Valorization of biomass waste to engineered activated biochar by microwave pyrolysis: Progress, challenges, and future directions

Activated carbon refers to a wide range of carbonised materials of high degree of porosity and high surface area. Activated carbon has many applications in the environment and industry for the removal, retrieval, separation and modification of various compounds in liquid and gas phases. Selection of the chemical activator agent is a major step controlling the performance and applicability of activated carbon. Here, we review chemical activators used to produce activated carbon. We compare the impregnation method with the physical mixing method used in activating with alkali hydroxides. We selected 81 articles from Google Scholar, PubMed, Scopus, Science Direct, Embase and Medlin databases. Eighteen articles report the activation with potassium hydroxide, 17 with phosphoric acid, 15 with zinc chloride, 11 with potassium carbonate, nine with sodium hydroxide, and 11 with new activating agents. Activation with phosphoric acid is commonly used for lignocellulosic material and at lower temperatures. Zinc chloride generates more surface area than phosphoric acid but is used less due to environmental concerns. Potassium carbonate, in comparison with potassium hydroxide, produces higher yields and a higher surface area for the adsorption of large pollutant molecules such as dyes. Activating with potassium hydroxide in terms of surface area and efficiency shows better results than sodium hydroxide for various applications. Also, the comparison of the physical mixing method and the impregnation method in activation with alkali metals indicates that the activated carbon obtained through physical mixing had a higher porosity than the activated carbon produced by the impregnation method.

Methods for preparation and activation of activated carbon: a review

Recent advances in removal techniques of Cr(VI) toxic ion from aqueous solution: A comprehensive review

There is an increased global demand for activated carbon (AC) in application of water treatment and purification. Water pollutants that have exhibited a greater removal efficiency by AC included but not limited to heavy metals, pharmaceuticals, pesticides, natural organic matter, disinfection by-products, and microplastics. Granular activated carbon (GAC) is mostly used in aqueous solutions and adsorption columns for water treatment. Commercial AC is not only costly, but also obtained from non-renewable sources. This has prompted the search for alternative renewable materials for AC production. Biomass wastes present a great potential of such materials because of their availability and carbonaceous nature. This in turn can reduce on the adverse environmental effects caused by poor disposal of these wastes. The challenges associated with biomass waste based GAC are their low strength and attrition resistance which make them easily disintegrate under aqueous phase. This paper provides a comprehensive review on recent advances in production of biomass waste based GAC for water treatment and highlights future research directions. Production parameters such as granulation conditions, use of binders, carbonization, activation methods, and their effect on textural properties are discussed. Factors influencing the adsorption capacities of the derived GACs, adsorption models, adsorption mechanisms, and their regeneration potentials are reviewed. The literature reveals that biomass waste materials can produce GAC for use in water treatment with possibilities of being regenerated. Nonetheless, there is a need to explore 1) the effect of preparation pathways on the adsorptive properties of biomass derived GAC, 2) sustainable production of biomass derived GAC based on life cycle assessment and techno-economic analysis, and 3) adsorption mechanisms of GAC for removal of contaminants of emerging concerns such as microplastics and unregulated disinfection by-products.

Synthesis and application of Granular activated carbon from biomass waste materials for water treatment: A review

Graphene and graphene-based nanocomposites used for antibiotics removal in water treatment: A review.

Preparation, characterization and Cr(VI) adsorption evaluation of NaOH-activated carbon produced from Date Press Cake; an agro-industrial waste.

Biodegradation of n-hexane as single pollutant and in a mixture with BTEX in a scoria/compost-based biofilter

Investigation of Common Microbial Indicators in Swimming Pool of Gorgan City

Mathematical modeling of biofiltration systems improves our understanding and design of such complex systems. This study focused on the theoretical and technical aspects of the modeling of xylene biofiltration in the absence and presence of a nonionic surfactant. In this regard, a mathematical model was developed based on mass balance principles in gas and biofilm phases. The developed model was calibrated and validated using the experimental data obtained from a lab-scale scoria-compost biofilter, which operated for 151 days in the absence and presence of Tween-20, a nonionic surfactant. First, the model was calibrated using the experimental data obtained at empty bed retention time (EBRT) of 90 s and then validated with the data obtained at two other EBRTs. The biofilter provided maximum elimination capacities (EC max ) of 97.5 and 93.6 g m −3 hr −1 , respectively, in the absence and presence of the surfactant at EBRT of 90 s. The corresponding predicted EC max values were 99.9 and 95.7 g m −3 hr −1 , respectively. Both model output and experimental data revealed that the nonionic surfactant improved the performance of the biofilter at moderate inlet loading rates. Various statistical measures, including fractional bias, average absolute relative error, and coefficient of determination (R 2 ), showed good agreement between experimental data and estimated model predictions. Sensitivity analysis of the model showed that the specific surface area and bioreactor length affected strongly the results of the model. In general, the results of this study would in turn form the design basis for engineering purposes. © 2019 American Institute of Chemical Engineers

Mathematical modeling and sensitivity analysis of xylene removal in a scoria-compost biofilter

This study examined the adsorption of methylene blue onto raw date fruit waste (DFW) and NaOH-modified date fruit waste (N-DFW). Experiments were done as function of contact time, initial pH (2-12), adsorbent dose (0.5-8 g/L) and initial dye concentration (20-200 mg/L). The solution pH had strong effect on the adsorption capacity of both adsorbents and the extent of the dye removal increased with increasing pH. The experimental data were fitted to different kinetic and isotherm models. The adsorption of methylene blue on both sorbents followed well the pseudo-second-order model. According to Langmuir isotherm model, the maximum monolayer adsorption capacities of DFW and N-DFW were 165.3 and 215.4 mg/g, respectively. Therefore, date fruit waste could be considered as an efficient adsorbent for the removal of MB from aqueous solutions and its adsorption properties were improved through modification with NaOH.

Samira Norouzi

Papers

Preparation, characterization and Cr(VI) adsorption evaluation of NaOH-activated carbon produced from Date Press Cake; an agro-industrial waste.

Biodegradation of n-hexane as single pollutant and in a mixture with BTEX in a scoria/compost-based biofilter

Investigation of Common Microbial Indicators in Swimming Pool of Gorgan City

Mathematical modeling and sensitivity analysis of xylene removal in a scoria-compost biofilter

Adsorption of Methylene Blue from aqueous solution by raw and NaOH-modified date fruit waste