Study on polyarginyl lysine grafted modified nano biochar as an environmentally friendly shale inhibitor

In the study, JL-BC, an environmentally friendly shale inhibitor with a temperature tolerance of 220 °C was synthesized by grafting modified nano biochar (BC) onto polyarginyl lysine (JL) for the first time. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric (TGA) tests indicated that JL-BC had been successfully synthesized and had good thermal stability. The inhibition performance of JL-BC was experimentally evaluated by linear swelling test, hot-rolling recovery test and sodium bentonite (Na-BT) block immersion test, and the inhibition mechanism of JL-BC was studied by various experimental characterization methods. The experimental results showed that compared with potassium chloride (KCl), polyether amine (PEA), bionic inhibitor dopamine (DA), 2, 3-epoxypropyltrimethylammonium chloride (EPTAC), and poly dimethyl diallyl ammonium chloride (PDMDAAC), Na-BT had the lowest linear swelling height of 4.49 mm in 4 % JL-BC solution at 150 °C. The recovery rates of shale cuttings were highest in 4 % JL-BC solution at 200 °C and 220 °C, which were 96 % and 92 %, respectively. The Na-BT block was immersed in 4 % JL-BC solution for 16 h basically retained its original morphology. The excellent inhibition performance of JL-BC was mainly attributed to the positive charge of JL-BC in aqueous solution at pH 9, which was strongly adsorbed on Na-BT, lowering the zeta potential of Na-BT, destabilizing Na-BT and causing it to aggregate. With the increase of JL-BC concentration, Na-BT gradually aggregated into larger flocs, increasing the particle size of Na-BT. Nano BC reduced water intrusion to a certain extent by physically blocking micropores. In addition, the EC 50 value of JL-BC was 2.93 × 10 5 mg/L, indicating that it was non-toxic. The addition of JL-BC to the soil effectively increased the content of organic matter, ammonium nitrogen and available potassium, and promoted the growth of wheat seedlings. This work may open a new avenue for the development and use of environmentally friendly treatment agents.