Biomass Cellulose Component and Fe Mineral Catalysis Help Cr(VI) to Realize Almost 100% Pyrolysis Reduction Efficiency

Abstract

Low-temperature pyrolysis reduction (<500 °C) for Cr­(VI) remediation in heavily polluted soil or slag has gained increasing attention. However, it is hard to realize almost 100% Cr­(VI) pyrolysis reduction at a high concentration of Cr­(VI) pollution (more than 104 mg/kg) due to insufficient reductive pyrolysis products. In the present study, almost 100% Cr­(VI) reduction was achieved by cellulose-enriched biomass assisted by an Fe mineral catalysis. Quantitative analysis of tar, reducing gases, and char on the Cr­(VI) reduction efficiency suggested that the produced tar is a crucial factor to promote Cr­(VI) pyrolysis reduction. Our results indicated that both the cellulose component of biomass and the Fe minerals catalyst could produce susceptible-cracking tar to help Cr­(VI) reduction indirectly. FT-ICR MS and online MS results further discerned that produced tar with aromatic and lignin/CRAM-like structures or high unsaturated and oxidized structures (DBE > 15, O x > O6) can be cracked via a decarbonylation reaction to generate reducing gases for promoting Cr­(VI) reduction. Thus, our present study provides a method to completely reduce Cr­(VI) in solid wastes, perfectly avoiding the reyellowing risk of residual Cr­(VI).

Ground-Breaking and Safe Recycling of Hazardous Hyperaccumulators

“…The capillary column-introduced voltage was 3.8 kV, and the accumulating time was 0.06 s. The signal-to-noise ratio was enhanced by accumulating 300 scans. Then, the statistics were analyzed to calculate the intensity weighted average values of O/C, H/C, DBE, and m / z for observing the transformation of the main chemical component of the samples. , …”

“…Then, the statistics were analyzed to calculate the intensity weighted average values of O/C, H/C, DBE, and m/z for observing the transformation of the main chemical component of the samples. 24,25 As for gaseous products, the samples were analyzed by gas chromatography (GC) (PerkinElmer Clarus 580) to identify the composition. The proportion and volume of smallmolecule gases (such as H 2 , CO, CO 2 , C 2 H 2 , C 2 H 4 , C 2 H 6 , C 3 H 6 , and C 3 H 8 ) were calculated to investigate the relationship between the FJH input power and the component changes.…”

Real-Time Emission, Chemical Properties, and Dynamic Evolution Mechanism of Volatile Organic Compounds during Co-Pyrolysis of Rice Straw and Semi-Bituminous Coal

“…Fossil energy consumption has recently increased drastically and led to global environmental problems, such as greenhouse gas and fine particulate matter emissions. − Mitigating the environmental impacts of current fossil energy consumption is an urgent and important topic. , As a clean and renewable energy, global biomass production has an annual output of approximately 100 billion tons and has attracted considerable attention in environmental pollution reduction. − It is worth noting that biomass utilization has the disadvantages of high moisture and oxygen content, and low energy density and calorific value. ,, The co-utilization of biomass and coal offers several advantages over their individual processes such as higher liquid yields and higher char conversion rates. , Therefore, realizing the effective synergistic utilization of coal and biomass provides a valuable choice for clean resource utilization with improved efficiency and reduced production costs.…”

Overlooked Role of Chromium(V) and Chromium(IV) in Chromium Redox Reactions of Environmental Importance

“…1,2 Industrial processes to extract metals may illegally discharge waste into the natural environment, creating pollution events that need complete remediation. 3 Anthropogenic disturbances of geochemical processes can cause background levels of heavy metals to elevate and bioaccumulate, posing health risks to humans and the ecosystem because of their persistence in the environment and damage to the nerve system and other organs. 4,5 Among heavy metals, chromium (Cr) is a major pollutant, entering soil from wastes of industrial activities such as coal-fired power generation, chrome pigment production, wood preservation, stainless steel production, galvanization, cement production, electroplating, and leather tanning.…”

“…Heavy metals are known to pollute water resources and have both natural and anthropogenic sources. Anthropogenic sources of heavy metals consist of sewage discharge, pesticides, mine tailings, and coal combustion residuals, while natural sources of heavy metals can include soil erosion and weathering. , Industrial processes to extract metals may illegally discharge waste into the natural environment, creating pollution events that need complete remediation . Anthropogenic disturbances of geochemical processes can cause background levels of heavy metals to elevate and bioaccumulate, posing health risks to humans and the ecosystem because of their persistence in the environment and damage to the nerve system and other organs. , Among heavy metals, chromium (Cr) is a major pollutant, entering soil from wastes of industrial activities such as coal-fired power generation, chrome pigment production, wood preservation, stainless steel production, galvanization, cement production, electroplating, and leather tanning. − Chromium has four isotopes in nature: isotopes 50 Cr, 52 Cr, 53 Cr, and 54 Cr with respective abundances of 4.35%, 83.79%, 9.50%, and 2.36% …”