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Lead (Pb²⁺) is a hazardous heavy metal commonly found in industrial wastewater and poses serious risks to human health and the environment due to its toxic and non-biodegradable nature. Therefore, an effective and environmentally friendly treatment method is required to reduce Pb²⁺ concentration in wastewater. This study aimed to evaluate the effect of pH and initial Pb²⁺ concentration on the adsorption capacity of ramie leaf (Boehmeria nivea) bioadsorbent activated with NaOH. The adsorption process was conducted using a batch system with pH variations of 4, 5, and 7 and initial Pb²⁺ concentrations of 20, 25, and 30 mg/L. The residual Pb²⁺ concentration was analyzed using Atomic Absorption Spectrophotometry (AAS), and the adsorption performance was evaluated based on removal efficiency and adsorption capacity (Qe). The results showed that pH and initial Pb²⁺ concentration significantly affected the adsorption performance. The optimum adsorption condition was obtained at pH 5, with a maximum removal efficiency of 99.20% and a total adsorption capacity of 18.56 mg/g. The increase in pH from 4 to 5 enhanced adsorption performance due to reduced competition between H⁺ and Pb²⁺ ions for active sites on the adsorbent surface. Increasing the initial Pb²⁺ concentration tended to increase adsorption capacity, although removal efficiency remained relatively stable due to the limited number of active adsorption sites. The Relative Standard Deviation (RSD) values ranged from 1.56% to 3.37%, indicating good precision and repeatability of the experimental data. These findings demonstrate that NaOH-activated ramie leaves have considerable potential as an effective, low-cost, and environmentally friendly bioadsorbent for Pb²⁺ removal from wastewater.

Lead (Pb²⁺) contamination in wastewater is a major environmental concern due to its toxicity, persistence, and ability to accumulate in living organisms. Adsorption using biomass-based materials has been developed as an alternative treatment method because it is efficient, economical, and environmentally friendly. This study aimed to analyze the effect of bioadsorbent dosage and contact time on Pb²⁺ removal efficiency and evaluate Pb²⁺ mass distribution using mass balance analysis in a batch adsorption system. Ramie leaf (Boehmeria nivea) was utilized as a bioadsorbent due to its lignocellulosic content, which provides active sites for metal ion adsorption. The research was conducted experimentally through bioadsorbent preparation, chemical activation, and batch adsorption using artificial Pb²⁺ solutions with variations in bioadsorbent dosage and contact time. Pb²⁺ concentrations before and after adsorption were analyzed using Atomic Absorption Spectroscopy (AAS). The obtained data were used to determine removal efficiency and Pb²⁺ distribution between the liquid phase and bioadsorbent. The results showed that ramie leaf bioadsorbent effectively reduced Pb²⁺ concentration, with the optimum condition obtained at 4 g/L bioadsorbent dosage and 90 minutes contact time, achieving 98.46% removal efficiency. Mass balance analysis indicated that Pb²⁺ ions were successfully transferred from the solution phase onto the bioadsorbent surface. These findings demonstrate that ramie leaf bioadsorbent has potential as a sustainable alternative material for heavy metal removal in wastewater treatment.

Chili (Capsicum annuum L) ) is one of the most important horticultural commodities widely consumed in Indonesia and has high economic value. To maintain productivity and prevent pest attacks, farmers commonly apply chemical pesticides intensively. However, excessive and improper pesticide application can leave harmful residues on the surface and within the tissues of chili fruits. The accumulation of these residues not only poses health risks to consumers but also contributes to environmental pollution, particularly in wastewater generated from chili washing activities. This study aims to reduce pesticide residues of Cherizeb and Emacel in chili washing water using the photolysis methodassisted by a ZnO/zeolite catalyst. Zinc oxide (ZnO) acts as a photocatalyst activated by ultraviolet (UV) light to produce reactive hydroxyl radicals (•OH) capable of decomposing complex organic compounds into simpler compounds such as CO₂ and H₂O. Meanwhile, zeolite is used as a catalyst support due to its large surface area and high adsorption capacity, allowing adsorption and photocatalytic processes to occur simultaneously. The results showed that the photolysis method using the ZnO/zeolite catalyst significantly reduced pesticide residues, with optimum degradation efficiencies of 85.66% for Cherizeb using 0.8 g ZnO/zeolite under UV irradiation for 60 minutes, and 83.97% for Emacel using 0.8 g ZnO/zeolite under UV irradiation for 75 minutes. The samples were characterized using Fourier Transform Infrared Spectroscopy (FTIR) to identify functional groups, indicating the disappearance of specific organic functional groups. Pesticide residues on chili samples were analyzed using UV-Vis spectrophotometry to determine concentrations before and after treatment. X-Ray Diffraction (XRD) analysis confirmed that the crystalline structure of the catalyst remained stable after the photolysis process. Based on these findings, the ZnO/zeolite catalyst is proven to be effective in reducing pesticide residues through photocatalytic degradation and has the potential to be applied as a safe, efficient, and environmentally friendly post-harvest technology to improve the quality of agricultural products.

Human activities, from household to industrial operations, generate liquid waste that poses a threat to the environment. Before discharge, liquid waste should be treated to ensure it is safe for release into the environment. This study aims to evaluate the effectiveness of a hybrid ozonation-adsorption method with varying contact times. This study collected leachate samples from the Rajabasa Landfill and used fly ash from the Tarahan Coal-Fired Power Plant as the adsorbent. First, the study used contact times of 20, 40, 60, and 80 minutes for ozonation. Subsequently, the 80-minute sample proceeded to the adsorption stage and was ultimately tested against six parameters. The measured parameters included COD, TSS, TDS, turbidity, UV254, and DO. The results showed that the 80-minute ozonation process significantly reduced TSS, TDS, and DO levels. However, the ozonation process still left intermediate compounds, which were subsequently removed by adsorption. Ultimately, the combination of the two processes yields good results, particularly for COD and UV254. This aligns with the theory that ozonation breaks down complex compounds while the adsorbent absorbs residual pollutants. This hybrid process achieves a 45.47% reduction in COD and an 87.83% reduction in UV254.

Acid mine drainage (AMD) is characterized by low pH and high concentrations of heavy metals such as iron (Fe) and manganese (Mn) that exceed environmental quality standards, thus requiring effective treatment to prevent environmental pollution. This study aims to evaluate the ability of a mixture of activated carbon derived from pineapple leaves mixed with coal to increase pH and reduce Fe, Mn, and Total Suspended Solids (TSS) levels in acid mine drainage at PT Alreksa Bara Mitra. The process to make activated carbon involved preparation, carbonization, and activation processes on the pineapple leaves and coal separately. The following step is to mix but pineapple leaves and coal the has been activated. The treatment was conducted using an adsorption method with variations in adsorbent mass of 4 g, 8 g, and 12 g and a contact time of 30 minutes. The parameters analyzed included pH, Fe, Mn, and TSS before and after treatment, and the results were compared with the quality standards stipulated in Minister of Environment and Forestry Regulation No. 05/2022. The results showed that the characteristics of the activated carbon mixture met the SNI 06-3730-1995 standard. Increasing the adsorbent mass contributed to the rise in pH from 5.5 to near the acceptable range of 6–9 and significantly reduced Fe, Mn, and TSS concentrations below the permitted limits.The findings indicate that the mixture of pineapple leaf- and coal-based activated carbon is an effective, economical, and environmentally friendly alternative adsorbent for acid mine drainage treatment.