In the context of the circular economy, used coffee grounds were transformed into powdered activated carbon by chemical activation using potassium hydroxide. Its characterisation was conducted in comparison with that of a commercial activated carbon by scanning electron microscopy (SEM) coupled with energy dispersive X-ray microanalysis (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Boehm titration, and point zero charge (pH_PZC) and by determination of the methylene blue number (MBN) and the iodine number (IN). Performance of the prepared activated carbon was tested in the adsorption of the cationic dye crystal violet (CV) and hexavalent chromium. Batch adsorption tests were carried out and the effects of operating parameters were studied. The results collected on the adsorption kinetics show that the adsorption followed pseudo-second order kinetics and that the Langmuir isotherm best fits the equilibrium data for crystal violet and hexavalent chromium. The thermodynamic study showed that the adsorption of both adsorbates is spontaneous and exothermic and leads to a decrease in disorder at the solid–liquid interfaces. These results indicate that this activated carbon can be used as an alternative adsorbent to remove cationic dyes and heavy metals from aqueous solutions.

Nitrogen deficiency frequently occurs at agricultural soil because of NH₃ volatilization to the environment which results in low urea-N use efficiency by rice plants. A pot experiment was conducted to assess the synergistic effects of a mixture of rice straw and rice husk biochars (RSRH) on (1) total N, soil exchangeable NH₄⁺, and available NO₃⁻, and (2) uptake of N, P, and K in rice plant. RSRH biochar at 5 and 10 t ha⁻¹ had significantly minimized ammonia volatilization by 33.5% and 40.7%. Further, RSRH biochars also had significantly increased available NH₄⁺, NO₃⁻, available P, and available K in the soil over T1. In line to increase in soil nutrient availability, the rice plant height, tiller number, greenness, and panicle number were increased. This resulted in an increase of nutrient uptake, use efficiency, and dry matter production of the rice plant. RSRH biochar altered the soil environment by minimizing NH₃ loss and increasing soil nutrients for efficient plant uptake.

MATEC Web of Conferences, open access proceedings in Materials science, Engineering and Chemistry

The accessibility of safe drinking water is a fundamental element of Sustainable Development Goal 6 (SDG 6). A novel nanomagnetic biocarbon composite (NBC) has been developed utilising coconut shells for purifying raw groundwater. One of the primary concerns associated with groundwater is turbidity, a condition resulting from the presence of clay, dirt, and silt particles. The presence of turbidity in untreated water has a significant effect on both the visual appeal and overall cleanliness of the water. For the purposes of comparison, commercialised activated carbon (CAC) was utilised in this study. According to the Brunauer-Emmett-Teller (BET) analysis, it was observed that the average pore diameter of NBC was smaller compared to commercially available activated carbon (CAC), despite having a higher BET surface (SBET) value of 916.189 m/g compared to CAC. Based on the results of the kinetic study, it was determined that intraparticle diffusion, specifically external film diffusion, exhibited the most suitable fit as the kinetic model for NBC and CAC. This conclusion was supported by the lowest root mean square error (RMSE) values obtained, which were 0.04 for NBC and 0.13 for CAC, surpassing the performance of alternative models. The diffusion coefficient (Di) values for NBC (7.40 x 10–15 cm2/s) and CAC (7.80 x 10–15 cm2/s) demonstrated the phenomenon of bulk diffusion from high to low concentration. Notably, the diffusion coefficient for NBC was found to be lower than that for CAC. Accordingly, it is suggested that average pore diameter played important roles in intraparticle diffusion of an absorbent.

Waterproof makeup has an everlasting effect, but difficult to remove and the residues can cause irritation and skin breakout. The use of oil-based makeup remover leaves the skin oily and requires further cleansing. Personal care and cosmetic industries evolve over time with new products coming into the growing market. This is often accompanied by thematic play such as nature inspired and more recently waterless beauty. This paper characterizes the inclusion of a surface modified new biocarbon composite (NBC) in formulating waterless masker that can cleanse, scrub, and at the same time be eco-friendly towards environmental sustainability. The parameters that influence the removal of makeup foundation (MF) up to 88.07% by NBC were determined through Box-Behnken experimental approach, i.e., adsorbent dosage (0.028 g), MF concentration (up to 300 mg/L), particle size (151-300 µm), and contact time (15 min). The kinetic model obeyed the pseudo second-order reaction (R²= 0.9993). New peaks were observed in the FTIR spectra of NBC that was subjected to makeup removal. The best NBC infused waterless masker formulation (S10) displayed acceptable pH (5-7), stable odour, colour, and texture properties, was easily rinseable, and gentle on the skin. Microbial growth was not observed after 2 weeks storage at room temperature. Less effort was needed for removing makeup as the number of rubs were reduced by 52-58% in comparison to just water, and commercial water-based charcoal face masker. Incorporation of NBC into various personal care product formulation such as cleansing balm, clay mask, face scrub, and shampoo can raise the competitiveness of local product line.