Integrated countercurrent reverse osmosis cascades for hydrogen peroxide ultrapurification

Defective UiO-66-NH2 (Zr) for Simultaneous Adsorption of Phosphate and Pb2+ for Hydrogen Peroxide Purification

Removal of hetero ions from the hydrogen peroxide solution is a crucial step in purifying electronic-grade H2O2. Conventional adsorption materials are challenged to meet the need for the simultaneous adsorption of both anions and cations in solvents. UiO-66 (Zr) modified by acetic acid and amino group for simultaneous adsorption of phosphate and Pb2+ in H2O2 purification was fabricated in this work. The as-prepared defective UiO-66-NH2 (Zr) demonstrated a significant increase in specific surface area and porosity, along with more exposed sites for phosphate and Pb2+ adsorption. The adsorption capacity of De-UiO-66-NH2 for phosphate and Pb2+ in H2O2 solution was 52.28 mg g-1 and 35.4 mg g-1, which is 1.19 times and 1.88 times that of unmodified UiO-66 (Zr), respectively. The trace simultaneous adsorption with both 100 ppb phosphate and Pb2+ showed removal rates of 94.0% and 88.7%, respectively, confirming the practicality of MOF materials in the purification of electronic chemicals. This work highlights the potential of Zr-based MOFs as anionic and cationic simultaneous adsorbents for highly efficient purification of electronic-grade solvents.

Techno-Economic Optimization of Multistage Membrane Processes with Innovative Hollow Fiber Modules for the Production of High-Purity CO2 and CH4 from Different Sources

Within the current climate emergency framework and in order to avoid the most severe consequences of global warming, membrane separation processes have become critical for the implementation of carbon capture, storage, and utilization technologies. Mixtures of CO2 and CH4 are relevant energy resources, and the design of innovative membranes specifically designed to improve their separation is a hot topic. This work investigated the potential of modified polydimethylsiloxane and ionic liquid-chitosan composite membranes for separation of CO2 and CH4 mixtures from different sources, such as biogas upgrading, natural gas sweetening, or CO2 enhanced oil recovery. The techno-economic optimization of multistage processes at a real industrial scale was carried out, paying special attention to the identification of the optimal configuration of the hollow fiber modules and the selection of the best membrane scheme. The results demonstrated that a high initial content of CH4 in the feed stream (like in the case of natural gas sweetening) might imply a great challenge for the separation performance, where only membranes with exceptional selectivity might achieve the requirements in a two-stage process. The effective lifetime of the membranes is a key parameter for the successful implementation of innovative membranes in order to avoid severe economic penalties due to excessively frequent membrane replacement. The scale of the process had a great influence on the economic competitiveness of the process, but large-scale installations can operate under competitive conditions with total costs below 0.050 US$ per m3 STP of treated feed gas.

A metal free catalyst for efficient and stable one-step photocatalytic production of pure hydrogen peroxide

Hydrogen peroxide (H2O2) is widely used as a green and clean energy. The pure H2O2 solution has attracted much attention for its special applications in many fields. Photocatalytic water splitting...

An optimization model for the treatment of perfluorocarboxylic acids considering membrane preconcentration and BDD electrooxidation

Treatment of persistent perfluorocarboxylic acids in water matrixes requires of strong oxidation conditions, as those achieved by boron doped diamond (BDD) electrooxidation (ELOX). However, large scale implementation of ELOX is still hindered by its high energy consumption and economical investment. In this work, we used process systems engineering tools to define the optimal integration of a membrane pre-concentration stage followed by the BDD electrolysis of the concentrate, to drastically reduce the costs of treatment of perfluorohexanoic acid (PFHxA, 100 mg L^-1) in industrial waste streams. A multistage membrane cascade system using nanofiltration (NF90 and NF270 membranes) was considered to achieve more sophisticated PFHxA separations. The aim was to minimize the total costs by determining the optimal sizing of the two integrated processes (membrane area per stage and anode area) and the optimal process variables (pre-concentration operating time, electrolysis time, input and output concentrations). The non-linear programming model (NLP) was implemented in the General Algebraic Modelling System (GAMS). The results showed that for a 2-log PFHxA abatement (99% removal), the optimal two membrane stages using the NF90 membrane obtains a 75.8% (6.4 $ m^-3) reduction of the total costs, compared to the ELOX alone scenario (26.5 $ m^-3). The optimized anode area and the energy savings, that were 85.3% and 88.2% lower than in ELOX alone, were the major contributions to the costs reduction. Similar results were achieved for a 3-log and 4-log PFHxA abatement, pointing out the promising benefits of integrating electrochemical oxidation with membrane pre-concentration through proper optimization for its large-scale application to waters impacted by perfluorocarboxylic acids.

A review on research progress in the direct synthesis of hydrogen peroxide from hydrogen and oxygen: noble-metal catalytic method, fuel-cell method and plasma method

The direct synthesis of H₂O₂ from H₂ and O₂ using Pd catalyst, fuel cell and plasma methods have been reviewed systematically.