Desalting and recovering naphthalenesulfonic acid from wastewater with concentrated bivalent salt by nanofiltration process

Recycle graphite from spent lithium-ion batteries for H2O2 electrosynthesis

On-site H2O2 synthesis via the two-electron route oxygen reduction reaction for environmental remediation is attractive. This work offers a novel strategy for both spent graphite recovery and H2O2 electrosynthesis catalyst preparation. The graphite is directly recycled from spent lithium-ion batteries to an H2O2 electrosynthesis catalyst. From the view of sustainable development and environmental protection, the H2O2 electrosynthesis catalyst prepared using spent graphite is eco-friendly and cost-efficient. The surface functional groups of the recycled graphite are finely tuned by the HNO3 medium to induce -COOH and C-O-C groups. The activated graphite exhibits high H2O2 activity and selectivity, compared to the raw spent graphite. The activated graphite can achieve an H2O2 Faradic efficiency of about 80%. The activated graphite has a good prospect for T-acid wastewater treatment as the H2O2 generation catalyst. Almost 92% of chemical oxygen demand can be removed.

Removal of 2-naphthalenesulfonic acid using novel dual functional weakly basic anion exchange resins from aqueous solution

Two novel weakly basic anion exchange resins BNH and BN2 bearing two different functional groups was fabricated via the two-step amination of chloromethylated polystyrene-divinylbenzene beads with dibutylamine and dimethylamine. The adsorption properties of BNH and BN2 for the 2-naphthalenesulfonic acid (NSA) removal from wastewater were compared with two synthesized monofunctional anion exchange resins BN0 and BN6 (derived from dimethylamine and dibutylamine, respectively). The experimental data revealed that the adsorption process on the four resins fitted well with the pseudo-second-order kinetics equation and the equilibrium isotherms were in good agreement with the Langmuir model. Thermodynamic analyses illustrated that 2-naphthalenesulfonic acid adsorption onto resins was an endothermic and spontaneous process. Importantly, BN2 still displayed relatively high adsorption capacity in the existence of Na2SO4, indicative of an excellent selectivity for 2-naphthalenesulfonic acid over sulfate than other resins. The obtained results elucidate that BN2 could have potential industrial application in effluent disposal fields because of its superior selectivity, acceptable kinetics, and desorption capability.