In the present study, we developed a new adsorbent product with zeolite crosslinked chitosan (ZL–CH hydrogel) to remove acid red 88 (AR88) in an aqueous solution. The effects of several factors, such as the comparison of ZL–CH hydrogel and the absence of chitosan, pH, adsorbent dosage, initial AR88 concentration, contact time, and ion strength, were determined. Obtained results showed that ZL–CH hydrogel improved AR88 removal compared to the absence of chitosan, with an adsorption capacity of 332.48 mg/g in equilibrium time of 1 min, and adding ionic strength had no significant effect. However, with optimal conditions at pH 2.0, dry ZL–CH became hydrogel due to protonation of amino and hydroxyl groups through hydrogen bonds in the AR88 solution. Volume fraction and interaction force decreased with increasing porosity, leading to an increase in adsorption capacity and swelling ratio. Experimental data of the adsorption process showed the Freundlich isotherm model. The equilibrium for adsorption and swelling kinetics studies showed and fitted a pseudo-second-order model. NaOH was successful as a desorbing agent with 93.8%, and it followed the pseudo-second-order kinetics model. The recycling process indicates great potential for AR88 removal.

To address Cu(II) and Cr(VI) water pollution, a carbonized zeolite/chitosan (C-ZLCH) composite adsorbent was produced via pyrolysis at 500 °C for two hours. C-ZLCH was characterized using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and zeta potential measurements. The batch experiments were performed by varying the initial pH, concentration, and contact time. The optimal pH values for Cu(II) and Cr(VI) were 8.1 and 9.6, respectively. The highest adsorption capacities for Cu(II) and Cr(VI) were 111.35 mg/g at 60 min and 104.75 mg/g at 90 min, respectively. The effects of chemicals such as sodium (Na+), glucose, ammonium (NH4+), and acid red 88 (AR88) were also studied. Statistical analysis showed that sodium had no significant effect on Cu(II) removal, in contrast to Cr(VI) removal. However, there was a significant effect of the presence of glucose, ammonium, and AR88 on both Cu(II) and Cr(VI) removal. The adsorption isotherm and kinetic models were fitted using Langmuir and pseudo-second-order models for Cu(II) and Cr(VI), respectively.

In the present study, alkaline-treated zeolite/chitosan/Fe3+ (ZLCH-Fe) composites were prepared and analyzed using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and pH of zero point of charge (pHzpc) to remove nitrates from water. The process was carried out using an adsorption method with a varied initial pH, adsorbent dosage, initial nitrate concentration and contact time. The pHzpc demonstrated that the ZLCH-Fe surface had a positive charge between 2 and 10, making it easier to capture the negative charge of nitrate. However, the optimal pH value is 7. After 270 min, the maximum adsorption capacity and percent removal reached 498 mg/g and 99.64%, respectively. Freundlich and pseudo-second-order were fitted to the adsorption isotherm and kinetic models, respectively. An evaluation was conducted on the effects of anions—SO42− and PO43−—and dyes—methylene blue (MB) and acid red 88 (AR88)—upon nitrate removal. The results indicated that the effect of the anion could be inhibited, in contrast to dye effects. However, the optimal pH values were changed to 10 for MB and 2 for AR88, resulting in a hydrogel formation. This might be indicated by the protonation of hydroxyl and amino groups resulting from a chitosan nitrate reaction in the AR88 solution.

Spent Coffee Ground (SCG) is characterized by high organic content, in the form of insoluble polysaccharides bound and phenol compounds. Phenol compounds are toxic to nature and are a cause of environmental pollution. Composting method of this study is aerobic static batch composting with temperature control with adding activators of some fungi such as Aspergillus sp, and Penicillium sp. The purpose of the research is to fill the research gap from previous studies of spent coffee grounds compost, which requires a long time in composting, so that if it is used directly on the soil and plants, the positive effect also requires a long time. The result of composting for 28 days with this method is that mature compost has black crumb and normal pH, with characteristics of C/N ratio below 10: C1 (7.06), C2 (6.99). This value is far from the control with a C/N ratio of 8.33. Decompose rate of macromolecule are above 40% for lignin and 70% for cellulose. Implementation of compost in radish plants, resulting Germination Index above 80% which indicates that the compost is ripe: control (92.39%), C1 (183.88%), C2 (191.86%). The results of the analysis with FTIR also showed that the compost was mature and stable, and rich in minerals. So, it can be concluded that this composting method can speed up composting time and optimize the results of compost produced.

Developing innovative technology for removing methylene blue (MB) from water is essential since the widespread discharge of MB from industrial effluents causes problems for humans and the environment. In this study, we conducted the adsorption method, a simple technique that utilizes an adsorbent. Chitosan is cross-linked with zeolite as a promising adsorbent material and environmentally friendly. For the characterization, FTIR, SEM-EDS, DLS, and pHzpc were analyzed. It was discovered that the removal percentage reached 97% with an adsorption capacity of 242.51 mg/g for 60 minutes at pH 10. The adsorption isotherm and kinetic model were investigated. As a result, the Freundlich model and pseudo-second-order model were fitted to the adsorption process. Moreover, the effect of other ions was investigated for 5 minutes of mixing time. The results showed that the removal percentage increased in the presence of H2O2 ion. Contrary to sodium chloride, glucose, and citric acid ions, the effectiveness of H2SO4 as a desorbing agent was 99.65% for 30 minutes at 45°C.