Straw pyrolysis co-production has been one of the most important ways to realize the efficient utilization of straw at present, particularly for the high high-quality biochar and combustible gas. Much efforts have has been made on the important data support for the development of straw pyrolysis carbonization technology. However, it is still lacking on the straw charcoal return to field utilization for the carbon quality under different pyrolysis conditions, especially the correlation analysis for the various physical and chemical properties of straw charcoal. In this study, a systematic investigation was carried out to clarify the effects of pyrolysis temperature and residence time on the physicochemical properties of rice straw pyrolysis products (mainly the return to field utilization index). The correlation analysis was also performed on the specific surface area of rice straw carbon, electrical conductivity, pH value, and cation exchange capacity. At the same time, the yield and energy distribution of products were explored under different experimental conditions. A simple and practical platform was established for the slow pyrolysis of rice straw and the collection of all components of carbon, gas and liquid products. An analysis was made to determine the influence of pyrolysis temperature (450, 500, 550, 600, and 650 ℃) and residence time (30, 40, 50, and 60 min) on the pyrolysis products of rice straw using the slow pyrolysis co-production. The results show that the pyrolysis temperature was posed the an outstanding effect on the product characteristics and yield, while only a little effect was observed in the residence time. When the pyrolysis temperature increased from 450 ℃ to 650 ℃, the carbon yield of rice straw gradually decreased from 40.8% to 35.1%, with a decrease of 5.7 percentage points. The calorific value also decreased slightly. The pyrolysis gas yield increased from 18.3% to 20.7%, with an increase of 2.4 percentage points. The gas calorific value increased from 10.3 to 15.1 MJ/Nm³, with an increase of 4.8 MJ/Nm³, due mainly to the increase in the yield of alkane and olefin olefin-enriched gases, such as H₂ and CH₄. The pyrolysis temperature was reduced the volatiles of rice straw carbon for the high content of fixed carbon. The O/C and H/C of rice straw carbon that produced in the range of 450-650 ℃ were lower than 0.2, indicating the better stability. There was a strong correlation between the specific surface area, conductivity, and pH value of rice straw carbon. Specifically, the correlation coefficients between the specific surface area and pH value, pH value and conductivity, and the specific surface area and conductivity were 0.83, 0.66, and 0.54, respectively. An increasing trend was found in the specific surface area, conductivity, and pH value of rice straw carbon with the increase of in temperature. The highest specific surface area, the highest electrical conductivity, and the highest pH were 83.4 m²/g, 1 059 μS/cm, and 10.5, respectively. There was no significant change in the cation exchange capacity in the temperature range. The average cation exchange capacity was 56.4 cmol/kg. The energy distribution of rice straw pyrolysis products also changed with the increase of in temperature. The more energy that contained in raw materials was transferred to the gas products. The carbon energy yields of rice straw were 53.8% and 45.2% at the temperatures of 450 ℃and 650 ℃, respectively, whereas, the pyrolysis gas energy yields were 11.6% and 19.1%, respectively. The finding can provide the basic data support to the simplified pyrolysis equipment for the rice straw.

This study aims to enhance the high-value utilization of agricultural wastes in the field of energy storage materials. A comparison was also made on the effects of the pyrolysis pretreatment and KMnO₄ addition on the electrochemical properties of the peanut shell-modified carbon. The raw material was taken as the peanut shell powder. The specific procedure was set as the solid mixing and milling, nitrogen environment, pyrolysis temperature of 800 °C, and deionized water admittance rate of 0.2 mL/min. The KMnO₄ powder was used as the modifying agent. The electrochemical properties of the peanut shell modified carbon were characterized by scanning electron microscope (SEM), elemental analyzer (EA), fully automated specific surface and porosity analyzer (BET). X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to identify the elemental content, surface morphology, and pore structure of the modified carbon. Galvanostatic charge/discharge and AC impedance (EIS, electrochemical impedance spectroscopy) were used to test the electrochemical properties. The test results showed that the modified carbon without pyrolytic pretreatment shared the relatively high hydrophilicity, the larger specific surface area, the a rich pore structure, and the electrochemical properties; . The specific surface area of the modified carbon increased gradually, with the increase of KMnO₄ addition. The hydrophilicity was enhanced to elevate the specific capacitance. Furthermore, the better performance was achieved after pyrolysis pretreatment, when the mass ratio of the peanut shell charcoal to KMnO₄ powder was 1.6∶1. The modified charcoal shared the best hydrophilicity, the largest specific surface area of 401.16 cm3/g, the mesoporosity of 5.88%, and the micropore rate of 64.71%, and the largest specific capacitance, which was 86.90 F/g at the current density of 0.5 A/g. When the mass ratio of peanut shell powder to KMnO₄ powder was 1.6:1 without pyrolysis pretreatment, the modified carbon shared the best hydrophilicity, the largest specific surface area of 1 422.79 cm³/g, and the highest pore richness, with a mesoporosity of 36.11% and a microporosity of 63.89%. Meanwhile, the largest specific capacitance was observed with a specific capacitance of 92.02 F/g at a current density of 0.5 A/g, which was higher than that of pyrolytic pretreatments. There was 1.2 times of the best coupled modified carbon. The optimal coupling-modified chars without and with pyrolytic pretreatment shared the specific capacitances of 94.00% and 80.26% of those at 0.5 A/g at a current density of 2 A/g, respectively. There was the specific capacitance retention after 10,000 charges and discharges at a current density of 5 A/g of 93.17% and 86.06%, respectively, with the electron transfer resistances of 0.02 and 0.04 Ω, respectively. The specific capacitance of the coupling-modified carbon was somewhat lower than that of the modified carbon prepared by the KMnO4 solution impregnation. The coupling-modified carbon shared the a much lower electron transfer resistance, higher specific capacitance retention, and stable cycling performance at high current density. The production cost was reduced significantly. This finding can provide an important reference to explore the electrode materials from the peanut shells.

Plastic binding ropes are necessary to hang or mulch some crops (such as peppers, eggplant, and beans) in the planting process. A large amount of plastic doping has been resulted in the straw of such crops. Since plastic is difficult to degrade, the exhaust gas that generated by its incineration has posed a serious threat to the ecological environment. General treatments cannot effectively deal with such mixed wastes, particularly for the soil absorption, composting, and incineration power generation. Among them, pyrolysis is one of the most important techniques to convert the waste into renewable biofuels. This study aims to deal with the crop straw and agricultural film in some areas. Taking pepper straw and low-density polyethylene as raw materials, the poly generation of slow pyrolysis was used to explore the effects of pyrolysis temperature (400, 500, 600, and 700℃) and mixing ratio (0, 5%, 10%, and 15%) on co-pyrolysis products. The results showed that the decomposition of mixed samples mainly included three stages: dehydration, volatilization, polymer degradation, and coke formation. The pyrolysis temperature shared the an outstanding influence on the product yield. Specifically, the average yield of co-pyrolysis char decreased from 46% to 31.1%, respectively, as the temperature increased from 400℃ to 700℃, whereas, the yields of co-pyrolysis gas and oil increased from 16.9% to 24.8% and from 37.1% to 44.1%, respectively. The Low heat value (LHV) of co-pyrolysis gas and char were 8.6-14.5 MJ/m³ and 19.6-28.5 MJ/kg, respectively, under the experimental conditions. The volatiles of co-pyrolytic carbon gradually decreased with the increase of in pyrolysis temperature, whereas, the fixed carbon and ash increased gradually. When the temperature was 400℃, the volatiles of co-pyrolysis char increased gradually with the increase of mixing ratio, whereas, the ash gradually decreased, indicating no outstanding change of fixed carbon. However, there was no influence of the mixing ratio on each component during pyrolysis at higher temperatures. The components showed a fluctuating trend. The specific surface area of the co-pyrolytic char increased slightly with the increase of in temperature, but there was the a decrease with the increase of in mixing ratio. The pH value of co-pyrolytic carbon was depended mainly on the pyrolysis temperature. There was little effect of the mixing ratio on the pH value. The relatively high pH value of the co-pyrolytic char was achieved between 10.1 and 12.5. The PAHs content and TEQ toxicity of pyrolytic char were lower than before. Only the total PAHs at 15%-500℃ was exceeded the EBC threshold of high high-quality grade (4 mg/kg). The main PAHs compound of co-pyrolytic char was 3-ring PAHs, where the less PAHs were found with the a high molecular weight. The co-pyrolysis with CS at a higher temperature decreased the TEQ value of the co-pyrolytic char under the mixing ratio with the addition of LDPE. But However, there was no increase in the toxicity of the co-pyrolytic char. High The high temperature was conducive to the decomposition of PAHs, and increasing temperature can fully meet the requirements of co-pyrolysis char returning to the field. The findings can provide a strong reference for the treatment of rural straw and agricultural film.