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This review covers research on the use of potassium hydroxide (KOH) to produce and modify activated carbon. The methods employed for activation by considering the activation process, carbonization, temperature, activation time, and KOH ratio to material are described and how the surface area, surface morphology, and functional groups are affected by the KOH ratio. Characterization techniques and preparation conditions are summarized. The activated carbon pore structure mainly depends on the burn‐off size and the time for activation is linked to the overall activation reaction rate. The increase in surface area and pore size depends on the ratio of KOH, showing that KOH affects the surface chemistry of the activated carbon. The sorbent‐sorbate interactions are strongly influenced by different parameters, which were also calculated in this review and used to evaluate such interactions.

Flexible methylene containing N,N'-bis-(benzyl)-3,4,9,10-perylenebis(dicarboximide) (1) was synthesized. Self-assembled microstructures (hollow tubes, average length and width: 7.7 and 0.8 μm) of 1 were also prepared (T-1). Comparative studies of the optical, thermal and electrochemical properties of 1 and T-1 have been extensively carried out. The T-1 hallow tubes have shown extremely broad absorption in the near-infrared (300-800 nm) region (NIR) even in solution and intensified conductivity in the solid-state compared to 1. Under daylight and a UV lamp (365 nm), the emission colors of 1 are uniform pink and fluorescent yellow, respectively. Under the same conditions the colors of T-1 change to deep brown and glowing red, respectively. Two different isopotential points obtained through CV scans for 1 indicate the presence of two interconvertible chromophores within the system. The results clearly indicate that the anodic and cathodic processes are extremely intensified in the self-assembled T-1 structure.

Novel African walnut shell (AWS) was treated and improved as an agricultural waste by-product to produce high surface area activated carbon via chemical activation with potassium hydroxide (KOH) to achieve extremely effective adsorptive characteristics for deltamethrin removal. The adsorbent (KOHAWS) was characterized by scanning electron microscopy, Fourier transform infrared (FT-IR) spectroscopy, the Brunauer–Emmett–Teller surface area, and pH point of zero charge (PHPZC). Batch sorption experiments were investigated to study the effect of pH, initial concentration and contact time, sorbent dosage, and agitation speed. The results reveal that the experimental data fitted well with Langmuir isotherm model (R2 = 0.997) with maximum adsorption capacity at 57.64 mg g−1 and the kinetics of the sorption follows the pseudo-first-order model (R2 = 0.995). The sorption of deltamethrin onto KOHAWS reveals a high removal efficiency of 98.2%. The findings show that the novel AWS has excellent regeneration and reusability properties and may be used to remove pesticides from aqueous solutions instead of conventional activated carbon.

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