Integrated glycolysis and pyrolysis process for multiple utilization and cadmium collection of hyperaccumulator Sedum alfredii

In vivo cadmium-assisted dilute acid pretreatment of the phytoremediation sweet sorghum for enzymatic hydrolysis and cadmium enrichment

Phytoremediation with energy crops is considered an integrated technology that provides both environment and energy benefits. Herein, the sweet sorghum cultivated on Cd-contaminated farmland (1.21 mg/kg of Cd in the soil) showed promising phytoremediation potential, and the approach for utilizing sorghum stalks was explored. Sweet sorghum bagasse with Cd contamination was pretreated with dilute acid in order to improve enzymatic saccharification and achieve Cd recovery, resulting in harmless and value-added utilization. After pretreatment, hemicelluloses were dramatically degraded, and the lignocellulosic structures were partially deconstructed with xylan removal up to 98.1%. Under the optimal condition (0.75% H₂SO₄), the highest total sugar yield was 0.48 g/g of raw bagasse; and nearly 98% of Cd was enriched in the liquid phase. Compared with normal biomass, Cd reduced the biomass recalcitrance and further facilitated the deconstruction of biomass under super dilute acid conditions. This work provided an example for the subsequent valorization of Cd-containing biomass and Cd recovery, which will greatly facilitate the development of phytoremediation of heavy metal contaminated soil.

Preparation of a ternary composite based on water caltrop shell derived biochar and gelatin/alginate for cadmium removal from contaminated water: Performances assessment and mechanism insight

A ternary composite (SA/GE@BC) for cadmium removal from wastewater was successfully prepared. The alginate and gelatin were successfully impregnated with biochar (derived from water caltrop shell) to improve the recyclability and adsorption capacity. The prepared SA/GE@BC demonstrated a good removal for cadmium at pH 4.0-7.0 conditions. The cadmium removal increased with increasing SA/GE@BC dosage. The adsorption kinetics process was well consistent with the pseudo-second order model. And the Langmuir model (R² > 0.99) best described the isotherm data. The calculated adsorption capacity reached a maximum of 86.25 mg/g. The adsorption was a spontaneous and endothermic process, and elevating temperature favored the removal of cadmium. The alginate-gelatin composition enhanced the number of oxygenated functional groups and exchangeable ions. This enhanced the removal of cadmium by complexation and cation ion exchange. Also, the removal mechanism of cadmium on SA/GE@BC involved electrostatic attraction and π-bond coordination. The saturated SA/GE@BC could be well regenerated by 0.1 M HNO₃. All these results suggested the preparation of SA/GE@BC could effectively use waste resources to produce highly effective adsorbents for removing cadmium from contaminated water.

Mechanism exploration of Solanum nigrum L. hyperaccumulating Cd compared to Zn from the perspective of metabolic pathways based on differentially expressed proteins using iTRAQ

It is challenging to determine the mechanism involved in only Cd hyperaccumulation by Solanum nigrum L. owing to the uniqueness of the process. Isobaric tags for relative and absolute quantitation (iTRAQ) were used to explore the mechanism by which S. nigrum hyperaccumulates Cd by comparing the differentially expressed proteins (DEPs) for Cd and Zn accumulation (non-Zn hyperaccumulator). Based on the comparison between the DEPs associated with Cd and Zn accumulation, the relative metabolic pathways reflected by 17 co-intersecting specific proteins associated with Cd and Zn accumulation included phagosome, aminoacyl-tRNA biosynthesis, and carbon metabolism. Apart from the 17 co-intersecting specific proteins, the conjoint metabolic pathways reported by 21 co-intersecting specific proteins associated with Cd accumulation and 30 co-intersecting specific proteins associated with Zn accumulation, the most differentially expressed metabolic pathways might cause Cd TF (Translocation factor)> 1 and Zn TF< 1, including protein export, ribosome, amino sugar, and nucleotide sugar metabolism. The determined DEPs were verified using qRT-PCR with the four key proteins M1CW30, A0A3Q7H652, A0A0V0IFB9, and A0A0V0IAC4. The plasma membrane H⁺-ATPase protein was identified using western blotting. Some physiological indices for protein-related differences indirectly confirmed the above results. These results are crucial to further explore the mechanisms involved in Cd hyperaccumulation.

Emerging disposal technologies of harmful phytoextraction biomass (HPB) containing heavy metals: A review

Phytoextraction is an effective approach for remediation of heavy metal (HM) contaminated soil. After the enhancement of phytoextraction efficiency has been systematically investigated and illustrated, the harmless disposal and value-added use of harmful phytoextraction biomass (HPB) become the major issue to be addressed. Therefore, in recent years, a large number of studies have focused on the disposal technologies for HPB, such as composting, enzyme hydrolysis, hydrothermal conversion, phyto-mining, and pyrolysis. The present review introduces their operation process, reaction parameters, economic/ecological advantages, and especially the migration and transformation behavior of HMs/biomass. Since plenty of plants possess comparable extraction abilities for HMs but with discrepancy constitution of biomass, the phytoextraction process should be combined with the disposal of HPB after harvested in the future, and thus a grading handling strategy for HPB is also presented. Hence, this review is significative for disposing of HPB and popularizing phytoextraction technologies.