Adsorptive Features of Magnetic Activated Carbons Prepared by a One-Step Process towards Brilliant Blue Dye

Magnetic biochar as a revolutionizing approach for diverse dye pollutants elimination: A comprehensive review

The term "biomass" encompasses all substances found in the natural world that were once alive or derived from living organisms or their byproducts. These substances consist of organic molecules containing hydrogen, typically oxygen, frequently nitrogen, and small amounts of heavy, alkaline earth and alkali metals. Magnetic biochar refers to a type of material derived from biomass that has been magnetized typically by adding magnetic components such as magnetic iron oxides to display magnetic properties. These materials are extensively applicable in widespread areas like environmental remediation and catalysis. The magnetic properties of these compounds made them ideal for practical applications through their easy separation from a reaction mixture or environmental sample by applying a magnetic field. With the evolving global strategy focused on protecting the planet and moving towards a circular, cost-effective economy, natural compounds, and biomass have become particularly important in the field of biochemistry. The current research explores a comparative analysis of the versatility and potential of biomass for eliminating dyes as a sustainable, economical, easy, compatible, and biodegradable method. The elimination study focused on the removal of various dyes as pollutants. Various operational parameters which influenced the dye removal process were also discussed. Furthermore, the research explained, in detail, adsorption kinetic models, types of isotherms, and desorption properties of magnetic biochar adsorbents. This comprehensive review offers an advanced framework for the effective use of magnetic biochar, removing dyes from textile wastewater.

Insight into Cu (II) adsorption on pyrochar and hydrochar resultant from Acacia Senegal waste for wastewater decontamination

Acacia Senegal waste (ASW) is remaining biomass following gum Arabic harvesting and has no use mentioned in the literature as of yet. This study aims to convert ASW into valuable biochar via two comparative thermal and hydrothermal techniques, which include pyrochar ASW at 300 °C (PC ASW300) and hydrochar ASW at 180 °C (HC ASW180), respectively, for Cu (II) adsorption from aqueous solutions. SEM-EDS, FTIR, XRD, and XPS were used to characterize the biochar. Adsorption performance was studied as a function of pH, contact time, and adsorbent concentration. Adsorption kinetics were best fit for a pseudo-second-order model. And thermodynamics studies revealed that Cu (II) on biochar was endothermic, spontaneous, and best fitted to the Langmuir isotherm model. Pyrochar adsorption capacity (31.93 mg g-1) was seven times that of hydrochar (5.45 mg g-1). ASW treated with phosphorus (PC H3PO4 and HC H3PO4) prior to the carbonization altered the pore structure and surface functional groups as well (O-P-O, P-CH3, and P-OH) of biochar. It was found that treating with phosphorous acid increased adsorption capacity to 141.7 mg g-1 and 22.24 mg g-1 for PC H3PO4 and HC H3PO4, respectively. The surface functional groups of biochar resulted from lignin, alkaloids, and polysaccharides combined with Cu (II) during the adsorption process via surface complexation accompanied by π-electron interaction and Cu (II) reduction. These findings shed light on the ASW biochar potential as a new green cost-effective adsorbent and drew an insightful understanding of Cu (II) adsorption performance and mechanism. It is concluded that ASW-derived biochar is highly effective and a promising alternative for Cu (II) decontamination from wastewater.

Development of activated carbons derived from wastes: coffee grounds and olive stones as potential porous materials for air depollution

Agro-industrial byproducts and food waste necessitate an environmentally friendly way of reducing issues related to their disposal; it is also necessary to recover as much new raw material from these resources as possible, especially when we consider their potential usage as a precursor for preparing depolluting materials, such as activated carbon. In this work, coffee grounds and olive stones were chosen as precursors and the adsorption capacity of the obtained porous carbons for volatile organic compounds (VOCs) was studied. Microporous activated carbons (ACs) were prepared using chemical (K2CO3) and physical (CO2) activation. The influence of the activation process, type, and time of activation was also investigated. Measurements of VOCs adsorption were performed, and methyl-ethyl-ketone (MEK) and toluene were chosen as the model pollutants. The surface areas and total pore volumes of 1487 m2/g and 0.53 cm3/g and 870 m2/g and 0.22 cm3/g for coffee ground carbons and olive stone carbons, respectively, were obtained via chemical activation, whereas physical activation yielded values of 716 m2/g and 0.184 cm3/g and 778 cm2 g-1 and 0.205 cm3/g, respectively. As expected, carbons without activation (biochars) showed the smallest surface area, equal to 331 m2/g and 251 m2/g, and, hence, the lowest adsorption capacity. The highest adsorption capacity of MEK (3210 mg/g) and toluene (2618 mg/g) was recorded for chemically activated coffee grounds. Additionally, from the CO2 isotherms recorded at a low pressure (0.03 bar) and 0 °C, the maximum CO2 adsorption capacity was equal to 253 mg/g.

Successful removal of fluoride from aqueous environment using Al(OH)3@AC: column studies and breakthrough curve modeling

In this study, we discuss the removal of fluoride from water through column adsorption methods using Al(OH)3@AC as a functional granular activated carbon. The height of the bed, fluoride concentration, and flow rate are the experimental factors used to obtain the breakthrough curves. As the flow rate increased, the breakthrough and saturation times decreased. The analysis of simplified column models, such as the Adams-Bohart, Thomas, and Yoon-Nelson models, revealed that the Clark model best described the adsorption process when fitting the experimental data. The obtained breakthrough curves agreed with the corresponding experimental data. The highest capacity for adsorption obtained during the column procedure was found to be 41.84 mg g-1 with a bed height of 3 cm, an initial fluoride concentration of 10 mg L-1 and a flow rate of 7.5 mL min-1.

Comprehensive adsorption and spectroscopic studies on the interaction of magnetic biochar from black wattle sawdust with beta-blocker metoprolol

The rise of contaminants of emerging concern in water-resources due to human activities has driven research toward wastewater treatment, specifically adsorption. The utilization of woody biomass for biochar production in adsorption has shown promise due to its high availability. This study shows the preparation of magnetic biochars (MB) from waste black wattle sawdust, utilizing ZnCl2 and NiCl2 (proportions: 1:0.5:0.5 = MB-0.5 and 1:1:1 = MB-1) as activating and magnetic agents. Synthesized via microwave-assisted-pyrolysis, MB boasts a high surface area (up to 765 m2.g-1) and functional groups, enhancing metoprolol medicine adsorption. Nonlinear kinetic and isothermal models were tested; the Avrami fractional-order kinetic model and Liu's isothermal model provided the best fits for experimental data. Thermodynamics and spectroscopic studies revealed spontaneous and exothermic adsorption processes, with physisorption magnitude and dominance of hydrogen-bond and π-π-interactions. MB can be easily extracted from an aqueous medium using magnetic fields, while adsorption capacity could be regenerated through green solvent elution.