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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.

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.

The evaluation of haul road geometry at PT Trubaindo Coal Mining was conducted to ensure that the haul road from the stockroom to the jetty meets applicable technical standards, thereby supporting the smoothness, safety, and efficiency of coal transportation activities. This study aims to analyze the conformity of haul road geometric parameters, including straight road width, curve width, curve radius, cross slope, longitudinal grade, and superelevation, based on the standards of AASHTO 7th Edition and Kepmen 1827 of 2018. The research method employed field measurements using a Terrestrial Laser Scanner (TLS), followed by data processing using Maptek and Surpac software. The obtained data were then compared with the applicable standards to determine the level of conformity of the haul road geometry. Based on field measurements, the average values obtained were 14.99 m for straight road width, 18.45 m for curve width, 0.22 m for cross slope, 6.97% for grade, 223.51 m for curve radius, and 1.40 m for superelevation. Furthermore, based on calculations and analysis referring to AASHTO 7th Edition and Kepmen 1827 of 2018, and considering the largest haulage equipment used (Volvo FMX 480), the ideal haul road geometry values were determined as follows: 13 m for straight road width, 17 m for curve width, 124 m for curve radius, 0.26 m for cross slope, 1 m for superelevation, and 6% for grade based on PT Trubaindo Coal Mining standards.

Jamu is a traditional medicine still widely consumed by the public, but it has the potential to be contaminated with the heavy metals lead (Pb) and cadmium (Cd), which are toxic and can cause health problems, particularly to the liver and kidneys. Heavy metal contamination can originate from raw materials grown in polluted environments and from processing, storage, and packaging that do not meet quality standards, particularly for products that have not undergone official supervision. This study aims to analyze the content of lead and cadmium metals in registered and unregistered herbal medicine products. The analysis was carried out using the Atomic Absorption Spectrophotometry (AAS) method after sample preparation through wet digestion using strong acid. Six herbal medicine dosage forms were analyzed, namely powder, chopped, pills, capsules, cream, and shake parem. Method validation included tests for linearity, precision, limit of detection, and limit of quantification to ensure the reliability of the analysis results. The results showed that all registered herbal medicine samples met the safety requirements for Pb and Cd. In contrast, several unregistered herbal medicine preparations, especially powder, chopped, and cream, did not meet the safety requirements for Cd, while the Pb levels in all samples met the safety requirements for Pb. These findings indicate that unregistered herbal medicines carry a higher risk of heavy metal contamination. Therefore, strengthening quality control, selecting safe raw materials, and increasing compliance with regulations are necessary to ensure the safety of herbal medicine consumption and protect public health.

Bintan Island has abundant bauxite soil resources; however, its utilization as road construction material remains limited. The scarcity of high-quality granular material in the region necessitates the use of available local resources, particularly for pavement subgrade layers. This article aims to analyze the classification and mechanical properties of native soils in Bintan Island through a systematic literature review. The reviewed literature includes laboratory test results of bauxite soil. The findings indicate that bauxite soil exhibits low plasticity, relatively high CBR values (±35%), and is classified as CL (USCS) and A-2-4 (AASHTO). These results suggest that bauxite soil is suitable for subgrade applications, although require stabilization with binding agents. The implication of this review highlights that the utilization of local materials could support sustainable infrastructure development in island regions by reducing dependency on imported materials.