Acidic Waste Research Articles

Upcycling spent graphite in LIBs into battery-grade graphene: Managing the produced waste and environmental impacts analysis

This study focuses on connecting graphite demand to battery materials demand, providing a solution to the identified shortage of battery materials and promoting sustainable development. This research used modified Hummer's method to synthesize graphene from the recycled graphite and compared it with graphene synthesized from purified recycled graphite. The purification of recycled graphite was implemented by acid curing-leaching and calcination. The analysis showed that the reduction reaction effectively removed oxygen-containing functional groups from the graphene, resulting in enhanced quality of the produced graphene. Hummer’s waste acid was used as a leaching reagent for different LIBs’ cathode types in waste management. The waste acid was found to be a strong reagent for transition metals leaching and obtained almost full recoveries of Li, Co, Mn, and Ni from spent LIB cathodes. The synthesized graphene exhibited higher specific surface areas and conductivity values compared to battery-grade graphite. The electrochemical performance of the graphene sheets in lithium half-cells was evaluated, and it was found that the graphene synthesized from recycled graphite enabled increased lithium insertion at active sites, suggesting its potential for enhanced lithium retention. Furthermore, a life cycle assessment study was conducted to evaluate the environmental impacts of the recycling and synthesis processes. This study demonstrates the potential of recycling graphite from spent battery anodes to produce high-quality graphene with improved electrochemical properties.

The Effect of some Soil Conditioners on the Readiness and Absorption of Nutrients

In the fall of 2022–2023, students from the Department of Plant Production at the Technical College / Musayyib, which is part of the Musayyib project area, conducted a potting experiment under the canopy of the college to investigate the impact of various soil conditioners on nutrient availability and uptake. The experiment followed a completely randomized block design (R.C.B.D.), with four replicates (1, 2, 3, 4 replicates) using four different soil conditioners (humic acid, agricultural sulfur, stucco and vermicompost waste). With 48 treatments across three replicates, we were able to compare means using the L.S.D. (0.05) test for statistical significance. The results showed that the readiness and absorption of nutritional elements were significantly affected by the overlap between the type of conditioners and the number of batches, that agricultural sulfur treatment was significantly superior compared to the rest of the treatments, and that the fourth batch was superior to the first.

The influence factors of dielectric barrier discharge plasma to production of syngas derived from H2S-CO2 acid gas

H2S and CO2, two harmful acid waste gases, often co-exist in important chemical production such as coal-chemical industry, natural gas chemical industry and petrochemical industry, causing corrosion of industrial equipment and pipelines, and must be treated innocuously. Co-conversion of H2S-CO2 mixed acid gas to syngas has been carried out using dielectric barrier discharge (DBD) plasma-catalysis, which renders the highly corrosive and toxic H2S and greenhouse gas CO2 harmless, and produces syngas. The effects of various parameters of the DBD plasma on the reaction of one-step conversion of H2S-CO2 to syngas were studied. Moreover, a comparative study of the different parameters of DBD plasma was carried out. The intrinsic correlation between the reaction performance of syngas production via H2S-CO2 conversion and these parameters, including specific energy input (SEI), discharge shape, discharge frequency, discharge gap and discharge length, was investigated and revealed. On this basis, a multi-tube parallel DBD plasma reaction system was designed and constructed.

Studies on the acidification of carbonate waste stream for separation of di-butyl phosphate and recovery of metal

Abstract The aqueous waste generated during the treatment of Purex lean organic phase with alkaline carbonate solution contains washable degradation products and actinides in the form of carbonate complex. Management of such aqueous waste demands quantitative removal of the main degradation product, dibutyl phosphate (HDBP) and actinides from aqueous solution. In this context, batch studies have been carried out on the separation of HDBP from aqueous solution using n-dodecane (n-DD). For this purpose, the extraction behaviour of HDBP in n-DD was studied after acidification of alkaline carbonate solution with nitric acid. The studies with simulated waste containing HDBP and U(VI) nitrate showed the loss of U(VI) as precipitate during acidification as the uranium–DBP was poorly soluble in aqueous phase. However, the loss of U(VI) decreased with increase of aqueous phase acidity showing that the adjusted acidity of the carbonate waste plays an important role in the recovery of actinides.

Reuse of waste acid from titanium dioxide industry: Efficient synthesis and functional exploration of titanium phosphate

The titanium phosphate particles were prepared from acidic wastewater containing titanium by a simple and efficient method, and characterized by XRD, SEM, FTIR and XPS. The results revealed that the titanium phosphate was a porous amorphous material with a high specific surface area. Its main chemical composition was determined to be Ti(OH)2(HPO4)•1·.5H2O based on the Ti-O skeleton and phosphate group. Due to its structural similarity to anatase titanium dioxide, it displayed excellent UV shielding ability along with ample modification potential. Additionally, it demonstrated strong selective adsorption capacity for thorium under acidic conditions, achieving a saturation adsorption capacity of 159.24 mg/g. The adsorption process followed the Langmuir isotherm and Pseudo-second-order kinetic model. The presence of phosphate groups and Ti-O bonds played pivotal roles in the-based adsorption mechanism dominated by ion exchange processes. Furthermore, desorption experiments confirmed its exceptional stability and reusability for practical applications.

Impact of Fertilizer Type and Vegetative Growth Duration on the Availability of Copper in Clay Loam Soil Planted of Maize (Zea mays L.) in Iraq

The present field trial aimed to study the effect of fertilizer type and growth duration on copper availability in the maize soil. In addition to the control, six different fertilizer treatments of mineral fertilizers, organic fertilizers, and humic acid (two levels each) were applied in the experiment. Soil samples were collected 70 and 100 days after planting. The results present that there were no significant differences between the half-recommendation fertilizer treatments (the first level) for all fertilizers, and the effect of the entire recommendation treatments (the second level) for poultry waste and humic acid 0.37 mg kg-1 and their superiority over the urea fertilization treatments 0.33 mg kg-1 in 70 days of cultivation. At 100 days, the fertilization treatments with poultry waste resulted in the highest concentration of available copper, 0.41 and 0.35 mg kg-1, respectively, the two levels. The results present a decrease in the concentration of available copper in the soil with an increase in the growth period.

Comparison of FDMed and compression molded biocomposites in polylactic acid and food flour waste

Polylactic acid resins are some of the most largely used bioplastics, some characteristics still limit their use, such as in mixing with other polymers or inclusion of additives. Currently, additive manufacturing technologies are enlarging their application sectors because they allow more rational use of raw materials, limiting both production waste and onerous post-processing stages. In this framework, polylactic acid resins, particularly favoured by their slow crystallization rate and the large availability, are some of the most used to obtain commercial filaments for fused deposition modeling. This research is then focused on the processability of the compounds, based on a commercial PLA resin, additivated with 1, 3, and 5 wt% of food flour wastes. The comparison of the performance of the products obtained with conventional and innovative technologies, respectively compression molding and FDM, is the key point of this study. Mechanical and morphological properties, obtained by the two technologies, were evaluated for neat and additivated resins. Preliminary results emphasize that, through compression molded, it was possible to obtain homogeneous components and the natural infilled used acts as reinforcement improving mechanical performances. For the additive technology, the samples obtained show a lower mechanical behavior due to the technological issues of 3d printing.

Development of a composite based on polylactic acid and lignocellulosic waste: new packaging for meat food storage

Pursuing new packaging that contributes to the safety of meat products, that can also be from renewable sources and that has adequate mechanical properties is a challenge. Therefore, this study attempted to incorporate a layer of polylactic acid (PLA) containing nisin and oregano oil extract (OEO) into biocomposites of cassava bran (CB) and coffee husk (CH) to improve their mechanical properties and enhance their antimicrobial properties. A compression molding process is carried out, the operating conditions for the preparation of the biocomposite were pressure: 40 bar, temperature: 170°C, and time: 2.5 min. The composition of the biocomposite was 80, 18, and 2% of CB, CH, and glycerol respectively, with 30% moisture. The polylactic acid (PLA) layer was added by immersion and contained nisaplin and OEO. PLA layer was evaporated in forced convection oven. Once the active packaging was obtained, inhibition in vitro against Listeria monocytogenes was performed. The packing containing OEO and nisin that showed the highest inhibition on the pathogen was used for stability analysis in pork. In order to measure changes in pork meat quality, the biocomposite with and without coating and with commercial polystyrene packaging were compared. Raw meat muscle was kept at 4° C and was tested for color, pH, moisture, and texture profile analysis (TPA) for 0, 7, 14, and 21 days. The values of the flexural test of the biocomposite were: 11.08 MPa of maximum flexural strength (σF), 1.81% of maximum deformation (εF), and 842.22 MPa of elastic modulus (EM). According to the results of in vitro inhibition, the packaging can contribute to reduce the proliferation of gram-positive microorganisms, such as L. monocytogenes. During storage, the hardness and gumminess of the meat showed significant changes, mainly in the PLA-free biocomposite. Results on pork meat showed that packaging with antimicrobials and PLA can maintain color, texture, moisture, and pH similar to commercial packaging.

Insights into the adsorptive separation of iron from pickling waste acid: The overlooked role of FeCl3 species

Elucidating the dominant adsorption species of FeCln3−n is fundamental for precisely regulating the adsorption process and thus enhancing the management of waste pickling liquor. In this work, anion resin (D201) exhibits great adsorption for FeCl4−, also exhibits the unexpectedly high adsorption for neutral species FeCl3. The contribution of various iron species was quantitatively evaluated via Ion Species Contribution Evaluation (ISCE). The results illustrate that both FeCl3 and FeCl4− were the dominant species adsorbed by D201 resin and exhibited similar adsorption activities. Experimental and computational results indicate that the adsorption of FeCl4− is accompanied by the shedding of Cl on FeCl4− and FeCl3 recombines with the Cl on D201, which indicate that FeCl3 is an intermediate species in the FeCl4− adsorption process. Accordingly, FeCl3 was revealed to be critical species for iron adsorption in hydrochloric pickling liquor. The concentration of HCl (20 % w/w) required for FeCl3 was sufficient for the removal of iron compared with the higher concentration (25 % w/w) required for FeCl4−, which broadened the concentration boundary for HCl reuse. Our strategy serves for industrial iron removal from hydrochloric pickling liquor and results in 86 % reduction in the amount of hydrochloric acid during 100 days pilot-scale test.

The Production of Hematite Powder from Spent Pickling Hydrochloric Acid

This research aimed to study the recycling process and the feasibility of recovering iron as hematite or red oxide powder (Fe2O3) from spent pickling acid (hydrochloric acid). The spent hydrochloric acid waste from the pickling bath in the sheet rolling steel industry contains approximately 233 g of iron dissolved in one liter of the spent acid. To recover iron, 2 M NaOH was added to the spent acid until reaching pH 7. The iron was precipitated as iron oxide and/or hydroxide. Next, the oxidation of ferrous oxide was carried out by adding H2O2 35%v/v to control the shade color. The precipitates were subsequently separated from the acid solution by a filter press. The precipitates were dried at 110°C for 24 h and calcined at 700°C for 2 h to synthesize and modify the crystallinity of ferric oxide. Ferric oxide was subject to water washing, where contaminating sodium chloride could be dissolved and filtered out. After drying at 110°C for 24 h, high-purity hematite was achieved. Hematite recovered from the spent pickling acid via this process provided more than 97% purity at 94.4% recovery.

Wet removal of elemental mercury by acid-assisted electrochemical oxidation method

As a global pollutant, mercury emission is increasingly restricted in recent years. It is urgent to explore a new and efficient mercury removal technology for coal-fired power plants. A new acid-assisted electrochemical oxidation (AEO) technique for mercury removal was proposed using platinum plate as cathode and fluorine-doped tin dioxide (FTO) glass as anode. The effects of acid type, acid concentration, applied direct current (DC) voltage, electrolyte type, SO2, NO and O2 on the Hg0 removal efficiency were carried out. The results indicated that the mercury removal efficiency increased with the increase of DC voltage and nitric acid concentration. When the concentration of nitric acid increased to 0.15 mol/L, the mercury removal efficiency remained unchanged. SO2 and NO inhibited the removal of Hg0 in AEO system, but the inhibition was reversible. Compared with the mercury removal efficiency under single experimental conditions, the mercury removal efficiency of electrochemical oxidation can reach 96% under the experimental conditions of 0.1 mol/L nitric acid and 4V DC voltage, suggesting that the synergistic effect of nitric acid and DC voltage plays a key role. According to the experimental results, the mechanism of Hg0 removal in AEO system was analyzed. At the anode, Hg0 was oxidized by hydroxyl radical (.OH) generated by the oxidation reaction on the anode surface. At the cathode, dissolved oxygen or O2 adsorbed on the surface of Pt is reduced to form anionic superoxide radicals (.O−2). Moreover, parts of .O−2 would produce .OH with the aid of electron at acidic condition. Free radicals capture experiments showed that .O−2 and .OH were the main active substances for the removal of Hg0 by acid-assisted electrochemical method. The research is helpful for the development of effective electrochemical techniques for industrial mercury removal and recycling of industrial acid waste.

Characteristics of solid waste from common generation source in nonferrous smelting industry reveal a new classification method

Solid waste produced by the nonferrous smelting industry has a significant number of notable differences. The lack of recognition of solid waste characteristics is the main factor restricting its disposal and utilization. In this study, we analyzed the main production processes of the nonferrous smelting industry; identified the key production nodes of solid waste; and clarified the characteristics, including the physical, chemical, and pollution characteristics of solid wastes, through a large sample statistical analysis. We found similarities among solid wastes from a common generation source as well as notable differences among the different generation sources: slags and sludges from waste acid treatment and wastewater treatment units had a water content of 27.43–52.71% and 51.14–68.27%, respectively, which were significantly higher than those of other metallurgy and dust collection units; the pH of slags from an electrorefining unit was strongly alkaline; the mineral phase of sludges from wastewater treatment was only calcite; slags from a waste acid treatment unit were mainly in phase of gypsum, claudetite, and anglesite; the chemical composition of slags from pyrometallurgy and hydrometallurgy units was mainly SiO2 and Fe2O3. In this paper, we discuss a new classification method based on a common generation source for the first time. These results are beneficial to guide the disposal, utilization, and management of solid waste.

Proton-blocking tadpole-type anion exchange membranes for acid recovery by electrodialysis

Three kinds of long-side-chain-modified tadpole-type anion exchange membranes (AEMs) named QPEK-DMODAs with microphase separated structures designed for electrodialysis (ED) acid recovery were fabricated from N,N-dimethyloctadecylamine (DMODA) as quaternization agent and poly(arylene ether ketone) (PEK) as skeleton, which is the copolymer of 2,2′,6,6′-tetramethyl biphenol (TMBP) and 4,4′-difluorobenzophenone (DFBP). QPEK-DMODAs were characterized systematically including basic structures and properties, ED recovery performance of H2SO4 solutions without or with metal impurities, and corrosive acid stability. The well-defined microphase separation structure of QPEK-DMODA-3 is formed by the suitable distribution of tadpole ionic groups at the highest IEC of 2.09 mmol g−1. The aggregate structure offers the membrane competent mechanical stability, ion conductivity and permselectivity, as well as low energy consumption and water transport ratio at the ED process. QPEK-DMODA-3 exhibits higher current efficiency (54.58 %) and recovery H+ concentration (1.74 M) than those of QPEK-DMODA-1, QPEK-DMODA-2 and commercial AMX with comparable energy consumption to that of AMX under the ED conditions of Fe2+ absence. Moreover, the Fe2+ removal rate (88.74 %) and ion selectivity (S = 57.32) of QPEK-DMODA-3 are remarkably higher than those of AMX (67.10 % and 17.32) without the scarce of recovery efficiencies in the ED recovery tests of 0.50 M H2SO4 solution containing 0.10 M of Fe2+. The combination of the comparable tolerance to strong acid to that of AMX and the confirmed good ED recovery performances declares a strong potential of tadpole-type QPEK-DMODA-3 in waste acid recovery by electrodialysis.

Coal mine wastes: Effective mitigation of coal waste slurry and acid mine drainage through bioflocculation using mixotrophic bacteria as bioflocculants

Acid mine drainage (AMD) and coal waste slurry, byproducts of global mining and coal processing activities, represent significant environmental pollution concerns due to their acidic nature and high total suspended solids (TSS) content. The exploration of microbial treatment methods, specifically the utilization of microorganisms and their metabolic byproducts as bioflocculants, is underway to mitigate the adverse effects of these byproducts. This investigation assessed the effectiveness of 54 mixotrophic bacterial strains in treating coal waste slurry and AMD from coal mines located in Kalimantan, Indonesia. The bacterium Citrobacter freundii (strain SKC-4), cultured in SKC1 medium (comprising 225 mL of seawater from the Java Sea and 15 g/L molasses), demonstrated superior performance, reducing the TSS value from 4998.20 ppm to 16 ppm within an hour. Fourier Transform Infrared (FTIR) analysis revealed an increase in the intensity of the CO and CN groups from protein amides and CH2 from carbohydrates, suggesting an interaction between bacteria and clay minerals in the coal waste slurry. The bacteria also played a crucial role in adjusting the pH of AMD, elevating it from 3.82 to 6.07 after one hour of conditioning with a bacterial culture to AMD ratio of 1:9. The interaction between bacteria and their metabolic products was further substantiated by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis, which detected the presence of an extracellular polymeric substance (EPS). To our knowledge, this study represents the first exploration of the potential of mixotrophic bacteria as bioflocculants in the biotreatment of coal waste slurry and AMD from coal mining operations.

Innovation in natural rubber latex coagulation using CO2 microbubbles

Traditionally, acids have been employed in the production of raw rubber sheets. Using concentrated acids to coagulate natural rubber latex has led to issues such as subpar product quality and the generation of a significant volume of acidic latex serum waste. In contrast, opting for weak acids results in increased production costs. To address these limitations, this research adopts an innovative approach that leverages CO2 microbubbles as a process intensification technique. CO2 was bubbling into a bubble column filled with fresh natural rubber latex and closely monitored the pH and coagulation percentage over time. The physical and mechanical properties of the solid rubber products were characterized, in comparison with the products gained from conventional techniques. The use of CO2 microbubbles yielded shorter processing times and reduced the generation of acidic waste serum. Notably, this approach also led to significant improvements in key properties such as initial Wallace plasticity (P0), plasticity retention index (PRI), nitrogen content, and biodegradability in soil of the rubber samples. Interestingly, the utilization of CO2 as a feedstock highlights its role in promoting a sustainable process. This innovative approach not only minimizes environmental impact but also results in the production of value-added rubber products with enhanced properties.

Catalytic pyrolysis of lignite with clay catalyst activated with spent pickling liquor

AbstractSpent pickling liquor (SPL) is an acidic waste with rich iron content from the stainless steel production industry. Reusability of SPL as a catalytic activity promoter in bentonite clay is crucial for the catalytic pyrolysis of various materials like biomass, coal, and waste plastics. For this aim, the bentonite catalyst activated with the SPL nomenclatured as SPL‐treated bentonite (SPLAB) catalyst was employed in the catalytic pyrolysis of lignite for an oil product with high yield and quality. The SPL‐treated bentonite catalytic pyrolysis oil (SPLABO) for the conditions of the final temperature of 600°C, heating rate of 10°C/min, and catalyst ratio of 15 wt% had a yield of 26.35 ± 1.14 wt% and good fuel properties in view of the higher heating value of 35.23 MJ/kg and density of 1076.4 kg/m3 at 20°C. Moreover, it has a rich chemical content by means of monocyclic aromatics and shorter chain alkanes compared with that of the thermal activated bentonite oil (TABO). Based on the chemical structure analysis results of the SPLABO and TABO comparatively, it was concluded that the SPL agent used as a catalytic activity promoter led to a significant increase in the catalytic activity of bentonite catalyst.

Evolution of the chemical form of zirconium in aqueous solution during denitration and its influence on extraction by TRPO

Denitration by formic acid is a process that can reduce the acidity of High-Level Liquid Waste (HLLW) generated by the Plutonium Uranium Reduction EXtraction (PUREX) process, making it compatible with the feed requirements of the TRPO (trialkylphosphine oxide) process. Unfortunately, the denitration leads to the formation of interfacial crud in the TRPO extraction due to the presence of zirconium; however, the mechanism remains elusive. In this work, the evolution of the chemical form of Zr(IV) during the denitration process by formic acid was investigated. The aggregates formed in the Zr(IV) solutions after denitration were characterized by dynamic and static light scattering (DLS and SLS). Afterwards, the solutions were vacuum-dried and the solids were characterized by elemental analysis, scanning electron microscope (SEM), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Zr(IV) is present in solutions with different forms such as the tetramers of Zr4(OH)8(NO3)8 and Zr4(OH)8(HCOO)8 and their aggregates, depending on the [HCOOH]/[HNO3] ratio. The evolution of the chemical form of Zr(IV) can impact the extraction of Zr(IV) by TRPO and is responsible for the formation of interfacial crud.

Mobility of antimony in contrasting surface environments of a mine site: influence of redox conditions and microbial communities.

Microbial processes can influence the complex geochemical behaviour of the toxic metalloid antimony (Sb) in mining environments. The present study is aimed to evaluate the influence of microbial communities on the mobility of Sb from solid phases to water in different compartments and redox conditions of a mining site in southwest (SW) Spain. Samples of surface materials presenting high Sb concentrations, from two weathered mining waste dumps, and an aquatic sediment were incubated in slurries comparing oxic and anoxic conditions. The initial microbial communities of the three materials strongly differed. Incubations induced an increase of microbial biomass and an evolution of the microbial communities' structures and compositions, which diverged in different redox conditions. The presence of active bacteria always influenced the mobility of Sb, except in the neutral pH waste incubated in oxic conditions. The effect of active microbial activities in oxic conditions was dependent on the material: Sb oxic release was biologically amplified with the acidic waste, but attenuated with the sediment. Different bacterial genera involved in Sb, Fe and S oxidation or reduction were present and/or grew during incubation of each material. The results highlighted the wide diversity of microbial communities and metabolisms at the small geographic scale of a mining site and their strong implication in Sb mobility.

Synthesis, characterization and uptake studies of diglycolamic acid and diglycolamide analogs adsorbents for extraction of rare earth elements

Tetraalkyldiglycolamides are known for their high extracting efficiency of rare earth elements (REEs) from nitric acid solutions (1–6 mol/L). Nevertheless, solid-phase extractants based on diglycolamides (DGA) are poorly studied for REEs extraction. This paper explores the design and synthesis of novel REEs adsorbents by grafting silica with diglycolic acid-based ligands. The newly developed solid-phase materials were investigated for their potential to effectively separate REEs from various media. The functionalization of the silica with different ligands was quantified, and the adsorbents' extraction capacities and selectivity for REEs over Calcium (Ca2+), Aluminium (Al3+) and Iron (Fe3+) were evaluated. Si-NH-DGA emerged as the most efficient adsorbent for Gd3+ extraction, exhibiting a remarkable capacity of 44 mg/g at pH 4–6. However, modifications involving ether oxygen substitution with a methylamino group or sulfur led to reduced extraction efficiencies. Si-NH-DGA-NMe2 demonstrated strong binding of REEs in nitric acid solutions (1–3 mol/L HNO3) with corresponding adsorption capacities for Y3+, La3+, Gd3+ and Yb3+ being 16.3, 14.2, 22.8, and 30.2 mg/g, respectively. Furthermore, it displayed remarkable selectivity for REEs over Ca2+. The equilibrium extraction for Gd occurred within 60 min for Si-NH-DGA and Si-NH-DGA-NMe2 under their respective optimal conditions. Disodium EDTA solution demonstrated a high stripping efficiency for Gd3+ in the Si-NH-DGA-NMe2 column extraction, yielding a significant concentration factor (CF = 85). In the same column, following five cycles of loading/stripping of Gd3+, there was an average capacity loss of 6%. Si-NH-DGA-NMe2 emerged as a promising material for solid-phase extraction from concentrated nitric acid solutions, characterized by high capacity and good selectivity towards middle and heavy REEs. This structure has the potential to be further optimized for the development of a solid-phase extraction column for REEs separation and purification. The findings also highlight the potential of Si-NH-DGA-NMe2 as a candidate for REEs adsorption for potential industrial applications and the purification of acidic waste solutions.

Catalytic upcycling of waste bisphenols via tandem amination-ammonolysis to high value diamines

Hydrogenated methylene dianiline (H12MDA) is a valuable precursor for thermoplastic polyurethane. Traditionally, H12MDA is obtained by hydrogenation of methylene dianiline (MDA). However, the route from aniline to MDA produces large acidic waste streams linked to the nitration of benzene and the HCl-catalyzed reaction with formaldehyde, as well as a poor selectivity for the 4,4′-isomer in the condensation reaction with formaldehyde. Herein, we report a green and efficient amination process for synthesis of H12MDA starting from (waste) bisphenols. Palladium on moderately acidic catalyst supports (carbon, Al2O3, ZrO2) provided excellent yields of H12MDA (>97%) in short reaction times (3 h) at 200 °C, with limited addition of H2 and NH3. It was found that the reaction partially proceeds via a secondary amine intermediate. A high dispersion of palladium is essential to achieve high yields of the desired H12MDA. Finally, the use of polycarbonate as an alternative feedstock for H12MDA was demonstrated via a tandem ammonolysis-amination process.