Chitosan as adsorbent has been used widely, however it was not effective yet for metal ions adsorption in industrial scale. In acidic condition, chitosan's active site tends to decrease. This drawback can was solved by coating of chitosan active site on alumina. This paper discloses to overcome that limitation. The charateristic of the active side was analysed by FTIR spectrometry toward vibration N-H group at 1679.15 cm-1 , C=O group of oxalate at 1703.30 cm-1 , and Al-O group of alumina at 924.07 cm-1. The adsorption capacity of the developed adsorbent was tester to adsorb Cr(VI) ions under various of pH value such as 1, 2, 3, 4, 5, 6, and 7. The contact time affect toward the adsorption was also reported in 20, 30, 40 50, 60, 70, and 80 minute. In addition, the concentration effects (100, 200, 300, 400, 500, and 600 ppm) was also studied. Chromium (VI) was measured using spectronic-20. Adsorption capacity was obtained at 66.90 mg/g under optimum conditions pH 2, and contact time 60 minute, respectively.

Textile sludge waste contains many organic matters so that it is potential to be used as mesoporous carbon precursor. Actived carbon with mesopore character is effective as adsorbent and catalyst carrier of large molecules. Synthesis of the activated mesoporous carbon was done with purpose to study influence of activation temperature toward characters of the carbon. Process of the synthesis involved dry sludge (50 g) as precursor, concentrated sodium silicate solution SiO2 24.5% and Na2O 7.5% (50 mL) as template source, 1 M HCl solution (50 mL) as polimering agent, carbonization condition at 600 °C 3 h under nitrogen gas flow, activation conditions with NaOH 50% and various temperatures (400, 500, 600, 700, and 800 °C), and demineralizatin conditions with 0.1 M HCl solution for 4 h and 125 rpm. All of the products were characterized with methylen blue method to determine specific pore volume and specific surface area. The carbon obtained at optimum temperature was characterized again with surface area analyzer. Result of the research showed that the optimum condition was achieved at activation temperature of 500 °C. Characters of the synthesized carbon at the optimum condition were specific surface area of 638.32 m2/g, specific pore volume of 0.35 cm3/g, average pore diameter of 21.78 Å, and methylene blue number of 358.87 mg/g.   Keywords: actived mesoporous carbon, textile sludge, temperature

Laterite soil is one of natural resources in East Kotawaringin regency, Central Kalimantan, Indonesia, which contains high element of Fe. Fe is one of micronutrients that is needed for plant in slight amount. This study aims to determine the effect of chitosan composition and composition of zeolite : laterite on the release of Fe activities from synthesized fertilizers result. Laterite is characterized by using XRF and XRD. Slow release iron fertilizer is synthesized by eliciting laterite to zeolite matrix. Then, It is stirred into chitosan gel with concentration of 2, 2.6, and 2.8 % for 30 minutes. After Zeolite - laterite - chitosan has been homogenized, then it is dropped into 0.4 M NaOH to form beads. Then testing the release of Fe with the batch method in distilled water. The result showed that the laterite soil is amorphous form, and Fe content reached 80.25 % . The higher the concentration of chitosan which is used , then more Fe is released from fertilizer. Whereas if the amount of zeolite is greater, the slower the release of Fe will be.

One techniques to reduce the concentration of heavy metal Cd(II) in aqueous solution is adsorption by chitosan. To modify the surface textures and expose the active binding sites, composite biosorbent has been prepared by coating chitosan onto alumina. The aims of this research were to identify the functional group of chitosan-alumina, to characterize adsorption of Cd(II) by using chitosan-alumina adsorbent including optimum pH, optimum agitation time, and to determine the adsorption capacity of the adsorbent. The functional group of chitosan-alumina was identified by infrared spectrophotometer. Determination of the optimum condition was carried out at 40 ppm Cd(II), 125 rpm and 0,1 g adsorbent. Calculation of adsorpted Cd(II) based on its concentration in aqueous phase before and after adsorption process. The concentrations of Cd(II) in aqueous phase after adsorption process  were determined by using Atomic Absorption Spectroscopy (AAS). Identified functional groups of chitosan-alumina were -OH (3466.39 cm-1), -NH amine (1625.15 cm-1), C=O (1703.30 cm-1), and Al-O (1302.07 cm-1). The optimum pH was reached at pH 7, optimum agitation time at 15 minutes, and adsorption capacity of chitosan-alumina was 15.35 ± 0.05 mg/g.   Keywords: adsorption, chitosan-alumina, characterization of adsorption

Study of dyes adsorption (rhodamine B, methylene blue and carmine) carried out by using mesoporous carbon synthesized at various carbonization time. The purpose of this research was to understand influence of carbonization time to performance of the mesoporous carbon in dyes adsorption. In addition, adsorption performance of the mesoporous carbon and commercial carbon were compared. The adsorption test were conducted at conditions: 0.1 g of adsorbent, 25 mL of dyes solutions 100 ppm and shaking rate 125 rpm for 4 hour. Filtrate was used to determine remain concentration of the dyes with UV-visible spectrophotometry. Result of the research showed that the carbonization time from 1 to 3 hours improved the adsorption, whereas from 3 to 5 hours decreased it. The best character of the mesoporous carbon obtained at carbonization time of 3 hours with adsorption values of 96.43 ± 0.37 % for rhodamine-B, 38.80 ± 1.44 % for methylene blue and 48.51 ± 1.55 % for carmine. The adsorption values of the mesoporous carbon were 0.97 times for rhodamine B, 0.48 times for carmine, and 0.39 times for methylene blue compared with the commercial activated carbon.