FTIR spectroscopy of adsorbed probe molecules has been existent for some decades and well-developed technique for analysis the composition and structure of the functional groups. In this research, we studied the surface structure of functional groups on modified kaolinite using pyridine. Modified kaolinite is made by a simple process, impregnation metakaolinite with zinc chloride and characterized by SEM-EDX and thermal gravimetric analysis. Zinc as a Lewis acid site is identified on modified kaolinite at 1449 cm⁻¹.

Penelitian mengenai TiO2 sebagai fotokatalis telah banyak menarik perhatian para peneliti, khususnya pada sifat optik dan kereaktifannya yang baik sehingga umum digunakan dalam pengolahan limbah maupun sebagai material dalam proses degradasi limbah organik di perairan. Karakteristik fotokatalis TiO2 berkaitan pada kemampuan material tersebut dalam meningkatkan laju reaksi kimia dengan bantuan cahaya. Sintesis TiO2 menggunakan metode sol-gel pada penelitian ini menghasilkan padatan yang memiliki fase anatase berukuran 18,25 nm dengan puncak difraksi yang khas, yakni 2θ = 25,3; 37,8; 48; 53,8; dan 62,7° berdasarkan karakterisasi XRD. Hasil analisis dengan instrumen DRS UV-Vis menunjukkan bahwa TiO2 memiliki energi celah pita sebesar 3,08 eV yakni setara dengan panjang gelombang 402 nm. Aktivitas fotokatalitik TiO2 diketahui berdasarkan prosedur degradasi dengan bantuan sinar tampak menggunakan zat warna metilen biru sebagai larutan uji. Hasil yang diperoleh menunjukkan bahwa fotokatalis TiO2 dapat menurunkan konsentrasi metilen biru dengan efisiensi degradasi mencapai 9% selama 125 menit.

Hard water can form deposits (scale) on pipe walls and operating units in industrial machines. One way to soften hard water is by using adsorbents to reduce the number of ions causing hardness, one of which is Mg²⁺. Kaolin is a natural mineral which has potential as an adsorbent. The ability of kaolin as an adsorbent can be enhanced utilizing activation. In this study, kaolin was chemically activated using HCl solution with varying concentrations, namely 4, 5, and 6 M. The activation was carried out by stirring kaolin with the activator solution for 24 hours. The adsorbent characterization was performed by the infrared spectrophotometer (FTIR) and the gravimetric method. The adsorption test for Mg²⁺ by activated kaolin was determined by adding 1g of adsorbent to 25 mL of 10 ppm Mg²⁺ solution with stirring rate 150 rpm. Furthermore, the adsorption contact time was varied, namely 30, 90, 150, and 180 minutes. The concentration of Mg²⁺was determined by a titration method using ethylenediaminetetraacetate (EDTA). The percentage of Mg²⁺ adsorbed was calculated as the concentration of Mg²⁺ adsorbed against the initial concentration. The results showed that kaolin activated by 6 M HCl could adsorb 68.9% of Mg²⁺ at the optimum contact time of 150 minutes. Activation of kaolin with HCl 6M can release organic impurities present in natural kaolin, which is thought to affect increasing its adsorption capacity for Mg²⁺.

Karbon aktif merupakan salah satu adsorben yang dapat dikompositkan dengan besi oksida menjadi karbon aktif magnetik (KAM) sehingga mempermudah proses pemisahannya dari dalam larutan. Penelitian ini menjelaskan kinerja KAM dalam mengadsorpsi anilin dengan menentukan isoterm dan kinetika adsorpsinya serta efektifitas sifat magnet dalam pemisahan KAM. Karbon aktif magnetik dibuat dari cangkang kelapa sawit dikarbonisasi (300 ºC, 2 jam), diaktivasi fisika (600 ºC, 30 menit), dan dilanjutkan aktivasi kimia (ZnCl2 0,05 M). Karbon aktif magnetik dibuat dengan mencampurkan karbon aktif dan larutan Fe(III)/Fe(II) (rasio mol 2:1). Pengukuran daya serap adsorpsi menggunakan variasi konsentrasi anilin (25, 50, 75, 100, dan 125 ppm) dan waktu kontak (60, 120, 180, 240, dan 300 menit). Adsorben KAM dikarakterisasi menggunakan spektrofotometer infra merah (FTIR), difraktometer sinar-X (XRD), fluoresensi sinar-X (XRF), Surface Area Analysis (SAA) dan konsentrasi anilin diukur dengan spektrofotometer UV-Vis. Hasil analisis FTIR menunjukkan munculnya serapan Fe-O pada bilangan gelombang 580,32 cm-1 yang mengindikasikan adanya besi oksida pada KAM. Difraktogram XRD menunjukkan puncak pada 2θ 18,39º; 34,09º; 34,82º; 35,03º; dan 35,87º dari magnetit Fe3O4, puncak 2θ 32,83º; 35,77º; dan 38,18º dari hematit. Hasil SAA menunjukkan luas permukaan KAM 179,40 m2/g, diameter rata-rata pori 24,95 Å dan XRF menunjukkan adanya kandungan Fe2O3 pada KAMsebesar 76,316%. Kapasitas adsorpsi optimum diperoleh pada konsentrasi anilin 100 ppm dengan waktu kontak selama 240 menit sebesar 86,254 mg/g. Kinetika adsorpsi sesuai dengan model pseudo-orde dua (R2 sebesar 0,9934) dengan konstanta kinetika 0,0073 g/(mg.menit).Aniline Adsorption by Oil Palm Shell Magnetic Activated Carbon. Activated carbon is one of the adsorbents that can be composted with iron oxide into magnetic activated carbon (KAM), making it easier to separate from the waste solution. This research investigated the KAM's performance in absorbing aniline by determining its adsorption isotherms and kinetics as well as the effectiveness of magnetic properties in KAM separation. Magnetic activated carbon was produced by oil palm shells carbonization at (300 ºC, 2 hours), followed by physical activation (600 ºC, 30 minutes), and continued by chemical activation (ZnCl2 0.05 M). Magnetic activated carbon was made by mixing activated carbon and Fe(III)/Fe(II) solution (mole ratio 2:1). Adsorption measurements use variations in aniline concentrations (25, 50, 75, 100, and 125 ppm) and contact times (60, 120, 180, 240, and 300 minutes). KAM adsorbents were characterized using infrared spectrophotometers (FTIR), X-ray diffractometers (XRD), X-ray fluorescence (XRF), and surface area analysis (SAA). Meanwhile, the adsorbed aniline concentrations were measured by UV-Vis spectrophotometers. The results of the FTIR analysis showed the appearance of Fe–O absorption in wavenumbers 580.32 cm-1 indicating the presence of iron oxide in KAM. XRD diffractogram shows peaks at 2θ 18.39º; 34.09º; 34.82º; 35.03º; and 35.87º of Fe3O4 magnetite, and peaks 2θ 32.83º; 35.77º; and 38.18º from hematite. SAA results showed a surface area of KAM of 179.40 m2/g and an average pore diameter of 24.95 Å. XRF showed the presence of Fe2O3 content in KAM of 76.316%. An optimum adsorption capacity of 86.254 mg/g was obtained at an aniline concentration of 100 ppm with a contact time of 240 minutes. Adsorption kinetics correspond to the second-order pseudo-model (R2 of 0.9934) with a kinetic constant of 0.0073 g/(mg.min).

Many organic dyes from natural extracts have been applied in dye-sensitized solar cells (DSCs) and reported in [1]-[8]. The natural dyes are obtained by purification from fruits, flowers, and leaves of plants. So far, the natural dyes give conversion efficiencies from 0.2%-7.6%. Thus, structure modification of the natural dyes promises to improve the efficiencies.

The increasing number of laundry businesses in Pontianak causes increased laundry waste, which is dangerous for health and the environment because anionic surfactants such as Linear Alkylbenzene Sulfonate (LAS) are hard degradable. Photocatalyst is a method that can be used to degrade the LAS structure. TiO2 carried in coconut fiber can optimize sunlight irradiation in degrading LAS content when light reaches the water's surface. This study aims to determine the characteristics and optimum activity time of photocatalyst TiO2-coconut fiber in degrading LAS. Photocatalyst characterization was carried out using XRD, XRF, and DR-UV, while the optimum activity test of photocatalysts in degrading LAS was carried out using a UV-Vis spectrophotometer. XRD diffractogram analysis showed the peaks of coconut fiber at 2θ = 22.2º, 34.8º and TiO2 at 2θ = 25.3º, 37.8º, 48.1º, 55.1º, and 62.1º. The TiO2 attached to the fiber after being synthesized was 21.12%. The band gap of TiO2 and TiO2-coconut fiber is 3.21 and 3.18 eV, with light absorption at 386.5 and 390.3 nm. Photocatalyst was carried out in LAS with a mass ratio of TiO2 and coconut fiber of 20:80; 30:70; 40:60, and 50:50 w/w with a time range of 0, 30, 60, 90, and 120 minutes. The results of photocatalysis of TiO2-coconut fiber in a ratio of 20:80 w/w showed the optimum photocatalytic activity at 120 minutes with the highest degradation rate of 80.43%. This research is expected to be applied as an alternative to handling LAS in laundry industry waste.