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Biomass pyrolysis by-products, such as biochar (BC) and wood vinegar (WV), are widely used as soil conditioners and efficiency enhancers in agriculture. A pot experiment was conducted to examine the effects of WV, both alone and in combination with BC, on soil properties in mildly saline soil and on cotton stress tolerance. The results demonstrated that BC and WV application, either individually or together, increased soil nutrient content. The combined application was more effective than the individual applications, resulting in a 5.18–20.12% increase in organic matter, a 2.65–15.04% increase in hydrolysable nitrogen, a 2.23–58.05% increase in effective phosphorus, and a 2.71–29.38% increase in quick-acting potassium. Additionally, the combined application of WV and BC led to greater improvements in cotton plant height, net photosynthetic rate (Pn), leaf nitrate reductase (NR), superoxide dismutase (SOD), and catalase (CAT) activities compared to the application of BC or WV alone. The enhancements in this study varied across different parameters. Plant height showed an increase of 14.32–21.90%. Net photosynthetic rate improved by 13.56–17.60%. Leaf nitrate reductase increased by 5.47–37.79%. Superoxide dismutase and catalase showed improvements of 5.82–64.95% and 10.36–71.40%, respectively (p < 0.05). Moreover, the combined treatment outperformed the individual applications of WV and BC, resulting in a significant decrease in MDA levels by 2.47–51.72% over the experimental period. This combined treatment ultimately enhanced cotton stress tolerance. Using the entropy weight method to analyze the results, it was concluded that the combined application of WV and BC could enhance soil properties in mildly saline soils, increase cotton resistance, and hold significant potential for widespread application. [ABSTRACT FROM AUTHOR]

As a good carbon source and soil conditioner, biochar is widely used in acidic soils but seldom in alkaline soils due to its high pH. In this study, cotton straw biochar was modified with five different acidic materials to obtain wood-vinegar- (WBC), monosodium-glutamate (MSG)-wastewater- (MBC), citric-acid- (CBC), phosphoric-acid- (PBC), and nitric-acid-modified biochars (NBC), and three dosages were used for each modifier. The pristine and modified biochars were characterized with scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy. The biochar properties such as pH, specific surface area (SSA), and elemental contents were measured. In addition, the technique for order preference by similarity to ideal solution (TOPSIS) model based on entropy weight was used to evaluate the application potential of the biochars in alkaline soils. The FTIR spectra showed that modification with the five acidic materials, MSG wastewater in particular, resulted in more oxygen-containing functional groups such as O-H, C=O, and C-O on the biochar surface. In addition, acid modification greatly decreased the pH: phosphoric acid modification significantly decreased the pH of cotton straw biochar by 5.71–7.88 units. For the same modifier, a higher dosage (i.e., a smaller biochar:modifier ratio) led to a larger decrease in the pH of cotton straw biochar. The magnitudes of increase in total soluble salt content followed the general order of CBCs > PBCs > WBCs > NBCs > MBCs. The SSA, average pore diameter, and total pore volume of biochar were changed as well. Modification using wood vinegar and MSG wastewater significantly decreased the SSA of cotton straw biochar by 15.58–16.24 m2 g−1 (82.7–86.2%) and 15.87–16.80 m2 g−1 (84.2–89.2%), respectively, whereas modification using citric acid and nitric acid significantly increased the SSA of cotton straw biochar by 4.51–4.66 m2 g−1 (23.9–24.7%) and 0.55–54.21 m2 g−1 (2.9–287.7%). The evaluation based on entropy weight TOPSIS model suggested that the MBCs have the highest potential for application in alkaline soils. This study presents a theoretical basis for evaluation of biochar application potential, demonstrates a way of improving biochar application potential, and provides a support for beneficial utilization of agricultural and industrial wastes such as cotton straw, wood vinegar, and MSG wastewater. [ABSTRACT FROM AUTHOR]

Nanoscale zero-valent iron loaded on N-doped biochar (nZVI/NBC) is a novel catalyst for activating peroxydisulfate (PDS) toward efficient degradation of endocrine disruptors in water. In this study, spent coffee grounds were modified by K 2 FeO 4 and then transformed into nZVI/NBC by one-step pyrolysis. The nZVI/NBC modified with 0.3 mol/L K 2 FeO 4 displayed an excellent PDS activating performance, and the specific surface area and average pore width of this nZVI/NBC were 277.19 m2/g and 2.47 nm, respectively. Bisphenol A (BPA) as a typical endocrine disruptor can be efficiently degraded by nZVI/NBC/persulfate advanced oxidation process. The optimum dosage of nZVI/NBC was 0.1 g/L, and the optimum PDS concentration was 20 mM. pH (3−9) had little effect on BPA degradation. In addition, the presence of Cl− had a facilitating effect on BPA degradation, while CO 3 2− and HPO 4 2− had strong inhibitory effects. nZVI/NBC had long-term stability in that the activation rate remained stable after five cycles and 90 days of storage in air and natural light. This study also investigated the activation mechanism of PDS by nZVI/NBC and concluded that radical (•OH, SO 4 •−, and O 2 •−) and non-radical (1O 2) processes were simultaneously presented under the synergistic catalysis of ZVI and N. The formation of metastable PDS intermediates on the surface of biochar substantially enhanced the adsorption of PDS/BPA and the electron transfer process. Finally, the degradation pathways of BPA were speculated based on nine identified intermediates. Overall, this study described a rapid and green method for nZVI/NBC fabrication, which simultaneously achieved the recycling of spent coffee grounds and the degradation of endocrine disruptors in water. [Display omitted] [ABSTRACT FROM AUTHOR]

Pollution of wastewater and natural waters by organic contaminants is a major health issue, yet actual remediation methods are limited by incomplete removal of recalcitrant contaminants and by secondary pollution by chlorinated contaminants and catalytic metals. To attempt to solve these issues, we tested the removal of acid orange by peracetic acid (PAA), a safe oxidant, activated by Fe-biochar that iron anchored on biochar to prevent secondary pollution by iron. Fe-biochar was synthesized using a simple, one-step pyrolysis method. We investigated the effects of PAA concentration, pH, humic acids, chloride, bicarbonate on the reaction. Radical quenching and electron paramagnetic resonance were used to identify reacting species. Results showed that the granulous structure of Fe-biochar and the presence of Fe, Fe 3 O 4 , Fe 2 O 3 , and Fe 3 C on Fe-biochar surface. The highest removal of acid orange of 99.9% was obtained with 1.144 mM PAA and 0.3 g/L Fe-biochar at pH 7. Acid orange removal increases with Fe-biochar dose, decreases with pH, is slightly inhibited by humic acids and bicarbonate, and is not modified by chloride. Our experimental results suggested that CH 3 C(O)OO· and CH 3 C(O)O· are the main radical species, but there may also be non-radical effects in Fe-biochar/PAA process. Fe-biochar displayed high re-usability, with 92.8% removal after five uses. [Display omitted] • The mechanism of the Fe-biochar/PAA process was investigated by removing acid orange. • CH 3 C(O)O· and CH 3 C(O)OO· act as the primary radicals. • There may also be non-radical effects in the process of acid orange removal. • Fe-biochar has a high recycling rate in the Fe-biochar/PAA process. [ABSTRACT FROM AUTHOR]