Removal of Cr(VI) from aqueous solution by a novel ZnO-sludge biochar composite

Removal of Cr(vi) in wastewater by Fe–Mn oxide loaded sludge biochar

“…32 However, since Cr( vi ) existed mainly as anion in solution, this could be the result of cationic–π interaction between Cr( iii ) generated by reduction and CC structure on FMBC during the adsorption process. 20 According to the previous findings, the CC group shifted from 1640 cm −1 to 1610 cm −1 after Cr( vi ) removal from solution, which was also consistent with the present study. 1,22 These analysis showed that FMBC adsorbed Cr( vi ) on surface through complexation and electrostatic interactions, and Cr( vi ) ion was reduced to cationic Cr( iii ), and then released cation Cr( iii ) into solutions by electrostatic repulsion.…”

“…9 The vibrational peak appearing at 1430 cm −1 was considered to be due to the –COOH group, while the vibrational peak at 1070 cm −1 was considered to be due to the C–O group. 20 Notably, the intensity of O–H, CC/CO, and –COOH groups on FMBC were all enhanced upon loading of Fe–Mn oxides, suggesting that the Fe–Mn oxide loading increased the number of O-containing groups in the adsorbents. 13 Additionally, the vibrational peak at 531 cm −1 corresponded to Fe–O group in BC.…”

“…16 Δ S 0 was positive, suggesting that Cr( vi ) removal processes for FMBC were entropy-driven, and degree of freedom at solid–liquid interface increased during removal process. 20…”

Removal of Chromium Species by Adsorption: Fundamental Principles, Newly Developed Adsorbents and Future Perspectives

“…FeMnOx/MWCNTs C0 = 50 mg/L; adsorbent dose: 1 g/L; contact time: 60 min; pH: 2.0 47.25 mg/g [34] Cr(III) GO@CZ C0 = 30 mg/L; adsorbent dose: 300 mg/L; contact time: 60 min; pH = 7.0 285.71 mg/g [43] Cr(VI) Gr-Si-PPy C0 = 100 mg/L; adsorbent dose: 400 mg/L; T = 25 °C; contact time: 60 min; pH: 2.0 429.2 mg/g [47] Cr(VI) GO@SiO2@C@Ni-400 C0 = 20 mg/L; T = 25 °C; adsorbent dose: 0.15 g/L; pH = 3.0 299.20 mg/g [50] Cr(VI) GO-NiFe LDH C0 = 20 mg/L; T = 30 °C; contact time: 280 min; adsorbent dose: 80 mg/L 53.6 mg/g [51] Cr(VI) Fe3O4-GO C0 = 600 mg/L; T = 25 °C; adsorbent dose: 125 mg/L; pH = 6.0 280.6 mg/g [55] Cr(VI) TSGA C0 = 50 mg/L; T = 25 °C; adsorbent dose: 800 mg/L; contact time: 40 min; pH = 2.0 100% removal [60] Cr(VI) APTES-NPSi C0 = 200 mg/L; T = 25 °C; adsorbent dose: 5 mg; contact time: 180 min; pH = 2.0 103.75 mg/g [64] Cr(VI) MnFe-LDH/MnFe2O3@3DNF C0 = 300 mg/L; T = 25 °C; contact time: 120 min; adsorbent dose: 5 mg; pH = 2.0 564.88 mg/g [121] Cr(VI) 3D porous CoFe2O4@SiO2-NH2 C0 = 150 mg/L; contact time: 600 min; adsorbent dose: 1 g/L; T = 25 °C; pH = 2.0 126.8 mg/g [138] Cr(VI) TCMR C0 = 150 mg/L; contact time: 360 min; adsorbent dose: 2 g/L; T = 25 °C; pH = 5.0 27.04 mg/g [150] Cr(VI) Rice husk C0 = 100 mg/L; contact time: 60 min; adsorbent dose: 50 g/L; T = 25 °C; pH = 5.0-6.0 30 mg/g [158] Cr(VI) BCS and BCW C0 = 320 mg/L; contact time: 24 h; adsorbent dose: 4 g/L; T = 25 °C; pH = 2.0 24.6 mg/g for BCS, 23.6 mg/g for BCW [159] Cr(VI) SDBC C0 = 100 mg/L; contact time: 24 h; adsorbent dose: 1 g/L; T = 25 °C; pH = 5.0 688~738 μmol/g [161] Cr(VI) ZBC C0 = 100 mg/L; contact time: 600 min; adsorbent dose: 4 g/L; T = 25 °C; pH = 1.0 33.87 mg/g [175] Cr Cr(VI) Co/Zn-based ZIF C0 = 15.0 mg/L; contact time: 30 min; adsorbent dose: 33 mg; T = 25 °C; pH = 6.5 69.4 mg/g [191] Cr(VI) NH2-SBA-15 C0 = 25.0 mg/L; contact time: 4 h; adsorbent dose: 100 mg; T = 30 °C; pH = 2.0 Removal efficiency of 88% [192] Cr(VI) Ficus carica bast fiber C0 = 350.0 mg/L; contact time: 210 min; adsorbent dose: 0.5 g; T = 25 °C; pH = 3.0 19.68 mg/g [193] Cr(VI) and Cr(III)…”

“…Recently, ACs prepared by industrial black liquor (BL) were activated with K 2 CO 3 to obtain a higher surface area and larger pore volume, and relatively higher adsorption capacities of ~670 mg/g for Cr(VI) could be observed [ 174 ]. The combination of ZnO with biochar (ZBC) could produce novel adsorbents with an enhanced adsorption capacity, owing to the introduced electrostatic attraction, surface complexation and ion-exchange interactions [ 175 ].…”