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This research has been conducted on process of production activated carbon from coconut shells, which are activated both physics and chemistry to improve the adsorption of methylene blue. The process of physical activation was done by burning the coconut shell using a furnace at a temperature of 700°C. The chemical activation was done using H3PO4 activator. The result of activated carbon physical activation (CAP) has a greater absorbency than activated carbon chemical activation (CAC) with each of the absorption of methylene blue at 99.42 and 98.64%. Analysis of surface morphology on the adsorbent was performed using a Scanning Electron Microscope (SEM). SEM results indicated that (CAP) has a surface morphology that is relatively similar to commercial activated carbon (CACm). Adsorption test was conducted on the determination of the optimum pH, adsorption rate, and isotherm adsorption of methylene blue. The results of the optimum pH on CAC, CAP, and CACm respectively obtained at pH 8 and the optimum contact time is obtained respectively at 40, 60, and 80 minutes. Adsorption kinetics data of methylene blue on CACm, CAP, and CAC tend to follow the pseudo second order kinetics with a correlation coefficient (R2) is 0.937; 0.950; and 0.999, respectively. Adsorption isotherm of methylene blue on CACm, CAP, and CAC tend to follow the model of Freundlich isotherms.

Algae-silica (AS) hybrid material from biomass Porphyridium sp. has been modified by coating Fe 3 O 4 particles (MPs) via a sol-gel process using tetraethyl orthosilicate to produce algae-silica-Fe 3 O 4 (AS-MPs). The AS-MPs produced were applied as adsorbent for the adsorption of methylene blue (MB). Identification of functional groups was performed by infrared spectrometer indicating that in AS-MPs there were active organic groups derived from Porphyridium sp., silanol and siloxane. Diffraction pattern of the AS-MP material analyzed by X-ray diffraction showed that the material showed that the average particle size distribution of the AS-MP material was 1.40 µm. In addition to the results of the analysis using scanning electron microscopy, material of AS-MPs has a more heterogeneous surface morphology. The models of MB adsorption by AS and AS-MP tend to follow the pseudo-second-order kinetic model and Freundlich adsorption isotherm. The adsorption of MB solution by AS-MP produces rate constants (k 2 ) of 0.003 g mg -1 min and adsorption capacity (q m ) of 96.927 mg g -1 under the experimental conditions of dose of adsorbent of 2.5 mg L -1 , interaction pH of this study can be used as an effective adsorbent because it can remove MB dyestuff in solution, it is chemically stable in acidic and neutral media, and it can be used repeatedly.

Modification of silica gel with 3-aminopropyltrimethoxysilane and 3-mercaptopropyltrimethoxysilane through sol-gel technique producing amino-silica hybrid (HAS) and mercapto-silica hybrid (HMS), respectively, has been carried out using tetraethylorthosilicate (TEOS) as silica source. The adsorbents were characterized using infrared spectroscopy (IR), and X-ray energy dispersion spectroscopy (EDX). Adsorption of Cd(II) individually as well as its binary mixture with Ni(II), Cu(II), and Zn(II) in solution was performed in a batch system. Adsorption capacities of Cd(II) ion on adsorbent of silica gel (SG), HAS, and HMS are 86.7, 256.4 and 319.5 μmol/g with the adsorption energies are 24.60, 22.61 and 23.15 kJ/mol, respectively. Selectivity coefficient (α) of Cd(II) ion toward combination of Cd(II)/Ni(II), Cd(II)/Cu(II), and Cd(II)/Zn(II) ions on HAS adsorbent is relatively smaller than those on HMS adsorbent which has α > 1.   Keywords: adsorption, amino-silica hybrid, mercapto-silica