改性核桃壳生物炭对枯草芽孢杆菌SL-44的吸附

为提高生物炭与微生物吸附能力及其协同改良土壤的性能,使用草酸和氨水对核桃壳生物炭改性,以期制备出性能更加优良的炭基菌剂,并通过红外光谱、动力学、热力学等研究方法,解析生物炭对枯草芽孢杆菌SL-44的吸附机制,并探究其稳定性。结果表明,草酸和氨水改性增加了生物炭在常温下对SL-44的吸附能力,且随着改性剂浓度的增加而增加,最大吸附量为1.5396×10¹¹ CFU·g^-1。此外,通过改性能够在生物炭表面引入COOH、C=O和—NH₂官能团,改变电负性,并保持生物炭原有形貌结构。生物炭对菌体的吸附以物理吸附为主,并涉及化学吸附作用,其表面的—OH、C=O、COOH、—NH₂均参与了吸附反应过程。生物炭吸附SL-44为放热过程(ΔH<0),随着温度的升高炭材料的吸附能力降低,低温更有利于吸附。常温下生物炭的吸附性能为氨水改性>草酸改性>未改性。因此增加生物炭表面氧、氮官能团含量可增加其吸菌量,同时在常温下可制得吸菌量更大的炭基菌剂。测定所得菌剂的活菌数和稳定性发现,被吸附的菌体数越多,其存活菌数量越大,且保藏稳定性越强。与未改性生物炭相比,改性后活菌数最高提高26.01%,而保藏4个月后存活率提高14.1个百分点。

Modifications of walnut shell-based biocar and its adsorption for Bacillus subtilis SL-44

To improve the synergistic effect of biochar and microorganisms and the quality of soil,walnut shell biochar was modified with oxalic acid and ammonia.Excellent and stable carbon-based microbial agents were thus prepared.The adsorption mechanism of biochar in Bacillus subtilis SL-44 and its stability was analyzed and explored by infrared spectroscopy,kinetics,and thermodynamics.The results showed that after modification with oxalic acid and ammonium hydroxide,the adsorption capacity of biochar increased at room temperature.This adsorption capacity increased with increasing modifier concentration,reaching a maximum adsorption of 1.5396×10¹¹ CFU·g^-1.The COOH,C=O,and-NH₂ functional groups appeared on the surface of the modified biochar,altering its electronegativity.The original morphology and structure of the biochar could be retained.The bacterial adsorption of biochar was mainly a physical process,although chemical adsorption still played an important role,and these additional functional groups participated in the adsorption.The adsorption of modified biochar on SL-44 was an exothermic process(ΔH<0);thus,with an increase in temperature,the adsorption capacity of biochar decreased,and low temperatures were advantageous for adsorption.The order of adsorption capacity at room temperature was as follows:ammonia-modified biochar>oxalic acid-modified biochar>unmodified biochar.The bacterial absorption of biochar will be improved with an increase in nitrogen and oxygen functional groups,and a higher absorption of carbon-based microbial agents could be achieved at room temperature.The more bacteria adsorbed by biochar,the greater the number of viable bacteria and the stronger the storage ability.Compared with virgin biochar,the number of viable bacteria increased by 26.01%,and the survival rate increased by 14.1 percentage points after storage for 4 months.