Low temperature pyrolytic biochar is a preferred choice for sulfonamide-Cu(II) contaminated soil remediation in tropical climate region.

Biochar is getting increasing consideration for eco-friendly soil amendment and environmental remediation. Once added to the soil, biochar would undergo the natural ageing process, affecting its physicochemical properties and, as a result, the adsorption and immobilization of pollutants in the water and soil. To evaluate the high/low temperature pyrolyzed biochar performance on complex contaminants and the effect of climate ageing, the batch experiments were conducted on the adsorption of the pollutants of antibiotics sulfapyridine (SPY) and a typical coexisting heavy metal Cu2+ as one or binary system on low/high pyrolytic temperature biochars before and after the simulated tropical climate and frigid climate region ageing treatment. The results showed that high-temperature ageing could enhance the SPY adsorption in biochar-amended soil. The SPY sorption mechanism was fully elucidated, and the result confirmed that H-bonding was the dominant role in biochar-amended soil, and π-π electron-donor-acceptor (EDA) interaction and micro-pore filling was another factor for SPY adsorption. This study could lead to the conclusion that low-temperature pyrolytic biochar is a better option for sulfonamide-Cu(II) contaminated soil remediation in tropical regions.

O/N/P-doped biochar induced to enhance adsorption of sulfonamide with coexisting Cu2+/ Cr (VI) by air pre-oxidation.

The aim of this work to study the effectiveness of newly synthesized O/N/P-doped biochar for the removal of antibiotics with coexisting heavy metals. This study developed a low-dose additive agent with air pre-oxidation (APO) to obtain O/N/P-doped biochar (ONPBC) at 650/350 °C pyrolysis temperature with adsorption amount of 76.99 mg·g-1 (ONPBC650) and 62.33 mg·g-1 (ONPBC350) for sulfapyridine (SPY), comparing to pristine biochar 9.25 mg·g-1 (BC650) and 11.60 mg·g-1 (BC350), indicating the adsorption capacity of biochar has been greatly improved after modification. The main sorption mechanisms were elucidated for ONPBC650 (surface physical sorption) and ONPBC350 (H-bonding). The coexisting Cu2+/Cr (VI) showed different inhibition effects on the adsorption of SPY by ONPBC650/350. Considering a trade-off between high adsorption capacity and low inhibition effect of coexisting heavy metals, economic low-temperature O/N/P-doped biochar such as ONPBC350 could be a preferred adsorbent for the removal of sulfonamide or similar organic pollutants from contaminated water.