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This study was undertaken at laboratory level to investigate the effect of nitrogen on gravimetric analysis of biomass. Nineteen samples of lignocellulosic biomass were collected. After preparation of the samples, their gravimetric analysis was performed to determine the moisture content, total solids, volatile solids, fixed solids, and ash content. In the present research work, four approaches were used to determine the value of moisture content, total solids, volatile solids, fixed solids, and ash including with nitrogen without lid, with nitrogen with lid, without nitrogen without lid, and without nitrogen with lid. After the gravimetric analysis of the biomass, the empirical models were developed using the linear regression analysis based on the least square method. The empirical equations were developed, and their mean errors were determined. The developed models were compared through regression coefficient (R2), mean absolute error, mean bias error, standard error, root sum square, and Akaike information criterion. In the developed 16 equations, the results based on the error analysis were in the specified range of R2(0.991 ± 0.01–0.995 ± 0.04), mean absolute error (4.881 ± 0.3–43.880 ± 0.3), mean bias error (0.253 ± 0.01–41.382 ± 0.1), standard error (1.178 ± 0.01–1.625 ± 0.4), root sum square (23.426 ± 0.1–1175.911 ± 0.2), and Akaike information criterion (13.829 ± 0.1–92.148 ± 0.8). Consequently, it is noteworthy that equation 38 (considering 4 factors total solids, volatile solids, fixed solids, and ash) showed the minimum root sum square and Akaike information criterion value, confirming that this equation is considered the best for gravimetric analysis under the inert atmosphere of nitrogen without placing lid on crucibles. As per the results, the nitrogen purging gives high accuracy, whereas the cost is high.

Polymer-modified bitumen undergoes phase separation during storage due to a lack of compatibility between the polymers and bitumen. However, phase separation can be minimized via the addition of various compatibilizers. This study investigated low-density polyethylene (LDPE)-modified bitumen blends at 3, 6, 9, and 12% concentration of LDPE sourced from waste plastic films. Furthermore, the combined compatibilizers (1% of maleic anhydride-grafted polyethylene (PE-g-MA) and 0.15% sulfur) were added to LDPE-modified blends. The combination of compatibilizers significantly improved the softening point and storage stability while subsequently increasing the compatibility between recycled plastics (LDPE) and bitumen. The addition of PE-g-MA and sulfur decreased the melting temperature of LDPE up to 10 °C due to the swelling of the polymers compared to blends prepared with LDPE only. Higher thermal stability was observed for LDPE blends with PE-g-MA and sulfur than for the blends with LDPE only. The major weight loss for LDPE–based blends and LDPE blends in the presence of PE-g-MA and sulfur occurred at 380–520 °C and 400–540 °C, respectively. LDPE blends in the presence of compatibilizers showed lower phase angle at higher temperatures than neat LDPE blends, suggesting that the compatibilizers tend to form a complete polymer–bitumen network. It was concluded that incorporation of both sulfur and PE-g-MA enhanced the compatibility, thermal characteristics, and rheological properties of waste plastic-modified bitumen.

Over the past few decades, there has been extensive research into the development of waste-biomass-derived adsorbents due to their sustainable nature, cost-effectiveness, and ability to manage waste effectively. Therefore, this study focused on improving the adsorption properties of rice husk, an agricultural residue, using a novel solvothermal and catalytic solvothermal carbonization technique. Water and alcoholic solvents (ethanol and isopropanol) were used in solvothermal carbonization, and potassium hydroxide (KOH) was used as the catalyst. The maximum yield of solvochar was obtained without catalytic effect at approximately 34–41%. The characterization results presented a maximum surface area of 63.69 m2g−1followed by 33.16 m2g−1by the solvochars synthesized with ethanol (RE) and isopropanol (RI) without catalytic effect, respectively. On the other hand, solvochar with ethanol and catalyst presented the highest negative surface charge of −40.2 mV. CHNS, FTIR, XRD, XRF and XPS analyses presented abundant amorphous carbon contents, oxygen-containing functional groups, and inorganic compounds. Further, a continuous adsorption study of multi-heavy metal ions Fe3+, Mn2+, Pb2+, Zn2+, and Cu2+was performed using a fixed-bed flow column. The maximum adsorption capacity of multi-heavy metal ions was obtained by RE (13.24 mg g−1Cu2+, 40.16 mg g−1Fe3+, 7.72 mg g−1Mn2+, 57.22 mg g−1Pb2+, and 41.88 mg g−1Zn2+) followed by RI (25.59 mg g−1Cu2+, 27.32 mg g−1Fe3+, 21.46 mg g−1Mn2+, 47.20 mg g−1Pb2+, and 26.98 mg g−1Zn2+). On the other hand, catalytic solvochars synthesized by ethanol (REK) and isopropanol (RIK) have a lower metal ion uptake, which is 16.74 mg g−1Cu2+, 0.6 mg g−1Fe3+, 13.84 mg g−1Mn2+, 22.19 mg g−1Pb2+, 19.42 mg g−1Zn2+and 16.92 mg g−1Cu2+, 10.05 mg g−1Fe3+, 12.13 mg g−1Mn2+, 21.3 mg g−1Pb2+, 20.43 mg g−1Zn2+, respectively. The kinetics of multi-heavy metal ion adsorption was analyzed using intra-particle diffusion modeling. Post-adsorption characterization results showed a significant drop in surface area and porosity in the catalytic solvochar, while the other solvochar remains almost unchanged. Therefore, it is recommended that the metal ions be recovered through a desorption process and the solvochars regenerated without catalysts for further study.

Hydrothermal liquefaction technology carried out on local Malaysian oil palm fronds (OPF) in a batch autoclave reactor to produce solid bio-char as well as liquid bio-oil is reported in this study. The parameters taken in consideration for study encapsulated variable reaction temperature (160–260 °C) and reaction times (20–100 min). Observations showed that the bio-oil yield percentage increased from 27.3% at 160 °C to 41.9% at 260 °C, whereas bio-char yield percentage decreased from 65.2% at 160 °C to 43.2% at 260 °C. Similarly, higher reaction time also produces higher yield bio-oil percentage and lower bio-char yield percentage. The characterization results showed that the combustion properties of bio-char and bio-oil were improved after hydrothermal liquefaction due to decrease in percentage of oxygen of bio-oil and bio-char and an increase in percentage of carbon content. The carbon percentage increased from 42.73% for OPF to 59.42% and 60.47% for bio-char and bio-oil, respectively. Whereas, the percentage of oxygen decreased from 52.51 for OPF to 36.30% and 35.61 for bio-char and bio-oil. The main chemical compounds identified in bio-oil by GC-MS were phenolic compounds and their derivatives, alcohols, ketones, and esters.

Oil palm industry generates different types of waste biomass in the form of oil palm empty fruit bunch (OPEFB), oil palm mesocarp fibers (OPMF), oil palm fronds (OPF), oil palm trunks (OPT), oil palm bark (OPB), oil palm leaves (OPL), and oil palm shell (OPS). These biomass wastes possess a great energy potential to be converted into biofuels, particularly bio-oil. Among all, the OPS have favorable physicochemical characteristics to be converted into bio-oil. Therefore, this paper mainly focuses to review the suitability of OPS as feedstock for bio-oil production compared to other oil palm biomasses. The physicochemical characteristics of the OPS, in terms of heating value, ultimate analysis, proximate analysis, and lignocellulosic composition, are presented and compared to those of the OPEFB, OPMF, OPF, OPT, OPB, and OPL. To illustrate further and signify the stability, the abovementioned properties of OPS bio-oil are also reviewed and compared to those of bio-oils produced from OPEFB, OPF, OPB, OPL, and petroleum fuels. The challenges and future prospects of OPS as a source of bio-oil are addressed and compared with other wastes of oil palm industry. Additionally, methods used for bio-oil production from oil palm industry biomass are discussed and illustrated in detail.

Agricultural biomasses are the underutilized sources that have extraordinary potential to synthesize green and cost-effective chemicals. This research focuses on the utilization of novel agricultural residue, i.e., waste neem cake, to produce highly efficient, cost-effective, and environment-friendly fuel, i.e., neem char (NC), through thermogravimetric pyrolysis. To study the effects of process variable on char yield and higher heating value (HHV), statistical modeling was applied by central composite design of response surface methodology. Furthermore, chemical and structural characterization of neem cake and char were carried out by using Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The reaction temperature was the most prominent variable found from the ANOVA (analysis of variances) to affect char yield and its HHV. The optimal result was achieved with 21.46% char yield and HHV value of 6371 kcal/kg at 600 °C, 60 min, and 3 mm. The heating value of char was highly improved indicating the potential application of char as a high-energy renewable fuel. Further, the carbon content and fixed carbon values increased, whereas hydrogen, oxygen, volatile matters, and moisture content decreased in char after the pyrolysis process.

This article aims investigating the solvo and hydrothermal liquefaction of sugarcane bagasse. Reaction temperature and solvents play an important role on the yield and physico-chemical properties of the liquefaction products. This study reports the effect of different temperatures, 240 °C, 260 °C and 280 °C and two different solvents, water and ethanol on yield and properties of bio-oil and char. The higher conversion was obtained at the higher temperatures with ethanol. The bio-oil yield ranged from 46.0% to 51.8% in presence of water and it ranged from 54.6% to 62.3% with ethanol solvent by changing reaction temperature from 240 °C to 280 °C. The char yield decreased from 36.3% to 28.2% and from 39.3% to 24.7% in presence of water and ethanol respectively by varying reaction temperature from 240 °C to 280 °C. The carbon content and HHV were increased and oxygen content was decreased in the products resulting in improved heating and combustion performance. The GC–MS results suggested that the all the bio-oils were mainly composed of phenols and its derivatives, alcohols, esters, hydrocarbons, ketones, aldehydes and other compounds. The TGA results proposed that the thermal stability of char was improved which is attributed to the reaction temperature of the liquefaction process.

This study introduces a novel concept of rice straw hydrochar incorporation at different loadings (5%, 10%, 15%, and 20%), produced from microwave-induced hydrothermal carbonization (HTC) of rice straw to polylactide (PLA) for production of polylactide/hydrochar (PLA/HC) composites. Higher storage modulus was found for PLA/HC composites than that of neat PLA, confirming the formation of a network structure between PLA and hydrochar. Further, the storage modulus is directly proportional to the amount of hydrochar loading added to the PLA matrix. SEM images suggest that the neat PLA displays a smooth and soft surface. At the same time, PLA/HC blends showed irregular voids and cracks due to the porous structure of hydrochar, allowing PLA to infiltrate through pores of the hydrochar. The tensile modulus of neat PLA was increased from 2.627 GPa for neat PLA to 4.376 GPa, 4.895 GPa, 5.217 GPa, and 6.182 GPa for PLA/HC composites of 5%, 10%, 15%, and 20% hydrochar loadings, respectively. The thermal degradation temperature of the PLA/HC composites was 335–360 °C, which is slightly less than that of neat PLA but still stable up to the range of process and applications of PLA (30–240 °C) without compromising thermal degradation.

Novel magnetic bio-nanocomposites were fabricated using polypropylene (PP) as polymer matrix and graphene supported magnetic carbon nanocomposite (MCNC, produced by solvothermal carbonization co-precipitation route integrating low-cost graphene, renewable biomass and iron oxide nanoparticles) serving as filler by incorporating nano-fillers of loading 5%, 10% and 15% with PP using a convenient and time efficient route melt processing. Utilizing waste biomass as integral part of MCNC offers cost effective solution for hybrid nanocomposite synthesis and its application in advance field as electromagnetic interference (EMI) shielding material. The study provides comprehensive analysis for its upgradation in rheological properties that have exclusive impact on its final application. Furthermore, the behaviour for thermal, structural, mechanical, chemical, magnetic, and electrical features using various characterization techniques. Field emission scanning electron micrographs revealed good dispersion of MCNC in PP matrix and formation of network for 15% loading of the filler facilitated 800% higher shielding effectiveness as compared to that of neat PP. It was revealed that functionalization with graphene supported magnetic nanocomposite and polymer matrix have improved the overall conductivity for the composites. Rheological studies indicated the upgradation in viscoelastic properties as solid like behaviour was seen with the increment of filler concentration. X-ray diffractometer demonstrated that MCNC had a substantial impact on the crystallinity of nanocomposite that is validated with modulated differential scanning calorimetry analysis.

In this study, an experimental investigation of pure bioethanol production from the waste biomass of the most significant cultivated feedstock (oil palm and rubber-wood) in Malaysia and life cycle cost analysis of bioethanol-gasoline blend on Malaysian transportation sector has been demonstrated. The experimental investigations presented all the stages from oil palm frond/leaves and rubber-wood sawdust collection to bioethanol purification. Both feedstocks have been pre-treated by sulfuric acid and sodium hydroxide, hydrolyzed by cellulase enzyme, and fermented by Saccharomyces cerevisiaewithin 12–72 h to produce bioethanol. After distillation, 35% and 45% pure bioethanol was obtained for mixed oil palm residues and rubber-wood sawdust, respectively. Detailed life cycle cost analysis of a large-scale bioethanol plant (20 ktonns/y) has been designed based on the experimental outcome for 20 years life time. The possibility of 5% (E5) and 10% (E10) replacement of total gasoline application for Malaysian transportation sector by the produced bioethanol has been simulated using simulation software code blocks. From the economic perspective, the results presented that both waste biomass can be converted into a value-added product, bioethanol, and a by-product, biomass content that can add market value as commercial biofertilizer. This study suggested that partial substitution of gasoline with bioethanol produced from forest residues could lead to the significant commercial aspect of fuel savings for the transportation sector in Malaysia.

Currently, nanotechnology is referred to be one of the attractive research sectors in several countries because of its vast potential and commercial impact. Nanotechnology includes the investigation, development, fabrication, and processing of structures and materials on a nanoscale in various fields of science, health care, agriculture, technology, and industries. As such, it has provided a steady restructuring of related technologies. However, the irregularities and uncertainties in dimensions and chemical compositions, makes the viability of such materials questionable. Concerns have been inclined about the transport, destiny, and transformation of nanomaterials discharged into the environment. A critical analysis of the present phase of knowledge concerning the exposure and effects of nanomaterials has been discussed in-depth. In this review, different nanomaterials along with their applications have also been reviewed, that include graphene-based nanomaterials, carbon nanotubes, and their composites, nanoclay composites, nanostructured thin films, metal-organic frameworks, conducting polymers and their composites, MXenes, chalcogenide nanocrystals, and quantum dots. Besides, a few of the groundbreaking applications of nanomaterials for different sectors like human health, processes, photochemical process, energy conversion and energy storage, separation and purification processes, optoelectronics, etc. are discussed in detail with their chemsitry. Moreover, the unique characteristics and applications of nanomaterials, they inherently introduce challenges for their applications and large-scale production. Acknowledgment of the potential benefits and unknown dangers of nanomaterials is critically is critically analyzed and discussed in the manuscript.

The bio-oil was upgraded in sub-supercritical ethanol using metal supported platinum on activated carbon (Pt/AC) and palladium on activated carbon (Pd/AC) as catalysts. The supercritical upgrading process revealed more effective process compared to the subcritical conditions. Esterification during catalytic upgrading of bio-oil remained prominent which facilitates the conversion of acids present in bio-oil into esters in sub-supercritical ethanol. In addition, heavy compounds of crude bio-oil cracked into lighter compounds in the presence of catalysts. Furthermore, the changes in the upgraded bio-oil relative to crude bio-oil was extensively investigated through higher heating value (HHV), elemental analysis, solution pH, chemical composition (GC-MS), chemical functional groups (FTIR), and 13C and 1H nuclear magnetic resonance spectroscopy (NMR). The chemical composition analysis showed a significant decrease in acid fractions in sub-supercritical upgrading process, hence the solution pH varied from 2.5 in bio-oil to 5.3 after supercritical reaction. The HHV of bio-oil increased from 28.55 to 36.4 MJ/kg. This research has shown that crude bio-oil can be efficiently upgraded with carbon-supported metal catalysts in a sub-supercritical upgrading process.

Development of advanced magnetic carbon nano-materials has provided new dimensions in numerous research areas due to their multiple applications. In this study, novel magnetic carbon nano-composites were synthesised by integration of magnetic nanoparticle on novel graphene and renewable carbon materials from rice husk. Magnetic carbon nano-composites were fabricated by hydrothermal carbonization-coprecipitation (HTCC) and solvothermal carbonization-coprecipitation (STCC) routes that are easily scalable. The objective of this work is a comparative study of HTCC and STCC processed and their products. The experiments were conducted using different process variables including process temperatures (180,220 and 260 °C), process time (0.5,1 and 2 h) and solvents (water and ethanol). Chemical interaction of well-dispersed magnetic nano-particles of 5–20 nm size with carbonaceous material was confirmed. Magnetically recoverable nano-composite is highly suitable for use in multiple applications including catalysis, super-capacitance, biosensing devices, environmental remediation and enzymes immobilization and can establish various opportunities for industry in future.

Microbial fuel cells offer a breakthrough for treatment of waste content coupled with energy generation. However, their applications are mostly limited to laboratories. Present research is focused on conducting the biological conversion of sludge originated from fermentation industry using microbial fuel cell (MFC). The efficiency of MFC was studied at different operating and nutritional conditions including pH, aeration rate and substrate concentration with biocatalyst Saccharomyces cerevisiae. The optimized conditions in terms of yielding maximum power density of 610 ± 30 mW/m2were reported at substrate concentration of 60% at 160 ml/min aeration rate and pH of 6, corresponding to a current density of 994 ± 41 mA/m2. Results suggested that utilization of fermented sludge in MFC could give direction to handle the problem of fermentation industries and also to overcome a small fraction of energy crisis.

The present energy generation from renewable resources does not meet the current global demand for energy supply, and there is a need to come up with more innovative technologies that could bridge the gap between the energy supply and demand. Phase change materials (PCM) are one of the most effective and on-going fields of research in terms of energy storage. Especially, organic phase change materials (OPCM) has grabbed a lot of attention due to its excellent properties that can be combined with thermal energy storage systems to preserve renewable energy. However, the practical application of OPCM is restricted to thermal energy storage due to their low thermal conductivity and leakage during the phase change. Entrapping OPCM in a shell using different encapsulation techniques is the best solution to eradicate the leakage and boost the storage capacity of the material. This review mainly highlights the thermal energy storage and thermal properties associated with it. Moreover, we emphasise the selection of materials based on different properties and different encapsulation processes from macro to nanoscale level. Finally, the use of PCMs in various applications challenges faced, and future directions are also discussed.

This article provides a comparative study of advanced single pot microwave versus conventional solvothermal co-precipitation synthesis for producing magnetic carbon nanocomposites and bio-oil from rice husk. The aim was to produce nanocomposites composed of magnetic nanoparticles and novel graphene on the surface of hydrochar improving the reaction efficiency. The experiments were conducted at two different temperatures (140 °C and 180 °C). The processing time was varied from 0.5 to 2 h. The main focus of the study was to investigate the effect of process parameters on the yield, thermal stability and morphology. Microwave-assisted solvothermal carbonisation (MSTC) provided a higher yield of bio-oil compared to solvothermal carbonisation (STC) due to more effective heat transfer to the core of the material. Microwave processing also resulted in less CC and C–H vibrations as measured by FTIR. Transmission electron microscopy confirmed the presence of well-dispersed nanoparticles, ranging in size from 5 to 20 nm in both MSTC and STC. Thermal stability of the nanocomposite materials was significantly higher for conventional solvothermal synthesis compared to the microwave system.

Nanomaterials are gaining significant importance in various industrial applications. One such example is explored in this research where the Multi-walled carbon nanotubes (MWCNTs) are utilised as fillers inorder to develop organic phase change materials (PCMs). The PCMs are characterised for their microscopic, thermal and mechanical properties. MWCNTs concentration, PCM composition, operating temperature, and sonication time are optimised. The MWCNTs were characterized by using Field Emission Scanning Electron Microscope (FESEM), thermogravimetric (TGA) analysis, Energy dispersive X-ray (EDX), and Fourier Transform Infrared Spectroscopy (FTIR). Meanwhile, analysis such as flexural and tensile testing were also carried out under mechanical testing. The optimum conditions obtained are 1:1 ratio of MWCNT and PCM at 65 °C and 1.5 h sonication time. PCM synthesised by using MWCNTs as fillers resulted in higher yields with a high density of carbon content and lower weight loss. The results indicated that organic PCM with MWCNT doping can be used in developing potential energy storage applications.

Strain sensors have been increasingly pervasive in modern life, owing to their ability to detect, respond and convert mechanical motion into an electrical signal, which can be measured in terms of electrical resistance. Novel strain sensing applications have broadened the technology scope and allow us to monitor the changes in the surroundings in distinctive ways we could barely imagine. In recent years, the development of carbon nanomaterials (CNMs) based films for sensing applications has been growing at an astounding pace, owing to their outstanding electrical and mechanical properties. Specifically, the fabrication of CNMs-based films provide groundbreaking approaches for the realization of highly flexible and sensitive strain sensors. In fact, strain sensors based on carbon nanomaterials (CNMs) (e.g., carbon nanotubes, graphene, carbon black, carbon nanofibers) can overcome the limitations of conventional metallic strain gauges, such as low sensitivity (GF ∼2), poor stretchability (ε<5%), fragile, geometrical and functional restrictions. This comprehensive article critically reviews the state-or-the-art CNMs-based strain sensors, with special emphasis on their fabrication techniques and performances (sensitivity and maximum strain) of strain sensor produced. The performances of each type of CNMs strain sensor are reviewed to determine the type of CNMs-based films, type of polymer substrate and fabrication technique best suited for producing flexible strain sensors with high sensitivity. Finally, the challenges that impair the commercialization of CNMs-based strain sensor, along with possible solutions and their future outlook are addressed.

Lipase is an enzyme used widely in many major industries. Immobilization of enzymes will help to enhance its sustainability as enzymes are more resistance to changes in environment and can be reused. This experiment examines effects the immobilization of lipase with adsorption technique through carbon nanotubes. The paper investigates the enzyme activity and efficiency of immobilized enzyme lipase by using assay solution. It also presents the effects of pH on immobilized enzyme and the characterization of the immobilized enzyme lipase with FTIR spectrum and FESEM technique. The results showed that there are as enzyme concentration increases, the enzymatic activity increases too. However, this lowers the immobilization efficiency due to saturation of binding pores on functionalized MWCNTs. Meanwhile, the optimum pH for maximum immobilization activity of enzyme lipase is at pH 6. Based on the characterization by FTIR spectrum and FESEM, it is confirmed by the presence of functional group in FTIR spectrography. On the other side, FESEM also confirms that immobilization of enzyme has occurred.

Water pollution regarding heavy metals issue keep lingering our days from time to time, and some problems even left unattended. The most crucial cause of this pollution is the industrial waste, especially waste water that had been released into the drainage system without being treated first. This activity had been done illegally and left a huge impact towards the environment also human. In this study multiwall carbon nanotubes (MWCNTs) are promising route for removal of chromium was investigated. Results revealed that the optimum conditions for highest removal (99.97%) of chromium are pH7,0.04g of MWCNTs dosage, and flowrate of 20.83 mL/s. Based on adsorption isotherm for this experiment, the amount of chromium adsorbed, qm calculated was 50.51 mg of chromium/gram of MWCNTs. From the results obtained, it had been proved that MWCNTs can be used as an effective adsorbent in chromium removal from aqueous solution due to high adsorption capacity.