Correlation between cocoa shell modifications by CTAB and its dye adsorption properties.

Cocoa shell was modified whit sodium hydroxide (NaOH) and cationic surfactant cetyltrimethylammonium bromide (CTAB) to increase surface functionality, surface area, and positive charge density. The prepared adsorbent CC-OH-CTAB was used to remove indigo carmine (IC) and bromocresol green (BCG) dyes from water. The optimal pH for IC and BCG adsorption were 2 and 4, respectively. The equilibrium was attained after a contact time of 30 min for IC and 120 min for BCG. The maximum adsorption capacity (Qmax) of IC and BCG obtained was 85.1 mg g-1 and 192.7 mg g-1, respectively. The Liu isotherm model best described the equilibrium results. The adsorption kinetics model showed that IC and BCG adsorption onto CC-OH-CTAB followed the pseudo-first-order and pseudo-second-order model, respectively. The regeneration and reusability experiments indicated that CC-OH-CTAB had much stability and excellent performance meanwhile repeatedly used. Finally, the insertion of CTAB on the CC-OH surface proved to be an excellent way to improve the adsorption performance of this material concerning dyes.

Herbs carbonization and activation for fast sorption of nitrate ions: a new challenge for a full treatment of groundwater pollution.

The evolution of low-cost ecotechnologies in water treatment and purification is highly increased. Face to the growing global demand for eco-friendly water treatment materials, the non-valorized herb-based biomass covering a large area could be a promising alternative. Herbs (HB) are currently one of the cheapest biomasses. Therefore, the utilization of HB for environmental applications is relevant. HB was treated and activated in this work to produce an eco-friendly adsorbent for nitrate removal from groundwater. HB was treated with modified carbonization at 220 °C to produce highly reactive biochar (BCH). Ammonium groups (AM) are immobilized covalently over the BCH surface, and then, the resulting materials BCH-AM are fully characterized. Results showed that ammonium is successfully grafted at the BCH surface, producing a highly stable material. Measurements on nitrate ion adsorption revealed that BCH-AM are of great interest as 80% of nitrate ions (NO3-) were removed. Importantly, the eco-friendly BCH-AM demonstrated the ability to easily desorb the nitrate ions using Na2CO3 as a green eluent. Parametric studies confirmed the effectiveness of the prepared adsorbent and approved that the adsorption occurred by electrostatic interactions. To demonstrate the performance of the adsorbent, BCH-AM was evaluated to remove NO3- from groundwater upstream in a water treatment plant. This work opens an immense perspective for herb biomass to be the actual challenge to resolve environmental problems.

Removal of Cu(II) from aqueous solution using a composite made from cocoa cortex and sodium alginate.

The aim of this work was to prepare a composite material based on cocoa cortex and sodium alginate and test it to remove Cu(II) ions in aqueous solution in batch conditions. The composite was characterized using elemental analysis, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTG), and point of zero charge. The highest amount of adsorbed Cu(II) for the composite was 19.54 mg/g, i.e., 95.32% of an initial concentration of 100 mg/L. Under the same conditions, the cocoa cortex untreated exhibited extremely low adsorption, while when it was treated with hot soda, it adsorbed 13.67 mg/g. Adsorption by the composite reached the equilibrium after 220 min. Kinetic data analysis suggested that the process was governed by adsorption (pseudo-second-order model) and diffusion through macropores and/or mesopores (intra-particle model). The adsorption isotherm that best described the system was Langmuir's. The maximum adsorption capacity of Cu(II) was 76.92 mg/g. The values of the thermodynamic parameters indicated that the process was spontaneous, with ΔG° values between (- 7.886 and - 9.458 kJ/mol) and endothermic, with ΔH° = 7.728 kJ/mol. Graphical abstract.

Chemical modification of the cocoa shell surface using diazonium salts.

The outer portion of the cocoa bean, also known as cocoa husk or cocoa shell (CS), is an agrowaste material from the cocoa industry. Even though raw CS is used as food additive, garden mulch, and soil conditioner or even burnt for fuel, this biomass material has hardly ever been investigated for further modification. This article proposes a strategy of chemical modification of cocoa shell to add value to this natural material. The study investigates the grafting of aryl diazonium salt on cocoa shell. Different diazonium salts were grafted on the shell surface and characterized by infrared spectroscopy and scanning electronic microscopy imaging. Strategies were developed to demonstrate the spontaneous grafting of aryl diazonium salt on cocoa shell and to elucidate that lignin is mainly involved in immobilizing the phenyl layer.