion exchange capacity (<5 c mol kg −1 ) and very limited sorption capacity towards the negatively charged anions, such as PO 4 3− [42] . The overall removal capacity for the different ions was as follows: MW: Co 2+ >Ni 2+ > PO 4 3− > NH 4 + SS: Co 2+ >Ni 2+ > NH 4 + > PO 4 3− TF: Co 2+ >Ni 2+ > NH 4 + > PO 4 3− …”

“…Apart from (un)treated wastewater, N and P source can be lost from soil, enriched when chemical fertilizers were additionally used [41] . The high level N-NH 4 + is toxic to plants, bacteria and aquatic animals [41] , whereas P is a major nutrient in soil possessing however lowest mobility and though phytoavailability [42] .…”