Two-step Pyrolysis Process Research Articles

Enhanced Removal of Chlorpyrifos, Cu(II), Pb(II), and Iodine from Aqueous Solutions Using Ficus Nitida and Date Palm Biochars

This study explores the adsorption efficiency of biochar derived from palm trees and Ficus nitida for the removal of various contaminants, including Cu(II), Pb(II), iodine, and chlorpyrifos from aqueous solutions. Biochar was prepared using a two-step pyrolysis process for date palm biochar and single-step pyrolysis for Ficus nitida biochar. Characterization techniques such as SEM, EDX, and FTIR revealed a significant surface area and a variety of functional groups in both types of biochar, essential for effective adsorption. The date palm biochar exhibited superior adsorption capacities for Cu(II) and Pb(II) ions, achieving efficiencies up to 99.9% and 100%, respectively, due to its high content of oxygen-containing functional groups that facilitated strong complexation and ion exchange mechanisms. Conversely, Ficus nitida biochar demonstrated a higher adsorption capacity for iodine, reaching 68% adsorption compared to 39.7% for date palm biochar, owing to its greater surface area and microporosity. In the case of chlorpyrifos, Ficus nitida biochar again outperformed date palm biochar, achieving a maximum adsorption efficiency of 87% after 24 h of incubation, compared to 50.8% for date palm biochar. The study also examines the effect of incubation time on adsorption efficiency, showing that the adsorption of chlorpyrifos by date palm biochar increased significantly with time, reaching a maximum of 62.9% after 48 h, with no further improvement beyond 12 h. These results highlight the importance of biochar characteristics, such as surface area, pore structure, and functional groups, in determining adsorption efficiency. The findings suggest that optimizing pyrolysis conditions and surface modifications could further enhance the performance of biochar as a cost-effective and sustainable solution for water purification and environmental remediation.

Interconnected hierarchical 3D porous carbon derived from Saccharum officinarum L. leaf based on the synergistic effect of KOH for high performance supercapacitor

ABSTRACT Porous carbon has continuously been explored based on biomass for green energy storage due to its abundant, renewable, environmentally friendly resource, economical features, and thermal-chemical stability. Therefore, this study aimed to present porous carbon derived from sugarcane or Saccharum officinarum L. leaf as a precursor, achieved through a KOH activation strategy that combines a two-step pyrolysis process. The synthesized material exhibited an interconnected 3D hierarchical structure, a high specific surface area of 752 m2/g, and a carbon purity of 91.38%. Supercapacitor cell electrode had the highest specific capacitance of 471 F/g induced by 0.5 M KOH. Furthermore, in the 1 M H2SO4 electrolyte solution, the symmetrical supercapacitor cell electrodes produced the highest specific energy of 65.55 Wh/Kg at a specific power output of 329 W/Kg. As a result, a sustainable green method was established by using a biomass energy source that is applied as high-performance supercapacitor cell material.

Utilization of macadamia nutshell-derived activated carbon for enhanced congo red adsorption

This study addresses the challenge of removing Congo red (CR) from aqueous solutions using activated carbon (AC) derived from macadamia nutshells (MNS). A unique two-step carbonization and pyrolysis process was employed to produce MNS-AC with high surface area and porosity. Key experimental variables, including initial CR concentration, contact time, and pH, were systematically varied in batch mode. Results indicated that the modified AC achieved significantly higher removal percentages compared to unmodified charcoal. At pH 2.0 and an initial dye concentration of 50 mg L−1, CR removal reached 97.48 % for MNS-AC3. The maximum adsorption capacity (qmax) of 58.29 mg g−1 was observed at an initial dye concentration of 200 mg L−1. The pseudo-second-order kinetic model closely matched the experimental data, and equilibrium data analysis using Langmuir and Dubinin-Radushkevich (D-R) isotherm models provided excellent fits. This research demonstrates the potential of using industrial biomass waste to develop sustainable solutions for dye removal in wastewater treatment.

Biochar from Date Palm Waste via Two-Step Pyrolysis: A Modified Approach for Cu (II) Removal from Aqueous Solutions

Heavy metals such as copper, often discharged from industrial processes and agricultural activities, pose significant environmental and health risks due to their toxicity, particularly in the soluble form of Cu (II). This study investigates the effectiveness of biochar produced from date palm leaf midrib waste via a two-step pyrolysis process, as a sustainable and economical adsorbent for removing Cu (II) from aqueous solutions The biochar was characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) surface area analysis. Adsorption experiments were conducted to evaluate the effects of pH, adsorbent dosage, contact time, and initial Cu (II) concentration. The maximum adsorption capacity was observed at pH 6, with a capacity of 70 mg/g. The adsorption data were best described by the pseudo-second-order kinetic model, indicating chemisorption as the primary mechanism. Thermodynamic studies indicated that the adsorption process was spontaneous and exothermic, with a Gibbs free energy change (ΔG) of −1.245 kJ/mol at 25 °C, enthalpy change (ΔH) of −15.71 kJ/mol, and entropy change (ΔS) of 48.36 J/mol·K. Reusability tests demonstrated that the biochar retained over 85% of its initial adsorption capacity after five cycles, with capacities of 60 mg/g in the first cycle, decreasing to 52 mg/g by the fifth cycle. This study highlights the potential of biochar derived from date palm waste as an efficient, sustainable adsorbent for the removal of Cu (II) from wastewater, contributing to both environmental management and waste valorization. Future research should focus on optimizing the biochar production process and exploring its application for the removal of other contaminants.

Insights into kinetics, thermodynamics, and mechanisms of chemically activated sunflower stem biochar for removal of phenol and bisphenol-A from wastewater

This study synthesized a highly efficient KOH-treated sunflower stem activated carbon (KOH-SSAC) using a two-step pyrolysis process and chemical activation using KOH. The resulting material exhibited exceptional properties, such as a high specific surface area (452 m2/g) and excellent adsorption capacities for phenol (333.03 mg/g) and bisphenol A (BPA) (365.81 mg/g). The adsorption process was spontaneous and exothermic, benefiting from the synergistic effects of hydrogen bonding, electrostatic attraction, and stacking interactions. Comparative analysis also showed that KOH-SSAC performed approximately twice as well as sunflower stem biochar (SSB), indicating its potential for water treatment and pollutant removal applications. The study suggests the exploration of optimization strategies to further enhance the efficiency of KOH-SSAC in large-scale scenarios. These findings contribute to the development of improved materials for efficient water treatment and pollution control.

An asymmetrically coordinated Zn-Co diatomic site catalyst for efficient hydrogen evolution reactions.

We propose an innovative preparation method, namely, a two-step pyrolysis process, to synthesize Zn-Co bimetallic catalysts with excellent hydrogen evolution performance. In the synthesized Zn1Co1-SNC catalyst, there exists a strong interaction between Zn and Co, along with synergistic effects with S/N atoms, collectively promoting the stability of the catalyst structure. Experimental results demonstrate that the overpotential of this catalyst at 10 mA cm-2 current density is only 49 mV, and it maintains excellent hydrogen evolution performance even after 5000 cycles.

Advanced High-Energy All-Solid-State Hybrid Supercapacitor with Nickel-Cobalt-Layered Double Hydroxide Nanoflowers Supported on Jute Stick-Derived Activated Carbon Nanosheets.

Developing efficient, lightweight, and durable all-solid-state supercapacitors is crucial for future energy storage systems. The study focuses on optimizing electrode materials to achieve high capacitance and stability. This study introduces a novel two-step pyrolysis process to synthesize activated carbon nanosheets from jute sticks (JAC), resulting in an optimized JAC-2 material with a high yield (≈24%) and specific surface area (≈2600m2g-1). Furthermore, an innovative in situ synthesis approach is employed to synthesize hybrid nanocomposites (NiCoLDH-1@JAC-2) by integrating JAC nanosheets with nickel-cobalt-layered double hydroxide nanoflowers (NiCoLDH). These nanocomposites serve as positive electrode materials and JAC-2 as the negative electrode material in all-solid-state asymmetric hybrid supercapacitors (HSCs), exhibiting remarkable performance metrics. The HSCs achieve a specific capacitance of 750Fg-1, a specific capacity of 209mAhg-1 (at 0.5Ag-1), and an energy density of 100Whkg-1 (at 250Wkg-1) using PVA/KOH solid electrolyte, while maintaining outstanding cyclic stability. Importantly, a density functional theory framework is utilized to validate the experimental findings, underscoring the potential of this novel approach for enhancing HSC performance and enabling the large-scale production of transition metal-based layered double hydroxides.

Reversible growth of solid electrolyte interface enhances charge capacity in cobalt sulfide-carbon nanotube anodes

The development of high-performance anode materials for lithium-ion batteries is a critical aspect of advancing energy storage technology. This study presents a novel approach to improve the charge capacity of anodes by harnessing the reversible growth of the solid electrolyte interface (SEI). This work focuses on cobalt sulfide (Co9S8) nanoparticles incorporated into a porous carbon nanotube (CNT) structure. Through a two-step pyrolysis process, Co9S8CNT composites, characterized by their conductive and mechanically robust CNT matrix are successfully synthesized. These Co9S8CNT anodes exhibit excellent initial charge capacity (560.5 mAh g−1 at 100 mA g−1) and remarkable stability, with a charge capacity of 633 mAh g−1 after 1000 cycles at 1000 mA g−1, accompanied by a Coulombic efficiency exceeding 99 %. Notably, this investigation reveals that the growth of the SEI plays a pivotal role in enhancing the charge capacity. Through in-situ Raman spectroscopy and other analytical techniques, it is suggested that the reversible reduction of organic solvent molecules within the large polymeric SEI is responsible for the increased charge capacity. This unique phenomenon is characterized by changes in the SEI's composition, driven by the charge and discharge processes. This study is a novel attempt to report a SEI's reversible growth that results in improved charge capacity, contrasting with prior research where SEI growth typically leads to capacity loss. Understanding this stable system provides valuable insights into increasing the cycle life and charge capacity of anodes, not only for transition metal sulfides but also for broader applications in energy storage.

EDA/PANI derived FeNxC with Fe-Nx active sites as room temperature hydrogen storage material

FeNxC is explored as an efficient and cost-effective hydrogen storage material. Fe/Ethylenediamine (EDA) complex formed initially is protected by (Polyaniline) PANI polymer that gets converted to FeNxC through two-step pyrolysis process. In the first pyrolysis, (Iron sulfide) FeS particles are formed, which get converted to Fe3O4 nanoparticles in second pyrolysis. Fe-Nx active sites get exposed in micro/mesoporous carbon matrix after oxide removal through acid wash. Hydrogen adsorption studies are conducted at 25–100 °C temperature, 5–30 bar pressure. The maximum hydrogen storage capacity is observed as 2.83 wt% at 26 bar, 25 °C for the two-step calcined, acid-washed FeNxC-900–800 A, which possesses large surface area of 995 m2/g, pore volume of 0.711 cm3/g when compared to FeNxC-900–800 and FeNxC-900. The adsorption mechanism, spillover occurring at covalently bonded Fe-Nx active sites and subsequent migration, diffusion to get physisorbed within porous carbon surface, leads to the enhancement in the hydrogen adsorption.

Biochar-ZnO Composites from Petung Bamboo Stems to Increase Adsorption and Photocatalytic Degradation of Methylene Blue in Wastewater

The rapid development of industrial sector worldwide has contributed greatly to environmental pollution. In many countries, surface and groundwater are polluted by industrial wastewater effluent, such as synthetic dyes. Dyes are difficult to decompose naturally and cause disruption to aquatic ecosystems. To eliminate risks associated with the presence of synthetic dyes, photocatalytic-adsorption is still considered the most environmentally friendly and effective for dye removal. In this work, a novel biochar-ZnO composite was synthesized from petung bamboo stems having a high cellulose content, and used to eliminate methylene blue dye in the water. Biochar-ZnO composite was prepared from bamboo stems via a two-step pyrolysis process in a furnace with nitrogen flow at 400°C and 700°C for one hour. The addition of ZnO into biochar enhanced methylene blue removal up to 94.6% at an initial concentration of 10 mg.dm-3, pH 3, and contact time of 180 minutes, under UV light. It can be concluded that biochar-ZnO composite is highly feasible for dye removal from wastewater.

Novel strategy to produce polyaromatic compounds at low temperature for the production of secondary chars

The production of polyaromatic compounds during biomass thermochemical processing at temperatures over 700 °C from the secondary reactions pyrolysis vapors is a well study phenomena. These compounds are sometimes used to produce carbonaceous materials (such as carbon black, carbon nanotubes). In the case of gasification these polyaromatic compounds form tars and are a major source of problems for the operation of these reactors. In this paper we explore the use of acid impregnation, particularly using phosphoric acid, to reduce the temperature at which small polyaromatic rings are formed and released from the biomass. The acid treatment of biomass was found to increase the yield of biochar (from 17 wt% to 40 wt%) and to be an excellent source of polyaromatic compounds (close to 15 wt% on biomass dry basis). In this manuscript we explored the use of the small polyaromatic ring systems produced from the carbonization of acid-pretreated biomass as precursors for the synthesis of secondary carbons. A two-step pyrolysis process was conducted on acid-treated biomass, revealing that the volatiles produced in the first stage were primarily derived from the dehydration of anhydrosugars. In contrast, the volatiles produced in the second stage were found to be primarily composed of aromatic compounds similar to those produced in gasification processes, with low to no oxygen content. In this research, we have introduced an innovative strategy to maximize the benefits of acid-treated biomass pyrolysis by utilizing the low oxygen aromatic hydrocarbons compounds produced as a carbon source for the production of carbon nanostructures (CNS) on biochar-supported nickel catalysts. This methodology allows to produce polyaromatic compounds at very low temperature from lignocellulosic materials. This not only optimizes the utilization of biomass resources but also enhances the yield of high-value products and aligns with the principles of a circular economy.

One-pot cogeneration of phenol-rich bio-oil, hydrogen-rich gas and solid carbon degradation material from reed

A newly developed two-step catalytic pyrolysis process (TSCP) based on poly-generation technology is proposed to convert reed straw (RS) into phenol-rich bio-oil, hydrogen-rich gas, and solid carbon degradation material over iron-loaded activated carbon. The effects of the first step pyrolysis temperature (T1) and catalyst composition on the product distribution and target product selectivity were investigated. When T1 was 350 °C and 10% Fe/AC catalyst was selected, the concentration of phenolic compounds and H2 peaked at 63.87 area% and 63.29 vol%, respectively. The iron-loaded activated carbon catalysts promoted the decarboxylation and decarbonylation reactions of cellulose and hemicellulose decomposition products, as well as the demethylation and demethoxylation reactions of lignin for the selective production of phenolic compounds and hydrogen gas. In addition, 94.7% quinclorac (10 mg/L) removal was achieved with 0.2 g/L 10% Fe/AC catalyst-doped pyrolysis carbon and 2 mM PMS within 90 min. This study could realize the high-value comprehensive utilization of reed and provide a reference for the full quantitative utilization of other agricultural and forestry wastes.

Influence of torrefaction as pretreatment on the fast pyrolysis of sugarcane trash

This study aims to perform a comprehensive analysis of the two-step pyrolysis process, including the three-phase products obtained from torrefaction followed by fast pyrolysis (FP), with particular attention to the redistribution of mass, elements and energy. Torrefaction pretreatment of sugarcane trash (ST) was carried out in a tube furnace at 220 °C, 260 °C and 300 °C for 60 min. Torrefaction results showed that the quality improvement of ST was in the increase in carbon content and the removal of low-calorific volatiles. Fast pyrolysis of raw and torrefied ST was carried out in a mechanically stirred fluidized bed reactor. The results showed that torrefaction pretreatment led to an increased biochar yield and a decreased bio-oil yield in the subsequent FP step. Nevertheless, the quality of obtained bio-oil was enhanced by the higher phenolic content and the lower water and acid contents. On the other hand, the total yield of liquid (including torrefaction liquid and FP bio-oil) of the two-step pyrolysis process decreased while the solid (biochar) yield increased and the total gas yield changed less, compared to the direct FP of raw ST. Furthermore, the elemental redistribution results revealed that most of the carbon (65.21–93.02 wt%) remained in ST after torrefaction, while considerable amounts of oxygen (26.14–69.58 wt%) and hydrogen (23.53–61.25 wt%) were transferred into the torrefaction liquid and non-condensable gases, including H2O, CO, and CO2, amongst others. Consequently, most of the feedstock energy (67.14–89.02 %) was transferred into FP products for the two-step pyrolysis process. In view of the redistribution properties and product quality (especially bio-oil), torrefaction prior to fast pyrolysis is recommended and 260 °C is regarded as a suitable temperature to balance product yield and quality. Overall, this study provides valuable data for a better understanding of the role of torrefaction pretreatment on biomass fast pyrolysis.

Structural design, preparation and characterization of an effective microwave absorbent: rGO-NiCo2O4 nanochains

Reduced graphene oxide-nickel cobaltate nanochain (RGO-NiCo2O4 nanochains) is prepared via two-step pyrolysis process. Carbon nanotubes were grown on the surface of GO by a one-step pyrolysis process, and then NiCo2O4 nanochains were prepared by adsorption of metal ions onto carbon nanotubes grown in situ on graphene sheets, followed by a step pyrolysis process. The sizes of NiCo2O4 are in the range of 5–10 nm; and lengths of the nanochains are approximately 200 nm. When the doping ratio in paraffin is 10 wt%, the microwave-absorbing performance is as follows: the minimum reflection loss (RL) value is − 42.10 dB which is founded at the frequency of 16.64 GHz while the thickness is 1.6 mm. Effective absorption bandwidth (RL < −10 dB) reaches 4.88 GHz when the thickness is 1.8 mm. The excellent absorption properties result from the unique microstructure and synergism of RGO and NiCo2O4. Therefore, it is expected to be a kind of light-weight microwave absorption materials.

Synthesis and Electrochemical Performances of a Versatile Nitrogen-Doped Carbon Skeleton Material Derived from a Humate-CoFe-ZIF/Melamine Precursor

Humic acid (HA), melamine, and ZIFs are superior precursors for preparing carbon materials. Especially, metal ions in ZIFs are excellent nanocatalysts for synthesizing CNTs or graphene, while melamine and ZIFs are good dopants for fabricating nitrogen-doped carbon materials. Here, nitrogen-doped carbon skeletal materials (NCS) assembled by a large number of bamboo-like CNTs and a small number of graphene layers were elaborately synthesized by a two-step pyrolysis process using a humate-CoFe-ZIF (HA-CoFe-ZIF) composite material as the template and melamine as the carbon and nitrogen source. NCS-II exhibits desirable supercapacitive characteristics and superior support performance due to a harmoniously assembled graphitic structure, favorite nitrogen incorporation mainly including pyridinic N and pyrrolic N at a high dosage of 5.24 wt %, abundant mesoporous structure, and large specific surface. As a supercapacitor electrode material, NCS-II demonstrates a high electrochemical capacitance (324 F g–1 at 1 A g–1), wide operating current density range (1–50 A g–1), and rate capability (64% from 5 A g–1 to 50 A g–1). And the prepared NCS-II//AC asymmetric supercapacitor also displays a large specific capacitance (129 F g–1 at 1 A g–1), good cycling stability (96% at 5 A g–1 for 10 000 cycles), and high energy density (25.6 Wh kg–1 at 600 W kg–1). As a catalyst support, the NCS-II provides plentiful active sites and a large specific surface area for the highly dispersed loading of PtCo nanoparticles. The prepared 1:1-PtCo/NCS-II catalyst exhibits high catalytic activity, good cycling stability, and strong CO tolerance ability for methanol oxidation reaction (MOR). Its ECSA value, CV peak current density, and peak current retention after 500 CV turns are high, up to 265.7 m2 gpt–1, 850 mA mgPt–1, and 79%, respectively.

A synergistic route of heterointerface and metal single-atom configurations towards enhancing microwave absorption

Derivatized multi-void composite microplates (CoNXC) were successfully fabricated for high-efficient electromagnetic wave absorption (EMA) using a two-step pyrolysis process assisted by molten dual-salt-mediated template. Structural analysis indicated that cobalt single atoms coexisted stably with Co nanoparticles in the derived carbon matrix, exhibiting the coupling of Co/graphite heterointerface. Various bonding configurations of Co/N atoms could be modulated by N-doping, in which the percentage of Co-NX single-atom coordination ranged from 18.58 % to 37.62 %, including CoN2, CoN3 and CoN4 configurations. Theoretical calculations demonstrated that the Co/graphite heterointerface and the Co single-atom configurations could significantly change the charge status and distribution, and synergistically promote dielectric polarization relaxation and electrons transport, which was in favor of strengthening the dielectric loss capacity. Benefiting from these, CoNXC remained high EMA performance even with filler loading of 10 wt%. In this regard, CoN20C exhibited strong RL peaks in multiple bands involving C-, X- and Ku-band, and its RLmin value reached −63.4 dB at 8.3 GHz, which were superior to most reported derivatized carbon-based composites. This work not only elucidates the synergistic mechanism of EMA by metal single-atom coordination and heterointerface, but also provides a new strategy for developing advanced carbon-based absorbers.

Design of Bronze-Rich Dual-Phasic TiO2 Embedded Amorphous Carbon Nanocomposites Derived from Ti-Metal-Organic Frameworks for Improved Lithium-Ion Storage.

Dual-phasic (DP)-TiO2 -based composites are considered attractive anode materials for high lithium-ion storage because of the synergetic contribution from dual-phases in lithium-ion storage. However, a comprehensive investigation on more efficient architectures and platforms is necessary to develop lithium-storage devices with high-rate capability and long-term stability. Herein, for the first time, a rationally designed bronze-rich DP-TiO2 -embedded amorphous carbon nanoarchitecture, denoted as DP-TiO2 @C, from sacrificial Ti-metal-organic frameworks (Ti-MOFs) via a two-step pyrolysis process is proposed. The bronze/anatase DP-TiO2 @C nanocomposites are successfully synthesized using a unique pyrolysis process, which decomposes individually the metal clusters and organic linkers of Ti-MOFs. DP-TiO2 @C exhibits a significantly high density and even distribution of nanoparticles (<5nm), enabling the formation of numerous heterointerfaces. Remarkably, the bronze-rich DP-TiO2 @C shows high specific capacities of 638 and 194mAhg-1 at current densities of 0.1 and 5Ag-1 , respectively, owing to the contribution of the synergetic interfacial structure. In addition, reversible specific capacities are observed at a high rate (5Ag-1 ) during 6000 cycles. Thus, this study presents a new approach for the synthesis of DP-TiO2 @C nanocomposites from a sacrificial Ti-MOF and provides insights into the efficient control of the volume ratio in DP-TiO2 anode architecture.

Theoretically Revealed and Experimentally Demonstrated Synergistic Electronic Interaction of CoFe Dual-Metal Sites on N-doped Carbon for Boosting Both Oxygen Reduction and Evolution Reactions.

Heteronuclear double-atom catalysts, unlike single atom catalysts, may change the charge density of active metal sites by introducing another metal single atom, thereby modifying the adsorption energies of reaction intermediates and increasing the catalytic activities. First, density functional theory calculations are used to figure out the best combination by modeling two transition-metal atoms from Fe, Co, and Ni onto N-doped graphene. Generally, Fe and Co sites are highly active for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), respectively. The combination of Co and Fe to form CoFe-N-C not only further improves the Fe's ORR and Co's OER activities but also greatly enhances the Co site's ORR and Fe site's OER activities. Then, we synthesize the CoFe-N-C by a two-step pyrolysis process and find that the CoFe-N-C exhibits exceptional ORR and OER electrocatalytic activities in alkaline media, significantly superior to Fe-N-C and Co-N-C and even commercial catalysts.

Production and characterization of porous magnetic biochar: before and after phosphate adsorption insights

AbstractThe modification process of biochars enables different advantages including enhanced adsorption properties for different pollutants. Herein, porous magnetic biochars (PMB) were successfully produced from softwood biomass through a two-step pyrolysis process together with FeCl3 modification. The effect of production temperature on adsorption was studied at 200 or 300 °C, followed by iron salt modification and subsequent pyrolysis at 600 or 800 °C. Biochars were characterized before and after phosphate adsorption via various characterization methods to acquire structural, elemental, and morphological properties of the adsorbent. The effects of phosphate concentration, contact time, and temperature on the adsorption process were examined in the batch mode. The characterization showed embedded iron oxide crystals of 23 nm within the biochar structure with a magnetic strength of 38.9 emu/g, which can assist the separation process of the powdered adsorbent from the aqueous medium. The surface area of the PMB was measured as 93 m2/g and 0.002 cm3/g pore volume. PMB showed complete removal (100%) of phosphate at the lower concentration (5 mg/l P). At higher concentration (25 mg/l P), the biochar prepared under 200/800 °C showed the highest removal (30%). The adsorption was enhanced with time (optimal 3 h) and temperature, which shows endothermic chemisorption following Langmuir isotherm and Pseudo-second order kinetic models. The desorption study suggested the slow release of phosphate from the spent adsorbent and potential reuse for soil enhancement. These results point towards the sustainable use of PMB as an effective and magnetically recyclable adsorbent for phosphate removal and reclaim.

Graphene nanosheets derived from waste plastic for cost-effective thermoelectric applications

Herein, we report the synthesis of graphene nanosheets (GNs) derived from plastic waste for cost-effective thermoelectric (TE) applications. The synthesis of GNs was done as per our present process, where a two-step pyrolysis process was carried at the temperature range of 400 °C–850 °C by using Al2O3 as the catalytic and degradation template, while nickel metal-based catalytic beds were used to get high-quality GNs from our indigenously developed 100 Kg per batch pilot-scale plant. Raman, X-ray diffraction (XRD), and transmission electron microscopy (TEM) analysis showed the presence of 4–5 nm thick sheets of GNs. After the successful synthesis of GNs from waste plastics, the TE properties of thus synthesized GNs were investigated. GNs showed low resistivity of 3.93 × 10−2 Ω-m at room temperature, which are further decreases with an increase in temperature. The Seebeck coefficient values of the GNs show that the material behaves as a p-type semiconductor. The TE figure of merit ZT showed a signatory value of 0.1 × 10−6 at the temperature of 426 K corresponding to the TE properties within the synthesized GNs. The results of TE analysis indicate that waste plastic-derived GNs can be used for a variety of TE applications.