Synergistic Effect Of Co-pyrolysis Research Articles

Co-pyrolysis of sewage sludge and phosphate tailings: Synergistically enhancing heavy metal immobilization and phosphorus availability

Phosphate tailings (PT) was used to reduce the release of heavy metals (HMs) during pyrolysis and the leachable rate of residual HMs, and simultaneously improve the bioavailability of phosphorus in the sludge-based biochar. The concentration of heavy metals and the fractions determined by BCR method was used to investigate the release and the transformation of Zn, Pb, Mn, Ni and Cu during pyrolysis involved with the effects of temperature and the addition of PT. The respective pyrolysis experiments shows that the release of Zn and Pb increases with temperature for both sewage sludge (SS) and PT, and the bioavailable fractions (F1 + F2) of Mn, Ni, and Cu increases with temperature for PT. During co-pyrolysis, blended samples released lower quantities of Zn and Pb and presented lower bioavailability of HMs than the individual SS or PT. A synergistic effect of co-pyrolysis was evident for volatile Zn and Pb. The decomposition of CaMg (CO3)2 from PT produced CaO, by which the volatile ZnCl2 and PbCl2 were transformed into ZnO and PbO with less volatility and higher reactivity with SiO2 and Al2O3 than the chlorides. Then SiO2 and Al2O3 from SS acted as the final stabilizer to immobilize the oxides. The final product combined with SiO2 and Al2O3, such as ZnSiO4 and ZnAl2O4, were detected. The addition of PT also introduced more Ca and P into sludge to produce biochar with higher concentration of apatite phosphorus with higher bioavailability.

Synergistic effect study of Chlorella vulgaris and polyethylene in co-pyrolysis process based on kinetic and thermodynamic analysis

The co-pyrolysis of algae and plastics shows great potential for bio-oil production. In this study, thermogravimetric analyzer was used to investigate the pyrolysis behavior of Chlorella vulgaris (CV) and polyethylene (PE) at different mixed ratios and heating rates. Their synergistic effects were discussed through kinetic and thermodynamic analyses. According to the thermogravimetric (TG) and Derivative thermogravimetric (DTG) curves, the co-pyrolysis process can be divided into five stages, corresponding to the decomposition of moisture, carbohydrates, proteins, lipids, and biochar, respectively. In the fifth stage, a clear synergistic effect is observed, with the highest ∆TG reaching about 4%. During the co-pyrolysis process, the average activation energy of the mixtures is much lower than expected, indicating the presence of a synergistic effect in co-pyrolysis. Among them, 3CV1PE is the optimal mixing ratio, with the average activation energy of 3CV1PE being 6% lower than that of CV pyrolysis alone. The master plots revealed that the power law reaction models (P3 and P4) are suitable for describing the experimental behavior of mixtures with higher CV content, while the third-order (F3) and eighth-order model (F8) are more appropriate for the decomposition reaction with higher PE content. The calculation of thermodynamic parameters further show that the co-pyrolysis of CV and PE is beneficial to the decomposition process, and the mixed ratio of 3:1 is the most favorable for the reaction. Results obtained in this work are valuable for guiding research on the co-pyrolysis of biomass and plastics.

Investigation of thermal behaviour and synergistic effect in co-pyrolysis of municipal solid waste and sewage sludge through thermogravimetric analysis

Municipal solid waste (MSW) and sewage sludge (SS) co-pyrolysis have the potential to revolutionize waste management and address energy challenges. Consequently, it is crucial to explore the thermal and synergistic effect of MSW, SS and their blends using thermogravimetric analysis. Different blending ratios (MSW90%SS10 %, MSW80%SS20 % and MSW65%SS35 %) were analyzed under an inert nitrogen (N2) gas atmosphere, at various heating rates (10,20 and 30 K min−1), from 30 °C to 900 °C. This paper specifically addressed the effect of heating rate and blending ratio on separate and jointed pyrolysis of the two raw materials. The analysis revealed two significant decomposition stages observed in the individual pyrolytic processes and their blends. Results showed that a higher heating rate slowed down the decomposition rate due to less effective heat transfer. The blending ratio of 35 % SS at 20 K min−1 exhibited a positive synergistic effect while an antagonistic effect was observed in another mixing ratio. Activation energy determined using the Coats-Redfern model in the second stage of active pyrolysis for MSW90%SS10 %, MSW80%SS20 % and MSW65%SS35 % was 41.879, 43.365 and 40.271 kJ mol−1 respectively. The negative ΔS (entropy) and positive ΔH (enthalpy) values indicated a decrease in disorder and an endothermic reaction respectively. This finding was consistent with the formation of complex products from the feedstock and the endothermic nature of the pyrolysis process. Therefore, strategic co-pyrolysis optimization of MSW and SS with the precise blending ratio of 35 % sewage sludge and controlled heating rate of 20 K min−1, exhibits substantial potential for advancing eco-friendly waste management practices while enabling effective energy recuperation.

Pyrolysis and co-pyrolysis of Egyptian olive pomace, sawdust, and their blends: Thermal decomposition, kinetics, synergistic effect, and thermodynamic analysis

The pyrolysis and co-pyrolysis kinetics of two Egyptian olive-pomace (Kroneiki and Shamlali), wood dust, and their blends were investigated by advanced isoconversional model-free methods (Vyazovkin and Senum-Yang) and model-fitting methods (Coats and Redfern integral method) using different integrated reaction mechanisms g(α) through TGA/DTG, and DTA techniques. Master Plot's method was applied to determine the best reaction mechanisms for the pyrolysis of the tested materials. The synergistic effect of co-pyrolysis on kinetics and the role of biomass were examined. The average values of activation energy estimated from VYA and SY kinetic methods, respectively, for KROP, SHOP, FSSD, Blend (1), and Blend (2) were 90.57 and 85.67 kJ/mol, 70.05 and 65.26 kJ/mol, 131.66 and 126.71 kJ/mol, 66.73 and 62.09 kJ/mol, and 113.12 and 108.21 kJ/mol. The co-pyrolysis of KROP, SHOP, and FSSD at a heating rate of 10 °C/min showed the best synergistic pyrolysis performance. The diffusional reaction mechanisms are the most likely reactions to describe the pyrolysis process of the first conversion stage (α = 0.1–0.5), while the reaction mechanism C8 and the reaction order model (F4) are the most likely reactions to describe the second stage (α = 0.5–0.9) pyrolysis process. The higher ΔH and ΔS values for the FSSD and Blend (2) signify that these materials consumed more energy during the pyrolysis process, while the lower ΔH and ΔS values for the KROP, SHOP, and Blend (1) showed the opposite. A blending ratio of 50% KROP, 25% SHOP, and 25% FSSD showed the best performance at a heating rate of 10 °C/min. The obtained kinetics parameters and the solution of the master plots method were validated by solving the Coats and Redfern integral method based on the reaction mechanism function g(α) that showed the best fit in the master plots method.

Recent Advances and Perspectives of Copyrolysis of Biomass and Organic Solid Waste

Pyrolysis is one of the substantial thermal conversion technologies for high-value reutilization of biomass and organic solid waste (OSW). Adding some typical OSWs to biomass pyrolysis can achieve directional regulation of target products that are considered potential alternatives to fossil energy. Understanding copyrolysis behaviors is vital for the optimizing pyrolysis process to minimize environmental pollution and efficiently utilize biomass and OSW. However, there is no overall review on the copyrolysis of biomass and various OSWs. This paper reviews and discusses recent advances in the copyrolysis mechanism, thermal–chemical processes of some typical OSWs and biomass, and effects of chemical compositions of raw materials and pyrolysis parameters on thermal–chemical conversion behaviors, synergistic effect, and copyrolysis product characteristics. Recent reports show that the synergistic effect in copyrolysis effectively improves the quality of bio-oil and biochar. Moreover, adding OSW to biomass pyrolysis can promote the secondary reaction of pyrolysis intermediates. The reaction mechanism and relative numerical simulation work of copyrolysis are summarized. Finally, the current challenges to energy- and environment-oriented conversion of biomass and OSW are discussed, and perspectives for further developing the copyrolysis process are highlighted. This paper provides valuable information for optimizing sustainable copyrolysis processes of OSW and biomass and improving the efficiency and selectivity of recycled OSW.

Microwave catalytic co-pyrolysis of low-density polyethylene and spent bleaching clay for monocyclic aromatic hydrocarbons

Combined with the fact that the poor heat transfer effect of low-density polyethylene (LDPE), the microwave absorption characteristics of spent bleaching clay (SBC) and the synergistic effect of co-pyrolysis, we conducted a study. In this study, microwave-assisted catalytic co-pyrolysis of SBC and LDPE was used to produce bio-oil rich in monocyclic aromatic hydrocarbons (MAHs). Then the conditions of co-pyrolysis, including pyrolysis temperature, catalytic temperature, the ratio of SBC/LDPE and catalytic mass were explored. The findings revealed that SBC and LDPE had a synergistic effect, SBC had microwave absorption characteristics, which could transfer heat to LDPE to improve heating rate. And the high H/Ceff of LDPE promoted the deoxidation of the SBC, which could optimize the quality of bio-oil. Compared with 43.69% for LDPE pyrolysis alone and 47.18% for SBC pyrolysis alone, the content of MAHs during co-pyrolysis was 54.92%. The optimum pyrolysis parameter was discovered at the pyrolysis temperature of 550 °C, 450 °C of catalytic temperature, 40:28.5 ratio of SBC to LDPE, 7 g of HZSM-5 mass, 69.89% of MAHs and 16.48% of Polycyclic aromatic hydrocarbons was obtained.

Kinetic synergistic effect in co-pyrolysis of Eucalyptus globulus with high and low density polyethylene

The pyrolysis of Eucalyptus globulus (EG) with different blends of high density polyethylene (HDPE) and low density polyethylene (LDPE) by thermogravimetry has been studied. ASTM-E1641-16 standard method has been used to evaluate the kinetics during the pyrolysis of the studied blends. For all feedstocks (EG, HDPE and LDPE) and blends studied, the relative content (%) of the volatile organic compound has been determined by GC–MS analysis. Different synergistic effects on the activation energy of EG blends with HDPE and LDPE have been found. EG-HDPE blends showed a minimum activation energy (Ea) (125 kJ mol−1) at the 80% EG–20% HDPE ratio, while the minimum Ea value for EG-LDPE blends was found at the 60% EG–40% LDPE ratio (135 kJ mol−1) has been identified. To test which components exert a greater synergistic effect, mixtures of HDPE and LDPE with the main components of eucalyptus (cellulose, hemicellulose and lignin) have also been studied. However, no synergistic effects on the pyrolysis of cellulose have been detected. Moreover, in hemicellulose and lignin with both types of polyethylene mixtures, a significant decrease in Ea has been appreciated. The lowest Ea values for 60% cellulose–40% HDPE (167 kJ mol−1) and 60% lignin–40% HDPE (140 kJ mol−1) has been calculated. On the other hand, minimum values for 40% cellulose–60% LDPE (166 kJ mol−1) mixture and for 40% lignin–60% LDPE (168 kJ mol−1) mixture have been detected. Thus, the decrease in both Ea and the Arrhenius pre-exponential factor on the eucalyptus-polyethylene blends to the presence of hemicellulose and lignin can be attributed. Moreover, during the co-pyrolysis of HDPE-EG mixtures, n-paraffins, ketones, phenols and sugars are the main VOCs identified. In contrast, in LDPE-EG mixtures, only n-paraffins (55%) and olefins (44%) have been identified.

Plastic regulates its co-pyrolysis process with biomass: Influencing factors, model calculations, and mechanisms

Co-pyrolysis of plastics and biomass can effectively improve the quality of bio-oil and solve the problem of plastic pollution. However, synergistic effect of co-pyrolysis on kinetics and the role of biomass H/Ceff in co-pyrolysis are still not conclusive. In this work, the co-pyrolysis synergistic effects of three different hydrogen-to-carbon ratio (H/Ceff) of biomass-rice husk (RH), sugarcane bagasse (SUG), and poplar wood (PW) with hydrogen-rich polypropylene (PP) were studied using a thermogravimetric method. The total synergy degree (φ) and the difference between experimental and theoretical weight losses (ΔW) were defined, and the activation energies of various experimental materials were calculated by the isoconversional method. The results showed that the addition of PP reduced the dependence of product species on biomass H/Ceff during co-pyrolysis. The synergistic effect of biomass and PP was related to biomass types, pyrolysis temperature, and mass ratio of biomass to PP. The mixture of SUG and PP showed positive synergistic effect at all mass ratios. Simultaneously, at the low temperature of pyrolysis, the synergistic effect is inhibited in all mixtures, which might be due to the melting of PP. Kinetic analysis showed that the activation energy could be reduced by 11.14–31.78% by co-pyrolysis with biomass and PP. A multi-step mechanism was observed in both the pyrolysis of a single sample and the co-pyrolysis of a mixture, according to Criado’s schematic analysis.

Co-pyrolysis of lignocellulosic biomass and plastics: A comprehensive study on pyrolysis kinetics and characteristics

Co-pyrolysis of biomass with plastics is an interesting research trend in improving both the yield and quality of oil products toward taking advantage of flexible material resources and sustainable fuel development. This study investigated the kinetic behaviors using thermogravimetric analysis and pyrolysis characterization for the co-pyrolysis of biomass (bamboo and oak wood) with plastics (polypropylene [PP] and polystyrene [PS]) in a fixed-bed reactor. The kinetic triplet for feedstocks was determined using the isoconversional method, compensation effect, and master plot method. The addition of 20 wt% plastics into biomass decreased the activation energy, with the most distinct positive synergistic effect for the bamboo/PS blend. In addition, the effect of co-pyrolysis temperature and biomass/plastic ratio on pyrolysis characteristics was investigated. Through biomass pyrolysis and biomass/plastic co-pyrolysis, the positive changes in distributions and physical-chemical properties of the products (i.e., char, oil, and gas) were observed using various analytical methods. Especially in the case of biomass/PS blends, the synergistic effect of co-pyrolysis was shown due to the difference in the actual and theoretical yields of the products. The liquid yields of the co-pyrolysis were 50.95, 50.17, 55.15, and 56.16 wt% for bamboo/PP, bamboo/PS, oak wood/PP, and oak wood/PS, respectively. The highest HHV of 28.22 MJ/kg was obtained for oil derived from the co-pyrolysis of bamboo/PS. Furthermore, co-pyrolysis chars have high HHVs in the range of 30.73–32.41 MJ/kg, suggesting that they can be used as solid fuels.

Mechanism of synergistic effects and kinetics analysis in catalytic co-pyrolysis of water hyacinth and HDPE

Co-pyrolysis of water hyacinth (Eichhornia crassipes) and HDPE is a commercially effective method to mitigate the pressure of environmental pollution and the problem of invasive alien species. In this paper, the thermal behavior and kinetic evaluation of the two raw materials with or without catalysts have been investigated. The mechanism of catalytic pyrolysis was also investigated by analyzing the free radicals generated during catalytic pyrolysis. The results showed that the heating rates had a negligible effect on the pyrolysis process. The addition of HDPE could reduce the formation of char and be conducive to the complete reaction with the higher value of the comprehensive pyrolysis index (CPI). The sample containing 75% water hyacinth exhibited the strongest synergistic effect in co-pyrolysis, with the lowest value of the difference between experimental and theoretical weight loss (ΔW) and activation energy among the co-pyrolysis samples. However, the sample with 25% water hyacinth showed an inhibiting effect due to the positive value of ΔW in the main decomposition temperature. Whereas the sample containing HZSM-5 had the lowest ΔW and activation energy compared to the blends without catalysts indicating that the presence of HZSM-5 was conducive to the synergistic effect in co-pyrolysis. The promotion was then demonstrated to be due to the abundance of free radicals generated in the catalytic process. This paper aims to provide some suggestions on the solution for the alleviation of environmental and energy crisis.

Efficient pyrolysis of ginkgo biloba leaf residue and pharmaceutical sludge (mixture) with high production of clean energy: Process optimization by particle swarm optimization and gradient boosting decision tree algorithm

Production of sustainable clean energy can be achieved by co-pyrolysis of agricultural residues and wastewater sludge. Herein, non-additive thermal behaviour of co-pyrolysis of pharmaceutical sludge and ginkgo biloba leaf residues was investigated. Synergistic effect of co-pyrolysis was not obvious at elevated temperatures. Further, kinetics of co-pyrolysis was studied by fitting Coats-Redfern integration method to thermogravimetric (TG) curve. The change of heat and mass transfer in the reactor caused the change of dynamic parameters. Moreover, hybrid particle swarm optimization and gradient boosting decision tree (PSO–GBDT) algorithm was designed to boost the energy production at full-scale pyrolysis plant by monitoring TG curves. PSO–GBDT model well predicts mass loss rate of the mixture at different heating rates confirming that co-pyrolysis of PS and GBLR can results in high energy production by increasing PS pyrolysis. Designing PSO–GBDT model help to reduced waste production by resourceful treatment of waste in to energy.

Synergistic effect of mixing wheat straw and lignite in co-pyrolysis and steam co-gasification

Co-pyrolysis and steam co-gasification of wheat straw (WS) and lignite coal (LC) were studied in a tube furnace between 700 °C and 900 °C. Synergistic effect in co-pyrolysis is not always apparent. However, with the introduction of H2O vapor, synergetic effect is more obvious. Gas volume generated by co-gasification was higher than the prediction in all cases. Meanwhile, temperature played an important role and had a linear relationship with the excess gas volume when it exceeded 800 °C. These findings can be explained by that sufficient H2O vapor could enhance synergy according raising catalytic effect of alkali and alkaline earth metals (AAEMs), promoting free radical generated and increasing reactivity of half-chars. Moreover, co-gasification of WS and LC with several blending ratios were studied at 850 °C. It found H2O vapor could promote free radical formation stronger with higher ratio of WS during co-gasification, thus showing an enhancing effect on the reactivity of WS-derived chars.

Pyrolysis kinetics and synergistic effect in co-pyrolysis of Samanea saman seeds and polyethylene terephthalate using thermogravimetric analyser

This work deals with co-pyrolysis of polyethylene terephthalate (PET) with Samanea saman seeds (SS) to understand the kinetics and synergistic effects between two different feedstocks. SS and PET were blended in different ratios (1:1, 3:1 and 5:1) and iso-conversional models such as Kissinger-Akahira-Sunose (KAS), Friedman method (FM), Starink (ST), Ozawa-Flynn-Wall method (OFW), and Coats-Redfern method (CR) were used to calculate the kinetic parameters. Results substantiate assumed hypothesis that blending of SS and PET at 3:1 provided higher synergistic effect and RMS value, which in turn indicated maximum formation of hot volatiles during pyrolysis. Kinetic analysis confirmed that individual SS and PET required higher activation energy while blended SS and PET at 3:1 ratio required lower activation energy to start the reaction. The thermodynamic and kinetic analysis confirmed that biomass had complex reaction kinetics which depends on reaction rate as well as its order.

Investigation of waste biomass co-pyrolysis with petroleum sludge using a response surface methodology

The treatment of waste biomass (sawdust) through co-pyrolysis with refinery oily sludge was carried out in a fixed-bed reactor. Response surface method was applied to evaluate the main and interaction effects of three experimental factors (sawdust percentage in feedstock, temperature, and heating rate) on pyrolysis oil and char yields. It was found that the oil and char yields increased with sawdust percentage in feedstock. The interaction between heating rate and sawdust percentage as well as between heating rate and temperature was significant on the pyrolysis oil yield. The higher heating value of oil originated from sawdust during co-pyrolysis at a sawdust/oily sludge ratio of 3:1 increased by 5 MJ/kg as compared to that during sawdust pyrolysis alone, indicating a synergistic effect of co-pyrolysis. As a result, petroleum sludge can be used as an effective additive in the pyrolysis of waste biomass for improving its energy recovery.

Thermogravimetric analysis and kinetics of co-pyrolysis of raw/torrefied wood and coal blends

The properties of biomass can be improved via torrefaction, and torrefied wood is a fuel with the potential to partially replace coal. In this study, raw Cryptomeria japonica (WRaw) is torrefied at 250 (TW250) and 300°C (TW300) for 1h, and then mixed with an anthracite coal to undergo co-pyrolysis. A thermogravimetric analyzer is used to examine the co-pyrolysis characteristics of fuel blends and five different biomass blending ratios (BBRs) of 100, 75, 50, 25, and 0wt.% are taken into consideration. When WRaw, TW250, and the coal are tested, the pyrolysis is characterized by a three-stage reaction, whereas four-stage thermal degradation is found for TW300 and fuel blends. The predictions from the linear superposition of the thermal decomposition of individual fuels fit the experimental data of the fuel blends, suggesting that the interaction or synergistic effect of co-pyrolysis between the raw/torrefied C. japonica and the coal is slight. The co-pyrolysis kinetics of the fuel blends is also analyzed. The variation of chemical kinetics with decreasing BBR in the second stage is different from that in the third stage. That is, an increase in BBR leads to an increase in the activation energy in the second stage, whereas it causes a decrease in the third stage. This is attributed to that the reactivities of cellulose and lignin in biomass are different from that of coal in the two stages.