Carboxymethyl cellulose (CMC) is one of the most promising cellulose derivatives. Due to its characteristic surface properties, mechanical strength, tunable hydrophilicity, viscous properties, availability and abundance of raw materials, low-cost synthesis process, and likewise many contrasting aspects, it is now widely used in various advanced application fields, for example, food, paper, textile, and pharmaceutical industries, biomedical engineering, wastewater treatment, energy production, and storage energy production, and storage and so on. Many research articles have been reported on CMC, depending on their sources and application fields. Thus, a comprehensive and well-organized review is in great demand that can provide an up-to-date and in-depth review on CMC. Herein, this review aims to provide compact information of the synthesis to the advanced applications of this material in various fields. Finally, this article covers the insights of future CMC research that could guide researchers working in this prominent field.

Activated carbon (AC) has been extensively utilized as an adsorbent over the past few decades. AC has widespread applications, including the removal of different contaminants from water and wastewater, and it is also being used in capacitors, battery electrodes, catalytic supports, and gas storage materials because of its specific characteristics e.g., high surface area with electrical properties. The production of AC from naturally occurring precursors (e.g., coal, biomass, coconut shell, sugarcane bagasse, and so on) is highly interesting in terms of the material applications in chemistry; however, recently much focus has been placed on the use of agricultural wastes (e.g., rice husk) to produce AC. Rice husk (RH) is an abundant as well as cheap material which can be converted into AC for various applications. Various pollutants such as textile dyes, organic contaminants, inorganic anions, pesticides, and heavy metals can be effectively removed by RH-derived AC. In addition, RH-derived AC has been applied in supercapacitors, electrodes for Li-ion batteries, catalytic support, and energy storage, among other uses. Cost-effective synthesis of AC can be an alternative for AC production. Therefore, this review mainly covers different synthetic routes and applications of AC produced from RH precursors. Different environmental, catalytic, and energy applications have been pinpointed. Furthermore, AC regeneration, desorption, and relevant environmental concerns have also been covered. Future scopes for further research and development activities are also discussed. Overall, it was found that RH-derived AC has great potential for different applications which can be further explored at real scales, i.e., for industrial applications in the future.

The kinetics of the forward and backward extraction of the title process have been investigated using a Lewis cell operated at 3 Hz and flux or (F) – method of data treatment. The dependences of (F) in the forward extraction on [Fe³⁺], [H₂A₂]_(o), pH, and [HSO₄ ⁻] are 1, 0.5, 1, and −1, respectively. The value of the forward extraction rate constant (k _f ) has been estimated to be 10^−7.37 kmol^3/2 m^−7/2 s⁻¹. The analysis of the experimentally found flux equation gives the following simple equation: F _f =10^0.13 [FeHSO₄ ²⁺] [A⁻], on considering the monomeric model of BTMPPA and the stability constants of Fe(III)‐HSO₄ ⁻ complexes. This indicates the following elementary reaction occurring in the aqueous film of the interface as rate determining: [FeHSO₄]²⁺+A⁻→[FeHSO₄.A]⁺. The very high activation energy of 91 kJ mol⁻¹ supports this chemical reaction step as rate-determining. The negative value of the entropy change of activation (−94 J mol⁻¹ K⁻¹) indicates that the slow chemical reaction step occurs via the S_N2 mechanism. The backward extraction rate can be expressed by the equation: F _b =10^−5.13 [[FeHSO₄A₂]]_(o) [H⁺] [H₂A₂]_(o) ^−0.5. An analysis of this equation leads to the following chemical reaction step as rate-determining: [FeHSO₄A₂]_(int)→[FeHSO₄A]+A_(i) ⁻. However, the activation energy of 24 kJ mol⁻¹ suggests that the backward extraction process is intermediate controlled with greater contribution of the diffusion of one or the other species as a slow process. The equilibrium constant obtained from the rate study matches well with that obtained from the equilibrium study.