All You Need to Know About Non‑Oxidizing Biocides

All You Need to Know About Non‑Oxidizing Biocides

I. Definition and Mechanism of Action

Non‑oxidizing biocides are chemicals that inhibit or kill microorganisms through non‑oxidative mechanisms.

Unlike oxidizing biocides (e.g., chlorine, ozone), they do not rely on oxidation to destroy microorganisms, but achieve disinfection via the following pathways:

Cell membrane destruction: e.g., quaternary ammonium salts interact with negative charges on microbial membranes using positive charges, causing membrane rupture and leakage of intracellular contents.

Enzyme activity inhibition: interfere with key metabolic enzymes of microorganisms, blocking energy synthesis or substance metabolism.

DNA/RNA synthesis interference: e.g., isothiazolinones damage nucleic acid structure and suppress microbial reproduction.

Metabolic pathway blockage: disrupt the metabolic chain so that microorganisms cannot sustain vital activities.

II. Main Types and Characteristics

1. Quaternary Ammonium Salts

Representative components:

Dodecyldimethylbenzylammonium chloride (1227), benzalkonium bromide, cetyltrimethylammonium bromide.

Characteristics:

Broad‑spectrum: effective against bacteria, fungi, and algae; especially good at penetrating slime layers to kill hidden microbes.

Surface activity: dual functions of disinfection and cleaning; can strip biofilms and remove them from the system.

Low toxicity & eco‑friendly: non‑toxic degradation products, low corrosion to metals; suitable for food processing, medical disinfection, etc.

Limitation: may cause false liquid‑level readings at high concentrations due to foaming; dosage must be controlled.

2. Isothiazolinones

Representative components:

Isothiazolinone, methylisothiazolinone.

Characteristics:

High efficiency & safety: excellent effect on fungi and algae; non‑toxic degradation products, meeting environmental requirements.

Strong stability: wide applicable pH range (3–9), heat‑resistant; suitable for industrial circulating water and reverse osmosis systems.

Application scenarios: food processing, swimming pool water treatment, cooling tower disinfection.

3. Chlorophenols

Representative components:

Dichlorophen, sodium pentachlorophenate.

Characteristics:

Long‑lasting effect: penetrate and strip microorganisms in sediments or slime.

High toxicity: harmful to aquatic organisms and mammals; use with caution.

Environmental risk: difficult to degrade and may cause pollution; must be used with corrosion and scale inhibitors.

4. Organic Amines

Representative components:

Morpholine derivatives, dodecyldimethylbenzylammonium bromide (partially similar to quaternary ammonium salts).

Characteristics:

Strong permeability: penetrate deep into biofilms to kill microorganisms.

Excellent environmental performance: low toxicity to fish, biodegradable; suitable for agricultural aquaculture water.

Good compatibility: synergistic with water stabilizers; wide applicable pH range.

5. Other Types

Macrolides (e.g., erythromycin): broad‑spectrum antibiotics for disinfection, but relatively high cost.

Halogenated amides (e.g., trichloramide): low toxicity and high efficiency; used in water treatment and food processing preservation.

Biological biocides (e.g., plant essential oils): natural extracts that damage microbial surface membranes; outstanding environmental compatibility.

III. Core Advantages and Application Scenarios

1. Core Advantages

Broad‑spectrum: effective against bacteria, fungi, algae, viruses, etc.; especially good at controlling biofilms.

Environmentally friendly: non‑toxic degradation products (e.g., low AOX, no formaldehyde); some components are biodegradable.

Strong anti‑interference: resistant to reducing substances in water (e.g., hydrogen sulfide, ammonia); slightly affected by pH changes.

Resistance management: alternating use with oxidizing biocides delays the development of microbial resistance.

2. Application Scenarios

Industrial water treatment: circulating cooling water and boiler water systems in petrochemical, power, metallurgy industries; control microbial growth and equipment corrosion.

Municipal & civil use: urban water supply, wastewater treatment, swimming pools, hot springs; ensure clean water quality.

Healthcare & food processing: medical device disinfection, food processing environment cleaning; ensure no contamination.

Special water treatment: printing & dyeing cooling water, agricultural aquaculture water; handle complex water quality challenges.

IV. Selection and Application Recommendations

1. Selection Principles

Microorganism type: choose targeted biocides based on species (bacteria, fungi, algae).

Water quality: consider pH, temperature, turbidity; select products with strong adaptability.

Equipment material: avoid biocides corrosive to metals (carbon steel, stainless steel).

Safety & environmental protection: prioritize low‑toxic, harmless, biodegradable products to reduce environmental and human impact.

2. Application Suggestions

Concentration control: generally maintained at 5–10 ppm to avoid equipment damage.

Alternating use: alternate with oxidizing biocides for long‑term efficiency and delayed resistance.

Pretreatment: in complex water, combine “filtration + activated carbon adsorption” to improve disinfection effect.

Regular monitoring: assess microbial resistance regularly and adjust biocide combinations timely.

V. Cases and Data Support

Industrial circulating water case: After using quaternary ammonium biocides, a petrochemical plant extended cooling system cleaning cycles by 30% and reduced equipment corrosion rate by 25%.

RO system case: After applying isothiazolinone biocides, microbial fouling rate of membrane systems dropped by 80%, with significantly improved operational stability.

Food processing case: Isothiazolinones used in creams and lotions effectively extended shelf life while complying with food safety standards.