Residual biomass of coffee as a binding agent in diffusive gradients in thin-films technique for Cd, Cu, Ni, Pb and Zn measurement in waters

Valorization of residual lignocellulosic biomass in South America: a review

Residual lignocellulosic biomass (RLB) is a valuable resource that can help address environmental issues by serving as an alternative to fossil fuels and as a raw material for producing various value-added molecules. To gain a comprehensive understanding of the use of lignocellulosic waste in South America, a review was conducted over the last 4 years. The review focused on energy generation, biofuel production, obtaining platform molecules (such as ethanol, hydroxymethylfurfural, furfural, and levulinic acid), and other materials of interest. The review found that Brazil, Colombia, and Ecuador had the most RLB sources, with sugarcane, oil palm, and rice crop residues being the most prominent. In South America, RLB is used to produce biogas, syngas, hydrogen, bio-oil, biodiesel, torrefied biomass, pellets, and biomass briquettes. The most studied and produced value-added molecule was ethanol, followed by furfural, hydroxymethylfurfural, and levulinic acid. Other applications of interest that have been developed with RLB include obtaining activated carbon and nanomaterials. Significant progress has been made in South America in utilizing RLB, and some countries have been more proactive in regulating its use. However, there is still much to learn about the potential of RLB in each country. This review provides an updated perspective on the typification and valorization of residual biomass in South America and discusses the level of research and technology being applied in the region. This information can be helpful for future research on RLB in South America.

Determination of Labile Cadmium in Soils Using a New Sodium Alginate-Polyglutamic Acid-Diffusive Gradient in Thin Films

Sodium alginate-polyglutamic acid was used to develop a new diffusive gradient in thin films (SA-PGA-DGT) device, which was proven to be suitable for the investigation of labile Cd in soil. The adsorption capacity of Cd was calculated to be approximately 16.8 μg/cm² , which was hardly affected by factors including pH (5-9), ionic strength (0.1-100 mM), and the presence of other metals (Pb, Cu, Ni, and Cr). The SA-PGA gel has dense and uneven pores with large specific surface area, which ensures the adsorption of Cd by functional groups of the gel. A kinetics study indicated that the adsorption rate of Cd by the binding gel can be described as a pseudo-second-order reaction. Deployment of the SA-PGA-DGT in the soils of Tang Gu (located in Binhai New District, Tianjin, China) showed a strong positive linear correlation between Cd measured by the device and exchangeable Cd measured by the Tessier method (R = 0.73, p < 0.01). Cadmium determined by the SA-PGA-DGT device was less affected by soil properties. This new SA-PGA-DGT has obvious advantages over other methods in respect of the labile Cd analysis in soil. The innovative novel device expands the variety of existing DGT technologies and can be utilized to monitor the level of labile Cd in soil effectively. Environ Toxicol Chem 2021;40:1559-1569. © 2021 SETAC.

PAMPS-graft-Ni3Si2O5(OH)4 multiwalled nanotubes as a novel nano-sorbent for the effective removal of Pb(ii) ions

The existence of Pb(ii) ions in water systems poses significant potential hazards to public health and the environment. In the present study, poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) brush-modified Ni₃Si₂O₅(OH)₄ nanotubes were prepared, and their adsorption efficiency against the Pb(ii) ions was investigated. The characterization results of FTIR spectroscopy, TGA, TEM, and XPS indicated the successful grafting of PAMPS on the surface of free Ni₃Si₂O₅(OH)₄ NTs, and the prepared PAMPS-g-Ni₃Si₂O₅(OH)₄ NTs exhibited a 6–8 nm grafting layer, which could provide abundant binding sites for metal adsorption. During the Pb(ii) removal process, a pH-dependent adsorption behavior was observed, and the adsorption processes fitted well with the pseudo-second-order kinetic model and the Langmuir isotherm model. Compared with unmodified Ni₃Si₂O₅(OH)₄, the PAMPS-g-Ni₃Si₂O₅(OH)₄ NTs exhibited obviously faster adsorption of Pb(ii) and higher equilibrium adsorption capacity for the removal of Pb(ii). The maximum adsorption capacity calculated via the Langmuir isotherm model was 0.653 mmol g⁻¹ (135.3 mg g⁻¹) at 298 K. In a metal coexisting system, the total adsorption capacity of the NTs was increased; this indicated the potential of the proposed NTs in the removal of Pb(ii) from metal coexisting wastewater. This study showed the significant potential of PAMPS-g-Ni₃Si₂O₅(OH)₄ NTs in the effective removal of Pb(ii).

PAMPS-g-Ni₃Si₂O₅(OH)₄ NTs for the effective removal of Pb(ii).