Removed heavy metal ions from wastewater reuse for chemiluminescence: Successive application of lignin-based composite hydrogels.

The novel sulfomethylated lignin-grafted-polyacrylic acid (SL-g-PAA) hydrogel was fabricated in this work via a facile and green synthetic strategy for the efficient removal of heavy metal ions from wastewater, and then successively reused for chemiluminescence (CL). The sulfomethylation of lignin was first performed to improve its water solubility and introduce numerous active sites for adsorption of heavy metal ions. The as-synthesized SL-g-PAA hydrogel with high content of lignin exhibited the highly efficient and rapid removal of various metal ions from simulated wastewater. More importantly, the spent hydrogel (M2+@SL-g-PAA) after adsorption was reused for the first time to develop a new CL system by an ingenious strategy, in which these metal ions adsorbed on M2+@SL-g-PAA act as heterogeneous catalytic sites to catalyze the CL reaction between N-(4-aminobutyl)-N-ethylisoluminol (ABEI) and H2O2. The resultant CL system displayed high CL intensity and long duration time, which could be observed by naked eye in the dark and lasted for > 24 h. The combination of facile fabrication process, renewable raw materials, and ingenious strategy for successive application in adsorption and CL endows this lignin-based composite hydrogel with a great potential for application in wastewater treatment, biological imaging and cold light sources.

Recent Advances and Challenges in Photoreforming of Biomass-Derived Feedstocks into Hydrogen, Biofuels, or Chemicals by Using Functional Carbon Nitride Photocatalysts.

Photoreforming of biomass into hydrogen, biofuels, and chemicals is highly desired, yet this field of research is still in its infancy. Developing an efficient, novel, and environmentally friendly photocatalyst is key to achieving these goals. To date, the nonmetallic and eco-friendly material carbon nitride has found many uses in reactions such as water splitting, CO2 reduction, N2 fixation, and biorefinery, owing to its outstanding photocatalytic activity. However, a narrow light absorption range and fast charge recombination are often encountered in the pristine carbon nitride photocatalytic system, which resulted in unsatisfying photocatalytic activity. To improve the photocatalytic performance of pure carbon nitride in biomass reforming, modification is needed. In this Review, the design and preparation of functional carbon nitride, as well as its photocatalytic properties for the synthesis of hydrogen, biofuels, and chemicals through biomass reforming, are discussed alongside potential avenues for its future development.

Nitrogen-doped lignin-derived biochar with enriched loading of CeO2 nanoparticles for highly efficient and rapid phosphate capture.

Development of lignin-derived carbon adsorbents with ultrahigh phosphate adsorption activity and rapid adsorption kinetics is of great importance, yet limited success has been achieved. Herein, we develop a CeO2 functionalized N-doped lignin-derived biochar (Ce@NLC) via a cooperative modification strategy for effective and fast phosphate capture. The novel modification strategy not only contributes greatly to the loading of well-dispersed CeO2 nanoparticles with a smaller size, but also significantly increases the relative concentration of Ce(III) species on Ce@NLC. Consequently, an enhanced capture capacity for phosphate (196.85 mg g-1) as well as extremely rapid adsorption kinetics were achieved in a wide operating pH range (2-10). Interestingly, Ce@NLC exhibited a strong phosphate adsorption activity at even low-concentration phosphorus-containing water. The removal efficiency and final P concentration reached 99.87% and 2.59 µg P L-1 within 1 min at the phosphate concentration of 2 mg P L-1. Experiments and characterization indicated that Ce(III) species plays a predominant role for the phosphate capture, and ligand exchange, together with electrostatic attraction, are the main adsorption mechanism. This work develops not only an efficient carbon-based adsorbent for phosphate capture, but also promotes the high-value application of industrial lignin.

Recent advances and challenges on removal and recycling of phosphate from wastewater using biomass-derived adsorbents.

As the severe damage of phosphate enrichment in the water ecosystem and the supply shortage of phosphate rock, developing an efficient method for the removal and recycling of phosphate from wastewater is of great significance. To achieve this goal, adsorption technology has been widely investigated, and various adsorbents were developed. Among them, the biomass-derived adsorbents including biomass-derived carbon-based materials, biomass-based anion exchangers and metal-biomass composites have attracted increasing attention over the past years due to the low cost, abundant renewable raw materials and environmental friendliness. However, different adsorbents usually exhibit variable adsorption performances for phosphate, which highly depends on their design strategies, preparation methods and potential adsorption mechanisms. Thus, this review comprehensively summarizes the recent researches on the removal and recycling of phosphate from wastewater using the biomass-derived adsorbents. Especially, the design strategies, preparation methods, adsorption performances and mechanisms of these reported biomass-derived adsorbents are discussed in detail. Moreover, as the significant strategies to recover and recycling phosphate, the elution and direct use of phosphate-loaded adsorbents as fertilizers are also presented. Although the excellent adsorption performance has been obtained, some challenges are still existing, which should be given more attention in the following researches to facilitate the development and industrial application of biomass-derived adsorbents.

Enhanced adsorption activity for phosphate removal by functional lignin-derived carbon-based adsorbent: Optimization, performance and evaluation.

Design of carbon-based adsorbents derived from industrial lignin with superior phosphate adsorption performance is of great significance, yet limited researches have been reported. Here, we report a MgO-functionalized lignin-based bio-charcoal (MFLC) as an efficient adsorbent for phosphate removal. The obtained MgO nanoparticles were dispersed homogeneously on MFLC with particle size of 50-100 nm and higher loading content (28.41%). Benefiting from the favorable morphology of MgO nanoparticles, the MFLC exhibits excellent regeneration ability for phosphate adsorption, which can be applied in a wide range of pH values (2-10). The maximum adsorption capacity could reach to 906.82 mg g-1 for phosphate. Interestingly, the MFLC shows extremely high adsorption activity in the low concentration of phosphate (2 mg P L-1), and its phosphate removal efficiency achieves 99.76%. Furthermore, the results also indicated that the higher loading content of MgO together with smaller particle size can effectively enhance the phosphate adsorption activity of MFLC. The adsorption mechanism revealed that the adsorption of phosphate on the surface of MFLC belongs to single-layer chemisorption, and ligand exchange plays a crucial role during adsorption/desorption. This work not only develops a new strategy for the preparation of high-efficiency carbon-based adsorbents, but also facilitates the value-added utilization of industrial lignin.