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Table 1 Chemical reaction in Zn2 +-HS- -e--H2O system

From: Surface stoichiometry of zinc sulfide and its effect on the adsorption behaviors of xanthate

(1) Acid-base reactions Log K No.
H+ + HS- <=> H2S 6.99 (1)
H+ + HS- <=> H2S(g) 7.99 (2)
HS- <=> H+ + S2- -19.0 (3)
H2O <=> H+ + OH- -14.00 (4)
Zn2+ + 2 HS- <=> Zn(HS)2 12.82 (5)
Zn2+ + 3 HS- <=> Zn(HS)3- 16.1 (6)
Zn2+ + 4 HS- <=> Zn(HS)42- 14.64 (7)
Zn2+ + 2 H2O <=> 2 H+ + Zn(OH)2 -16.4 (8)
Zn2+ + 3 H2O <=> 3 H+ + Zn(OH)3- -28.2 (9)
Zn2+ + 4 H2O <=> 4 H+ + Zn(OH)4- -41.3 (10)
2 Zn2+ + 6 H2O <=> 6 H+ + Zn2(OH)62- -54.3 (11)
2 Zn2+ + H2O <=> H+ + Zn2OH3+ -9.0 (12)
4 Zn2+ + 4 H2O <=> 4 H+ + Zn4(OH)44+ -27.0 (13)
Zn2+ + H2O <=> H+ + ZnOH+ -7.5 (14)
Zn2+ + 2 HS- <=> H+ + ZnS(HS)- 6.84 (15)
Zn2+ + 3 HS- <=> H+ + ZnS(HS)22- 6.15 (16)
(2)Redox reactions
2 H+ + 2e- <=> H2 -3.15 (17)
2 H+ + 2e- <=> H2(g) 0.0 (18)
2 H2O <=> 2 H+ + 2e- + H2O2 -59.60 (19)
4 HS- <=> 2 H+ + 6e- + H2S4 7.88 (20)
5 HS- <=> 3 H+ + 8e- + H2S5 8.99 (21)
4 HS- <=> 3 H+ + 6e- + HS4- 3.68 (22)
5 HS- <=> 4 H+ + 8e- + HS5- 5.09 (23)
2 H2O <=> 4 H+ + 4e- + O2 -86.08 (24)
2 H2O <=> 4 H+ + 4e- + O2(g) -83.12 (25)
3 H2O <=> 6 H+ + 6e- + O3 -156.05 (26)
3 H2O <=> 6 H+ + 6e- + O3(g) -153.25 (27)
2 HS- <=> 2 H+ + 3e- + S2- -5.09 (28)
2 HS- <=> 2 H+ + 2e- + S22- -12.73 (29)
2 HS- + 3 H2O <=> 8 H+ + 8e- + S2O32- -28.79 (30)
3 HS- <=> 3 H+ + 4e- + S32- -7.27 (31)
4 HS- <=> 4 H+ + 6e- + S42- -3.022 (32)
5 HS- <=> 5 H+ + 8e- + S52- -1.007 (33)
6 HS- <=> 6 H+ + 10e- + S62- 0.84 (34)
HS- + 3 H2O <=> 7 H+ + 6e- + SO32- -37.09 (35)
HS- + 4 H2O <=> 9 H+ + 8e- + SO42- -33.69 (36)
2 HS- + 3 H2O <=> 6 H+ + 8e- + H2S2O3 -26.52 (37)
HS- + 4 H2O <=> 7 H+ + 8e- + H2SO4 -33.70 (38)
2 H2O <=> 3 H+ + 2e- + HO2- -71.25 (39)
2 HS- + 3 H2O <=> 7 H+ + 8e- + HS2O3- -27.11 (40)
HS- + 3 H2O <=> 6 H+ + 6e- + HSO3- -29.87 (41)
HS- + 4 H2O <=> 8 H+ + 8e- + HSO4- -31.71 (42)
2 HS- + 6 H2O <=> 14 H+ + 14e- + S2O62- -75.43 (43)
2 HS- + 8 H2O <=> 18 H+ + 18e- + S2O82 -133.65 (44)
4 HS- + 6 H2O <=> 16 H+ + 18e- + S4O62- -54.88 (45)
HS- + 2 H2O <=> 5 H+ + 6e- + SO2(aq) -28.03 (46)
HS- + 2 H2O <=> 5 H+ + 6e- + SO2(g) -28.35 (47)
Zn2+ + 8 H2O + 2 HS- <=> 18 H+ + 16e- + Zn(SO4)22- -64.10 (48)
Zn2+ + 16 H2O + 4 HS- <=> 36 H+ + 32 e- + Zn(SO4)46- -133.07 (49)
Zn2+ + 3 H2O + 2 HS- <=> 8 H+ + 8e- + ZnS2O3 -26.49 (50)
Zn2+ + 4 H2O + HS- <=> 9 H+ + 8e- + ZnSO4 -31.32 (51)
3) Precipitation and dissolution reactions
Zn2+ + 2 H2O <=> 2 H+ + Zn(OH)2(s) -12.45 (52)
HS- <=> H+ + 2e- + S(s) 2.15 (53)
2e- + Zn2+ = Zn(c) -25.76 (54)
Zn2+ + HS- <=> H+ + ZnS(s) 9.06 (55)
2 Zn2+ + 6 H2O + HS- <=> 11 H+ + 8e- + Zn2(OH)2SO4(s) -41.19 (56)
3 Zn2+ + 9 H2O +2 HS- <=> 20 H+ + 16e- + Zn3O(SO4)2(s) -86.40 (57)
4 Zn2+ +10 H2O + HS- <=> 15 H+ + 8e- + Zn4(OH)6SO4(s) -62.09 (58)
Zn2+ + 4 H2O + HS- <=> 9 H+ + 8e- + ZnSO4(s) -36.70 (59)
Zn2+ + HS- <=> 9 H+ + 8e- + ZnSO4·6 H2O(s) -31.93 (60)
Zn2+ + HS- <=> 9 H+ + 8e- + ZnSO4·7 H2O(s) -31.73 (61)
(4) Surface complexation reactions*
≡SZn + H+ <=> ≡ZnSH+ 6.91 (62)
≡SZn + H2O <=> ≡SZnOH- + H+ -10.28 (63)
≡SZn + 2H+ <=> ≡SH2 + Zn2+ 9.59 (64)
  1. * Surface complexationwas a concept presented by Stumm and Schindler et al in the end of 1960s and the beginning of 1970s and now it is widely used as a useful tool to treat the sorption data in mineral suspensions [34]. The basic ideal of that is to regard the mineral surfaces as a functional groups carrier; therefore the surface chemical reaction can be treated in the same way as those of solution chemical reactions. The only difference between the surface and solution chemical reactions is the former one has surface charge, thus the situation of the electrical double layer EDL of mineral surfaces should be considered in performing the surface complexation studies.
  2. The three surface complexation reactions of ZnS presented in table 1 are the surface protonation (62), deprotonnation (63) and ion exchange (64) reaction respectively. ≡SZn denotes the surface binding site of ZnS.