The Role of Oxygenated Functional Groups on Cadmium Removal using Pyrochar and Hydrochar Derived from Guadua angustifolia Residues

Abstract

In the Ecuadorian Amazonia, there is a concern about the presence of high concentrations of cadmium (Cd) in rivers and sediments because of changes in land use and anthropogenic activities, e.g., mining and oil exploitation. Hence, the research related to water treatment processes to meet environmental standards has gained relevance. The use of biochar (BC) as adsorbent is considered a promising and low-cost alternative to improve the water quality in developing countries. In this work, lignocellulosic wastes from Guadua angustifolia were transformed through thermochemical treatments, into a promising carbonaceous material, such as BC. BC samples were prepared by pyrolysis (termed pyrochar, PC) and hydrothermal carbonization (termed hydrochar, HC). Their physicochemical properties were correlated with the Cd adsorption removal performance, analyzing the effect of adsorbent dosage, initial solution pH, adsorption kinetics and adsorption isotherms. HC showed the highest Cd adsorption performance, due to the presence of a higher number of oxygenated functional groups, as confirmed by FTIR, XPS and Raman spectroscopy. This research has proposed a sustainable alternative for the recovery of an available waste, contributing to mitigate the effects of the presence of metals on the health and economy of the most vulnerable sectors of society.

Accumulation and Release of Cadmium Ions in the Lichen Evernia prunastri (L.) Ach. and Wood-Derived Biochar: Implication for the Use of Biochar for Environmental Biomonitoring

“…Biochemical ageing can also increase the amount of oxygenated functional groups on the BC surface, although without increasing the surface area [ 64 ], thus providing an additional sequestration surface for Cd. Indeed, the importance of these groups for the removal of Cd from contaminated sites is well known [ 65 , 66 ]. However, it is important to specify that, since these two types of BC came from different biomass sources, the differences in Cd accumulation between the two investigated BCs may simply be due to variations in their chemical and physical characteristics [ 67 , 68 ], such as surface area [ 69 ] and cation exchange capacity (CEC, i.e., the substrate’s ability to exchange ions), parameters that are closely related.…”

The influence of sodium alginate on the structural and adsorption properties of resorcinol‐formaldehyde resins and their porous carbon derivatives

“…All reagents were commercially available and used without further purification. Granular AC 3.47 [39] Commercial AC 10.3 [40] AC from waste tea 0.11 [41] Microwaved AC from olive stones 11.72 [42] Activated carbon 6.19 [43] modified Carbon nanofibers 2.1 [38] Hydrochar from raffia fibers, and magnetite nanoparticles 6.34 [44] Hydrochar from Guadua angustifolia 0.16 [45] Pyrochar from Guadua angustifolia 0.59 [45] Biochar from sunflower husks 4.15 [46] Carbon aerogel (commercial) 15.53 [47] Carbon aerogel obtained by acid catalysis 18.6…”

Effect of Synthesis Conditions on CuO-NiO Nanocomposites Synthesized via Saponin-Green/Microwave Assisted-Hydrothermal Method

“…The observed band gaps fall in the visible light range (1.65-3.1 eV), which means that the prepared composites are capable of absorbing and interacting with visible light. This range is favorable for applications in photocatalytic reactions, solar cells, optical devices, sensors, and optoelectronics [38,[61][62][63]. The reported Eg of pure CuO and NiO pristine nanoparticles are 1.2-2 eV and 3.4-4.0 eV, respectively, and the Eg of CuO-NiO nanocomposite is 2.84 eV [4,7].…”