Lignite-Activated Carbon Grafted PAA Combined with Conventional Drinking Water Treatment Processes for the Emergency Removal of Trace Pb(II) Pollution
2020
Dong, Lihua | Pan, Shujie | Wang, Zhansheng | Hou, Li’an | Zhou, G. | Chen, Guanyi
In response to the emergency treatment of trace Pb(II) pollution, taking cost and coordination with existing conventional processes into account, based on the lignite upgrading by-products (waste) as raw materials, a low cost adsorbent lignite-based activated carbon/polyacrylic acid (LAC/PAA) was developed by the in situ grafting of PAA on the surface of LAC. The declination of the pH from 8.71 for LAC to 4.83 for LAC/PAA and FT-IR analyses of LAC/PAA before and after Pb(II) adsorption confirmed the appearance of carboxyl groups on the surface of LAC/PAA. The adsorption experiments reveal that more than 90% of Pb(II) were removed by LAC/PAA within 20 min (only 31% for LAC). Its adsorption behavior obeys the Freundlich isotherm model (R² = 0.973), and the adsorption kinetics agrees with the pseudo-second-order kinetic model (R² = 0.961). The performances for the removal of Pb(II) in XJ River (South of China) were investigated for LAC/PAA and the conventional water treatment processes, respectively. Based on the results, a combination process (LAC/PAA adsorption + conventional water treatment) was developed, which achieved the best Pb(II) removal (99.8%) under a lower LAC/PAA and coagulant dosages (both 20 mg/L) at a pH of 10, 3 times better than that of the conventional water treatment processes (only 30%). Undoubtedly, the above results will provide significant technical support for the emergency treatment of trace Pb(II) pollution of drinking water. Moreover, converting the lignite upgrading by-products (waste) into LAC will add considerable economic value and reduce the costs of waste disposal.
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