Battery-Grade Nickel Sulfate: Where Product-Liquor TOC Comes From and How to Strip It Out

In new-energy battery material production, the TOC (Total Organic Carbon) content of product liquors is treated as a direct purity indicator. When TOC in nickel sulfate, cobalt sulfate or manganese sulfate product liquor exceeds its limit, dissolved organic matter - extractant residues, organic additives and similar - travels into the cathode material precursor and sets off a cascade: capacity fade, shortened cycle life, and product that fails specification downstream.

So where does the dissolved organic load come from, and what actually removes it? The answer from SINOKLE combines ozone catalytic oxidation flotation with activated carbon, and it works in three stages.

Two Routes Into the Product Liquor

The first is extractant residue. Hydrometallurgical processing puts organic extractants in contact with the product liquor, and trace amounts dissolve into the aqueous phase. These molecules are large and structurally stable, which is exactly why conventional methods leave them alone.

The second is organic additives. The various auxiliaries and modifiers dosed during production leave organic components behind in the liquor as well.

What makes both routes awkward is that the organics co-exist in solution with the metal ions. Simple precipitation or filtration will not separate them. Once they reach downstream cathode material, they interfere with crystal growth and undermine electrochemical stability. That is why high-end battery material manufacturers treat TOC as a hard metric.

A Three-Step Purification Chain

The CDOF plus activated carbon combined process reaches deep TOC removal through systematic synergy across three stages: oxidative chain-scission, flotation separation, and adsorption refining.

Step 1: multi-catalytic oxidation breaks up the large molecules

Product liquor enters the CDOF integrated unit, where four catalytic pathways switch on simultaneously - homogeneous catalysis, heterogeneous catalysis, hydrodynamic cavitation catalysis, and pressurized catalysis. Working together, they convert ozone into hydroxyl radicals at high efficiency, with an oxidation potential of 2.8 V. As one of the strongest oxidizing species available in water treatment, the hydroxyl radical uses that 2.8 V potential to attack the chemical bonds of large-molecule organics, opening rings and cutting chains. Extractant residues and organic additives degrade into small-molecule organics and are ultimately mineralized into CO2 and H2O.

The contrast with conventional practice is worth noting. Traditional ozone oxidation relies on a single catalyst, or none at all, so radical generation is inefficient. The multi-catalytic arrangement is effectively several production channels running in parallel.

Step 2: cyclone flotation scoops out the intermediates

Once the large molecules are opened and cut, they produce non-dissolved intermediates and colloids. Left in the liquor, those can re-dissolve or agglomerate and hand the TOC straight back. Cyclone flotation removes them at the same time the oxidation reaction is running, cutting off that secondary contribution at the source.

Step 3: activated carbon catches what is left

Effluent from CDOF passes into an activated carbon column, where the media's specific surface area and adsorption capacity take out residual trace organics. This stage acts as a refining safety net: even if influent TOC fluctuates, the carbon column holds effluent TOC compliant.

Why the Catalyst Lasts Beyond Five Years

Catalysts are the core of ozone catalytic oxidation and traditionally its weak point. The dedicated high-efficiency catalyst used here addresses three dimensions. Material: multiple active metal oxides, including noble-metal catalytic components, giving high activity and fast reaction rates. Structure: high porosity plus super-hydrophilic modification, so it resists fouling and clogging and organics do not accumulate on the surface. Maintenance: a fully automatic backwash activation and regeneration mechanism keeps service life beyond 5 years, avoiding the clogging, scaling and passivation that ends the life of conventional catalyst.

The Generation Gap, Side by Side

Set against coagulation sedimentation plus traditional ozone catalytic oxidation, the contrast runs across every line. Reaction principle moves from single-catalyst or no-catalyst ozone oxidation to multi-catalytic oxidation with flotation and activated carbon polishing. Technology level moves from conventional to PCT international patent plus 2 invention patents. Reaction time drops from 60~90min to 10~15min. The ozone dosing ratio falls from 1.5~4 to 0.5~1.2. Ozone utilisation goes from low, with partial leakage, to a figure at or above 99.98 percent. Operating cost lands at two thirds of traditional, or lower. Catalyst life moves from prone to clogging, scaling and passivation to fully automatic backwash regeneration beyond 5 years. And where the traditional route runs at atmospheric pressure with ozone leakage risk, the new one is fully enclosed and pressurized with zero leakage.

Pilot Data From Zhejiang

In 2023 a new-energy raw-material enterprise in Zhejiang ran a nickel sulfate solution TOC-removal pilot using a CDOF integrated unit plus activated carbon column, with ozone output at 300 g/h and a treatment scale of 24 m3/d. Influent TOC at 200 mg/L or below came out of the adsorber at 100 mg/L or below, meeting the deep-removal target. Product-liquor viscosity fell from 50 or below to 28 or below, which satisfies the downstream battery-material process requirement. Oil was removed in the same pass, with effluent oil content at 3 mg/L or below - one system solving several indicators at once.

Patents and Market Endorsement

The combined process holds 1 PCT international patent and 2 invention patents, giving a complete intellectual-property position. It is deployed as a partner technical solution by leading enterprises such as CATL (Contemporary Amperex Technology Co. Limited) and GEM (Green Eco-Manufacture), which means the reliability of the process has been tested in the most demanding market available.