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In recent years, concrete has been accessible and economical in the construction industry, resulting in high demand for its components. Cement is known for its negative impact on the environment, which has led researchers to investigate alternative supplementary materials. Recently, biochar has been proposed as a replacement to cement in small amounts, with an optimum amount of 0.08–5, resulting in increased strength and enhancement of other properties of concrete composites. The biochar production process and its components are more economical and environmentally friendly than that of cement. In this review, we focus on research highlighting the properties of biochar that aid in the enhancement of biochar mortar and concrete composite properties. We explore properties of biochar such as water absorption, as well as compressive, flexural and tensile strength. Progress has been made in research on biochar concrete composites; however, additional investigations are required with respect to its carbon-sequestering abilities and life cycle assessment for its production process. [ABSTRACT FROM AUTHOR]

The use of sustainable materials in the construction industry has been on the rise recently. Studies have proven that the use of conventional concrete and its raw materials has a negative impact on the environment. Research on incorporating biochar as a supplementary cementitious material has been recently evolving and has shown that the attributes of biochar are highly affected by the pyrolysis parameters. These attributes have enhanced the properties of biochar concrete and mortar composite. This paper identifies the different physiochemical properties exhibited by palm kernel shell biochar through optimization by response surface methodology. Focusing on some of the properties of biochar that have proven beneficial when used as a cement replacement. Very limited research has used optimization tools for the production of biochar with the intention of using it as a cement substitute. Pyrolysis was conducted by a tubular furnace at different temperature ranges from 200 °C to 800 °C. The biomass and biochar have been analyzed with TGA and FESEM-EDX. The targeted biochar properties and selected responses are the yield, carbon, oxygen, silica, and potassium content. The optimized parameters obtained are 409 °C, 15 °C/min, 120 min with responses of 38.2% yield, 73.37% carbon, 25.48% oxygen, 0.39% potassium and 0.44% silica. Thermal properties of the palm kernel shell biochar affected by the pyrolysis factors such as temperature, heating rate and residence time have also been discussed. In conclusion, this study supports and encourages the use of palm waste, which is abundant in Malaysia, as a supplementary cementitious material to promote sustainable growth in construction. [Display omitted] • Hypothesis for a high potential of palm kernel shell biochar to be used as supplementary cementitious replacement. • The factors that are taken into consideration are pyrolysis temperature, heating rate and residence. The responses are biochar yield, carbon, oxygen, potassium, and silica content. • Optimized round of palm kernel shell biochar is 409 °C, 15 °C/min and 120 min. • The carbon content of the biochar is directly proportional to the pyrolysis temperature. • The pyrolysis temperature and residence time are more effective than heating rate on the physiochemical properties. [ABSTRACT FROM AUTHOR]

Renewable energy sources such as biomass have been proven to be one of the promising sustainable alternatives to fossil fuels. However, using biomass directly as a fuel is less attractive due to its high moisture content, poor grindability, low bulk density, and low energy density nature. Hence biomass can be converted into biochar to overcome these challenges. In this study, biochar was derived from citrus peels biomass by slow pyrolysis over the temperature range of 300–700 °C. The effect of pyrolysis temperature on the quality of citrus peels-derived biochar was examined based on the physical and chemical properties obtained from various analyses. The citrus peels biomass and biochar were characterized by means of higher heating value (HHV) analysis, field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDX), Fourier transform infrared ray (FTIR) analysis, proximate and thermogravimetric analysis. Based on the characterization results, the potential usage of the derived biochar as a solid fuel was discussed. Results obtained from the pyrolysis experiments indicated that a lower pyrolysis temperature produced a higher char yield. The carbon content and energy content of biochar were found to be increasing with pyrolysis temperature. Biochar produced at 500 °C presented the best fuel properties by having the highest value of HHV and carbon content. The results from this study provided great insights into biomass waste reutilisation to generate value-added biochar for renewable energy production in Malaysia. [Display omitted] • Promising potential for citrus peels biomass to biochar for energy conversion. • Higher heating value of citrus peels biochar comparable to sub-bituminous coal. • Carbon and energy content increased with increasing pyrolysis temperature. • Better combustion stability for biochar of higher pyrolysis temperature. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) technology emerges as a sustainable method to convert wet biomass, including food waste and municipal solid waste into high‐energy dense biocoal. This process, conducted at temperatures ranging from 180 to 260°C and pressures of 10–50 bar, effectively transforms the organic material in wet biomass into solid, liquid, and gaseous outputs. The solid product, biocoal, possesses a high carbon concentration and heating values on par with lignite coal, presenting a cleaner alternative to traditional fossil fuels. Despite operational commercial‐scale HTC facilities globally, further adoption across various feedstocks can improve waste management and energy production. The process can achieve energy yields up to 80%, particularly at temperatures favoring the generation of secondary char with higher heating values. HTC not only aids in reducing greenhouse gas emissions through carbon sequestration in solid waste but also promotes environmental sustainability by yielding nutrient‐rich by‐products for agriculture. As a versatile and energy‐efficient solution, HTC technology is a pivotal innovation in waste‐to‐energy conversion, addressing the imperative for sustainable waste management. Other supplementary benefits are presented; they include higher employability, reduction of a nation's reliance on imported energy, and better waste control, therefore considering all pillars of sustainability. Future research should focus on optimizing process efficiency and exploring the broader applicability of HTC to various biomass feedstocks, enhancing its role in the global pursuit of sustainable energy solutions. [ABSTRACT FROM AUTHOR]

Palm oil extraction is one of the important industries in Malaysia. The extraction of palm oil will not only result in the production of palm oil for human consumption but also generate palm oil mill effluent (POME), which contains highly polluting properties. Synthetic coagulants such as aluminum sulfate (alum), aluminum chloride, and sodium aluminate contribute toward environmental pollution and risk to human health. Thus, natural coagulants and flocculants have been introduced throughout the globe to slowly replace synthetic coagulants. In this study, rambutan (Nephelium lappaceum) seed was used as natural coagulants combining with aloe vera as natural flocculants. The standard jar test experiments were conducted to study the effects of pH, coagulant dosages, and rapid mixing speed on the removal efficiency of chemical oxygen demand (COD), total suspension solid (TSS), and turbidity of POME. The model of the coagulation–flocculation process was evaluated by using response surface methodology (RSM) and artificial neural network (ANN). RSM associated with Box–Behnken design was used to identify the optimum parameters (inputs), which consist of pH, coagulants dosages and rapid mixing speed for the optimum removal efficiency (outputs) of COD, TSS, and turbidity of POME. In terms of removal efficiency of COD, TSS, and turbidity of POME, rambutan seed has the optimum removal efficiency of 28.48%, 56.38%, and 60.36%, respectively. ANN was utilized with the aim of evaluating the performance of 12 training algorithms to predict the output results. Levenberg–Marquardt (LM) training algorithm was verified to be the best training algorithm for coagulation–flocculation process of rambutan seed based on the lowest mean squared error (MSE), mean absolute error (MAE), and mean absolute percentage error (MAPE) for validation data and the correlation coefficient R of.9347. [ABSTRACT FROM AUTHOR]

[Display omitted] • Spent coffee grounds can be dried efficiently by blending reusable biochar hygroscopic biochar. • Dried spent coffee grounds can be used as a potential co-firing fuel for net zero. • Competition of heat conduction and hygroscopicity of biochar in drying are addressed. • Heterogeneous mixing strategy can save the drying cost up to 44%. • The biochar-to-SCG mixing ratio of 1 has the lowest drying cost and mildew opportunity. Drying is an important but energy-intensive industrial process, while spent coffee grounds can be used as an abundant and potential biomass waste to replace part of the coal consumption for green fuel production and circular economy. In this study, an energy-saving strategy for efficiently drying spent coffee grounds (SCGs) by adding hygroscopic water chestnut shell biochar with 422% water holding capacity is developed. It is found that the contributions of the thermal conductivity and hygroscopicity of the biochar on the moisture removal of the SCG exhibit a competitive relationship. The hygroscopicity is dominant when the drying temperature is below 50 ℃, whereas the thermal conductivity reigns over the drying process once the drying temperature is equal to or above 50 ℃. To prevent mildew growth with lower drying cost at 105 ℃, the optimum trade-off outcomes of CSCG (i.e., the mixture of SCG and biochar) are the moisture content, water activity, and HHV of 21.71%, 0.60 aw, and 18.88 MJ kg−1, respectively. The S/C mixing ratio of 1 at 105 ℃ and around 20% moisture content has the lowest drying cost of 2.3 × 10−5 USD g−1, which reduces 44% cost compared to SCG with the same conditions. Overall, it was demonstrated that water chestnut shell biochar is a good additive to achieve the energy-saving drying process of SCG, and the dried SCG can be used as a coal co-firing fuel. [ABSTRACT FROM AUTHOR]

• Microwave heating method offers many benefits as compared to conventional heating. • Microwave-assisted pyrolysis (MAP) can be employed to turn waste into biofuels. • Carbon material like biochar can be used as both a catalyst and microwave absorber. • There is almost 91% recovery of energy from biomass in the MAP process. • Hydrocarbons present in bio-oil and syngas serve for carbon nanotube formation. The current scenario of environment urgently needs alternative biologically synthesized fuels, value-added products, and preparation of catalyst to create a pollution free environment. Usually, several methods are available for the synthesis of various commodities from many biological resources. Microwave-assisted pyrolysis (MAP) is a relatively new process and has emerged as a promising technique to transform biomass feedstock into biofuels, including bio-oil, syngas and biochar. This paper provides a state-of-art review on MAP of several wastes such as lignocellulosic biomass, waste oils, municipal solid waste and electronic waste, discussing on the biofuels produced (bio-oil, syngas and biochar) as well as the synthesis of carbon nanomaterials (carbon nanotubes and carbon nanofibers). The use of microwave adsorbent and catalyst in MAP process are reviewed, including utilization of biochar as one of the microwave absorbers. Life cycle analysis and scale-up process with the global view of MAP are presented to contribute to the further advancement and commercialization of this technology. Although there are several challenges to be resolved, MAP has a high energy efficiency and is an increasingly feasible technique to be scalable, economical and environmental friendly. [ABSTRACT FROM AUTHOR]

Microalgae biorefinery is a platform for the conversion of microalgal biomass into a variety of value-added products, such as biofuels, bio-based chemicals, biomaterials, and bioactive substances. Commercialization and industrialization of microalgae biorefinery heavily rely on the capability and efficiency of large-scale cultivation of microalgae. Thus, there is an urgent need for novel technologies that can be used to monitor, automatically control, and precisely predict microalgae production. In light of this, innovative applications of the Internet of things (IoT) technologies in microalgae biorefinery have attracted tremendous research efforts. IoT has potential applications in a microalgae biorefinery for the automatic control of microalgae cultivation, monitoring and manipulation of microalgal cultivation parameters, optimization of microalgae productivity, identification of toxic algae species, screening of target microalgae species, classification of microalgae species, and viability detection of microalgal cells. In this critical review, cutting-edge IoT technologies that could be adopted to microalgae biorefinery in the upstream and downstream processing are described comprehensively. The current advances of the integration of IoT with microalgae biorefinery are presented. What this review discussed includes automation, sensors, lab-on-chip, and machine learning, which are the main constituent elements and advanced technologies of IoT. Specifically, future research directions are discussed with special emphasis on the development of sensors, the application of microfluidic technology, robotized microalgae, high-throughput platforms, deep learning, and other innovative techniques. This review could contribute greatly to the novelty and relevance in the field of IoT-based microalgae biorefinery to develop smarter, safer, cleaner, greener, and economically efficient techniques for exhaustive energy recovery during the biorefinery process. [Display omitted] • IoT helps real-time monitoring of microalgae biorefinery process parameters. • IoT assists in sufficient data collection to make smart prediction and decision. • IoT promotes automation in microalgae biorefinery. • IoT guides microalgal biorefinery towards low-cost and high efficiency. [ABSTRACT FROM AUTHOR]