Water pollution, particularly from dyeing wastewater, poses a significant environmental threat. Activated carbon, a commonly used adsorbent, often proves ineffective for high-molecular-weight pollutants like dyes. This limitation stems from its pore size and reliance on van der Waals forces. Previous research by the authors demonstrated that incorporating electrostatic adsorption could overcome this limitation, significantly increasing the adsorption capacity of polyquaternium gel adsorbents. This study aims to develop a super-efficient adsorbent material with an adsorption capacity exceeding 1000 times that of activated carbon, achieving a major breakthrough in dyeing wastewater purification. The key lies in overcoming the limitations of existing interaction mechanisms and material skeleton functions. Traditional three-dimensional gel adsorbents suffer from inefficient electrostatic adsorption within their structure. The hypothesis is that a near two-dimensional flat distribution of cationic adsorption sites will significantly enhance exposure to water and adsorption efficiency.

Existing literature highlights the challenges of removing high-molecular-weight dyes from wastewater using conventional adsorbents like activated carbon. Studies demonstrate the limitations of van der Waals forces in such scenarios and the potential of electrostatic interactions for improvement. Previous work by the authors showed that polyquaternium gel adsorbents, leveraging electrostatic adsorption, greatly enhanced dye removal compared to activated carbon. However, the literature lacks examples of adsorbents achieving adsorption capacities over 1000 times that of activated carbon. This study builds upon this gap, aiming to create a novel adsorbent with superior performance.

The study involved several key steps: 1. **Development of RRQG:** A reactive hetero-ring derived polyquaternium gel (RRQG) with a flat distribution was synthesized using an optimized procedure determined through a four-factor three-level orthogonal experiment. The experiment varied monomer concentration, reaction temperature, initiator dosage, and reaction time, with dye removal percentage used as the evaluation index. The optimized conditions yielded RRQG with the highest dye removal capacity. 2. **Synthesis of CDC:** Cyclodextrin carbide (CDC) was formed through a novel low-temperature solution carbonization process using a γ-CD hydrochloric acid solution, offering advantages over traditional high-temperature methods. 3. **Construction of RRQG@CDC:** The RRQG matrix material was loaded onto the CDC carrier to create the RRQG@CDC adsorbent system. Optimal preparation conditions were determined using a six-factor three-level orthogonal experiment, focusing on factors such as γ-CD mass fraction, HCl concentration, soaking time and temperature, and acidification time and temperature. The objective was to maximize the adsorption capacity of the resulting material. 4. **Material Characterization:** The RRQG, CDC, and RRQG@CDC were characterized using various techniques including optical microscopy, Fourier Transform infrared spectroscopy (FT-IR), elemental analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), zeta potential analysis, and X-ray photoelectron spectroscopy (XPS). This comprehensive characterization allowed for a deep understanding of the materials' structures and properties. 5. **Adsorption Experiments:** Isothermal adsorption, adsorption kinetics, and adsorption thermodynamics experiments were performed to evaluate the adsorption performance of RRQG and RRQG@CDC towards various dyes under different conditions (varying pH, salinity, and temperature). Multiple parallel repeated experiments were conducted to ensure data reliability. 6. **Resource Utilization Study:** Thermogravimetric analysis (TGA) in both N₂ and air atmospheres was used to assess the potential of RRQG@CDC waste residues (after dye adsorption) as carbonized materials and high-calorific fuels. This explored methods for sustainable waste management and resource recovery.

The key findings of the study are: 1. **Super-efficient Adsorption Capacity:** RRQG@CDC demonstrated an adsorption capacity 1250 times higher than activated carbon for Reactive Scarlet 3BS dye, reaching a maximum adsorption capacity (Qmax) of 2312.54 mg g⁻¹. 2. **Broad Applicability:** RRQG@CDC exhibited consistent high adsorption performance across a range of pH values (optimal at pH ≤7) and salinity conditions (with Na₂SO₄ and CaCl₂). It also showed high effectiveness against other dyes, including Reactive Blue 19, Reactive Black KN-B, and Methyl Blue, demonstrating versatility. 3. **Scale-up Feasibility:** Simulated scale-up tests confirmed the potential of RRQG@CDC for practical engineering applications in wastewater treatment plants. Results from larger-scale tests were consistent with smaller-scale findings. 4. **Novel Adsorption Mechanism:** The study proposed a novel enhanced quasi-planar electrostatic adsorption mechanism, explaining the superior performance of RRQG@CDC compared to traditional three-dimensional adsorbents. The flat distribution of cationic adsorption sites facilitates highly efficient electrostatic interactions with anionic dyes. The CDC skeleton plays a crucial role in consolidating this flat distribution, enhancing adsorption efficiency. 5. **Resource Recovery:** The post-adsorption waste residues of RRQG@CDC showed potential for resource utilization as high-calorific fuels, significantly reducing the environmental impact of wastewater treatment.

The findings significantly advance the field of dyeing wastewater treatment by introducing a highly efficient and sustainable adsorbent. The superior adsorption capacity of RRQG@CDC surpasses that of existing materials, offering a practical solution for removing recalcitrant dye pollutants. The consistent performance across varying pH and salinity levels expands its applicability in diverse industrial settings. The proposed quasi-planar electrostatic adsorption mechanism provides a valuable theoretical framework for designing future high-performance adsorbents. The feasibility of utilizing waste residues as fuels addresses the critical issue of waste management and promotes circular economy principles. These combined advantages make RRQG@CDC a promising alternative to conventional methods, contributing to more efficient and environmentally friendly wastewater treatment processes.

This study successfully developed RRQG@CDC, a super-efficient adsorbent material with significantly enhanced adsorption capacity, broad applicability, and potential for waste resource utilization. The proposed quasi-planar electrostatic adsorption mechanism offers new insights into adsorbent design. Future research could focus on further optimizing the synthesis process, exploring other applications of RRQG@CDC in various pollutant removal scenarios, and investigating the long-term stability and durability of the material in real-world wastewater treatment plants.

While RRQG@CDC demonstrates exceptional performance, certain limitations should be noted. The study primarily focused on laboratory-scale experiments; further large-scale field tests are needed to validate the findings under real-world conditions. The cost-effectiveness of large-scale production and implementation needs to be fully evaluated. The long-term stability and reusability of the adsorbent also require further investigation, including studies on potential leaching of components and changes in adsorption capacity over multiple cycles. Further research into the specifics of the quasi-planar electrostatic adsorption mechanism would strengthen the theoretical foundation.