Biomass Conversion and Biorefinery

This paper addresses the use of loose biomass material like sawdust and other agro residues as fuel to generate electricity for captive power requirements using gasification system and a reciprocating engine. The development of open-top downdraft re-burn gasifiers at the Indian Institute of Science has made it capable of using agro residues after processing them into briquettes—a multi-fuel option. The inherent design feature that provides adequate residence times and establishes the right flux has made this possible. A typical closed-top design has a high superficial flux at the throat in the range of 2–2.5 kg m−2 s−1 as against the open-top design at 0.2–0.4 kg m−2 s−1 at the lowest cross section. This essentially prevents ash softening and fusion, an issue that needs to be addressed while using agro residues containing higher inorganic content. Further, captive power generation systems based on this design are installed in pencil manufacturing industries to use the sawdust generated. This paper addresses the performance of the gasification and engine system in the dual fuel mode. One industrial unit has operated for over 11,000 h in dual fuel mode in 2 years and generated about 400 MWh consuming about 400 tonnes of briquettes and about 35,000 l of diesel. The details of the system configuration, performance, and operations are reported here. Some of the critical issues that were addressed to ensure good industrial operations are highlighted.

Mannanases are of great importance as they are able to hydrolyze polysaccharides for industrial applications and can be easily produced by fermentation. Purification of a β-mannanase produced from carob extract in a bioreactor is of great importance in order to obtain information about its structural and functional features and to foresee its implementations. Therefore, the aims of this study were to purify a β-mannanase from Aspergillus fumigatus expressed in Aspergillus sojae grown on carob extract by implementation of various flocculant agents in the fermentation medium, followed by the determination of its physico-chemical, kinetic, and thermodynamic characteristics. Flocculants increase the visible size of the dispersed particles by agglomeration, simplifying the separation of solids and liquids, and thereby reducing process costs. Optimum flocculation conditions for chitosan- and PAC-PAM-implemented processes were determined as 40 mg/L of chitosan, 30 min of implementation time, no agitation and 3 g/L PAC-PAM, 30 min implementation time, and no agitation. Under these conditions, more than a 2-fold increase in the enzyme activity was achieved in both flocculation processes. Further investigations determined molecular weight, optimum pH, and temperature values of the produced β-mannanase to be 56–60 kDa, pH 6, and 60 °C, respectively. Additionally, Km and Vm determination of the enzyme for various substrates concluded that the β-mannanase showed the highest substrate specificity against locust bean gum among the substrates evaluated. Furthermore, experimental results for substrate specificity were further modeled and successfully represented by the Weibull model. In conclusion, this study provides valuable and important information about β-mannanase production and purification for industrial-scale applications.

This work briefs the ability of Sterculia foetida methyl ester (SFME) as an alternate fuel in determining the engine characteristics. Non-edible nature of the Sterculia foetida kernel oil favored choosing as a feedstock. The Acid-catalyzed transesterification process is conducted for converting Sterculia foetida kernel oil into methyl ester. Experimental analysis was conducted using blends such as SFME20, SFME40, SFME60, SFME80, SFME100, and standard diesel at atmospheric conditions. The observations concluded that the Smoke opacity, Hydro carbon emissions, and carbon monoxide emissions lowered with increase in SFME content in diesel. In addition, the performance aspects  namely BTE lowered with increase in SFME in diesel/SFME blends. Carbon-di-oxide and Nitroden oxide emissions increased when compared with standard diesel becausce of its higher O2 concentration. The combustion analysis witnessed a reduction in HRR and ICP for SFME-diesel blends relative to standard diesel.

In Pakistan, bioenergy from agricultural residues (AR) plays a remarkable contribution to mitigating environmental pollution due to immense quantity of AR being produced. Pretreatment is a well-matured technique to disintegrate lignocellulose matter. This study evaluated pretreatment of rice straw (RS), canola straw (CS), and banana plant substrate (BPS) to be co-digested with buffalo dung in order to optimize the methane potential. Five different concentrations (0.1, 0.2, 0.3, 0.4, and 0.5%) of calcium hydroxide (Ca(OH)2) reagent were utilized for disintegrating residues at ratios of RS:BD (30:70), CS:BD (40:60), and BPS:BD (60:40). Co-digestion experiment was conducted on 5-g volatile solids (VS). The experiments revealed that Ca(OH)2 pretreatment significantly enhanced the methane yield. Maximum methane yield of 346.7, 417.3, and 284.3 mLCH4/gVS was obtained at a concentration of 0.4%, 0.4%, and 0.3% for RS, CS, and BPS respectively. However, maximum cellulose biodegradability was observed at 0.5% about 45.1% in CS. In addition, cumulative methane yields were kinetically assessed by S-Gompertz. Based on R2 simulated values, i.e., 0.9968, 0.9971, and 0.9940 for RS, CS, and BPS, the applied model validates optimal experimental results. Regarding optimization, CS generates the highest yield of methane than RS and BPW due to carbon content and oilseed substrate.

In this research study, a non-deformable, stiff electromagnetic interference (EMI) shielding material was prepared and characterized. The composites were prepared using industrial waste silver slag fine particles; woven abaca fiber and silk fabric with two different stacking order designated as ASSA and SAAS. The composites were created utilizing a hand layup technique and the American society for testing of materials (ASTM) standards were used to assess their performance. The findings showed that the abaca/silk/silk/abaca sequence of fibers had greater dielectric values. The ASSA2 composite designation was observed to have a maximum dielectric constant of 4.81. Similar to this, the ASSA2 configuration produced a total EMI shielding effectiveness of 56.85 dB at 20 GHz. Moreover, the ASSA2 composite configuration resulted in enhanced mechanical and hardness qualities. These mechanically hardened epoxy-based composites with increased EMI shielding could be employed in applications for radar, radomes, and the telecommunications industry.

In order to effectively utilize energy of agricultural biomass, there is a need to evaluate energy potential. For such a purpose, chemical exergy and standard entropy of typical agricultural biomass were examined analytically. Element compositions of the exergy and entropy were acquired for further statistical evaluation. Adaptive neuro fuzzy inference system (ANFIS) was used as the statistical methodology for data analyzing. ANFIS is an efficient estimation model among machine learning techniques. The main weakness of the ANFIS is its dimensionality problem with large inputs. Therefore, the main goal in this study was to estimate the parameters’ influence on the chemical exergy and standard entropy prediction in order to reduce the number of inputs. Principal component analysis was used for presentation of the obtained ANFIS predictive models. Obtained results have shown the best predictive performances for standard entropy based on hydrogen as composite element of the agricultural biomass. Exergy prediction was the best for oxygen as composite element of the agricultural biomass. ANFIS coefficient of determination for standard entropy prediction based on hydrogen is 0.9832 and for chemical exergy prediction is 0.919. The results show the high predictive accuracy of ANFIS models.

Mangifera indica L. is an important tropical fruit having a high nutrient composition of dietary fiber, carbohydrates, vitamins, minerals, and polyphenols. Ultrasound-assisted extraction (UAE) and enzyme-assisted ultrasound extraction (EAUE) were used to optimize bioactive molecule extraction from the agro-industrial waste of mango peels. Both extraction strategies were adopted to deal with the extraction yield and environmental compatibility aspects. The mango peel extracts were pretreated using a combination of enzymes and ultrasound irradiation and used to extract bioactive phytochemicals. Results revealed that the highest total phenolic contents (33.56 ± 1.04 mg GAE/g fresh weight) were detected in mango peel extracts pretreated with 3.3% alcalase enzyme, pH 5.5 at 63 °C for 110 min and 90 Watt (UP) in EAUE, while the same set of optimized extraction conditions for UAE yielded the highest polyphenolics (25.64 ± 0.98 mg GAE/g). Mango peel extract pretreated under predefined optimized conditions (EAUE-1 coded extract) showed the highest trolox equivalent antioxidant capacity (TEAC) value (215.42 ± 1.21 mM TE/g). Likewise, the DPPH-scavenging capacity (1C50: 11.38 μg/mL) was also higher than the control. Characterization by high-performance liquid chromatography corroborated the abundant presence of vanillic acid and 4-hydroxy-3-methoxy benzoic acids (phenolic acids) in mango peel extract. In conclusion, EAUE appears as an efficient technique with broad-spectrum applications in extracting and recovering bioactive compounds from natural resources.

In the present experimental investigation, novel Himalayacalamus falconeri fiber reinforced polylactic acid biocomposites were developed via direct injection molding. Standard test procedures were used to evaluate the mechanical, thermal, microstructural, and water absorption properties of the developed biocomposites as a function of fiber concentration (5–20%) and alkali treatment (5% w/v NaOH solution). It was observed that the tensile, flexural, and impact strength of all developed biocomposites were gradually enhanced with the addition of fiber concentration up to 15 wt.% and thereafter start decreasing with increasing fiber concentration up to 20%. Alkali-treated biocomposite with 15 wt.% fiber content (PLA/THF-15) exhibited the highest tensile strength (44.59 MPa ± 1.55 MPa) and flexural strength (75.68 MPa ± 0.88 MPa). Untreated biocomposite (PLA/UHF-15) showed a maximum impact strength of 41.61 J/m. Meanwhile, the fractured surfaces from mechanical testing were examined using a scanning electron microscope to identify the causes of failure in the developed biocomposites. Alkali-treated biocomposite with 20 wt.% fiber content (PLA/THF-20) exhibited the highest hardness value of 90.66 HD, while untreated biocomposite with 20 wt.% fiber content (PL/UHF-20) exhibited the maximum water absorption rate (2.60%) and soil degradation rate (2.18%). The Vicat softening temperature (VST) and heat deflection temperature (HDT) were found to be 56.7 °C for PL/THF-20 and 57.55 °C for PLA/THF-15, respectively. It can be concluded from this present investigation that short Himalayacalamus falconeri fiber can be used as reinforcement in PLA-based matrix to make entirely biodegradable green composites that can replace petroleum-based synthetic polymer composites in lightweight and non-structural applications.

High toughness and high-impact damage resistance fibre-metal hybrid laminate epoxy composites were prepared and characterized. In this present research, a hybrid fibre-metal laminate was reinforced into SiC-toughened epoxy resin for making high performance structural material for automobile and aircraft applications. Novel natural fibre caryota urens and silicon carbide (SiC) particles were surface-treated using 3-aminopropyltriethoxysilane (APTES) whereas the aluminium foil was sandblasted. The hybrid fibre-metal laminate with different stacking sequenced epoxy composites were prepared using vacuum bag moulding followed by post curing. A highest strength factor of 97 is observed for composite designation CAC1, which contains 0.5 vol.% of SiC. The drop load impact toughness of ACA1 composite gives the highest energy absorption of 20.6 J. Similarly, the CAC1 composite designation gives fracture toughness of 32.1 MPa. $$ \sqrt{\mathrm{m}} $$ and energy release rate of 1.557 mJ/m2. The scanning electron microscope images revealed highly reacted phase of surface-treated reinforcements with epoxy resin matrix.