Key Takeaways & Executive Findings
- •• • PCE static adsorption capacity on GAC reached 556.6 mg·g−1, while multi-component dynamic adsorption capacity was 179.6 mg·g−1, demonstrating high efficacy for low-concentration Cl-VOCs. • • During 500 °C nitrogen desorption, HCl yield was 3.61% of the chlorine molar content in adsorbed PCE, indicating partial dechlorination and necessitating corrosion control above 200 °C. • • After 4 adsorption-desorption cycles, GAC iodine value fell below 600 mg·g−1; water washing and alkali immersion extended cycle life to 8 and 9 cycles, respectively, enhancing industrial viability. • • The proposed classification strategy (RTO for high-concentration, adsorption-nitrogen desorption for low-concentration) reduced annual costs by 49.5×10⁴ CNY compared to conventional adsorption+RTO, offering economic advantage.
Abstract
To treat large-air-volume, low-concentration volatile organic compounds (VOCs) containing tetrachloroethylene (PCE) generated from rubber-metal bonding, this study systematically investigated the adsorption-desorption behavior and interaction mechanisms of PCE, toluene, and methyl isobutyl ketone (MIBK) on granular activated carbon (GAC). Static adsorption experiments showed that PCE adsorption capacity reached 556.6 mg·g−1, while dynamic multi-component adsorption capacity was 179.6 mg·g−1. Kinetic analysis indicated that PCE adsorption was controlled by both intraparticle diffusion and external surface adsorption, whereas toluene and MIBK were primarily intraparticle diffusion-limited. During high-temperature nitrogen desorption, PCE underwent dechlorination, hydrogenation, and recombination, producing trichloroethylene, 1,2-dichloroethane, 1,2-dichloropropane, and HCl, with HCl accounting for 3.61% of the chlorine molar content in adsorbed PCE. After four adsorption-desorption cycles, the iodine value of GAC dropped below the industry standard of 600 mg·g−1; however, water washing and alkali immersion extended the cycle life to 8 and 9 cycles, respectively. The HCl generation pattern in co-adsorption systems was consistent with single-PCE systems. A regeneration process combining alkali immersion and water washing was proposed and integrated into an engineering strategy. Compared to conventional activated carbon adsorption coupled with RTO incineration, the proposed classification strategy reduced annual costs by 49.5×10⁴ CNY. This work provides a cost-effective and safe solution for Cl-VOCs treatment.
1. Introduction
Rubber-metal bonding in the rubber products industry relies on Chemlok adhesives, which commonly use tetrachloroethylene (PCE) as a solvent. This process generates large volumes of low-concentration waste gas containing PCE, toluene, and methyl isobutyl ketone (MIBK), all of which are toxic and carcinogenic. Conventional treatment methods, such as activated carbon adsorption followed by incineration, face challenges including high energy consumption and the risk of HCl-induced corrosion during thermal desorption of chlorinated VOCs. The lack of data on gas-phase PCE adsorption and the unclear mechanisms of HCl generation hinder the design of safe and cost-effective treatment systems.
This study addresses these gaps by systematically evaluating the adsorption and desorption performance of granular activated carbon for PCE, toluene, and MIBK under realistic conditions. It quantifies adsorption capacities, identifies rate-controlling steps, and examines the evolution of HCl during high-temperature nitrogen desorption. Furthermore, it proposes a regeneration strategy involving alkali immersion and water washing to extend adsorbent life, and integrates these findings into a cost-effective engineering approach for Cl-VOCs treatment. The results provide critical parameters for designing robust systems that mitigate corrosion and reduce operational costs.
Loading authentic research manuscript (Pages 1–5)...
HUANG Yuting, MA Ling, CAI Yufei, WANG Zhentao, WANG Yuxuan, JIN Ke, JIANG Xingyu, ZHAO Weirong (2026). Adsorption and High-Temperature Nitrogen Desorption Performance and Mechanism of Granular Activated Carbon for Large-Air-Volume Low-Concentration PCE-Containing Waste Gas. Chinese Journal of Environmental Engineering. https://doi.org/10.12030/j.cjee.202511002
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the maximum adsorption capacity of granular activated carbon for PCE under static conditions, and how does it compare to dynamic multi-component adsorption?
Under static conditions at 40 °C, the PCE adsorption capacity reached 556.6 mg·g−1. In dynamic multi-component adsorption (PCE, toluene, MIBK), the total capacity was 179.6 mg·g−1. The lower dynamic capacity is attributed to competitive adsorption and mass transfer limitations.
How does the HCl generation during nitrogen desorption affect the process design and material selection?
During 500 °C nitrogen desorption, HCl accounted for 3.61% of the chlorine molar content in adsorbed PCE. HCl generation begins above 200 °C, necessitating corrosion-resistant materials and careful control of desorption temperature to mitigate equipment damage.
What is the cycle life of activated carbon under repeated PCE adsorption-desorption, and how can it be extended?
After four cycles, the iodine value dropped below the industry standard of 600 mg·g−1. Water washing extended the cycle life to 8 cycles, while alkali immersion (NaHCO3) extended it to 9 cycles, indicating that chemical regeneration effectively restores adsorption capacity.
What is the economic advantage of the proposed classification strategy compared to conventional adsorption+RTO?
The proposed strategy, which uses RTO for high-concentration streams and adsorption-nitrogen desorption for low-concentration streams, reduces annual costs by 49.5×10⁴ CNY compared to a unified adsorption+RTO approach, primarily due to lower energy consumption for low-concentration streams.
Are there any differences in HCl generation between single-component PCE and multi-component adsorption systems?
No significant differences were observed in HCl generation temperature and total yield between single-PCE and co-adsorption systems, indicating that the presence of toluene and MIBK does not alter the dechlorination behavior of PCE under the tested conditions.
Related Chinese Research & Cross-Citations
Analysis of National and Local Policies for Medical Waste Treatment and Disposal in China
The escalating generation of medical waste, driven by healthcare expansion and frequent medical activities, poses significant environmental and public health risks. Under the framework of ecological civilization, China is developing a comprehensive policy system for medical waste treatment and disposal, yet the current framework remains nascent and exhibits inconsistencies between national and local policies. This study systematically analyzes the status of national and local policies from 2003 to 2024, collecting 413 policy documents (166 from national ministries and 247 from provincial governments). The analysis examines temporal evolution, regional distribution, and policy focus, alongside the influence of medical waste output, treatment technologies, facility infrastructure, and major epidemic responses. Findings reveal distinct policy phases: initial self-disposal, exploratory management, foundational system building, and rapid development. Regional disparities are pronounced, with eastern coastal areas showing more advanced policies due to greater technical and financial resources. The surge in medical waste, particularly during the COVID-19 pandemic, underscores the need for enhanced regulatory guidance. Non-incineration technologies are gaining traction for their environmental and cost benefits, and facility coverage has improved but remains uneven. The study proposes five policy principles to foster technological innovation and industrial upgrading, ensuring safe medical waste management and environmental protection.
Kinetic Analysis and Simulation of Pollutant Removal in Sewage Networks
This study investigates pollutant removal characteristics and kinetic behaviors in sewage networks, and analyzes their impact on the carbon-to-nitrogen ratio (C/N, as COD/TN) of influent to wastewater treatment plants. Source water quality sampling at drainage outlets revealed spatial and temporal variations in C/N, with domestic sewage exhibiting higher C/N than industrial sewage, and diurnal peaks reaching 6.92 versus 4.71 during off-peak hours. Using a pilot-scale adjustable sewage network system in Kunshan, experiments were conducted under high (0.491 m·s−1) and low (0.089 m·s−1) flow velocities, monitoring pollutant removal over 144 hours. Pseudo-first-order kinetics were applied to model COD and TN removal. Results showed that COD (including SCOD and PCOD), BOD5, and SS achieved approximately 80% removal within 144 h, with higher removal at low flow velocity. TN, NH3-N, and TP exhibited lower overall removal rates. Kinetic fitting revealed that COD removal rate constants (kCOD) were significantly higher than those for TN (kTN), and both decreased with increasing flow velocity: at low velocity, kCOD=0.0167 h−1 and kTN=0.0029 h−1; at high velocity, kCOD=0.0127 h−1 and kTN=0.0020 h−1. Simulations based on actual source pollutant concentrations indicated that the time for C/N to drop to the denitrification critical value of 4.50 was 12.24 h at high velocity, but shortened to 9.49 h at low velocity. These findings demonstrate that increasing flow velocity effectively retards the decline of C/N. Therefore, regulating network flow velocity to reduce hydraulic retention time is a key strategy for maintaining adequate C/N at the terminal and ensuring denitrification efficiency in wastewater treatment plants.
Preparation of Trimetallic-Carbon Composite Catalysts and Their Application in Catalytic Ozonation of Industrial Wastewater
Advanced oxidation processes (AOPs) are promising for degrading organic pollutants in water treatment. Heterogeneous catalytic ozonation (HCO) has gained attention due to its high oxidation efficiency, strong interference resistance, and low secondary pollution. In this study, a series of trimetallic-carbon composite ozone catalysts were prepared via an organic precursor calcination method using γ-Al2O3 as support. This method enhanced catalytic activity and mechanical strength while overcoming the limitations of carbon materials (low mechanical strength) and metal-based materials (poor mass transfer). The optimized catalyst, CA-FeCoCu, comprising Fe, Co, Cu, carbon, and alumina, exhibited excellent performance in phenol degradation and real industrial wastewater treatment. Characterization revealed that the synergistic effect of trimetals and the introduction of multiple carbon types increased specific surface area and hydroxyl radical (·OH) generation. In a pilot-scale fixed-bed reactor, the CA-FeCoCu/O3 system reduced COD from 120 mg·L−1 to below 40 mg·L−1, with an O3 consumption ratio (O/C) of less than 1, effectively lowering operational costs. This work provides a new strategy for developing efficient and stable heterogeneous O3 catalysts and offers a reference for the practical application of HCO in industrial wastewater treatment.
Differentiated Characteristics of Suspended Particulate Matter and Their Effects on Water Quality in the Middle and East Routes of the South-to-North Water Diversion Project
This study investigates the spatiotemporal differentiation of suspended particulate matter (SPM) characteristics, sources, and their impacts on water quality between the Middle Route (closed artificial channel) and East Route (open natural water system) of the South-to-North Water Diversion Project. Thirty sampling sites (13 on the Middle Route, 17 on the East Route) were established, and samples were collected during dry and wet seasons. Water quality parameters and SPM characteristics were analyzed, including particle size distribution, total suspended solids (TSS), chlorophyll a, and stable carbon and nitrogen isotopes. Results show that the Middle Route maintains good and stable water quality, with SPM dominated by coarse particles (>63 μm, 61.43%–94.68%), total phosphorus (TP) <0.01 mg·L−1, and a significant positive correlation between chlorophyll a and coarse particles (r=0.60), indicating algal aggregation dominates particle formation. In contrast, the East Route exhibits high and fluctuating nitrogen and phosphorus concentrations, with SPM dominated by fine particles (<20 μm, 51.26%–88.61%), TP ranging from 0.03 to 1.11 mg·L−1, and a positive correlation with fine particles, suggesting significant external inputs. Carbon and nitrogen isotope analysis reveals that Middle Route SPM primarily originates from autochthonous algae (contribution >46.75%), while East Route SPM is influenced by both terrestrial C3 plants and algae. The distinct engineering and management approaches of the two routes lead to significant differences in SPM characteristics and sources, thereby affecting water quality dynamics. The Middle Route requires an 'algal reduction and hydrodynamic optimization' strategy to control algal-derived coarse particle deposition, whereas the East Route benefits from 'retention-sedimentation and wetland purification' to reduce external fine particles and pollutant inputs. This research provides theoretical support and practical guidance for differentiated SPM management in long-distance water diversion systems.
Combined Ozone Micro-Nano Bubble Oxidation and Powdered Activated Carbon Adsorption for Removal of Taste and Odor Compounds from Drinking Water
Algal-derived taste and odor compounds (2-methylisoborneol, 2-MIB, and geosmin, GSM) in drinking water sources are poorly removed by conventional treatment. This study systematically evaluated the standalone and combined performance of ozone micro-nano bubbles (O3-MNBs) oxidation and powdered activated carbon (PAC) adsorption for removing 2-MIB, GSM, and algal cells from source water. Results showed that O3-MNBs pre-oxidation achieved >97.5% removal of odorants at 400 ng·L−1 and 67.2% algal cell removal within 30 min. When applied as a deep treatment stage, the degradation rate constant (k) was 10.1%–25.6% higher than in pre-oxidation due to lower background matrix interference. Both pre-oxidation and deep treatment reduced effluent concentrations of 2-MIB and GSM to below 10 ng·L−1, with oxidation kinetics fitting pseudo-first-order models (R²>0.95). PAC adsorption of both compounds followed pseudo-second-order kinetics (R²>0.99), with GSM equilibrium adsorption capacity approximately 20.0% higher than that of 2-MIB. In pure water, adsorption capacity increased by >10.0% compared to raw water. Based on kinetic models, a quantitative prediction method was established for O3-MNBs oxidation and PAC adsorption processes, aiming to achieve efficient odorant removal and cost optimization, providing theoretical support for advanced drinking water purification and smart water plant construction.
Pulsed Electric Field Enhancement of Nitrogen Removal Performance and Microbial Community Structure Response in Anammox Granular Sludge
This study investigated the effects of a ring-shaped pulsed electric field (PEF) (1.5 V, 4 h on-time per cycle) on nitrogen removal performance and microbial community structure of anammox granular sludge (AnGS). Two anaerobic sequencing batch reactors (R1 control, R2 with PEF) were operated under stepwise increasing nitrogen loading rates (NLR). At NLR below 1,155 mg·(L·d)−1, R2 exhibited total nitrogen removal efficiency (TRE) 7.5%–17.0% higher than R1, with biomass, specific anammox activity (SAA), and extracellular polymeric substances (EPS) increased by 5%–7%, 21%–71%, and 54%–77%, respectively. However, at NLR above 1,320 mg·(L·d)−1, the toxic effect of nitrite dominated, and PEF enhancement diminished or even reversed to inhibition. Microbial community analysis revealed that at low-to-moderate NLR, PEF increased the relative abundance of Planctomycetes and key anammox bacteria (Candidatus Brocadia and Candidatus Jettenia), along with enhanced community richness (Chao1) and diversity (Shannon/Simpson indices). At high NLR, PEF decreased microbial richness compared to R1. Principal component analysis and redundancy analysis indicated that PEF was the key factor driving community differences at low-to-moderate NLR, whereas nitrite concentration became the dominant factor at high NLR. This study provides theoretical support for enhancing the resilience and engineering application of anammox processes.