Endang Tri Wahyuni

The growing prevalence of pharmaceutical contaminants, particularly amoxicillin (AMX), in aquatic environments poses serious threats to both ecosystems and public health. Addressing this issue requires the development of efficient photocatalysts capable of degrading such pollutants under visible-light irradiation. This study explores the enhanced photocatalytic degradation of AMX under visible light using copper and nitrogen co-doped titanium dioxide (TiO₂-Cu/N) synthesized utilizing copper recovered from electroplating wastewater. Comprehensive characterization through XRD, UV-Visible DRS, and TEM demonstrated that a Cu doping level of 0.60%, combined with 30% nitrogen co-doping and calcination at 500 °C, resulted in the most significant enhancement in photocatalytic activity under visible-light irradiation, attributed to the most effective bandgap narrowing. Notably, the TiO₂-Cu/N photocatalyst with optimized composition exhibited superior physicochemical properties and photocatalytic performance compared to its singly doped counterparts. The optimal condition of the AMX degradation was achieved using 100 mg of TiO₂-Cu/N to treat 100 mL of a 20 mg/L AMX solution at pH 6 under 2 h of visible-light irradiation, which was 90%. Furthermore, the Cu dopant in the TiO₂-Cu/N matrix remained stable during the photocatalytic process, as evidenced by the sustained activity even after three consecutive cycles. Additionally, the use of radical scavengers confirmed that hydroxyl radicals (•OH) were the predominant reactive species responsible for the degradation of amoxicillin. These findings highlight the promising potential of utilizing industrial wastewater as a dopant source for the sustainable development of high-performance photocatalysts in water treatment applications.

The growing need for sustainable nanomaterial production has driven research into more environmentally friendly synthesis methods. This study presents an innovative approach for the green synthesis of silver nanoparticles (AgNPs) by valorizing argentometric laboratory waste using Sandoricum koetjape (kecapi) fruit pericarp extract as a natural reducing agent. Unlike previous studies that separately investigated the chemical reduction of silver waste or plant-mediated reduction of AgNO₃, this work integrates both approaches. Initially, the synthesis of AgNPs from silver waste was optimized using response surface methodology with central composite design (RSM-CCD) to determine optimal reaction conditions. Then, a comparison was conducted on the resulting AgNP characteristics and performance with one synthesized from AgNO₃ under the same conditions. The optimized waste-derived AgNPs exhibited a crystallite size of 12 nm and an average particle size of 38.41 nm, along with a distinct surface plasmon resonance (SPR) peak at 420 nm, confirming their nanoscale formation. Comprehensive characterization by UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), XRD, TEM, and zeta potential analysis verified the nanoparticles' functionalization, stability, and crystallinity. In photocatalytic performance tests, the waste-derived AgNPs achieved 96% degradation of methylene blue, comparable to the AgNO₃-derived counterpart.

The development of photocatalysts with wastewater management has drawn the attention of many scientists. This research investigates the enhancement activity of TiO₂ photocatalyst codoped with N and Cu from urea and electroplating wastewater respectively as sources, for photodegradation of amoxicillin (AMX) residual in water media. The synthesis of codoped TiO₂ photocatalyst has been done through sol-gel process to determine the optimal concentration for each single dopant of Cu and N based on the highest band gap energy (E _g) narrowing and their performance in photodegradation of AMX. The synthesized photocatalysts are investigated by material characterization. The effect of the double dopants on the photocatalyst activity was examined through photodegradation of AMX. The optimum N and Cu dopant concentrations were 30 and 0.60 wt %, giving E _g values of 2.88 and 2.93 eV, respectively. This ratio is used to synthesize the codoping photocatalyst that significantly reduces E _g in 2.74 eV with AMX photodegradation reaching 95.76%. This dwindling of band gap energy in codoping photocatalyst could be widely applied in visible light exposure for the photodegradation of AMX having 20 mg/L in 50 mL over TiO₂-N,Cu (30:0.6 wt %) using 1 g/L of the photocatalyst dose, solution pH 5, and 120 min irradiation time.

This study investigates the feasibility of use electroplating wastewater as a source of copper (Cu) dopants to improve the photocatalytic efficacy of TiO ₂ under visible light for the disinfection of water contaminated with Escherichia coli . The Cu-doped TiO ₂ was produced by the sol-gel process, employing titanium tetra-isopropoxide (TTIP) and Cu(II) ions derived from wastewater. By modifying the concentration of Cu(II), TiO ₂ -Cu photocatalysts with differing copper concentrations were synthesized. The doping procedure substantially decreased the band gap of TiO ₂ , facilitating activation under visible light and markedly enhancing its photocatalytic efficacy. The ideal Cu doping concentration was determined to be 0.60 %, which decreased the band gap from 3.20 eV (pure TiO ₂ ) to 2.88 eV. Under visible light, the TiO ₂ -Cu (0.60 %) photocatalyst attained a remarkable 98.21 % reduction of E. coli after 30 min, in contrast to a mere 38.42 % reduction by undoped TiO ₂ . This study emphasizes the feasibility of using industrial wastewater to develop economical and effective TiO ₂ photocatalysts for water purification purposes.

This paper discusses the use of electroplating wastewater containing Cr and Cu as a single dopant source to improve the activity of TiO2 photocatalysts under visible light. Sol-gel doping was used to dop TiO2 with Cr and Cu in the wastewater. The doped TiO2 photocatalysts were characterized using SRUV/visible and XRD instruments, and their effect on the degradation of linear alkyl benzene sulphonate (LAS) in laundry wastewater was evaluated. The electroplating wastewater used in this research contains Cr and Cu about 2000 and 20 mg/L, respectively. These metals were successfully doped into a TiO2 structure, which significantly reduced the gap energy of TiO2, allowing it to be more active under visible light. The highest photodegradation of the 125 mg/L LAS in 25 mL of the laundry wastewater with pH 7 was achieved by using 30 mg of TiO2/Cr-Cu (200/2) photocatalyst, which degraded up to 60% of LAS in 60 min. With the same conditions, the LAS photodegradation increased to 100% upon the second run. This approach can help turn hazardous electroplating wastewater into a valuable material to solve environmental problems.